CN115184463A - Laser ultrasonic detection device - Google Patents

Abstract

The invention relates to the technical field of non-destructive testing, in particular to a laser ultrasonic testing device, comprising: a laser ultrasonic scanning module and a microphone array; the laser ultrasonic scanning module includes: an optical fiber interface, a galvanometer and a field mirror; the optical fiber interface is arranged on the laser A through hole on the surface of the ultrasonic scanning module and communicated with the galvanometer; the galvanometer, the field mirror and the microphone array openings are coaxial. The laser is controlled by the laser ultrasonic scanning module, and after the laser ultrasonic signal of multiple reflections is excited on the surface and inside of the material to be tested, it is received by the microphone array; the laser ultrasonic detection device integrates the laser ultrasonic scanning module and the microphone array. Plug and play on the optical fiber not only ensures the detection effect of the laser ultrasonic signal, but also increases the portability and versatility of the detection device.

Description

A laser ultrasonic testing device

technical field

The invention relates to the technical field of non-destructive testing, in particular to a laser ultrasonic testing device.

Background technique

As a new type of non-destructive testing technology emerging in the past ten years, laser ultrasound has the advantages of high resolution, non-contact and wide frequency band. There are two main methods of receiving laser ultrasonic signals: optical method and electrical method. The optical method mainly uses an optical interferometer to receive laser ultrasonic signals, but the optical interferometer is bulky and has high requirements for the detection object and detection environment; the electrical method mainly uses piezoelectric The transducer receives ultrasonic signals, but requires the use of couplant during the detection process, and the detection range is small.

SUMMARY OF THE INVENTION

The present application provides a laser ultrasonic detection device, which solves the problems in the prior art that the detection range of the laser ultrasonic signal is small and the instrument is complicated and bulky.

The application provides a laser ultrasonic testing device, including:

Laser ultrasound scanning module and microphone array;

The laser ultrasonic scanning module includes: an optical fiber interface, a galvanometer and a field mirror; the optical fiber interface is a through hole arranged on the surface of the laser ultrasonic scanning module and communicated with the galvanometer;

The microphone array includes microphones with multiple center frequencies, and the center of the microphone array is provided with an opening for the laser beam to pass through;

The galvanometer mirror, the field mirror and the microphone array openings are coaxial.

Optionally, in the microphone array, the spacing between adjacent microphones satisfies the spatial sampling theorem, specifically:

Among them, d is the spacing of the microphones, and λ is the acoustic wavelength corresponding to the highest center frequency in the microphone array.

Optionally, in the microphone array, there are multiple microphones of each center frequency, and the multiple microphones of the same center frequency are evenly distributed around the center of the microphone array.

Optionally, in the microphone array, microphones with different center frequencies are arranged alternately around the center of the array in the array.

Optionally, there are multiple types of microphones in the microphone array, including: multi-band MEMS digital microphones, multi-band MEMS analog microphones, multi-band ECM analog microphones, and multi-band ECM digital microphones.

Optionally, the center frequency range of the microphone is 20KHz-100KHz.

Optionally, the microphone array is arranged on a PCB board, and a through hole is formed in the center of the PCB board, and the area of the through hole is larger than the scanning range of the galvanometer.

Optionally, the optical fiber interface is provided with a fixing clip for fixing the connection between the optical fiber and the optical fiber interface.

Optionally, the laser ultrasonic testing device further includes:

The signal transmission module is electrically connected with the signal acquisition and processing module, and is used for transmitting the preprocessed laser ultrasonic signal to the computer.

Optionally, the signal transmission module is specifically a Bluetooth module or a WIFI module.

In the laser ultrasonic testing device provided by this application, after the optical fiber interface of the laser ultrasonic testing device is connected to the optical fiber or injected into the laser beam, the laser is controlled by the laser ultrasonic scanning module and passes through the microphone array, and then passes through the surface and inside of the material to be tested. The laser ultrasonic signal with multiple reflections is excited, and then received by the microphone array; the laser ultrasonic detection device integrates the laser ultrasonic scanning module and the microphone array, and is plug-and-play on the optical fiber, which not only ensures the detection effect of the laser ultrasonic signal, but also It also increases the portability and versatility of the detection device, and compared with piezoelectric transducers and optical interferometers, the microphone has the advantages of low cost, small size and high sensitivity, and the detection distance can be as high as tens to hundreds of millimeters. Industrial preparation of large-scale arrays is easy.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

Fig. 1 is the first schematic diagram of the structure of the laser ultrasonic testing device provided by the application;

2 is a schematic structural diagram of a microphone array of a laser ultrasonic detection device provided by the application;

FIG. 3 is a second schematic diagram of the structure of the laser ultrasonic testing device provided by the application.

Among them, the reference numerals are:

10. Laser ultrasound scanning module; 11. Optical fiber interface; 12. Galvo mirror; 13. Field lens; 20. Microphone array; 21. Microphone; 22. PCB board; 30. Signal transmission module; 40. Signal acquisition and processing module.

Detailed ways

In order to make the purpose, features and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the following The described embodiments are only some, but not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

The present application provides a laser ultrasonic detection device, which solves the problems in the prior art that the detection range of the laser ultrasonic signal is small and the instrument is complicated and bulky.

Please refer to FIG. 1 . FIG. 1 is a first structural schematic diagram of the laser ultrasonic testing device provided by the present application.

A first aspect of this embodiment provides a laser ultrasonic detection device, including:

Laser ultrasound scanning module 10 and microphone array 20;

The laser ultrasonic scanning module 10 includes: an optical fiber interface 11, a galvanometer 12 and a field lens 13; the optical fiber interface 11 is a through hole arranged on the surface of the laser ultrasonic scanning module 10 and communicated with the galvanometer 12;

It should be noted that the optical fiber interface 11 is provided on the laser ultrasonic scanning module 10, so that the optical fiber can be connected to the laser ultrasonic scanning module 10 to conduct the laser beam to the galvanometer 12 and the field mirror 13; The outgoing laser beam is aimed at the optical fiber interface 11, and the laser beam is directly injected into it.

Further, the galvanometer 21 is used for driving the deflection of the laser beam, and the field mirror 22 is used for focusing to ensure the intensity of the excited ultrasonic waves, and the two are combined to control the laser scanning.

The microphone array 20 includes microphones with various center frequencies, and the center of the microphone array 20 is provided with an opening for the laser beam to pass through;

It should be noted that the microphones are acoustic microphones. In the microphone array 20, microphones with various center frequencies can increase the receiving range of the ultrasonic wave band and improve the sensitivity of laser ultrasonic signal detection. Further, compared with piezoelectric transducers and optical interferometers, microphones have the advantages of low cost, small size, and high sensitivity, and the detection distance can be as high as tens to hundreds of millimeters, which is easy for industrial fabrication of large-scale arrays.

After the laser beam passes through the laser ultrasonic scanning module 10, it passes through the opening in the center of the microphone array 20, shoots on the object to be detected, and excites the laser ultrasonic signal; the opening is used to prevent the microphone array from blocking the laser beam and affecting the laser scanning.

The galvanometer mirror 12, the field mirror 13 and the microphone array openings are coaxial.

It should be noted that, in this embodiment, a housing adapted to the laser ultrasound module can be used to install the galvanometer and field mirror of the laser ultrasound scanning module, as well as the microphone array, so that they are coaxially arranged.

In this embodiment, after the optical fiber interface 11 of the laser ultrasonic detection device is connected to the optical fiber or injected into the laser beam, the laser is controlled by the laser ultrasonic scanning module 10 and passes through the microphone array 20. The laser ultrasonic signal with multiple reflections is excited, and then received by the microphone array 20; the laser ultrasonic detection device integrates the laser ultrasonic scanning module 10 and the microphone array 20, and is plug-and-play on the optical fiber, which not only ensures the laser ultrasonic signal. The detection effect also increases the portability and versatility of the detection device.

The above is the detailed description of the first embodiment of the laser ultrasonic testing device provided by the application, and the following is the detailed description of the second embodiment of the laser ultrasonic testing device provided by the application.

The microphone in this embodiment is specifically an acoustic microphone. The ultrasonic signal excited by laser ultrasound is a broadband signal, which has no specific range. When the inspector uses the transducer, in order to ensure the detection resolution, the ultrasonic frequency range of the inspection is usually 20-100Mhz, ignoring other excited low-frequency ultrasonic waves. Therefore, the acoustic microphone with a lower receiving frequency will not be considered for signal reception. In the early stage of the development of the laser ultrasonic testing field, the sensitivity and response range of the acoustic microphone were not enough to meet the detection requirements. Industry bias.

Please refer to FIG. 2 . FIG. 2 is a schematic structural diagram of a microphone array of the laser ultrasonic detection device provided by the present application. The microphone array is composed of a microphone 21 and a PCB board 22 . This embodiment provides a microphone array of a laser ultrasonic detection device.

In the microphone array, in order to avoid spatial aliasing, when the sampled signals are restored to continuous signals, they overlap each other and become distorted. When the sampled signals are restored to continuous signals, they overlap each other and become distorted. The distance needs to satisfy the spatial sampling theorem, namely:

Among them, d is the spacing of the microphones, and λ is the acoustic wavelength corresponding to the highest center frequency in the microphone array.

According to the characteristics of the circle, we use the cosine law to get the relationship between the spacing and the radius:

Among them, R is the radius of the ring array, and M is the number of microphones.

After substituting the relation of the spatial sampling theorem, we get:

The relationship between the radius R of the annular array of microphone arrays, the number M of microphones, and the wavelength λ of the microphone frequencies can be obtained.

Further, there are multiple microphones of each center frequency, and the multiple microphones of the same center frequency are evenly distributed around the center of the microphone array.

Further, microphones with different center frequencies are arranged alternately around the center of the array in the array.

It should be noted that the multiple microphones with the same center frequency are evenly distributed around the center of the microphone array 20; the microphones with multiple center frequencies can increase the receiving range of the ultrasonic wave band, and improve the laser beam with the same type of microphones Sensitivity of ultrasonic signal reception, complete sampling of the signal.

Further, in this embodiment, we select four microphones with different center frequencies, namely 20KHz, 30KHz, 40KHz and 50KHz, 8 microphones for each frequency, a total of 32, and set the microphones of each center frequency in On a circular array of the same radius; it should be noted that the center frequency means that the microphone is more sensitive to ultrasonic waves at this frequency.

Based on the above calculations, in order to ensure that the microphone arrangement satisfies the spatial sampling theorem, we calculate the corresponding wavelength with the maximum center frequency of the microphone 50KHz, because the radius of the corresponding microphone matrix and the microphone spacing are the smallest; at the same time, in order to facilitate the arrangement of the microphones For cloth installation, we directly set the microphones of each center frequency evenly with the minimum spacing that needs to be met, that is, 50KHz and the number of 32 microphones are substituted into the above formula, and the annular radius of the microphone array is 17.4mm and the spacing is 3.4mm. It can meet the sampling of the four selected center frequency microphones, and the four microphones are arranged alternately in turn to form a uniform annular array. The inspector can also set the microphone arrangement of the microphone array according to the actual inspection requirements and microphone types, such as selecting different center frequency microphones to form annular arrays with different radii, multi-plane microphone arrays, etc.

Further, the center of the PCB board 22 is provided with a through hole opening, and the size of the through hole is much larger than the scanning range of the laser beam, which will not affect the laser scanning; the center opening of the microphone array is adapted to the through hole.

Further, there are various types of microphones 21 in the microphone array 20, and the types include: multi-band MEMS digital microphones, multi-band MEMS analog microphones, multi-band ECM analog microphones, and multi-band ECM digital microphones. The size of the microphone can reach the millimeter level, and it has the advantage of small size compared with optical interferometers and transducers.

In this embodiment, by using a plurality of microphones with different center frequencies, the microphone array has a wide detection range, and is set as a spaced annular array that satisfies the spatial sampling theorem, so that the microphone array has the advantage of high detection sensitivity, and the microphone array has the advantages of high detection sensitivity. The array itself can realize non-contact detection of laser ultrasonic signals. The received ultrasonic signals have a relatively low frequency, slow propagation and attenuation in the air, and have the advantages of long detection distances, improving the receiving effect of laser ultrasonic signals, and compared with other receiving equipment. It has the advantage of small size.

The above is the detailed description of the second embodiment of the laser ultrasonic testing device provided by the application, and the following is the detailed description of the third embodiment of the laser ultrasonic testing device provided by the application.

Please refer to FIG. 3. FIG. 3 is a second schematic diagram of the structure of the laser ultrasonic testing device provided by the application. The present embodiment provides a laser ultrasonic testing device, in addition to the modules described in the foregoing embodiments, it also includes:

The signal transmission module 30 is electrically connected to the microphone array 20 and is used for transmitting the preprocessed laser ultrasound signal to the computer.

It should be noted that, based on the plug-and-play effect of the laser ultrasonic inspection device, after the laser ultrasonic signal is excited and detected, the signal needs to be transmitted to the computer for processing, so as to facilitate defect detection and three-dimensional imaging. After receiving the preprocessed laser ultrasonic signal of the microphone array 20, it can be directly transmitted to the computer through the line electrical connection, or can be sent to the computer by wireless transmission through the signal transmission module set as a Bluetooth module or a WIFI module, and further. Improve convenience.

Further, between the signal transmission module 30 and the microphone array 20 , a signal acquisition and processing module 40 may be provided, which is electrically connected to the microphone array 20 for preprocessing the laser ultrasound signals received by the microphone array.

The preprocessing of the laser ultrasonic signal received by the microphone array specifically includes: phase locking, amplifying and filtering; the signal acquisition and processing module 40 can collect the signal received by the microphone array 20 and perform preprocessing, so as to facilitate the detection personnel to analyze the laser ultrasonic signal. Perform sound source localization and defect detection to improve detection accuracy and efficiency.

Further, a fixing clip is provided on the optical fiber interface 11 to fix the connection of the optical fiber on the optical fiber interface. After the laser ultrasonic detection device is inserted into the optical fiber, the optical fiber is clamped and fixed by the fixing clip, so as to facilitate the inspection personnel to measure the object to be measured. Perform laser ultrasound testing.

In this embodiment, by setting the signal acquisition and processing module 40 and the signal transmission module 30, the laser ultrasonic signal received by the microphone array 20 is preprocessed in real time, and then transmitted to the computer for processing, so that the laser ultrasonic detection device is plug-and-play. In the case of use, the laser ultrasonic signal can be transmitted with the computer more conveniently, and the detection result of the object to be tested can be obtained, which improves the flexibility and portability of use.

Those skilled in the art can clearly understand that, for the convenience and brevity of description, for the specific working process of the device described above, reference may be made to the corresponding process in the foregoing method embodiments, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed modules may be implemented in other manners. For example, the above-described embodiments are only illustrative. For example, the division of the modules is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or may be Integration into another system, or some features can be ignored, or not implemented. On the other hand, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, indirect coupling or communication connection of devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution in this embodiment.

In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically alone, or two or more units may be integrated into one unit.

As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand: The technical solutions described in the embodiments are modified, or some technical features thereof are equivalently replaced; and these modifications or replacements do not make the essence of the corresponding technical solutions depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A laser ultrasonic testing apparatus, comprising:

the system comprises a laser ultrasonic scanning module and a microphone array;

the laser ultrasonic scanning module comprises: the optical fiber interface, the galvanometer and the field lens; the optical fiber interface is a through hole which is arranged on the surface of the laser ultrasonic scanning module and is communicated with the galvanometer;

the microphone array comprises microphones with various center frequencies, and an opening for laser beams to pass through is formed in the center of the microphone array;

the opening of the vibrating mirror, the field lens and the microphone array are coaxial.

2. The laser ultrasonic detection device according to claim 1, wherein in the microphone array, a distance between adjacent microphones satisfies a spatial sampling theorem, specifically:

wherein d is the distance between the microphones, and λ is the acoustic wavelength corresponding to the highest center frequency in the microphone array.

3. The laser ultrasonic testing device of claim 1, wherein a plurality of microphones are provided in the microphone array, each of the microphones having a center frequency, and the plurality of microphones having the same center frequency are uniformly distributed around the center of the microphone array.

4. The laser ultrasonic testing apparatus of claim 1, wherein the microphone array comprises microphones with different center frequencies arranged alternately in the array in sequence around the center of the array.

5. The laser ultrasonic detection device of claim 1, wherein the microphone array comprises a plurality of microphone types, including: a multi-band MEMS digital microphone, a multi-band MEMS analog microphone, a multi-band ECM analog microphone, and a multi-band ECM digital microphone.

6. The laser ultrasonic testing apparatus according to claim 1, wherein the central frequency range of said microphone is 20KHz-100KHz.

7. The laser ultrasonic detection device of claim 1, wherein the microphone array is disposed on a PCB, and a through hole is disposed in the center of the PCB, and the area of the through hole is larger than the scanning range of the galvanometer.

8. The laser ultrasonic testing device according to claim 1, wherein a fixing clip is disposed on the optical fiber interface for fixing the connection between the optical fiber and the optical fiber interface.

9. The laser ultrasonic inspection device of claim 1, further comprising:

and the signal transmission module is electrically connected with the microphone array and is used for transmitting the preprocessed laser ultrasonic signals to a computer.

10. The laser ultrasonic detection device according to claim 9, wherein the signal transmission module is specifically a bluetooth module or a WIFI module.

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