JP4113654B2 - Laser ultrasonic inspection equipment - Google Patents

Description

の時間間隔を有する時間ゲート４９を信号処理装置１４に設けておけば、他のモードに干渉されることなく所望の信号を観察することが可能となる。
【０１０５】
このように本実施形態では、信号処理手段１４において、発生した超音波のうち被検査材３の表面を伝播する表面波成分、内部に伝播する縦波成分または横波成分を抽出し、その情報から被検査材３表面、内部および裏面におけるき裂の有無、き裂の寸法および表面波、被検査材の厚さ、裏面状態および縦波または横波の伝播現象を表示および記録するようにしたものである。
【０１０６】
［第１０実施形態］
図１６は本発明に係るレーザ超音波検査装置の第１０実施形態を示すブロック構成図、図１７は第１０実施形態においてウェーブレット変換を用いた信号処理を示す説明図である。
【０１０７】
受信用光学系５と光検出器１３で検出された超音波信号は、場合によって、例えば外乱ノイズであるとか、あるいは光検出器１３や信号処理装置１４で発生するノイズなどでＳ／Ｎ比が良好に得られない場合がある。
【０１０８】
その際、本実施形態のように信号処理装置１４内にＳ／Ｎ比改善手段５０を設置しておくことで、良好な信号観察が可能となる。Ｓ／Ｎ比改善手段５０としては、例えば信号がある周波数帯域をもって混入することが分かっている場合、その帯域を除去するローパスフィルタ、ハイパスフィルタ、あるいはバンドエリミネートフィルタを用いればよいし、逆に信号成分の周波数帯域があらかじめ分かっていたり、あるいはある周波数帯域の信号成分のみに着目したい場合には、その帯域のみを通過させるバンドパスフィルタを用いるようにしてもよい。
【０１０９】
また、支配的なノイズが熱雑音のようにランダムな周波数成分を有する場合には、信号を複数回加算平均する平均化処理機能を有したものでもよい。この場合、レーザによる超音波の送受信間隔が常に同じであるならば、レーザ光源１の発信タイミングを基準時刻（トリガー）として平均化処理を行うと、タイミング制御上好都合であるが、装置の設置や送受信点の走査などの問題で送受信間隔が時刻に応じて変化する場合には、超音波信号をデジタル化して蓄積しておき、ほぼ同距離とみなし得るデータのみをその中から選択して加算平均するのでもよい。
【０１１０】
さらに、観察すべき超音波信号が、超音波エコー信号などのようにほぼ相似形とみなしうる波形を有する繰り返し信号の場合には、その信号の自己相関あるいはあらかじめ準備したリファレンスとなる信号との相互相関を演算することでもＳ／Ｎ比を改善することができる。
【０１１１】
また、検出された超音波信号に含まれる周波数成分が重要な場合には、図１７に示すようなウェーブレット変換を用いて信号処理することで、特定の現象を感度よく検知することも可能である。なお、これらの処理は、光検出器１３の出力信号をアナログ電気信号として処理する場合だけでなく、信号処理手段１４内にアナログ−デジタル変換器を設置し、デジタル信号として処理する場合も含まれる。
【０１１２】
このように本実施形態では、信号処理装置１４において、受信した超音波信号に、適切な帯域で信号フィルタ処理、複数回の信号平均化処理、適切な領域の相関処理、または適切な帯域のウェーブレット変換処理を行うようにしたものである。
【０１１３】
［第１１実施形態］
図１８は本発明に係るレーザ超音波検査装置の第１１実施形態を示すブロック構成図である。
【０１１４】
本実施形態は、図１８に示すようにレーザ光ＥＬおよび計測光ＭＬをそれぞれ光ファイバ２４、２９でファイバ出射用光学系２５および３０に伝送し、各々のファイバ出射用光学系２５および３０を個別の駆動機構５１ａおよび５１ｂに搭載し、これら駆動機構５１ａおよび５１ｂを、あらかじめ敷設したレール５２上で走査・駆動可能に構成することで、被検査材３上の１点または複数点の検査を自動的に行うものである。これら駆動機構５１ａ，５１ｂおよびレール５２により走査手段が構成されている。
【０１１５】
したがって、本実施形態では、出射用光学系２５および３０を個別にあるいは同時に走査するための走査手段を有し、かつ信号処理装置１４において、受信された超音波情報を前記走査手段による走査位置と関連付けて多次元表示するようにしている。
【０１１６】
被検査材３が狭隘部や高所にある場合、あるいは被検査材３自体が高温や高放射能などのように検査員が接近しにくい場合はもとより、例えば機器の定期検査など、同じ個所を定期的に検査する場合にもあらかじめ設置しておいたレール５２によって所定の位置の検査を短時間で行うことができる効果がある。
【０１１７】
さらに、駆動機構５１ａ，５１ｂに位置検出機構を取り付けておけば、検査記録と検査位置を定量的に対応付けることも可能となる。
【０１１８】
なお、本実施形態では、ファイバ出射用光学系２５および３０を、個別の駆動機構５１ａおよび５１ｂに搭載した例を示したが、それらを１つの駆動機構上に設置すれば、超音波の送受信間隔を常に一定に保持することが可能となる。
【０１１９】
［第１２実施形態］
図１９（Ａ），（Ｂ）は本発明に係るレーザ超音波検査装置の第１２実施形態の表示例を示す説明図である。
【０１２０】
なお、図１９（Ａ），（Ｂ）は、例えば図１８に示したような送受信位置を走査可能なレーザ超音波検査装置によって計測されたデータの表示例である。
【０１２１】
今、図１９（Ｂ）に模式的に示したような裏面に減肉部Ｇを有する被検査材３に対し、２点鎖線で示した経路で送受信点を走査させたとする。すると、減肉部Ｇは他の部分よりも薄いため、例えば縦波や横波など内部を伝播する超音波ＵＳの伝播時間が異なってくる。そこで、走査中に得られた超音波信号にあらかじめ予想される伝播時間付近（上述のｔ_ｂ〜ｔ_ｅ）で時間ゲートを設置し、走査に従って各位置（ｙ）における計測データを図１９（Ａ）に示すように表示すれば、図中に太点線で示したように被検査材３の裏面形状を計測することができる。
【０１２２】
さらに、被検査材３中の音速が既知であれば、その形状を定量的に検知することも可能である。
【０１２３】
図２０（Ａ），（Ｂ）は走査を２次元的に行った場合の表示例であり、これは１次元的には図１９（Ａ）のように得られた超音波信号において、そのピークとなる時刻を、２次元的に走査した位置と関連付けて、被検査材３が厚い、すなわちピーク時刻が遅い場合を濃く、早い場合に淡くなるように色（濃淡）で表示したものである。また、図２１（Ａ），（Ｂ）は同じ計測結果を３次元的に示した場合の表示例であり、本装置によって被検査材３の裏面形状を可視化できることが分かる。
【０１２４】
一方、図２２（Ａ），（Ｂ）は表面波に着目した場合の一例である。図２２（Ｂ）に示すように被検査材３上にき裂Ｆ１，Ｆ２，Ｆ３が存在する場合、図中の２点鎖線で示した経路で方位（ｙ）に指向性を有する表面波を送受信すると、き裂Ｆがある場合には、そのき裂Ｆで表面波が反射し、き裂エコーが観察される。
【０１２５】
そこで、検査領域に相当する時間ゲートを設け、その時間領域における超音波信号レベルを濃淡あるいは色で表示すれば、図２２（Ａ）に示すように表面き裂を可視化することができる。
【０１２６】
このように本実施形態では、信号処理装置ＳＰの表示装置１５において、受信された超音波信号の強度情報、計測されたき裂寸法情報、あるいは計測された超音波伝播情報を送受信位置と関連付けて線、濃淡あるいは色で多次元的に表示するものである。
【０１２７】
以上説明したように、第９〜第１２実施形態によれば、受信された超音波信号に適切な電気的信号処理を加えたり、あるいは被検査材の周辺雰囲気あるいは表面状態を整えることにより、Ｓ／Ｎ比を改善して評価精度を高めるとともに、検知された情報を検査員が容易に理解できるように提示することが可能となる。
【０１２８】
［第１３実施形態］
図２３は本発明に係るレーザ超音波検査装置の第１３実施形態を示す構成図である。
【０１２９】
本実施形態では、図２３に示すようにレーザ光源１、受信用光学系５、光検出器１３および信号処理装置１４が搬送手段としての無軌道走行台車５３に、レーザ光ＥＬ用のファイバ出射用光学系２５および計測光ＭＬ用のファイバ出射用光学系３０が無軌道走行台車５３上に取り付けられた検査アーム５４に、それぞれ設置されている。また、無軌道走行台車５３には、検査位置を確認するための位置検出装置５５が、検査アーム５４には検査作業を監視するための監視手段としての監視用ＴＶカメラ５６がそれぞれ設置されている。
【０１３０】
また、レーザ光源１、受信用光学系５、光検出器１３および信号処理装置１４上には、通信装置５７ａが設置される一方、制御手段としての遠隔の駆動・制御装置５８上に通信装置５７ｂが設置されている。
【０１３１】
したがって、レーザ光源１、受信用光学系５および光検出器１３により計測された超音波データは、信号処理装置１４で処理された後、位置データ、画像データとともに通信装置５７ａ，５７ｂを経て遠隔の駆動・制御装置５８に無線伝送される。この駆動・制御装置５８で受信した計測データ、位置データおよび画像データは、各々関連付けられて表示装置１５に表示されるとともに、評価装置１６に記録される。
【０１３２】
なお、評価装置１６に予め被検査材３およびその周辺機器の設計図面あるいはＣＡＤデータなどを記録させておき、検査位置データや画像データをもとに対応する機器や部位の設計情報、形状などを表示装置１５に同時に表示することで、より効率的かつ高度な検査を行うことができる。
【０１３３】
また、駆動・制御装置５８は、無軌道走行台車５３および検査アーム５４を遠隔から駆動・制御可能な構成となっている。このような構成によれば、被検査材３が運転中の機器であったり、高温や高放射能環境など検査員が接近しにくい場合でもレーザ超音波検査装置による検査が可能となる。
【０１３４】
なお、監視手段としては上記監視ＴＶカメラ５６や距離センサの他、溶接金属を検知するフェライト検知機、あるいは複視差を適用した３次元ＴＶカメラなども使用可能である。
【０１３５】
［第１３実施形態の第１変形例］
図２４は本発明に係るレーザ超音波検査装置の第１３実施形態の第１変形例を示す構成図である。
【０１３６】
図２３に示す実施形態は、無線式、無軌道走行台車にレーザ超音波検査装置を搭載した例であるが、図２４に示す第１変形例は軌道付きの場合である。
【０１３７】
この第１変形例では、図２４に示すように軌道５９があらかじめ固定して設置され、この軌道５９上を走行する搬送手段としてのモノレール式走行台車６０にファイバ出射用光学系３９が搭載されている。この場合、モノレール式走行台車６０が十分なスペースを有していればレーザ光源１、受信用光学系５、光検出器１３および信号処理装置１４などをモノレール式走行台車６０上に搭載することも可能であるが、多くの場合そのスペースがない上、軌道５９を用いて光ファイバ４０を取り廻せるので、それらは駆動・制御装置５８などとともに遠隔の基地局に設置し、ヘッド部のみを搭載するのが簡便である。
【０１３８】
また、上記第１３実施形態と同様、モノレール式走行台車６０に監視カメラ、距離センサ、位置センサなどを搭載しておけば、より確実な検査を施工することができる。
【０１３９】
［第１３実施形態の第２変形例］
図２５は本発明に係るレーザ超音波検査装置の第１３実施形態の第２変形例を示す構成図である。
【０１４０】
第２変形例は、前記第１変形例において、図２５に示すように軌道として可搬型レール６１を用い、この可搬型レール６１上を走行する搬送手段としての走行台車６２を設けたものである。この走行台車６２に光軸と平行方向へ微動可能な微動機構を設けておくことで、レーザ光ＥＬや計測光ＭＬの焦点を微調整することもできる。
【０１４１】
このような構成にすることで、被検査材３が高所に多数本設置された配管である場合など、検査しにくい部位である場合にも効率的に検査することが可能となる。
【０１４２】
なお、第１３実施形態およびその各変形例において、無軌道走行台車５３などの搬送手段上に設置された搬送手段位置検出手段と、第１および第２のレーザ光であるレーザ光ＥＬおよび計測光ＭＬの照射位置を検出する照射位置同定手段と、これらの情報から被検査材３および被検査材３上の検査位置を検出する検査位置同定手段とを設けるようにしてもよい。
【０１４３】
また、第１３実施形態およびその各変形例において、信号処理装置１４に被検査材３の寸法および形状に関する多次元情報データベースを設け、信号処理装置ＳＰの表示部１５に、上記検査位置同定手段の出力情報と上記多次元情報データベースの該当する部位の情報を対応させて表示するようにしてもよい。
【０１４４】
［第１４実施形態］
図２６は本発明に係るレーザ超音波検査装置の第１４実施形態を示す構成図である。
【０１４５】
第１４実施形態は、被検査材３が特に原子炉６３あるいは原子炉内構造物６４の場合であり、周辺雰囲気としては気中あるいは水中が考えられる。超音波を送信可能なレーザ光ＥＬの伝送は「Ｙｕｊｉ Ｓａｎｏ ｅｔ． ａｌ．“Ｐｒｏｃｅｓｓ ａｎｄ ａｐｐｌｉｃａｔｉｏｎ ｏｆ ｓｈｏｃｋ ｃｏｍｐｒｅｓｓｉｏｎ ｂｙ ｎａｎｏ−ｓｅｃｏｎｄ ｐｕｌｓｅｓ ｏｆ ｆｒｅｑｕｅｎｃｙ−ｄｏｕｂｌｅｄ Ｎｄ： ＹＡＧ ｌａｓｅｒ，”Ｐｒｏｃ． ｏｆＡＬＰＨＡ´９９ ＳＰＩＥ， Ｏｓａｋａ， Ｎｏｖｅｍｂｅｒ １９９９年」で述べられているような炉内へのパルス光伝送装置６５が既知である。
【０１４６】
本実施形態では、原子炉６３上に備えた光学機器室６６中にレーザ光源１、受信用５、光検出器１３、信号処理装置１４などを設置し、そこから光ファイバ２９を搬送手段としての炉内用遠隔操作機構の一例であるパルス光伝送装置６５に沿わせて設置することで、計測光ＭＬを検査位置まで導き、パルス光伝送装置６５の先端部に設置したファイバ出射用光学系３０で計測光ＭＬを送受信することで、被検査材としての原子炉６３あるいは炉内構造物６４を検査する装置である。
【０１４７】
［第１４実施形態の第１変形例］
図２７は本発明に係るレーザ超音波検査装置の第１４実施形態の第１変形例を示す構成図である。
【０１４８】
本変形例は、図２７に示すように前記第１４実施形態のようなパルス光伝送装置６７を用いることなく、レーザ光ＥＬの伝送も光ファイバで行う場合には、原子炉６３あるいは炉内構造物６４に沿って移動する搬送手段としての炉内用遠隔操作機構の一例である炉内検査ロボット６７にファイバ出射用光学系２５，３０を設置し、これらファイバ出射用光学系２５、３０にレーザ光ＥＬおよび計測光ＭＬを光ファイバ２４、２９により伝送するものである。
【０１４９】
このレーザ超音波検査装置を適用することで、原子炉６３内など過酷な条件下で、しかも狭隘部の検査を効率的に行うことが可能となる。なお、この場合、材料の耐放射線性を配慮して、レンズや光ファイバなど光学部品の材質には石英を、構造材にはステンレス鋼やアルミニウムを用いるのが望ましい。
【０１５０】
［第１４実施形態の第２変形例］
図２８は本発明に係るレーザ超音波検査装置の第１４実施形態の第２変形例を示す構成図である。
【０１５１】
本変形例は、図２８に示すように被検査材が配管６８であり、この配管６８の内側を移動、走査、固定停止可能な搬送手段としての配管内面走行機構の一例である移動ロボット６９にファイバ出射用光学系４１を設置し、光ファイバ４０を用いてレーザ光ＥＬの送信および計測光ＭＬの送受信を行うことで、長手配管の内面を効率的に検査可能としたものである。
【０１５２】
［第１５実施形態］
図２９（Ａ），（Ｂ）は本発明に係るレーザ超音波検査装置の第１５実施形態を示す構成図である。
【０１５３】
本実施形態は、図２９（Ａ），（Ｂ）に示すように被検査材が配管６８であり、その配管６８外面に軌道７０を敷設し、この軌道７０上に走行台車７１を走行可能に設置し、この走行台車７１にレーザ光源１およびファイバ出射用光学系３０ａ，３０ｂを搭載したものである。なお、軌道７０には、図示しない軸方向移動機構を備えている。そして、軌道７０および走行台車７１は、搬送手段としての配管外面走行機構を構成する。
【０１５４】
上記の構成において、レーザ光源１から発振したレーザ光ＥＬは、レンズ２、照射用ミラー７２ａ，７２ｂを備えた導波管７３で伝送され、配管６８表面に照射される一方、図示しないレーザ光源４から発振した計測光ＭＬは、図５に示したような構成に基づいて２本の光ファイバ２９ａ，２９ｂで伝送され、ファイバ出射用光学系３０ａ，３０ｂで配管６８表面に照射される。
【０１５５】
ここで、ファイバ出射用光学系３０ａ，３０ｂを配管６８に対向するように設置すれば、例えばファイバ出射用光学系３０ａで照射した計測光ＭＬの反射光ＰＬを同じファイバ出射用光学系３０ａで集光し、受信用光学系５で検知することになる。一方、図２９（Ａ）に示すように、ある適切な角度をもって２つのファイバ出射用光学系３０ａ，３０ｂを配置すれば、ファイバ出射用光学系３０ａから配管６４に斜めに照射された計測光ＭＬの正反射成分をファイバ出射用光学系３０ｂが集光し、またその逆を行うなど、照射と集光を各々異なるファイバ出射用光学系で行うことも可能である。このように構成したことにより、長手配管の検査を自動的かつ効率的に行うことが可能となる。
【０１５６】
［第１６実施形態］
図３０は本発明に係るレーザ超音波検査装置の第１６実施形態を示す斜視図である。
【０１５７】
本実施形態は、図３０に示すように図示しない被検査材が水中に存在する場合であり、搬送手段としての水中遊泳機構の一例である水中遊泳ロボット７４によってファイバ出射用光学系２５および３０を検査位置近傍まで搬送して検査を行うものである。この水中遊泳ロボット７４には、監視ＴＶカメラ５６が設置され、この監視ＴＶカメラ５６により水中での検査作業を監視可能な構成となっている。
【０１５８】
また、ファイバ出射用光学系２５および３０は、駆動モータ７５により微動可能であり、大まかな位置決めを水中遊泳ロボット７４が行った後、駆動モータ７５を駆動させることで、ファイバ出射用光学系２５および３０を詳細な検査位置に位置決めをすることができる。
【０１５９】
さらに、水中の流れが速い場合に対応するため本実施形態では、周辺の構造部材７６に固定機構７７を用いて水中遊泳ロボット７４を固定させることで、定点検査を行うこともできる。そして、例えばき裂などを検知し、それを継続的に評価・監視する場合には、レーザ光ＥＬによって検知されたき裂近傍にマークし、その位置を監視ＴＶカメラ５６で検出することで、毎回の検査において常に同じき裂を計測することができる。
【０１６０】
［第１７実施形態］
図３１は本発明に係るレーザ超音波検査装置の第１７実施形態を示すブロック構成図である。
【０１６１】
本実施形態は、図３１に示すように予め被検査材３上の決められた検査位置近傍にファイバ出射用光学系２５および３０を複数個設置しておき、使用するファイバ出射用光学系を切り替えることで、１式のレーザ超音波検査装置で複数箇所を検査することができるようにしたものである。
【０１６２】
そのため、被検査材３（図示したように、複数の検査位置は１つの被検査材３に設定される場合には限定されない）側には、ファイバ出射用光学系２５ａ，２５ｂ，２５ｃ…および３０ａ，３０ｂ，３０ｃ…と、各々それらに接続された光ファイバ２４ａ，２４ｂ，２４ｃ…および２９ａ，２９ｂ，２９ｃ…を設置し、これらの光ファイバの他端には光ファイバコネクタ７８ａ，７８ｂ，７８ｃ…および７９ａ，７９ｂ、７９ｃ…を設置しておく。当然、それらは図示しない適当な固定治具で被検査材３あるいはその他の周辺部材に焦点などの照射集光条件が変化しないように固定されていてもよい。
【０１６３】
一方、レーザ光ＥＬを伝送する光ファイバ２４には、着脱部材としての光ファイバコネクタ７８を、計測光ＭＬを伝送する光ファイバ２９には着脱部材としての光ファイバコネクタ７９をそれぞれ設置しておく。
【０１６４】
このように構成したことにより、光ファイバコネクタ７８，７９をそれぞれ光ファイバコネクタ７８ａ，７８ｂ，７８ｃ…および７９ａ，７９ｂ、７９ｃ…に対する接続対象を適宜切り替えれば、複数点を１つの装置で検査することが可能なレーザ超音波検査装置を実現することが可能となる。
【０１６５】
［第１８実施形態］
図３２は本発明に係るレーザ超音波検査装置の第１８実施形態を示すブロック構成図である。
【０１６６】
本実施形態は、図３２に示すように前記第１７実施形態の構成に加え、被検査材３が保温材８０で遮蔽された配管、容器、機器、構造材が対象であり、ファイバ出射用光学系２５ａ，２５ｂ，２５ｃ…および３０ａ，３０ｂ，３０ｃ…が被検査材３と保温材８０との内側に設置されている。それらに接続された光ファイバ２４ａ，２４ｂ，２４ｃ…および２９ａ，２９ｂ，２９ｃ…は保温材８０を貫通、専用ペネトレーションあるいはその構造境界を利用して外側へと導かれる。光ファイバの他端に設置された光ファイバコネクタ７８ａ，７８ｂ，７８ｃ…および７９ａ，７９ｂ，７９ｃ…は、ほぼ一個所に集めておく。当然、それらは図示しない適当な固定治具で被検査材３あるいはその他の周辺部材に焦点などの照射集光条件が変化しないように固定されていてもよい。このように構成することにより、遮蔽物内部を対象とする検査が可能なレーザ超音波検査装置を実現することができる。
【０１６７】
なお、本実施形態において、被検査材３は狭隘部に設置された配管、容器、機器、構造材を対象としてもよい。この場合、光ファイバ２４ａ，２４ｂ，２４ｃ…および２９ａ，２９ｂ，２９ｃ…は保温材８０を貫通し、検査装置が設置される遠隔部まで導かれる。
【０１６８】
以上説明したように、第１３〜第１８実施形態によれば、搬送機構やその制御機構などと組み合せて構成することにより、効果的な検査を行うことが可能となる。
【０１６９】
［第１９実施形態］
図３３は本発明に係るレーザ超音波検査装置の第１９実施形態を示すブロック構成図である。
【０１７０】
本実施形態は、図３３に示すように被検査材３の表面に付着物８１、特に錆や塗装など超音波の伝播や受信感度を低下させる物質が付着している対象を検査する場合に有効な構成である。
【０１７１】
レーザ光源８２から発振したレーザ光ＣＬを方位Ｄに走査することによる付着物８１の除去技術（レーザクリーニング技術）は、例えば特開平７−２２５３００号公報によって公知となっている。このレーザ光ＣＬは、付着物８１の除去プロセスで超音波も励起するので、これと受信用光学系５などを組み合わせることで、表面を清掃しつつレーザ超音波検査を行うことが可能となる。特に、既存のレーザクリーニング装置の先端にファイバ出射用光学系３０を設置するだけなので装置構成上の負荷も少なく、既存のレーザクリーニング設備をほとんど変更することなしに、清掃だけでなく検査を行うことが可能なレーザ超音波検査装置を実現することができる。
【０１７２】
［第２０実施形態］
図３４は本発明に係るレーザ超音波検査装置の第２０実施形態を示すブロック構成図である。
【０１７３】
本実施形態は、図３４に示すように被検査材３表面の応力状態を改善しつつ、対象を検査する場合に有効な構成である。レーザ光源８３から発振したレーザ光ＰｅＬを方位Ｄに走査することによる被検査材３の表面応力改善技術（レーザピーニング技術）は、例えば前述の“「Ｙｕｊｉ Ｓａｎｏ ｅｔ．ａｌ．“Ｐｒｏｃｅｓｓ ａｎｄ ａｐｐｌｉｃａｔｉｏｎ ｏｆ ｓｈｏｃｋ ｃｏｍｐｒｅｓｓｉｏｎ ｂｙ ｎａｎｏ−ｓｅｃｏｎｄ ｐｕｌｓｅｓ ｏｆ ｆｒｅｑｕｅｎｃｙ−ｄｏｕｂｌｅｄ Ｎｄ： ＹＡＧ ｌａｓｅｒ，”Ｐｒｏｃ． ｏｆ ＡＬＰＨＡ′９９ ＳＰＩＥ， Ｏｓａｋａ， Ｎｏｖｅｍｂｅｒ １９９９年」によって公知となっている。
【０１７４】
このレーザ光ＰｅＬは、被検査材３表面の応力状態を改善するプロセスで超音波も励起するので、これと受信用光学系５などを組み合わせることで、表面応力を改善しつつ、レーザ超音波検査を行うことが可能となる。特に、既存のレーザピーニング装置の先端にファイバ出射用光学系３０を設置するだけなので、装置構成上の負担も少なく、既存のレーザピーニング設備をほとんど変更することなしに、応力改善だけでなく検査を行うことが可能なレーザ超音波検査装置を実現することができる。
【０１７５】
［第２１実施形態］
図３５は本発明に係るレーザ超音波検査装置の第２１実施形態を示すブロック構成図である。
【０１７６】
本実施形態は、図３５に示すように被検査材３の材質を分析しつつ、対象を検査する場合に有効な構成である。パルスレーザ光源としてのレーザ光源８４から発振したレーザ光ＢＬを照射して被検査材３表面の微小体積をアブレーションさせ、その発光を集光用光学系８５を用いて集光し、光ファイバ８６でぷ前せき手段としての分光分析・評価装置８７まで導いて分光分析することで、材料組成を分析する手法はレーザブレークダウン分光分析技術として公知となっている。
【０１７７】
このレーザ光ＢＬは、被検査材３をプラズマ発光させるプロセスで超音波も励起するので、これと受信用光学系５などを組み合わせることで、材料組成を分析しつつレーザ超音波検査を行うことが可能となる。
【０１７８】
本実施形態では、特に既存のレーザブレークダウン分光分析装置の先端にファイバ出射用光学系３０を設置するだけなので、装置構成上の負担も少なく、既存のレーザブレークダウン分光分析設備をほとんど変更することなしに材料組成分析だけでなく、検査を行うことが可能なレーザ超音波検査装置を実現することができる。
【０１７９】
［第２２実施形態］
図３６は本発明に係るレーザ超音波検査装置の第２２実施形態を示すブロック構成図である。
【０１８０】
本実施形態は、被検査材３のき裂や材料特性などを、レーザ光ＥＬで励起した超音波のうち表面波成分の伝播に着目して検査する場合に有効な構成である。
【０１８１】
一般に、表面波は被検査材３の表面に液体Ｗが付着していると減衰が早くなるため、被検査材３が液中に設置されている場合には検出可能な表面波信号レベルが低下するなどの課題がある。
【０１８２】
そこで、本実施形態では、図３６に示すようにコンプレッサ８８と、このコンプレッサ８８に連結されファイバ出力光学系４１の近傍に先端が配置された配管８９とを設置し、コンプレッサ８８を駆動してエアＡｉｒを配管８９の先端から検査点近傍に吹き付け、超音波送受信点すなわちレーザ光の照射位置と、表面波の伝播経路とを気体雰囲気に置換するものである。したがって、これらコンプレッサ８８および配管８９により局所気体雰囲気生成手段が構成される。
【０１８３】
このように構成すれば、減衰の少ない表面波を観察可能である上、レーザ光ＥＬの照射によってダストなどが発生した場合にも、吹き付けられたエアＡｉｒによってダストなどが飛散されてレーザ光の伝播経路上の散乱体になりにくいという効果がある。
【０１８４】
［第２２実施形態の変形例］
図３７は本発明に係るレーザ超音波検査装置の第２２実施形態の変形例を示すブロック構成図である。
【０１８５】
本変形例は、図３７に示すようにレーザ光の照射位置と、表面波の伝播経路とを気体雰囲気に置換した領域が局所気体雰囲気生成手段としての容器９０により覆われている。
【０１８６】
したがって、被検査材３のレーザ光照射位置と表面波の伝播経路とを気体雰囲気に置換した状態に保持するのが難しい場合には、本変形例のようにその領域を容器９０で覆うことで、より容易に置換状態を保持することが可能となる。
【０１８７】
［第２３実施形態］
図３８は本発明に係るレーザ超音波検査装置の第２３実施形態を示すブロック構成図である。
【０１８８】
本実施形態は、被検査材３が表面損傷や熱入力を極力防止する必要がある場合の検査の際に有効な構成である。レーザ光ＥＬによる超音波励起過程は、熱歪みモードとアブレーションモードとの２種類がある。
【０１８９】
一般に、熱歪みモードでは被検査材３の表面損傷あるいは熱的な材質変化は生じないが、アブレーションモードでは、ごく表層の蒸発とわずかな入熱が生ずる。
【０１９０】
これを防止するために、本実施形態では、図３８に示すように予め検査する被検査材３表面に保護膜９１を形成しておき、レーザ光ＥＬを保護膜９１に照射すれば、アブレーションモードにおける表面損傷あるいは入熱を抑制することができる。この保護膜９１としては、レーザ光ＥＬを効率よく吸収する物質が適しており、レーザ光ＥＬの波長やエネルギーによって選択すべきであり、例えば墨汁や油などの有色液や着色粉末などの微粒子、固体、粉体などでもよい。
【０１９１】
［第２４実施形態］
図３９は本発明に係るレーザ超音波検査装置の第２４実施形態を示すブロック構成図である。
【０１９２】
本実施形態は、被検査材３が遠隔に設置され、監視ＴＶカメラの画像などからは確認することができない計測光ＭＬの詳細な焦点合わせが必要な検査の場合に有効な構成である。被検査材３表面からの反射光ＰＬは、ファイバ出射用光学系３０から被検査材３の距離が最適になった場合に最も大きくなり、この状態で超音波信号の検出感度も最大となる。しかし、光検出器１３に入射する光は反射光ＰＬだけでなく、各光学素子の端面反射や迷光なども存在するため、反射光ＰＬの状況は必ずしも明らかでない。
【０１９３】
そこで本実施形態では、図３９に示すように遮蔽板駆動制御装置９２からの駆動信号で遮蔽板駆動装置９３を駆動させ、これにより戻り光確認手段としての遮蔽板９４を動作させ、計測光ＭＬが被検査材３に到達しない状態を形成することにより、その際の光検出器１３の出力信号変化から、反射光ＰＬの戻り具合を確認することができる。
【０１９４】
なお、遮蔽板９４は計測光ＭＬの散乱体であり、かつ反射率が低いものが望ましい。また、遮蔽板９４は光軸に対して直交しないよう角度を付けて設置するのも効果的であり、この場合には遮蔽板９４はミラーでもよい。さらに、例えば図３０に示したようにファイバ出射用光学系３０を予め微動ステージに搭載しておき、遮蔽板９４の動作による光検出器１３の出力信号の変化が最大となる位置にファイバ出射用光学系３０を位置合わせすることも可能である。
【０１９５】
［第２５実施形態］
図４０は本発明に係るレーザ超音波検査装置の第２５実施形態を示すブロック構成図である。
【０１９６】
本実施形態は、被検査材３が遠隔に設置され、監視ＴＶカメラの画像などからは確認することができない計測光ＭＬの詳細な焦点合わせが必要な検査の場合に有効な別の構成例である。被検査材３表面からの反射光ＰＬは、ファイバ出射用光学系３０から被検査材３の距離が最適になった場合に最も大きくなり、この状態で超音波信号の検出感度も最大となる。
【０１９７】
ファイバ出射用光学系３０から被検査材３の距離の最適値は、ファイバ出射用光学系３０の焦点距離からあらかじめほぼ推定することができるので、本実施形態では、図４０に示すようにファイバ出射用光学系３０の先端に距離センサ９５を設置し、この距離センサ９５により測定した距離が予め推定された最適値となるよう微動制御装置９６で微動ステージ９７を動作させることで、常に最適な反射条件で計測することができる。これら微動制御装置９６および微動ステージ９７により位置調整手段が構成される。
【０１９８】
［第２５実施形態の変形例］
図４１は本発明に係るレーザ超音波検査装置の第２５実施形態の変形例を示すブロック構成図である。
【０１９９】
本変形例は、図４１に示すようにファイバ出射用光学系３０から被検査材３の距離を最適値に保持するものであり、ファイバ出射用光学系３０に距離固定用治具９８を取り付け、この距離固定用治具９８を図示しないばね機構などによって被検査材３に押し当てるようにしている。これにより、簡易な構成でファイバ出射用光学系３０から被検査材３の距離を最適値に保持することが可能となる。
【０２００】
【発明の効果】
以上説明したように本発明によれば、超音波の送受信を行うためのレーザ光を光ファイバ、照射用光学系または照射・集光用光学系を用いて伝送することにより、遠隔非接触性を損なわず、狭隘部の被検査材を効率的に検査することが可能なレーザ超音波検査装置を提供することができる。
【図面の簡単な説明】
【図１】本発明に係るレーザ超音波検査装置の第１実施形態を示すブロック構成図。
【図２】本発明に係るレーザ超音波検査装置の第１実施形態の変形例を示すブロック構成図。
【図３】図２の構成による効果を示す説明図。
【図４】本発明に係るレーザ超音波検査装置の第２実施形態を示すブロック構成図。
【図５】本発明に係るレーザ超音波検査装置の第２実施形態の第１変形例を示すブロック構成図。
【図６】図５の構成による効果を示す説明図。
【図７】本発明に係るレーザ超音波検査装置の第２実施形態の第２変形例を示すブロック構成図。
【図８】本発明に係るレーザ超音波検査装置の第３実施形態を示すブロック構成図。
【図９】本発明に係るレーザ超音波検査装置の第４実施形態を示すブロック構成図。
【図１０】（Ａ），（Ｂ）は本発明に係るレーザ超音波検査装置の第５実施形態を示す説明図。
【図１１】本発明に係るレーザ超音波検査装置の第５実施形態の変形例を示す説明図。
【図１２】本発明に係るレーザ超音波検査装置の第６実施形態を示すブロック構成図。
【図１３】本発明に係るレーザ超音波検査装置の第７実施形態の受信用光学系を示すブロック構成図。
【図１４】本発明に係るレーザ超音波検査装置の第８実施形態のファイバ入射用光学系を示す構成図。
【図１５】本発明に係るレーザ超音波検査装置の第９実施形態を示すブロック構成図。
【図１６】本発明に係るレーザ超音波検査装置の第１０実施形態を示すブロック構成図。
【図１７】第１０実施形態においてウェーブレット変換を用いた信号処理を示す説明図。
【図１８】本発明に係るレーザ超音波検査装置の第１１実施形態を示すブロック構成図。
【図１９】（Ａ），（Ｂ）は本発明に係るレーザ超音波検査装置の第１２実施形態の表示例を示す説明図。
【図２０】（Ａ），（Ｂ）は走査を２次元的に行った場合の表示例を示す説明図。
【図２１】（Ａ），（Ｂ）は同じ計測結果を３次元的に示した場合の表示例を示す説明図。
【図２２】（Ａ），（Ｂ）は表面波に着目した場合の一例を示す説明図。
【図２３】本発明に係るレーザ超音波検査装置の第１３実施形態を示す構成図。
【図２４】本発明に係るレーザ超音波検査装置の第１３実施形態の第１変形例を示す構成図。
【図２５】本発明に係るレーザ超音波検査装置の第１３実施形態の第２変形例を示す構成図。
【図２６】本発明に係るレーザ超音波検査装置の第１４実施形態を示す構成図。
【図２７】本発明に係るレーザ超音波検査装置の第１４実施形態の第１変形例を示す構成図。
【図２８】本発明に係るレーザ超音波検査装置の第１４実施形態の第２変形例を示す構成図。
【図２９】（Ａ），（Ｂ）は本発明に係るレーザ超音波検査装置の第１５実施形態を示す構成図。
【図３０】本発明に係るレーザ超音波検査装置の第１６実施形態を示す斜視図。
【図３１】本発明に係るレーザ超音波検査装置の第１７実施形態を示すブロック構成図。
【図３２】本発明に係るレーザ超音波検査装置の第１８実施形態を示すブロック構成図。
【図３３】本発明に係るレーザ超音波検査装置の第１９実施形態を示すブロック構成図。
【図３４】本発明に係るレーザ超音波検査装置の第２０実施形態を示すブロック構成図。
【図３５】本発明に係るレーザ超音波検査装置の第２１実施形態を示すブロック構成図。
【図３６】本発明に係るレーザ超音波検査装置の第２２実施形態を示すブロック構成図。
【図３７】本発明に係るレーザ超音波検査装置の第２２実施形態の変形例を示すブロック構成図。
【図３８】本発明に係るレーザ超音波検査装置の第２３実施形態を示すブロック構成図。
【図３９】本発明に係るレーザ超音波検査装置の第２４実施形態を示すブロック構成図。
【図４０】本発明に係るレーザ超音波検査装置の第２５実施形態を示すブロック構成図。
【図４１】本発明に係るレーザ超音波検査装置の第２５実施形態の変形例を示すブロック構成図。
【図４２】従来のレーザ超音波検査装置を示すブロック構成図。
【図４３】ファブリ・ペロー共振器の動作を示す説明図。
【図４４】ファブリ・ペロー共振器の動作を示す説明図。
【図４５】従来の他のレーザ超音波検査装置を示すブロック構成図。
【図４６】従来のさらに他のレーザ超音波検査装置を示すブロック構成図。
【符号の説明】
１ レーザ光源（第１のレーザ光源）
２ 光学系
３ 被検査材
４ レーザ光源（第２のレーザ光源）
５ 受信光学系
６ａ〜６ｃ １／２波長板
７ａ〜７ｆ 偏光ビームスプリッタ
１３ 光検出器（信号変換手段）
１４ 信号処理装置
１５ 表示装置
１６ 評価装置
１７ ファブリ・ペロー共振器
１８ 光検出器
１９ 制御器
２０ 駆動機構
２１ １／４波長板
２３ ファイバ入射用光学系（第１の入射用光学系）
２４ 光ファイバ（第１の光ファイバ）
２５ ファイバ出射用光学系（照射用光学系）
２６ 光分岐器
２８ ファイバ入射用光学系（第２の入射用光学系）
２９ 光ファイバ（第２の光ファイバ）
３０ ファイバ出射用光学系（照射・集光用光学系）
３１ 結像光学系
３２ 結像光学系
３４ ファイババンドル
３５ ファイバ出射用光学系
３６ ２次元アレイ型光検出器
３７ 光学系
３８ 光分岐器（光合成・分岐手段）
３９ ファイバ入射用光学系（両用入射用光学系）
４０ 光ファイバ（両用光ファイバ）
４１ ファイバ出射用光学系（両用照射・集光光学系）
４２ 狭帯域光フィルタ
４３ａ，４３ｂ 無反射コート付き窓部
４４ａ，４４ｂ 容器
４５ａ，４５ｂ 媒質
４６ 凹レンズ
４７ マイクロレンズアレイ
４８ レンズ
４９ 時間ゲート
５０ Ｓ／Ｎ比改善手段
５１ａ，５１ｂ 駆動機構
５２ レール
５３ 無軌道走行台車
５４ 検査アーム
５５ 位置検出装置
５６ 監視用ＴＶカメラ
５７ａ，５７ｂ 通信装置
５８ 駆動・制御装置
５９ 軌道
６０ モノレール式走行台車
６１ 可搬型レール
６２ 走行台車
６３ 原子炉
６４ 原子炉内構造物
６５ パルス光伝送装置
６７ 炉内検査ロボット
６８ 配管
６９ 移動ロボット
７０ 軌道
７１ 走行台車
７２ａ，７２ｂ 照射用ミラー
７３ 導波管
７４ 水中遊泳ロボット
７５ 駆動モータ
７６ 構造部材
７７ 固定機構
７８，７８ａ〜７８ｃ 光ファイバコネクタ
７９，７９ａ〜７９ｃ 光ファイバコネクタ
８０ 保温材
８１ 付着物
８２ レーザ光源
８３ レーザ光源
８４ レーザ光源
８５ 集光用光学系
８６ 光ファイバ
８７ 分光分析・評価装置
８８ コンプレッサ
８９ 配管
９０ 容器
９１ 保護膜
９２ 遮蔽板駆動制御装置
９３ 遮蔽板駆動装置
９４ 遮蔽板
９５ 距離センサ
９６ 微動制御装置
９７ 微動ステージ
９８ 距離固定用治具
ＳＰ 信号処理装置[0001]
BACKGROUND OF THE INVENTION
The present invention is a laser that performs non-contact, non-destructive and high-precision inspection of cracks and defects or material evaluation on a measurement object that is difficult to contact or approach, such as a small size, high temperature, narrow part, or working part. The present invention relates to an ultrasonic inspection apparatus.
[0002]
[Prior art]
For example, in recent years, a laser ultrasonic method has been proposed as one means for inspecting cracks in power plant equipment and structural materials. An outline of this technique is described in, for example, “Yamawaki:“ Laser Ultrasound and Non-Contact Material Evaluation ”, Journal of the Japan Welding Society, Vol. 64, No. 2, P. 104-108 (issued in 1995). As described above, in many cases, an ultrasonic wave is transmitted using thermal stress or vaporization reaction force generated by irradiating a material to be inspected with pulsed laser light. This is a technique for irradiating a receiving point with laser light and receiving a displacement or vibration speed induced by ultrasonic waves using its straightness and coherence. It is a well-known technique to detect material cracks and internal defects using ultrasonic waves, or to evaluate material properties. According to the laser ultrasonic method, these can be performed in a non-contact manner. Application to the field of material evaluation is expected.
[0003]
Several different optical systems have been proposed as means for transmitting and receiving ultrasonic waves in the laser ultrasonic method. Here, generation of ultrasonic waves by pulse laser light irradiation and Fabry-Perot resonators, which are closely related to the present invention, are proposed. FIG. 42 shows a block diagram of a typical conventional laser ultrasonic inspection apparatus for reception of ultrasonic waves used.
[0004]
As shown in FIG. 42, the laser light EL oscillated from the laser light source 1 for generating ultrasonic waves is irradiated through the optical system 2 to a predetermined position on the surface of the inspection object 3 in a predetermined beam shape. As this laser light source 1, a Q-switch YAG laser or the like is often used.
[0005]
Therefore, in the conventional laser ultrasonic inspection apparatus, ultrasonic waves in various modes such as longitudinal waves, transverse waves, and surface waves are generated in the inspection target material 3 due to the interaction between the inspection target material 3 and the irradiation laser light EL. The ultrasonic waves generate phenomena such as reflection, scattering, and change in sound velocity depending on cracks, defects, or material properties of the material to be inspected 3, and a detailed description thereof will be omitted here. In any case, when an ultrasonic wave propagated based on a certain propagation process reaches an arbitrary measurement point on the material to be inspected 3, a displacement occurs in that part.
[0006]
On the other hand, in FIG. 42, a laser beam ML oscillated from the laser light source 4 for ultrasonic detection irradiates the measurement point on the inspection object 3 by a predetermined amount via the lens 8. As the laser light source 4, a continuous wave laser light source such as a frequency stabilized He—Ne laser, argon laser, YAG laser or the like is often used.
[0007]
When the measurement point is displaced by the arrival of the ultrasonic wave, the frequency of the laser light PL irradiated and reflected on the point is shifted by an amount proportional to the vibration speed due to the Doppler effect. Here, if the surface of the material to be inspected 3 is optically rough, the reflected light PL is scattered, and a part thereof is incident on the optical fiber 10 through the lens 9. The light transmitted through the optical fiber 10 is guided to the Fabry-Perot resonator 17 in the receiving optical system (ROP) 5 through the coupling optical system 11.
[0008]
A part of the light component PL guided to the Fabry-Perot resonator 17 is transmitted through the Fabry-Perot resonator 17 and then guided to the photodetector 13 through the lens 12. In this way, the output light of the receiving optical system 5 is converted into an electric signal by the photodetector 13, and this electric signal is amplified to a predetermined signal and filtered by the signal processing device 14 in the signal processing device SP. The display device 15 displays the result, and the evaluation device 16 evaluates and records the signal.
[0009]
Next, the operation of the Fabry-Perot resonator 17 will be described.
[0010]
As shown in FIG. 42, the Fabry-Perot resonator 17 is an optical resonator composed of two opposing mirrors 17a and 17b whose reflectivities are both less than 100%, and the distance r between the mirrors 17a and 17b. Is an integer n times the wavelength λ of the incident light, the light resonates between the mirrors 17a and 17b, and the transmitted light quantity I is maximized.
[0011]
FIG. 43 shows a change in the amount of transmitted light I of the Fabry-Perot resonator 17 when the resonator length r is artificially scanned by a distance longer than the wavelength λ. As shown in FIG. 43, it can be seen that the transmitted light amount I becomes maximum when the resonator length r becomes an integer n times the wavelength λ, and then decays rapidly for each wavelength.
[0012]
On the other hand, when the resonator length r is fixed to the point A where the transmitted light amount change rate per unit length change is maximum in the curve shown in FIG. 43 and the optical frequency ν (= c / λc: speed of light) is scanned. The change in the light quantity I is shown in FIG. This is relatively the same behavior as when the resonator length r is changed while the optical frequency ν (or wavelength λ) is fixed, and (ν ₀ It becomes a curve having a peak at + Δν) = r / n.
[0013]
A case where the light PL reflected from the material to be inspected 3 is incident on the Fabry-Perot resonator 17 adjusted as described above will be described. Since the surface of the material to be inspected 3 is stationary in a normal case, the frequency of the light PL reflected by the surface of the material to be inspected 3 is ν. ₀ The transmitted light quantity I of the Fabry-Perot resonator 17 is I ₀ It is constant at.
[0014]
However, when the ultrasonic wave reaches the measurement point, as described above, the frequency of the measurement light PL is ± ν due to Doppler shift. _D Therefore, as schematically shown in FIG. 44, the amount of transmitted light I of the Fabry-Perot resonator 17 is also ± I _D Will only change.
[0015]
That is, the Fabry-Perot resonator 17 can detect the arrival of ultrasonic waves as a change in the intensity of transmitted light. This change in the intensity of light is caused by an avalanche photodiode (hereinafter referred to as APD), a PIN photodiode (hereinafter referred to as PIN-PD), a photodiode (hereinafter referred to as PD), a photomultiplier tube (hereinafter referred to as PM), etc. Since it can be converted into an electric signal using the photodetector 13, if an oscilloscope or the like is used to display time on the horizontal axis and electric signal intensity on the vertical axis, an ultrasonic signal can be displayed on the display device 15. Record and observe.
[0016]
On the other hand, as described above, the distance r between the mirrors 17a and 17b facing each other in the Fabry-Perot resonator 17 is a spatial length sufficiently shorter than the wavelength of incident light (for example, about 633 nm in the case of He-Ne laser light). In this case, the adjustment may be easily deviated due to thermal expansion of parts due to changes in ambient temperature and mechanical vibrations around the parts.
[0017]
Therefore, there is a conventional laser ultrasonic inspection apparatus having a resonance length control system as shown in FIG. In FIG. 45, the same parts as those in the laser ultrasonic inspection apparatus shown in FIG.
[0018]
In this laser ultrasonic inspection apparatus, the plane of polarization of the laser light ML oscillated from the laser light source 4 for ultrasonic detection is controlled by the half-wave plate 6a in the receiving optical system (ROP) 5 as shown in FIG. After that, the measurement point on the inspection object 3 is irradiated by a predetermined amount via the polarizing beam splitter 7a and the lens 8.
[0019]
When the measurement point is displaced by the arrival of the ultrasonic wave, the frequency of the laser light PL irradiated and reflected on the point is shifted by an amount proportional to the vibration speed due to the Doppler effect. Here, if the surface of the material to be inspected 3 is optically rough, the reflected light PL is scattered, and a part thereof is incident on the optical fiber 10 through the lens 9. The light transmitted through the optical fiber 10 is guided to the Fabry-Perot resonator 17 via the coupling optical system 11 and the polarization beam splitter 7b. A part of the light component PL guided to the Fabry-Perot resonator 17 is transmitted through the Fabry-Perot resonator 17 and then guided to the photodetector 13 through the lens 12 and the polarization beam splitter 7c. In this way, the output light of the receiving optical system 5 is converted into an electric signal by the photodetector 13, and this electric signal is amplified to a predetermined signal and filtered by the signal processing device 14 in the signal processing device SP. The display device 15 displays the result, and the evaluation device 16 evaluates and records the signal.
[0020]
On the other hand, a part of the laser light ML is branched in advance by the polarization beam splitter 7a, and directly enters the Fabry-Perot resonator 17 as the reference light RL via the polarization beam splitter 7b without passing through the inspection target material 3. The transmitted light is separated from the reflected light PL from the material to be inspected 3 by the polarization beam splitter 7 c and detected by the photodetector 18.
[0021]
Here, since the reference light RL is not subjected to any frequency shift on the optical path, the output signal level of the photodetector 18 should always be constant. If the signal level of the photodetector 18 changes, it means that the resonator length r has changed for some reason, so that the output signal level of the photodetector 18 is passed through the controller 19. The resonator length r is always controlled to an optimum value by driving the mirror 17b so that the output signal level of the photodetector 18 becomes constant by inputting the signal to a driving mechanism 20 such as a piezo element that drives the mirror 17b. Can do.
[0022]
With this configuration, the photodetector 13 uses a high-speed detector in the MHz band for ultrasonic measurement, and the photodetector 18 uses a low-speed detector in the at least kHz band for detecting disturbance vibrations and temperature changes. Therefore, a signal in a specific band can be detected with high sensitivity.
[0023]
On the other hand, means for controlling the Fabry-Perot resonator 17 using the measurement light PL without using the reference light RL as in the conventional laser ultrasonic inspection apparatus shown in FIG. 46 is also well known. This is based on the fact that the ultrasonic signal band to be detected (MHz band) and the vibration / temperature fluctuation band (up to kHz band) which are the disturbance factors of the Fabry-Perot resonator 17 are greatly different. The Fabry-Perot resonator 17 is controlled so as to respond only to disturbances by applying a relatively slow response mechanism to the ultrasonic signal. In addition, when the surface of the material to be inspected 3 is close to the optical mirror surface, means for spatially guiding the reflected light PL to the Fabry-Perot resonator 17 without using the optical fiber 10 can be applied.
[0024]
[Problems to be solved by the invention]
The laser ultrasonic inspection apparatus according to the prior art is effective when there is no particular shielding object between the inspection object 3 and the laser beam for transmitting and receiving ultrasonic waves can be transmitted well in the space. is there.
[0025]
However, while the material to be inspected 3 is difficult to contact such as high temperature, high place, high radiation field, complicated shape part, etc., there are parts where the proximity is poor and remote non-contact inspection means is required, In many cases, they are located at a position where it is difficult to spatially transmit the laser beam, such as a narrow part or the inside of a shield.
[0026]
Further, the surfaces of the materials to be inspected 3 are non-uniform and have different reflection characteristics, and the signal / noise ratio (hereinafter referred to as S / N ratio) of the optical signal that can be detected by the receiving optical system 5 such as the Fabry-Perot resonator 17. Is also expected to be bad.
[0027]
Furthermore, when an inspection operation for an actual narrow portion is assumed, it is necessary to transfer a part or all of the laser ultrasonic inspection apparatus to an inspection site using a robot or the like. Although many material processing and material improvement methods using a laser beam have been proposed at present, it is desirable to perform crack inspection and material evaluation before and after the application of these methods.
[0028]
Therefore, the present invention has been made in consideration of the above circumstances, and its object is to transmit a laser beam for transmitting and receiving ultrasonic waves using a small inspection probe such as an optical fiber and an irradiation optical system. Thus, an object of the present invention is to provide a laser ultrasonic inspection apparatus capable of efficiently inspecting a material to be inspected such as a narrow portion without impairing the remote non-contact property.
[0029]
[Means for Solving the Problems]
In order to solve the above-mentioned problem, the invention described in claim 1 is generated in the inspection material, the first laser light source that oscillates the first laser light for generating the ultrasonic wave in the inspection material. A second laser light source that oscillates a second laser beam applied to the material to be inspected to receive an ultrasonic signal, and a reflection component of the second laser light on the surface of the material to be inspected. A receiving optical system for optically detecting information about the signal, a signal converting means for converting an ultrasonic signal received in the receiving optical system into an electric signal, a signal processing of an output signal of the signal converting means, and In a laser ultrasonic inspection apparatus having signal processing means for displaying and recording information relating to the propagation of the ultrasonic wave, at least the first laser light oscillated from the first laser light source is transmitted to the vicinity of the inspection object. A first optical fiber of the present, the focus dispersive optical system for incident first laser beam emitted from the first laser light source to the optical fiber, The first Provided at the tip of the optical fiber on the inspection material side, irradiates the inspection material with the first laser light under predetermined irradiation conditions. for With illumination optics The second laser light oscillated from the second laser light source is transmitted to the vicinity of the material to be inspected, and the reflection component of the second laser light irradiated by the second laser light source on the surface of the material to be inspected At least one second optical fiber that transmits the light to the receiving optical system and the second optical fiber provided at the tip of the inspection material side for irradiating and condensing the second laser light Irradiation / condensing optics It is characterized by comprising.
[0031]
According to a second aspect of the present invention, there is provided a first laser light source that oscillates a first laser beam for generating an ultrasonic wave in a material to be inspected, and an ultrasonic signal generated in the material to be inspected. A second laser light source that oscillates a second laser beam irradiated on the inspection material, and reception that optically detects information on the ultrasonic wave from a reflection component of the second laser light on the surface of the inspection material. Optical system, signal converting means for converting an ultrasonic signal received by the receiving optical system into an electric signal, signal processing of an output signal of the signal converting means, and display of information on propagation of the ultrasonic wave And a laser ultrasonic inspection apparatus having a signal processing means for recording, A focus dispersion type optical system for entering the first laser light oscillated from the first laser light source, and output from the focus dispersion type optical system A light synthesizing / branching means for superimposing the first laser light and the second laser light on the same optical axis; a dual-use incident optical system for making the first and second laser lights incident; A dual-purpose optical fiber that transmits the first and second laser beams to the vicinity of the material to be inspected and transmits a reflection component of the second laser light on the surface of the material to be inspected to the receiving optical system; Installed at the tip of the optical fiber on the inspection material side, irradiates the inspection material with the first and second laser light under a predetermined irradiation condition, and condenses the reflected component under the predetermined light collection condition. And a dual-purpose irradiation / condensing optical system.
[0032]
The invention described in claim 3 3. The laser ultrasonic inspection apparatus according to claim 1, wherein the first laser light source that generates ultrasonic waves on the material to be inspected is a pulsed Nd: YAG laser light source. It is characterized by that.
[0033]
The invention according to claim 4 is the invention according to claim 1. Or 2 In the described laser ultrasonic inspection apparatus, the second laser light source for irradiating the surface of the inspection material and receiving the ultrasonic signal is a second harmonic light source of a continuously oscillating Nd: YAG laser. Laser ultrasonic inspection equipment.
[0034]
The invention according to claim 5 is the invention according to claim 1. Alternatively, in the laser ultrasonic inspection apparatus described in 2, the antireflection means for reducing the amount of return light due to the reflection of the end face is provided in the incident / exit portion of the optical fiber. It is characterized by that.
[0035]
The invention according to claim 6 is the invention according to claim 1. Alternatively, in the laser ultrasonic inspection apparatus according to 2, the receiving optical system for optically detecting information about the ultrasonic wave is a Michelson interferometer, and a reflection component on the surface of the inspection material is transmitted to the receiving optical system. The optical fiber to do is a single mode optical fiber It is characterized by that.
[0036]
The invention described in claim 7 7. The laser ultrasonic inspection apparatus according to claim 6, wherein the receiving optical system for optically detecting information relating to the ultrasonic wave is a Fabry-Perot optical meter, and the Fabry-Perot optical meter reflects the reflection on the surface of the material to be inspected. The optical fiber for transmitting the component is either a graded index optical fiber or a step index optical fiber It is characterized by that.
[0037]
The invention described in claim 8 8. The laser ultrasonic inspection apparatus according to claim 7, wherein the reference light for controlling the resonator of the Fabry-Perot optical meter is transmitted through an optical fiber having the same core diameter as that of the optical fiber for transmitting the reflection component on the surface of the inspection object. It is characterized by that.
[0040]
Accordingly, claims 1 to 8 According to the described invention, by transmitting a laser beam for transmitting and receiving ultrasonic waves using a small inspection probe of an optical fiber, an irradiation optical system, or an irradiation / condensing optical system, remote non-contact property is achieved. Without damaging, it is possible to efficiently inspect the material to be inspected in the narrow portion.
[0041]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a laser ultrasonic inspection apparatus according to the present invention will be described below with reference to the drawings. In the respective embodiments and modifications, portions that are the same as or correspond to those in the conventional configuration are denoted by the same reference numerals as in FIGS. 42 to 46, and redundant descriptions are omitted, and only different configurations are described.
[0042]
[First Embodiment]
FIG. 1 is a block diagram showing a first embodiment of a laser ultrasonic inspection apparatus according to the present invention.
[0043]
In the present embodiment, as shown in FIG. 1, the ultrasonic wave excited by the first laser light EL oscillated from the laser light source 1 for generating ultrasonic waves as the first laser light source is stabilized using the reference light RL. The reflected light PL, which is the reflected light from the measurement point on the material 3 to be inspected, is applied to the Fabry-Perot resonator 17 controlled as follows. 45 is the same as the configuration in which the conventional optical fiber 10 is not used in FIG. 45 except for the operation that is measured by being incident on the Fabry-Perot resonator 17 through 6b.
[0044]
That is, in the present embodiment, similarly to the laser ultrasonic inspection apparatus shown in FIG. 45, a first laser light source that oscillates a laser beam (first laser beam) EL for generating an ultrasonic wave on the inspection object 3. And a laser light source 4 as a second laser light source that oscillates a laser beam (second laser beam) ML irradiated to the material 3 to be inspected to receive the generated ultrasonic signal. The receiving optical system 5 for optically detecting information related to the ultrasonic wave from the reflection component of the second laser beam ML on the surface of the inspection object 3 and the ultrasonic signal received by the receiving optical system 5 And a signal processing unit SP that appropriately processes the output signal of the photodetector 13 and displays and records information related to the propagation of the ultrasonic wave. ing.
[0045]
By the way, in the present embodiment, the laser light EL oscillated from the laser light source 1 is incident on a fiber incident optical system 23 as a first incident optical system, and the fiber incident optical system 23 is an optical fiber (first optical system). An optical fiber 25 is attached to the rear end of the optical fiber 24, and a fiber emitting optical system 25 as an irradiation optical system is attached to the front end of the optical fiber 24.
[0046]
Therefore, the laser light EL oscillated from the laser light source 1 is incident on the optical fiber 24 through the fiber incident optical system 23 and transmitted to the vicinity of the material 3 to be inspected using the optical fiber 24. The fiber emitting optical system 25 provided at the tip irradiates the surface of the inspection object 3 with a predetermined irradiation shape.
[0047]
Next, the operation of this embodiment will be described.
[0048]
Normally, the laser beam EL used for ultrasonic excitation uses a pulsed laser beam having a pulse energy of mJ class or higher, but this is a harmful level when accidentally irradiated to the human body. In order to propagate spatially over a long distance, safety considerations such as providing an optical path shielding means are necessary.
[0049]
Therefore, as shown in FIG. 1, the laser light EL is incident on the optical fiber 24 via the fiber incident optical system 23, and is transmitted to the vicinity of the material 3 to be inspected using the optical fiber 24. By irradiating the surface of the inspection object 3 with a predetermined irradiation shape by the system 25, only a very short distance from the laser light source 1 to the fiber incident optical system 23 and from the fiber emission optical system 25 to the inspection object 3 is obtained. The optical path shielding is sufficient, and the cost related to the installation of the optical path shielding means can be reduced. On the other hand, the inspected material 3 installed in a narrow part or the like can be efficiently inspected without impairing the remote non-contact property.
[0050]
[Modification of First Embodiment]
FIG. 2 is a block configuration diagram showing a modification of the first embodiment of the laser ultrasonic inspection apparatus according to the present invention, and FIG. 3 is an explanatory diagram showing the effect of the configuration of FIG.
[0051]
In this modification, as shown in FIG. 2, the laser beam EL is branched into a predetermined number of beams by a plurality of optical branching devices 26a, 26b,... 26n, and each of the beams is divided into a plurality of optical systems 23a, 23b for fiber incidence. ,... Are incident and transmitted to a plurality of optical fibers 24a, 24b,... 24n via a plurality of optical systems 25a, 25b,. is there.
[0052]
Regarding the excitation of ultrasonic waves by laser light irradiation, it is known that the directivity, frequency, etc. of ultrasonic waves generated depending on the irradiation shape can be controlled [for example, C.I. B. Scruby and L.M. E. See Drain, “Laser Ultrasonics: Technologies and Applications” (Bristol: Adam Hillger, 1990, etc.).
[0053]
In a normal case, such a spot shape is formed by using a lens system. For example, using the configuration shown in FIG. 2, the irradiation spot is formed in a line shape like points 27a, 27b,. When arranged, sound waves on a circle centered on each point are phase-matched on the surface of the material to be inspected 3 and are strengthened in the directions of D1 and D2 in the figure to form surface waves that hardly propagate in the vertical direction. be able to.
[0054]
Thus, according to this modification, the same effect as that of the first embodiment can be obtained.
[0055]
[Second Embodiment]
FIG. 4 is a block diagram showing a second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0056]
In this embodiment, the ultrasonic wave excited by the laser beam EL as shown in FIG. 4 is sent from the measurement point on the inspection object 3 to the Fabry-Perot resonator 17 stably controlled using the reference light RL. The measurement light PL, which is reflected light, is measured by being incident on the Fabry-Perot resonator 17 via the quarter-wave plate 21, the polarization beam splitter 7d, the mirror 22, and the half-wave plate 6b. .
[0057]
In the present embodiment, a fiber incident optical system 28 as a second incident optical system for allowing the measurement light ML, which is the second laser light, to enter the optical fiber 29 as the second optical fiber, and the measurement light An optical fiber 29 that transmits ML to the vicinity of the inspection target material 3 and transmits a reflection component of the measurement light ML on the surface of the inspection target material 3 to the receiving optical system 5, and an optical fiber 29 at the front end of the inspection target material 3 side. A fiber emitting optical system 30 as an irradiation / condensing optical system for irradiating the inspection light 3 to the inspection material 3 under a predetermined irradiation condition and condensing the reflection component under the predetermined light collection condition; It has.
[0058]
In other words, a fiber incidence optical system 28 is attached to the rear end of the optical fiber 29, and a fiber emission optical system 30 is attached to the front end thereof.
[0059]
Since the configuration and operation other than those described above are the same as those of the conventional example shown in FIG.
[0060]
Therefore, in the present embodiment, not only the reflected light PL from the material to be inspected 3 but also the optical fiber is used for transmission of the measuring light ML using the fiber incident optical system 28, the optical fiber 29, and the fiber emitting optical system 30. There is. At this time, the reflected light PL from the material to be inspected 3 propagates through the same path and is guided to the Fabry-Perot resonator 17.
[0061]
If comprised in this way, it will become possible to receive an ultrasonic wave only by installing the small fiber emission optical system 30 in the vicinity of the comparatively high energy laser beam EL, and a laser welding apparatus, a laser cutting apparatus, By using it in combination with an existing pulse laser system such as a laser processing device or a laser material improvement device, an ultrasonic inspection can be performed at the same time.
[0062]
[First Modification of Second Embodiment]
FIG. 5 is a block diagram showing a first modification of the second embodiment of the laser ultrasonic inspection apparatus according to the present invention, and FIG. 6 is an explanatory diagram showing the effect of the configuration of FIG.
[0063]
As shown in FIG. 5, the first modification includes two transmission systems including a fiber incident optical system 28, an optical fiber 29, and a fiber emission optical system 30 for transmitting the measurement beam ML and the reflected light PL. It is a system. That is, the transmission system of the first modification is configured in two systems, such as fiber incidence optical systems 28a and 28b, optical fibers 29a and 29b, and fiber emission optical systems 30a and 30b.
[0064]
At this time, an imaging optical system 31 for transferring the images of a plurality of fiber end faces to the Fabry-Perot resonator 17 is installed in the front stage of the fiber incidence optical systems 28a, 28b, while the photodetectors 13a, An imaging optical system 32 for transferring the transferred images to the respective light detection surfaces is provided in the preceding stage of 13b. As a result, it is possible to individually detect the beams propagated through the respective transmission systems, and a plurality of points can be measured using one Fabry-Perot resonator 17.
[0065]
In addition, although FIG. 5 demonstrated the structure which uses two transmission systems, based on this modification, the structure using many transmission systems is also possible. In the invention disclosed in Japanese Patent Laid-Open No. 10-351440, as shown in FIG. 6, the ultrasonic wave US transmitted by the laser beam EL is detected by a plurality (two in the figure) of measurement beams PL1 and PL2, Means have been proposed for improving the detection performance of the crack 33 by measuring both the ultrasonic component UT that passes through the crack 33 and the reflected component UR. In order to realize this technique, a configuration in which the measurement beam is propagated in space and guided to the measurement point is conceivable. However, if an optical fiber as shown in FIG. The detection performance of 33 can be further improved.
[0066]
[Second Modification of Second Embodiment]
FIG. 7 is a block diagram showing a second modification of the second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0067]
The configuration and basic operation of the second modification are the same as those of the second embodiment shown in FIG. 5, but in this second modification, a fiber bundle 34 is used in the transmission system as shown in FIG. Rather than receiving multiple points, it enables distribution measurement.
[0068]
Although the laser beam irradiated to the inspection object 3 by the fiber emitting optical system 35 is reflected at each point on the surface of the inspection object 3, the positional relationship is preserved by the fiber bundle 34. The spatial information, that is, the image of the end face of the fiber bundle 34 is transferred to the Fabry-Perot resonator 17 by the imaging optical system 31. If the light emitted from the Fabry-Perot resonator 17 is transferred to the detection surface of the two-dimensional array type photodetector 36 via the imaging optical system 32, the information on each surface of the inspection object 3 is converted into the two-dimensional array type light. It is detected by each element of the detector 36, and the propagation of the ultrasonic wave can be visualized spatially.
[0069]
In this case, as the two-dimensional array-type photodetector 36, a CCD sensor with an image intensifier can be used in addition to a normal CCD sensor.
[0070]
In the second embodiment and each modified example, the optical fiber 29 or the fiber bundle 34 is used as the transmission system. However, the same operation and the same can be achieved in spatial transmission using an optical system such as an imaging lens. An effect is obtained.
[0071]
[Third Embodiment]
FIG. 8 is a block diagram showing a third embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0072]
This embodiment is a combination of the transmission system for transmitting the laser beam EL of the first embodiment and the transmission system for transmitting the measurement light ML and the reflected light PL of the second embodiment.
[0073]
That is, in this embodiment, as shown in FIG. 8, a fiber incident optical system 23 for making a laser beam EL incident on one or a plurality of optical fibers 24 and the laser beam EL corresponding to the optical system 23 to be inspected 3 One or a plurality of optical fibers 24 that transmit to the vicinity, and one or a plurality of optical fibers 24 for irradiating the inspected material 3 with laser light EL on the inspected material 3 side tip under predetermined irradiation conditions A fiber emitting optical system 25, a fiber incident optical system 28 for allowing the laser light ML to be incident on one or a plurality of optical fibers 29, and the laser light ML are transmitted to the vicinity of the material 3 to be inspected. One or a plurality of optical fibers 29 that transmit the reflection component of the ML on the surface of the inspection material 3 to the fiber emitting optical system 30, and the laser light ML on the inspection material 3 side tip of the optical fiber 29. And a predetermined irradiation with irradiation conditions, and fiber emission optical system 30 of the reflected component as the irradiation-condensing optical system for condensing light in a predetermined light condensing conditions.
[0074]
With this configuration, if only the fiber emitting optical systems 25 and 30 are installed in the vicinity of the material to be inspected 3, inspection can be performed, and even when the material to be inspected 3 is in a narrow portion or the like, Laser ultrasonic inspection can be performed without spatially transmitting light.
[0075]
[Fourth Embodiment]
FIG. 9 is a block diagram showing a fourth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0076]
In the present embodiment, the transmission system for transmitting the laser beam EL of the first embodiment and the transmission system for transmitting the measurement light ML and the reflected light PL of the second embodiment are used together, and those transmission systems are used. It is the same.
[0077]
That is, in the present embodiment, as shown in FIG. 9, the optical path of the laser light EL is adjusted by an optical system 37 such as a mirror, and the laser light EL is coaxial with the measurement light ML by an optical branching unit 38 as a light combining / branching means. After superposition, transmission to the inspection object 3 is performed by a fiber incident optical system 39 as a dual use optical system, an optical fiber 40 as a dual use optical fiber, and a fiber emission optical system 41 as a dual use irradiation / condensing optical system. To do.
[0078]
In such a configuration, the reflected light PL from the material to be inspected 3 is guided to the Fabry-Perot resonator FP via the same path. At this time, the reflected component of the laser light EL is also simultaneously converted into the Fabry-Perot resonator 17. And it enters into the photodetector 13 as stray light and becomes noise. In this case, laser light sources having different wavelengths are used for the laser light source 1 and the laser light source 4, and a narrow-band optical filter 42 that transmits only the oscillation wavelength of the laser light source 4 is disposed in front of the photodetector 13. It is necessary to prevent the reflection component of the laser beam EL from entering the photodetector 13.
[0079]
In the laser ultrasonic inspection apparatus of the first to fourth embodiments, the laser light source 1 includes a fundamental wave Nd: YAG laser light source that can oscillate laser light having pulse energy sufficient to excite ultrasonic waves. Is used.
[0080]
Further, in the laser ultrasonic inspection apparatus of the first to fourth embodiments, the laser light source 4 can oscillate laser light having coherence and narrow bandwidth sufficient to receive ultrasonic waves, A second harmonic Nd: YAG laser light source having a wavelength different from that of the fundamental wave of the Nd: YAG laser is used.
[0081]
[Fifth Embodiment]
FIGS. 10A and 10B are explanatory views showing a fifth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0082]
This embodiment is the same as the laser ultrasonic inspection apparatus according to any of the first to fourth embodiments, except that the optical fibers 24, 29, 40 and the fiber incident optical systems 23, 28, 39 or the optical fibers 24, 29, 40 are irradiated and collected. Antireflection means for reducing the amount of return light due to the reflection of the end face is provided at least in the incident / exit part of one of the optical fibers 25, 30, 41 of the optical fiber optical system.
[0083]
That is, the present embodiment is characterized in that the both ends of the optical fibers 24, 29, and 40 have an antireflection function as shown in FIG. 10B, for example. A normal optical fiber has a structure composed of a core Cr and a clad Cl as shown in FIG. 10A. When the measurement light ML is incident on the optical fiber, the incident light is incident on the reflected light PL from the material 3 to be inspected. End face reflection Lt and the end face reflection Lx of the emitting part are mixed, propagated through the same optical axis and detected by the photodetector 13, and become noise on the reflected light RL measurement, and return to the incident light path to return to the laser light source 1 or 4 is adversely affected, such as re-incident on 4 and degrading the stability of the light source.
[0084]
Therefore, as shown in FIG. 10B, if both ends of the fiber are inclined at an appropriate angle, the stray light of the end face reflection Lt and the end face reflection Lx overlaps the same optical axis as the reflected light PL or the measurement light ML. Therefore, good measurement can be realized. Therefore, according to the present embodiment, it is possible to suppress the influence due to reflection from the fiber incident surface.
[0085]
[Modification of Fifth Embodiment]
FIG. 11 is an explanatory view showing a modification of the fifth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0086]
In this modification, in the laser ultrasonic inspection apparatuses of the first to fourth embodiments, as shown in FIG. 11, containers 44a and 44b in which window portions 43a and 43b with non-reflective coating are formed on the fiber entrance and exit end surfaces, respectively. And filling the containers 44a and 44b with mediums 45a and 45b having a refractive index close to the refractive index of the core Cr of the fiber, respectively, it is possible to considerably reduce the end surface reflection Lt of the incident portion and the end surface reflection Lx of the emission portion. .
[0087]
In addition, it is also included in the range of this embodiment to use the fiber which gave the non-reflective coating to the incident / exit end face of the fiber. Further, when the optical fibers 23 and 29 are connected in the middle using a connector or the like, the same effect can be obtained by performing the same processing as described above on the end surfaces.
[0088]
[Sixth Embodiment]
FIG. 12 is a block diagram showing a sixth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0089]
In the present embodiment, in the laser ultrasonic inspection apparatus of the first to fourth embodiments, a Michelson interferometer that measures surface displacement induced by ultrasonic waves is used as the receiving optical system 5 as shown in FIG. Is. Here, in the Michelson interferometer, since coherence of the interference light becomes a problem, it is efficient to use a single mode optical fiber as the optical fiber 29.
[0090]
In the receiving optical system 5 in FIG. 12, quarter-wave plates 21a and 21b are installed, and deflected beam splitters 7e and 7f are installed.
[0091]
On the other hand, the laser ultrasonic inspection apparatus shown in FIGS. 1, 2, 4, 5, 7, 8, 9 has a configuration using a Fabry-Perot resonator 17 as the receiving optical system 5. Here, the type of the optical fiber used in each embodiment is not limited, but when the Fabry-Perot resonator 17 is used, the optical fiber 29 is a multimode optical fiber such as a step index optical fiber or a graded index optical fiber. It is more efficient to use
[0092]
[Seventh Embodiment]
FIG. 13 is a block diagram showing a receiving optical system of a seventh embodiment of the laser ultrasonic inspection apparatus according to the present invention. FIG. 13 shows only the Fabry-Perot resonator 17 that is the receiving optical system 5.
[0093]
In the present embodiment, as shown in FIG. 13, a fiber incident optical system 28b, an optical fiber 29b, and a fiber emission optical system 30b are installed in the optical path of the reference light RL in the same manner as the optical path of the measurement light ML. That is, the reference light RL that controls the Fabry-Perot resonator 17 is configured to pass through the third optical fiber 29 b having the same core diameter as the second optical fiber 29.
[0094]
As a result, the optical characteristics such as the beam diameter and mode of the reference light for controlling the Fabry-Perot resonator 17 become closer to the reflected light RL that is actually measured, and the receiving optical system 5 is highly sensitive and easy to adjust. It becomes possible to provide.
[0095]
[Eighth Embodiment]
FIG. 14 is a block diagram showing a fiber incident optical system of an eighth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0096]
As shown in FIG. 14, the present embodiment has a focus dispersion type optical system for allowing laser light oscillated from the laser light source 1 to enter the optical fiber 24. That is, this focus dispersion type optical system is a micro lens that adjusts the optical path so that the concave lens 46 that expands the laser beam EL and the beam that passes through each point in the beam cross section of the laser beam EL are condensed at spatially different positions. A lens array 47 and a lens 48 are included.
[0097]
In the above configuration, the laser light EL oscillated from the laser light source 1 is once magnified by the concave lens 46, and then the beam passing through each point in the beam cross section is condensed at a spatially different position by the microlens array 47. The optical path is adjusted so as to be incident on the optical fiber 24 by the lens 48 thereafter.
[0098]
Here, since the laser light EL has relatively high pulse energy, if it is simply spatially condensed at one point, breakdown may occur at that point, and the optical fiber 24 or the like may be damaged.
[0099]
Therefore, if the configuration shown in FIG. 14 is adopted, the laser light EL does not have a focal point at one point, so that there is no concentration of energy, and the optical fiber 24 is not damaged, and the laser light EL having a higher energy is transmitted to the optical fiber. 24 can be transmitted.
[0100]
As described above, according to the first to eighth embodiments, laser light for transmitting and receiving ultrasonic waves is transmitted using an optical fiber, an irradiation optical system, or a small inspection probe of an irradiation / collection optical system. By transmitting, the inspected material 3 in the narrow portion can be efficiently inspected without impairing the remote non-contact property.
[0101]
[Ninth Embodiment]
FIG. 15 is a block diagram showing a ninth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0102]
In the ultrasonic excitation method by laser irradiation, longitudinal waves, transverse waves, surface waves and the like are generated simultaneously as described above. Among these ultrasonic modes, for example, longitudinal waves and transverse waves propagating through the inspected material 3 are suitable for measuring defects, material characteristics, or plate thickness inside the inspected material 3, Propagating surface waves are suitable for measuring surface cracks, surface properties, or properties of films attached to the surface.
[0103]
Here, these ultrasonic modes have a specific sound speed determined by the material of the material to be inspected 3. For example, when the material 3 to be inspected is steel, the surface wave sound velocity is about 2,900 m / sec, the longitudinal wave sound velocity is about 6,000 m / sec, and the transverse wave sound velocity is about 3,240 m / sec.
[0104]
Therefore, in this embodiment, as shown in FIG. 15, a spatial region (distance from a sound source: d _b ~ D _e ) And known sound speed v
[Expression 1]

If the time processing gate 49 having the time interval is provided in the signal processing device 14, it is possible to observe a desired signal without being interfered with other modes.
[0105]
As described above, in the present embodiment, the signal processing means 14 extracts the surface wave component propagating on the surface of the inspection object 3 from the generated ultrasonic wave, the longitudinal wave component or the transverse wave component propagating inside, and from the information. Display and record the presence / absence of cracks on the surface, inside and back of the material to be inspected, crack size and surface wave, thickness of the material to be inspected, back surface condition, and propagation phenomenon of longitudinal or transverse waves. is there.
[0106]
[Tenth embodiment]
FIG. 16 is a block diagram showing a tenth embodiment of a laser ultrasonic inspection apparatus according to the present invention, and FIG. 17 is an explanatory diagram showing signal processing using wavelet transform in the tenth embodiment.
[0107]
The ultrasonic signal detected by the receiving optical system 5 and the photodetector 13 may have an S / N ratio due to, for example, disturbance noise or noise generated by the photodetector 13 or the signal processing device 14. It may not be obtained well.
[0108]
At this time, it is possible to observe a good signal by installing the S / N ratio improving means 50 in the signal processing apparatus 14 as in the present embodiment. As the S / N ratio improvement means 50, for example, when it is known that a signal is mixed in a certain frequency band, a low-pass filter, a high-pass filter, or a band-eliminate filter that removes the band may be used. When the frequency band of a component is known in advance or when it is desired to focus only on a signal component in a certain frequency band, a band pass filter that passes only that band may be used.
[0109]
Further, when the dominant noise has a random frequency component such as thermal noise, it may have an averaging processing function for averaging the signals multiple times. In this case, if the transmission / reception interval of the ultrasonic waves by the laser is always the same, it is convenient for timing control to perform the averaging process using the transmission timing of the laser light source 1 as a reference time (trigger). If the transmission / reception interval changes depending on the time due to problems such as scanning of the transmission / reception points, the ultrasonic signals are digitized and stored, and only the data that can be regarded as almost the same distance is selected from them and added up You may do it.
[0110]
Furthermore, in the case where the ultrasonic signal to be observed is a repetitive signal having a waveform that can be regarded as a similar shape, such as an ultrasonic echo signal, the autocorrelation of the signal or the mutual relationship with a signal that serves as a reference prepared in advance. The S / N ratio can also be improved by calculating the correlation.
[0111]
Further, when the frequency component included in the detected ultrasonic signal is important, it is possible to detect a specific phenomenon with high sensitivity by performing signal processing using a wavelet transform as shown in FIG. . These processes include not only the case where the output signal of the photodetector 13 is processed as an analog electric signal, but also the case where an analog-digital converter is installed in the signal processing means 14 and processed as a digital signal. .
[0112]
As described above, in the present embodiment, in the signal processing device 14, the received ultrasonic signal is subjected to signal filtering in an appropriate band, multiple signal averaging processes, correlation processing in an appropriate region, or wavelet in an appropriate band. Conversion processing is performed.
[0113]
[Eleventh embodiment]
FIG. 18 is a block diagram showing an eleventh embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0114]
In the present embodiment, as shown in FIG. 18, the laser light EL and the measurement light ML are transmitted to the fiber emitting optical systems 25 and 30 through the optical fibers 24 and 29, respectively, and the fiber emitting optical systems 25 and 30 are individually transmitted. Are mounted on the drive mechanisms 51a and 51b, and the drive mechanisms 51a and 51b are configured so as to be able to scan and drive on the rails 52 laid in advance, thereby automatically inspecting one or more points on the inspection object 3 Is what you do. These drive mechanisms 51a and 51b and the rail 52 constitute a scanning means.
[0115]
Therefore, in the present embodiment, scanning means for scanning the output optical systems 25 and 30 individually or simultaneously is provided, and in the signal processing device 14, the received ultrasonic information is converted into the scanning position by the scanning means. It is related to multi-dimensional display.
[0116]
If the material 3 to be inspected is in a narrow space or high place, or if the material 3 to be inspected is not easily accessible due to high temperature, high radioactivity, etc. Even when the inspection is performed periodically, there is an effect that the inspection of a predetermined position can be performed in a short time by the rail 52 installed in advance.
[0117]
Furthermore, if a position detection mechanism is attached to the drive mechanisms 51a and 51b, the inspection record and the inspection position can be associated quantitatively.
[0118]
In the present embodiment, the fiber emitting optical systems 25 and 30 are mounted on the separate drive mechanisms 51a and 51b. However, if they are installed on one drive mechanism, the transmission / reception interval of the ultrasonic waves is shown. Can always be kept constant.
[0119]
[Twelfth embodiment]
19A and 19B are explanatory views showing display examples of the twelfth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0120]
FIGS. 19A and 19B are display examples of data measured by a laser ultrasonic inspection apparatus capable of scanning a transmission / reception position as shown in FIG. 18, for example.
[0121]
Now, assume that a transmission / reception point is scanned along a path indicated by a two-dot chain line with respect to the inspection object 3 having the thinned portion G on the back surface as schematically shown in FIG. Then, since the thinned portion G is thinner than the other portions, for example, the propagation time of the ultrasonic wave US propagating inside such as a longitudinal wave and a transverse wave is different. Therefore, in the vicinity of the propagation time expected in advance in the ultrasonic signal obtained during the scanning (the above-mentioned t _b ~ T _e ), And when the measurement data at each position (y) is displayed as shown in FIG. 19A according to the scan, the back surface shape of the material 3 to be inspected is shown as indicated by the thick dotted line in the figure. It can be measured.
[0122]
Furthermore, if the speed of sound in the material to be inspected 3 is known, the shape can be detected quantitatively.
[0123]
FIGS. 20A and 20B are display examples when scanning is performed two-dimensionally. This is one-dimensionally, in the ultrasonic signal obtained as shown in FIG. In association with the two-dimensionally scanned position, the time when the material to be inspected 3 is thick (ie, the peak time is late) is dark and the color is displayed so that it is light when it is early. 21A and 21B are display examples when the same measurement result is shown three-dimensionally, and it can be seen that the back surface shape of the material 3 to be inspected can be visualized by this apparatus.
[0124]
On the other hand, FIGS. 22A and 22B are examples when focusing on surface waves. As shown in FIG. 22B, when cracks F1, F2, and F3 exist on the material 3 to be inspected, surface waves having directivity in the azimuth (y) along the path indicated by the two-dot chain line in the figure. When transmitting and receiving, if there is a crack F, the surface wave is reflected by the crack F and a crack echo is observed.
[0125]
Therefore, if a time gate corresponding to the inspection region is provided and the ultrasonic signal level in the time region is displayed in shades or colors, the surface crack can be visualized as shown in FIG.
[0126]
As described above, in this embodiment, the display device 15 of the signal processing device SP associates the received ultrasonic signal intensity information, the measured crack size information, or the measured ultrasonic propagation information with the transmission / reception position. In other words, the image is displayed in multi-dimensions in shades or colors.
[0127]
As described above, according to the ninth to twelfth embodiments, by applying appropriate electrical signal processing to the received ultrasonic signal, or adjusting the ambient atmosphere or surface state of the material to be inspected, S It is possible to improve the accuracy of evaluation by improving the / N ratio and present the detected information so that the inspector can easily understand it.
[0128]
[Thirteenth embodiment]
FIG. 23 is a block diagram showing a thirteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0129]
In this embodiment, as shown in FIG. 23, the laser light source 1, the receiving optical system 5, the photodetector 13, and the signal processing device 14 are placed on a trackless traveling carriage 53 as a conveying means, and a fiber emitting optical for laser light EL. The system 25 and the fiber emitting optical system 30 for the measurement light ML are respectively installed on the inspection arm 54 attached on the trackless traveling carriage 53. The trackless carriage 53 is provided with a position detection device 55 for confirming the inspection position, and the inspection arm 54 is provided with a monitoring TV camera 56 as monitoring means for monitoring the inspection work.
[0130]
A communication device 57a is installed on the laser light source 1, the receiving optical system 5, the photodetector 13, and the signal processing device 14, while a communication device 57b is installed on a remote drive / control device 58 as a control means. Is installed.
[0131]
Therefore, the ultrasonic data measured by the laser light source 1, the receiving optical system 5, and the photodetector 13 are processed by the signal processing device 14, and then transmitted via the communication devices 57a and 57b together with the position data and the image data. Wirelessly transmitted to the drive / control device 58. The measurement data, position data, and image data received by the drive / control device 58 are displayed in association with each other on the display device 15 and recorded in the evaluation device 16.
[0132]
In addition, the design drawing or CAD data of the material to be inspected 3 and its peripheral equipment or CAD data is recorded in the evaluation device 16 in advance, and the design information, shape, etc. of the corresponding equipment and part based on the inspection position data and image data are stored. By simultaneously displaying on the display device 15, more efficient and advanced inspection can be performed.
[0133]
The drive / control device 58 is configured to be able to drive and control the trackless carriage 53 and the inspection arm 54 from a remote location. According to such a configuration, the inspection by the laser ultrasonic inspection apparatus can be performed even when the inspected material 3 is an operating device or when it is difficult for an inspector to approach such as high temperature or high radiation environment.
[0134]
As the monitoring means, in addition to the monitoring TV camera 56 and the distance sensor, a ferrite detector for detecting a weld metal, or a three-dimensional TV camera using double parallax can be used.
[0135]
[First Modification of Thirteenth Embodiment]
FIG. 24 is a block diagram showing a first modification of the thirteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0136]
The embodiment shown in FIG. 23 is an example in which a laser ultrasonic inspection apparatus is mounted on a wireless, trackless traveling cart, but the first modification shown in FIG. 24 is a case with a track.
[0137]
In this first modified example, as shown in FIG. 24, a track 59 is fixedly installed in advance, and a fiber emitting optical system 39 is mounted on a monorail traveling carriage 60 as a conveying means that travels on the track 59. Yes. In this case, if the monorail traveling carriage 60 has sufficient space, the laser light source 1, the receiving optical system 5, the photodetector 13, the signal processing device 14, and the like may be mounted on the monorail traveling carriage 60. Although it is possible, in many cases there is no space, and since the optical fiber 40 can be routed using the track 59, they are installed in the remote base station together with the drive / control device 58 and the like, and only the head portion is mounted. It is easy to do.
[0138]
As in the thirteenth embodiment, if a monitoring camera, a distance sensor, a position sensor, and the like are mounted on the monorail traveling carriage 60, a more reliable inspection can be performed.
[0139]
[Second Modification of Thirteenth Embodiment]
FIG. 25 is a block diagram showing a second modification of the thirteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0140]
In the second modification, in the first modification, a portable rail 61 is used as a track as shown in FIG. 25, and a traveling carriage 62 is provided as a conveying means that travels on the portable rail 61. . By providing the traveling carriage 62 with a fine movement mechanism capable of fine movement in the direction parallel to the optical axis, the focus of the laser light EL and the measurement light ML can be finely adjusted.
[0141]
By adopting such a configuration, it is possible to efficiently inspect even when the material to be inspected 3 is a portion that is difficult to inspect, such as a pipe that is installed at a high number in a high place.
[0142]
In the thirteenth embodiment and the modifications thereof, the conveyance means position detection means installed on the conveyance means such as the trackless carriage 53, the laser light EL that is the first and second laser light, and the measurement light ML. The irradiation position identifying means for detecting the irradiation position of the inspection object 3 and the inspection position identification means for detecting the inspection position on the inspection object 3 and the inspection object 3 from these pieces of information may be provided.
[0143]
In the thirteenth embodiment and its modifications, the signal processing device 14 is provided with a multidimensional information database relating to the size and shape of the material 3 to be inspected, and the display unit 15 of the signal processing device SP has the above-described inspection position identifying means. You may make it display output information and the information of the applicable site | part of the said multidimensional information database correspondingly.
[0144]
[Fourteenth embodiment]
FIG. 26 is a configuration diagram showing a fourteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
[0145]
The fourteenth embodiment is a case where the material to be inspected 3 is in particular a nuclear reactor 63 or a reactor internal structure 64, and the ambient atmosphere can be air or water. The transmission of laser light EL that can transmit ultrasonic waves is described in “Yuji Sano et. Al. A pulsed light transmission device 65 into the furnace as described in “November 1999” is known.
[0146]
In the present embodiment, the laser light source 1, the receiving 5, the photodetector 13, the signal processing device 14, and the like are installed in the optical equipment chamber 66 provided on the nuclear reactor 63, and the optical fiber 29 is used as a conveying means from there. By installing along the pulsed light transmission device 65, which is an example of the in-furnace remote control mechanism, the measurement light ML is guided to the inspection position, and the fiber emitting optical system 30 is installed at the tip of the pulsed light transmission device 65. The apparatus inspects the nuclear reactor 63 or the in-furnace structure 64 as the material to be inspected by transmitting and receiving the measurement light ML.
[0147]
[First Modification of Fourteenth Embodiment]
FIG. 27 is a block diagram showing a first modification of the fourteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0148]
In this modification, as shown in FIG. 27, when the pulse light transmission device 67 as in the fourteenth embodiment is not used and the laser light EL is also transmitted by an optical fiber, the reactor 63 or the in-reactor structure is used. Fiber exit optical systems 25 and 30 are installed in an in-furnace inspection robot 67 which is an example of a remote operation mechanism for in-furnace as a transport means that moves along the object 64, and lasers are provided to these fiber exit optical systems 25 and 30. The light EL and the measurement light ML are transmitted through the optical fibers 24 and 29.
[0149]
By applying this laser ultrasonic inspection apparatus, it becomes possible to efficiently inspect a narrow portion under severe conditions such as in the nuclear reactor 63. In this case, in consideration of the radiation resistance of the material, it is desirable to use quartz for the material of optical parts such as lenses and optical fibers and stainless steel or aluminum for the structural material.
[0150]
[Second Modification of Fourteenth Embodiment]
FIG. 28 is a block diagram showing a second modification of the fourteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0151]
In this modified example, as shown in FIG. 28, a material to be inspected is a pipe 68, and a mobile robot 69 which is an example of a pipe inner surface traveling mechanism as a conveying means capable of moving, scanning, and stopping inside the pipe 68 is provided. By installing the fiber emitting optical system 41 and using the optical fiber 40 to transmit the laser light EL and transmit / receive the measurement light ML, the inner surface of the longitudinal pipe can be efficiently inspected.
[0152]
[Fifteenth embodiment]
FIGS. 29A and 29B are configuration diagrams showing a fifteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
[0153]
In this embodiment, as shown in FIGS. 29A and 29B, the material to be inspected is a pipe 68, a track 70 is laid on the outer surface of the pipe 68, and a traveling carriage 71 can travel on the track 70. It is installed and the traveling carriage 71 is mounted with the laser light source 1 and the fiber emitting optical systems 30a and 30b. The track 70 is provided with an axial movement mechanism (not shown). The track 70 and the traveling carriage 71 constitute a piping outer surface traveling mechanism as a conveying means.
[0154]
In the above configuration, the laser light EL oscillated from the laser light source 1 is transmitted through the waveguide 73 having the lens 2 and the irradiation mirrors 72a and 72b, and is irradiated on the surface of the pipe 68, while the laser light source 4 (not shown). The measurement light ML oscillated from is transmitted through the two optical fibers 29a and 29b based on the configuration as shown in FIG. 5, and is irradiated onto the surface of the pipe 68 by the fiber emitting optical systems 30a and 30b.
[0155]
Here, if the fiber emitting optical systems 30a and 30b are installed so as to face the pipe 68, for example, the reflected light PL of the measurement light ML irradiated by the fiber emitting optical system 30a is collected by the same fiber emitting optical system 30a. The light is detected and detected by the receiving optical system 5. On the other hand, as shown in FIG. 29A, if the two fiber emitting optical systems 30a and 30b are arranged at an appropriate angle, the measurement light ML obliquely irradiated onto the pipe 64 from the fiber emitting optical system 30a. It is also possible to perform irradiation and condensing with different fiber emitting optical systems such that the regular reflection component is collected by the fiber emitting optical system 30b and vice versa. By comprising in this way, it becomes possible to test | inspect a longitudinal piping automatically and efficiently.
[0156]
[Sixteenth Embodiment]
FIG. 30 is a perspective view showing a sixteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0157]
In this embodiment, as shown in FIG. 30, a test object (not shown) is present in the water, and the fiber emitting optical systems 25 and 30 are set by an underwater swimming robot 74 which is an example of an underwater swimming mechanism as a transport means. It is transported to the vicinity of the inspection position and inspected. The underwater swimming robot 74 is provided with a surveillance TV camera 56, and the surveillance TV camera 56 can monitor inspection work in water.
[0158]
The fiber emitting optical systems 25 and 30 can be finely moved by the drive motor 75. After the underwater swimming robot 74 performs rough positioning, the drive motor 75 is driven to drive the fiber emitting optical system 25 and 30. 30 can be positioned at a detailed inspection position.
[0159]
Furthermore, in order to cope with a case where the flow of water is fast, in this embodiment, the fixed swimming point inspection can be performed by fixing the underwater swimming robot 74 to the surrounding structural member 76 using the fixing mechanism 77. For example, when a crack or the like is detected and continuously evaluated and monitored, the vicinity of the crack detected by the laser beam EL is marked, and the position is detected by the monitoring TV camera 56, so that each time. The same crack can always be measured in the inspection.
[0160]
[Seventeenth embodiment]
FIG. 31 is a block diagram showing a seventeenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0161]
In this embodiment, as shown in FIG. 31, a plurality of fiber emitting optical systems 25 and 30 are installed in the vicinity of a predetermined inspection position on the inspection object 3, and the fiber emitting optical system to be used is switched. Thus, a plurality of locations can be inspected with one set of laser ultrasonic inspection apparatus.
[0162]
Therefore, the fiber emitting optical systems 25a, 25b, 25c,... And 30a are provided on the side of the inspection object 3 (as shown in the drawing, a plurality of inspection positions are not limited to the case where one inspection object 3 is set). , 30b, 30c ... and optical fibers 24a, 24b, 24c ... and 29a, 29b, 29c ... connected thereto, respectively, and optical fiber connectors 78a, 78b, 78c ... at the other end of these optical fibers. And 79a, 79b, 79c... Are installed. Of course, they may be fixed to the inspection object 3 or other peripheral members with an appropriate fixing jig (not shown) so that the irradiation and focusing conditions such as the focal point do not change.
[0163]
On the other hand, an optical fiber connector 78 as an attachment / detachment member is installed in the optical fiber 24 that transmits the laser light EL, and an optical fiber connector 79 as an attachment / detachment member is installed in the optical fiber 29 that transmits the measurement light ML.
[0164]
By configuring in this way, the optical fiber connectors 78 and 79 can be inspected at a plurality of points with a single device by appropriately switching the connection target to the optical fiber connectors 78a, 78b, 78c... And 79a, 79b, 79c. It is possible to realize a laser ultrasonic inspection apparatus capable of performing the above.
[0165]
[Eighteenth embodiment]
FIG. 32 is a block diagram showing an eighteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0166]
32. In addition to the configuration of the seventeenth embodiment, the present embodiment is intended for pipes, containers, equipment, and structural materials in which the material to be inspected 3 is shielded by the heat insulating material 80. The systems 25a, 25b, 25c... And 30a, 30b, 30c... Are installed inside the material to be inspected 3 and the heat insulating material 80. The optical fibers 24a, 24b, 24c... And 29a, 29b, 29c... Connected to them penetrate the heat insulating material 80 and are guided to the outside by using a dedicated penetration or its structural boundary. The optical fiber connectors 78a, 78b, 78c... And 79a, 79b, 79c... Installed at the other end of the optical fiber are collected in almost one place. Of course, they may be fixed to the inspection object 3 or other peripheral members with an appropriate fixing jig (not shown) so that the irradiation and focusing conditions such as the focal point do not change. By comprising in this way, the laser ultrasonic inspection apparatus in which the test | inspection which makes object the inside of a shield is possible is realizable.
[0167]
In the present embodiment, the material 3 to be inspected may be a pipe, container, device, or structural material installed in a narrow part. In this case, the optical fibers 24a, 24b, 24c... And 29a, 29b, 29c... Penetrate the heat insulating material 80 and are guided to a remote part where the inspection apparatus is installed.
[0168]
As described above, according to the thirteenth to eighteenth embodiments, an effective inspection can be performed by combining with the transport mechanism and its control mechanism.
[0169]
[Nineteenth Embodiment]
FIG. 33 is a block diagram showing a nineteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0170]
This embodiment is effective when inspecting an object to which an adherent 81, in particular, a substance that reduces propagation of ultrasonic waves or reception sensitivity, such as rust or paint, adheres to the surface of the inspection object 3 as shown in FIG. It is a simple configuration.
[0171]
A technique (laser cleaning technique) for removing the deposit 81 by scanning the laser beam CL oscillated from the laser light source 82 in the direction D is known, for example, from JP-A-7-225300. Since this laser beam CL also excites ultrasonic waves in the removal process of the deposit 81, it is possible to perform laser ultrasonic inspection while cleaning the surface by combining this with the receiving optical system 5 and the like. In particular, since the fiber emitting optical system 30 is simply installed at the tip of an existing laser cleaning device, the load on the device configuration is small, and inspection is performed as well as cleaning, with almost no change to existing laser cleaning equipment. Can be realized.
[0172]
[20th embodiment]
FIG. 34 is a block diagram showing a twentieth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0173]
This embodiment is an effective configuration for inspecting an object while improving the stress state on the surface of the inspection object 3 as shown in FIG. The surface stress improvement technique (laser peening technique) of the material 3 to be inspected by scanning the laser beam PeL oscillated from the laser light source 83 in the direction D is, for example, the above-mentioned ““ Yuji Sano et. Al. ”“ Process and application of shock ”. compression by nano-second pulses of frequency-doubled Nd: YAG laser, “Proc. of ALPHA'99 SPIE, Osaka, November 1999”.
[0174]
This laser beam PeL also excites ultrasonic waves in the process of improving the stress state on the surface of the material 3 to be inspected. By combining this with the receiving optical system 5 etc., laser ultrasonic inspection is performed while improving the surface stress. Can be performed. In particular, since the fiber emitting optical system 30 is only installed at the tip of the existing laser peening apparatus, the burden on the apparatus configuration is small, and not only the stress improvement but also the inspection is performed without almost changing the existing laser peening equipment. A laser ultrasonic inspection apparatus that can be performed can be realized.
[0175]
[Twenty-first embodiment]
FIG. 35 is a block diagram showing a twenty-first embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0176]
This embodiment is an effective configuration for inspecting an object while analyzing the material of the material to be inspected 3 as shown in FIG. A laser light BL oscillated from a laser light source 84 as a pulse laser light source is irradiated to ablate a minute volume on the surface of the material to be inspected 3, and the emitted light is condensed using a condensing optical system 85. A technique for analyzing a material composition by conducting a spectroscopic analysis by introducing it to a spectroscopic analysis / evaluation apparatus 87 as a pre-weighing means is known as a laser breakdown spectroscopic analysis technique.
[0177]
Since this laser beam BL also excites ultrasonic waves in the process of causing the material to be inspected 3 to emit plasma, the laser ultrasonic inspection can be performed while analyzing the material composition by combining this with the receiving optical system 5 and the like. It becomes possible.
[0178]
In the present embodiment, since the fiber emitting optical system 30 is only installed at the tip of the existing laser breakdown spectroscopy analyzer, there is little burden on the apparatus configuration, and the existing laser breakdown spectroscopy analyzer is almost changed. It is possible to realize a laser ultrasonic inspection apparatus capable of performing not only the material composition analysis but also the inspection.
[0179]
[Twenty-second embodiment]
FIG. 36 is a block diagram showing a twenty-second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0180]
This embodiment is an effective configuration when inspecting the crack or material characteristics of the material 3 to be inspected by paying attention to the propagation of the surface wave component in the ultrasonic wave excited by the laser beam EL.
[0181]
In general, the surface wave is attenuated quickly when the liquid W adheres to the surface of the material 3 to be inspected. Therefore, when the material 3 to be inspected is installed in the liquid, the level of the detectable surface wave signal is lowered. There are issues such as.
[0182]
Therefore, in the present embodiment, as shown in FIG. 36, a compressor 88 and a pipe 89 connected to the compressor 88 and having a tip disposed in the vicinity of the fiber output optical system 41 are installed, and the compressor 88 is driven to operate the air. Air is sprayed from the tip of the pipe 89 to the vicinity of the inspection point, and the ultrasonic transmission / reception point, that is, the irradiation position of the laser beam and the propagation path of the surface wave are replaced with a gas atmosphere. Therefore, the compressor 88 and the pipe 89 constitute a local gas atmosphere generating means.
[0183]
With this configuration, it is possible to observe a surface wave with little attenuation, and even when dust or the like is generated by irradiation with the laser beam EL, the dust or the like is scattered by the air Air that is blown to propagate the laser beam. There is an effect that it is difficult to become a scatterer on the path.
[0184]
[Modification of the twenty-second embodiment]
FIG. 37 is a block diagram showing a modification of the twenty-second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0185]
In this modification, as shown in FIG. 37, the region where the irradiation position of the laser beam and the propagation path of the surface wave are replaced with a gas atmosphere is covered with a container 90 as a local gas atmosphere generating means.
[0186]
Therefore, when it is difficult to keep the laser light irradiation position of the inspection object 3 and the propagation path of the surface wave in a state of being replaced with a gas atmosphere, the region is covered with a container 90 as in this modification. Thus, the replacement state can be held more easily.
[0187]
[Twenty-third embodiment]
FIG. 38 is a block diagram showing a twenty-third embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0188]
This embodiment is an effective configuration for inspection when the material to be inspected 3 needs to prevent surface damage and heat input as much as possible. There are two types of ultrasonic excitation processes using the laser beam EL: a thermal strain mode and an ablation mode.
[0189]
In general, in the thermal strain mode, the surface damage or thermal material change of the material to be inspected 3 does not occur, but in the ablation mode, evaporation of a very surface layer and slight heat input occur.
[0190]
In order to prevent this, in this embodiment, as shown in FIG. 38, if a protective film 91 is formed on the surface of the material 3 to be inspected in advance and the protective film 91 is irradiated with the laser light EL, an ablation mode is obtained. Surface damage or heat input can be suppressed. As the protective film 91, a substance that efficiently absorbs the laser beam EL is suitable, and should be selected according to the wavelength and energy of the laser beam EL. For example, a colored liquid such as ink or oil, a fine particle such as a colored powder, It may be solid or powder.
[0191]
[Twenty-fourth embodiment]
FIG. 39 is a block diagram showing a twenty-fourth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0192]
This embodiment is an effective configuration for an inspection in which the material 3 to be inspected is remotely installed and detailed focusing of the measurement light ML that cannot be confirmed from an image of a monitoring TV camera or the like is necessary. The reflected light PL from the surface of the material to be inspected 3 becomes the largest when the distance from the fiber emitting optical system 30 to the material to be inspected 3 is optimized, and the detection sensitivity of the ultrasonic signal becomes maximum in this state. However, since the light incident on the photodetector 13 includes not only the reflected light PL but also end-face reflection and stray light of each optical element, the situation of the reflected light PL is not necessarily clear.
[0193]
Therefore, in this embodiment, as shown in FIG. 39, the shielding plate driving device 93 is driven by the drive signal from the shielding plate drive control device 92, thereby operating the shielding plate 94 as return light confirmation means, and the measurement light ML. By forming a state that does not reach the inspection material 3, the return state of the reflected light PL can be confirmed from the change in the output signal of the photodetector 13 at that time.
[0194]
The shielding plate 94 is preferably a scatterer of the measurement light ML and has a low reflectance. It is also effective to install the shielding plate 94 at an angle so as not to be orthogonal to the optical axis. In this case, the shielding plate 94 may be a mirror. Further, for example, as shown in FIG. 30, the fiber emitting optical system 30 is mounted on the fine movement stage in advance, and the fiber emitting optical system 30 is placed at a position where the change in the output signal of the photodetector 13 due to the operation of the shielding plate 94 is maximized. It is also possible to align the optical system 30.
[0195]
[25th Embodiment]
FIG. 40 is a block diagram showing a 25th embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0196]
This embodiment is another configuration example that is effective in the case of inspection in which the inspected material 3 is remotely installed and detailed focusing of the measurement light ML that cannot be confirmed from the image of the monitoring TV camera or the like is necessary. is there. The reflected light PL from the surface of the material to be inspected 3 becomes the largest when the distance from the fiber emitting optical system 30 to the material to be inspected 3 is optimized, and the detection sensitivity of the ultrasonic signal becomes maximum in this state.
[0197]
Since the optimum value of the distance from the fiber emitting optical system 30 to the material to be inspected 3 can be estimated in advance from the focal length of the fiber emitting optical system 30, in this embodiment, as shown in FIG. A distance sensor 95 is installed at the tip of the optical system 30 for use, and the fine movement stage 97 is operated by the fine movement control device 96 so that the distance measured by the distance sensor 95 becomes an optimum value estimated in advance. It can be measured under conditions. These fine movement control device 96 and fine movement stage 97 constitute position adjustment means.
[0198]
[Modification of 25th Embodiment]
FIG. 41 is a block diagram showing a modification of the twenty-fifth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
[0199]
As shown in FIG. 41, this modification is to hold the distance from the fiber emitting optical system 30 to the inspection object 3 at an optimum value, and a distance fixing jig 98 is attached to the fiber emitting optical system 30. The distance fixing jig 98 is pressed against the material 3 to be inspected by a spring mechanism (not shown). Thereby, it becomes possible to keep the distance of the inspection object 3 from the fiber emitting optical system 30 to an optimum value with a simple configuration.
[0200]
【The invention's effect】
As described above, according to the present invention, a laser beam for transmitting and receiving ultrasonic waves is transmitted using an optical fiber, an irradiation optical system, or an irradiation / condensing optical system, so that remote non-contact property is achieved. It is possible to provide a laser ultrasonic inspection apparatus capable of efficiently inspecting a material to be inspected in a narrow part without being damaged.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a first embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 2 is a block configuration diagram showing a modification of the first embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 3 is an explanatory diagram showing an effect of the configuration of FIG. 2;
FIG. 4 is a block configuration diagram showing a second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 5 is a block diagram showing a first modification of the second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
6 is an explanatory diagram showing an effect of the configuration of FIG. 5;
FIG. 7 is a block diagram showing a second modification of the second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 8 is a block diagram showing a third embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 9 is a block diagram showing a fourth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
10A and 10B are explanatory views showing a fifth embodiment of a laser ultrasonic inspection apparatus according to the present invention. FIG.
FIG. 11 is an explanatory view showing a modification of the fifth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 12 is a block diagram showing a sixth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 13 is a block diagram showing a receiving optical system of a seventh embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 14 is a configuration diagram showing a fiber incident optical system of an eighth embodiment of the laser ultrasonic inspection apparatus according to the invention.
FIG. 15 is a block diagram showing a ninth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 16 is a block diagram showing a laser ultrasonic inspection apparatus according to a tenth embodiment of the present invention.
FIG. 17 is an explanatory diagram showing signal processing using wavelet transform in the tenth embodiment.
FIG. 18 is a block diagram showing an eleventh embodiment of a laser ultrasonic inspection apparatus according to the present invention.
19A and 19B are explanatory views showing display examples of a twelfth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIGS. 20A and 20B are explanatory diagrams showing display examples when scanning is performed two-dimensionally.
FIGS. 21A and 21B are explanatory diagrams showing a display example when the same measurement result is three-dimensionally shown.
FIGS. 22A and 22B are explanatory diagrams showing an example when focusing on surface waves. FIGS.
FIG. 23 is a block diagram showing a thirteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 24 is a block diagram showing a first modification of the thirteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 25 is a configuration diagram showing a second modification of the thirteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 26 is a configuration diagram showing a fourteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 27 is a block diagram showing a first modification of the fourteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 28 is a block diagram showing a second modification of the fourteenth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
29A and 29B are configuration diagrams showing a fifteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 30 is a perspective view showing a sixteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 31 is a block diagram showing a seventeenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 32 is a block diagram showing an eighteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 33 is a block diagram showing a nineteenth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 34 is a block diagram showing a twentieth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 35 is a block diagram showing a twenty-first embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 36 is a block diagram showing a twenty-second embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 37 is a block diagram showing a modification of the 22nd embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 38 is a block diagram showing a twenty-third embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 39 is a block diagram showing a twenty-fourth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 40 is a block diagram showing a twenty-fifth embodiment of a laser ultrasonic inspection apparatus according to the present invention.
FIG. 41 is a block diagram showing a modification of the twenty-fifth embodiment of the laser ultrasonic inspection apparatus according to the present invention.
FIG. 42 is a block diagram showing a conventional laser ultrasonic inspection apparatus.
FIG. 43 is an explanatory diagram showing the operation of a Fabry-Perot resonator.
FIG. 44 is an explanatory diagram showing the operation of a Fabry-Perot resonator.
FIG. 45 is a block diagram showing another conventional laser ultrasonic inspection apparatus.
FIG. 46 is a block diagram showing still another conventional laser ultrasonic inspection apparatus.
[Explanation of symbols]
1 Laser light source (first laser light source)
2 Optical system
3 Inspected material
4 Laser light source (second laser light source)
5 Receiving optical system
6a-6c half-wave plate
7a-7f Polarizing beam splitter
13 Photodetector (Signal conversion means)
14 Signal processing equipment
15 Display device
16 Evaluation device
17 Fabry-Perot resonator
18 Photodetector
19 Controller
20 Drive mechanism
21 1/4 wave plate
23 Fiber Incident Optical System (First Incident Optical System)
24 optical fiber (first optical fiber)
25 Optical system for fiber emission (irradiation optical system)
26 Optical splitter
28 Optical system for fiber incidence (second incident optical system)
29 Optical fiber (second optical fiber)
30 Fiber optical system (irradiation / condensing optical system)
31 Imaging optics
32 Imaging optical system
34 Fiber bundle
35 Optical system for fiber emission
36 Two-dimensional array type photodetector
37 Optical system
38 Optical splitter (photosynthesis / branching means)
39 Optical system for fiber incidence (Optical system for dual use)
40 Optical fiber (both-use optical fiber)
41 Optical system for fiber emission (both irradiation / condensing optical system)
42 Narrow band optical filter
43a, 43b Non-reflective coated window
44a, 44b container
45a, 45b Medium
46 concave lens
47 Micro lens array
48 lenses
49 hour gate
50 S / N ratio improvement means
51a, 51b drive mechanism
52 rails
53 Trackless trolley
54 Inspection Arm
55 Position detector
56 Surveillance TV camera
57a, 57b communication device
58 Drive and control equipment
59 Orbit
60 Monorail traveling cart
61 Transportable rail
62 Traveling cart
63 nuclear reactor
64 Reactor internal structure
65 Pulsed light transmission equipment
67 In-furnace inspection robot
68 Piping
69 Mobile robot
70 orbit
71 Traveling cart
72a, 72b Irradiation mirror
73 Waveguide
74 Underwater swimming robot
75 Drive motor
76 Structural members
77 Fixing mechanism
78, 78a-78c Optical fiber connector
79, 79a to 79c Optical fiber connector
80 thermal insulation
81 Deposits
82 Laser light source
83 Laser light source
84 Laser light source
85 Condensing optical system
86 Optical fiber
87 Spectroscopic analysis / evaluation equipment
88 Compressor
89 Piping
90 containers
91 Protective film
92 Shielding plate drive control device
93 Shield plate driving device
94 Shield plate
95 Distance sensor
96 Fine movement control device
97 Fine movement stage
98 Distance fixing jig
SP signal processor

Claims (8)

A first laser light source that oscillates a first laser beam for generating an ultrasonic wave on the material to be inspected, and a first laser light irradiated on the material to be inspected to receive an ultrasonic signal generated on the material to be inspected. A second laser light source that oscillates the second laser light, a receiving optical system that optically detects information about the ultrasonic wave from a reflection component of the second laser light on the surface of the inspection object, and the receiving optical system Signal converting means for converting an ultrasonic signal received in the optical system into an electrical signal, and signal processing means for processing an output signal of the signal converting means and displaying and recording information relating to the propagation of the ultrasonic waves the laser ultrasonic inspection apparatus having at least one first optical fiber for transmitting the first laser light oscillated from the first laser light source to the vicinity of the inspected material, wherein the optical fiber first First and focal distributed optical system for incident laser light, the first of the inspection material the provided inspection material side tip of the first laser light from the optical fiber oscillated from the laser light source An irradiation optical system for irradiating under a predetermined irradiation condition, and a second laser beam oscillated from the second laser light source is transmitted to the vicinity of the material to be inspected, and is irradiated by the second laser light source. And at least one second optical fiber that transmits a reflection component of the second laser beam on the surface of the material to be inspected to the receiving optical system, and the second optical fiber provided at the front end of the material to be inspected. And an irradiation / condensing optical system for performing irradiation / condensation of the second laser beam. A first laser light source that oscillates a first laser beam for generating an ultrasonic wave on the material to be inspected, and a first laser light irradiated on the material to be inspected to receive an ultrasonic signal generated on the material to be inspected. A second laser light source that oscillates the second laser light, a receiving optical system that optically detects information about the ultrasonic wave from a reflection component of the second laser light on the surface of the inspection object, and the receiving optical system Signal converting means for converting an ultrasonic signal received in the optical system into an electric signal, and signal processing means for processing the output signal of the signal converting means and displaying and recording information relating to the propagation of the ultrasonic waves In the laser ultrasonic inspection apparatus, the focus dispersion type optical system for entering the first laser light oscillated from the first laser light source and the first laser output from the focus dispersion type optical system light Photosynthesis / branching means for superimposing the second laser light on the same optical axis, dual-use incident optical systems for entering the first and second laser lights, respectively, and the first and second laser lights Both to the vicinity of the material to be inspected and to transmit the reflection component of the second laser light on the surface of the material to be inspected to the receiving optical system, and to the material to be inspected of the optical fiber for both A dual-use irradiation / condensing for irradiating the inspected material with the first and second laser light under a predetermined irradiation condition and condensing the reflection component under the predetermined light condensing condition. A laser ultrasonic inspection apparatus comprising an optical system. 3. The laser ultrasonic inspection apparatus according to claim 1, wherein the first laser light source for generating ultrasonic waves on the material to be inspected is a pulsed Nd: YAG laser light source. . 3. The laser ultrasonic inspection apparatus according to claim 1 or 2 , wherein the second laser light source for irradiating the surface of the material to be inspected and receiving an ultrasonic signal is a second harmonic light source of a continuously oscillating Nd: YAG laser. The laser ultrasonic inspection apparatus characterized by being. 3. The laser ultrasonic inspection apparatus according to claim 1, wherein an antireflection means for reducing a return light amount due to reflection of the end face is provided at an incident / exit portion of the optical fiber. 3. The laser ultrasonic inspection apparatus according to claim 1, wherein the receiving optical system for optically detecting information related to the ultrasonic wave is a Michelson interferometer, and the reflection on the surface of the material to be inspected is received by the receiving optical system. A laser ultrasonic inspection apparatus, wherein an optical fiber for transmitting a component is a single mode optical fiber. 7. The laser ultrasonic inspection apparatus according to claim 6, wherein the receiving optical system for optically detecting information relating to the ultrasonic wave is a Fabry-Perot optical meter, and the Fabry-Perot optical meter reflects the reflection on the surface of the material to be inspected. A laser ultrasonic inspection apparatus, wherein an optical fiber for transmitting a component is either a graded index optical fiber or a step index optical fiber. 8. The laser ultrasonic inspection apparatus according to claim 7, wherein the reference light for controlling the resonator of the Fabry-Perot optical meter is transmitted through an optical fiber having the same core diameter as that of the optical fiber for transmitting a reflection component on the surface of the inspection object. A laser ultrasonic inspection apparatus characterized by that.

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