CN106442624A - Infrared thermal-wave imaging system based on time-space modulation mode and detection method - Google Patents

Abstract

An infrared thermal wave imaging system and detection method based on a time-space modulation method belong to the field of infrared imaging non-destructive testing. The computer is connected to the DMD controller signal through the VGA control line, the DMD controller is connected to the DMD digital microchip board signal through the control line, the power supply of the semiconductor laser is electrically connected to the semiconductor laser through the power line, and the semiconductor laser is connected to the collimator through an optical fiber. The computer is connected to the infrared thermal imaging camera through an Ethernet cable. The infrared thermal wave imaging system and detection method based on time-space modulation of the present invention can evenly heat the test piece, be sensitive to micro-cracks on the test piece during detection, and have low system cost.

Description

An Infrared Thermal Wave Imaging System and Detection Method Based on Time-Space Modulation

technical field

The invention relates to an infrared thermal wave imaging system and detection method based on a time-space modulation mode, belonging to the field of non-destructive detection of infrared imaging.

Background technique

At present, common thin-layer materials such as composite materials, coating materials, metal sheets and resin materials have good mechanical properties, but in the process of manufacturing, cracks, pores and debonding are prone to defects, which seriously affect Material performance. Therefore, how to ensure the good performance of materials and detect material defects in a timely and efficient manner is particularly important in the entire process. As an active infrared detection technology, infrared thermal wave non-destructive testing technology is widely used in various thin-layer material defect detection fields due to its advantages of non-contact, intuitive, large detection area and no damage.

At present, the research on infrared thermal wave nondestructive testing technology mainly focuses on the related research fields of active excitation thermal signal loading method and thermal radiation signal extraction algorithm. According to the different loading methods of active excitation thermal signals, it can be mainly divided into infrared pulse method thermal wave nondestructive testing technology, infrared phase-locking method thermal wave nondestructive testing technology and infrared thermal wave radar nondestructive testing technology. However, the above methods all have problems such as uneven heating of the test piece by the excitation heat flow, insensitivity to the detection of micro-crack defects, and expensive equipment.

Contents of the invention

The purpose of the present invention is to propose an infrared thermal wave imaging system and detection method based on time-space (time and space) modulation, so as to overcome the current common infrared thermal imaging non-destructive detection technology/system, namely pulse method, lock The phase method and the thermal wave radar method have disadvantages such as uneven heating, insensitivity when detecting micro-cracks, and high system cost.

The invention proposes a DMD (Digital Micro mirror Device) digital microchip-based time and space synchronously modulated infrared thermal wave imaging system and detection method.

Realize above-mentioned object, the technical scheme that the present invention takes is as follows:

An infrared thermal wave imaging system based on time-space modulation, which consists of a computer, an Ethernet cable, an infrared thermal imager, a semiconductor laser power supply, a power cord, a semiconductor laser, an optical fiber, a collimator, and a DMD digital microchip board , control line, DMD controller and VGA control line;

The computer is provided with two signal output ends, one of the signal output ends of the computer is connected with the signal input end of the DMD controller through the VGA control line, and the other signal output end of the computer is connected with the infrared thermal imager through the Ethernet line. The signal input end of the instrument is connected, the signal output end of the DMD controller is connected with the signal input end of the DMD digital microchip board through the control line, and the current output end of the semiconductor laser power supply is connected with the semiconductor laser through the power line The current input end is connected, the laser emitting end of the semiconductor laser is connected with the laser receiving end of the collimating mirror through an optical fiber, and the mirror port of the collimating mirror is aligned with the DMD digital microchip board.

Further, the semiconductor laser is an 808nm semiconductor laser.

Further, the DMD digital microchip board is provided with several DMD digital microchips, and each DMD digital microchip is arrayed with at least 100,000 micromirrors.

Utilize the system of the present invention to realize the detection method based on the infrared thermal wave imaging of time-space modulation mode, described detection method comprises the following steps:

Step 1: Clamp and fix the test piece to be tested;

Step 2: Turn on the computer, thermal imaging camera, DMD controller, semiconductor laser and DMD digital microchip board in the infrared thermal wave imaging system based on the time-space modulation mode;

Step 3: set the peak power of the semiconductor laser to 1W, adjust the position of the collimator or the DMD digital microchip plate to realize the calibration of the laser light path;

Step 4: By observing the display of the computer in real time, adjust the focal length of the thermal imaging camera, so that the thermal imaging camera focuses reasonably and the image is clear;

Step 5: Turn all the micro-mirrors included in each DMD digital microchip to the OFF state, increase the power of the semiconductor laser to 20W~50W, and the computer controls the DMD controller to make the DMD controller control The DMD digital microchip board is opened point by point and line by line. At this time, the laser beam reflected by the DMD digital microchip plate scans the surface of the tested test piece point by point or line by line; Or, make the micro-mirrors in different regions of the DMD digital microchip controlled by the DMD controller switch ON or OFF states at different frequencies, and at this time it appears that the laser beam reflected by the DMD digital microchip is being detected Different positions on the surface of the specimen are injected with heat flow at different frequencies;

Step 6: While the laser beam irradiates the surface of the test piece, the computer records the image sequence collected by the infrared thermal imager through the Ethernet cable, and performs image data processing and signal extraction through the computer control software, and then conducts the test. The identification and judgment of the surface defects of the workpiece, so far, the infrared thermal wave imaging detection of the tested sample 4 is completed.

Further, in step 1, step 5 and step 6, if the surface material of the tested test piece is a material with high light reflection.

The beneficial effect of the present invention relative to prior art is:

(1) The invention overcomes the influence of uneven heating of traditional detection methods by controlling the light intensity of different regions on the DMD digital microchip by computer;

(2) The present invention overcomes the shortcomings of insensitivity to detection of crack defects of the tested specimen and long detection time by controlling different areas on the DMD digital microchip to perform progressive scanning or multi-frequency simultaneous detection;

(3) The present invention replaces the use of expensive function generators or acousto-optic modulators through the use of cheap DMD digital microchips, reducing equipment costs.

Description of drawings

FIG. 1 is a schematic structural diagram of an infrared thermal wave imaging system based on a space-time modulation method according to the present invention.

In the figure: 1-computer, 2-Ethernet cable, 3-infrared thermal imager, 4-tested sample, 5-semiconductor laser power supply, 6-power line, 7-semiconductor laser, 8-optical fiber, 9-collimation mirror, 10-DMD digital microchip board, 11-control line, 12-DMD controller, 13-VGA control line.

detailed description

Specific embodiment one: as shown in Figure 1, an infrared thermal wave imaging system based on time-space modulation, its composition includes a computer 1, an Ethernet cable 2, an infrared thermal imager 3, a semiconductor laser power supply 5, and a power cord 6 , semiconductor laser 7, optical fiber 8, collimating mirror 9, DMD digital microchip board 10, control line 11, DMD controller 12 and VGA control line 13;

Described computer 1 is provided with two signal output terminals, wherein one of the signal output terminals of computer 1 is connected with the signal input terminal of DMD controller 12 by VGA control line 13, and another signal output terminal of computer 1 is connected through Ethernet Network cable 2 is connected with the signal input end of infrared thermal imager 3, and the signal output end of described DMD controller 12 is connected with the signal input end of DMD digital microchip plate 10 by control line 11, and described semiconductor laser power supply 5 The current output end of the semiconductor laser is connected to the current input end of the semiconductor laser 7 through the power line 6, and the laser emitting end of the semiconductor laser 7 is connected to the laser receiving end of the collimating mirror 9 through the optical fiber 8, and the 9 mirrors of the collimating mirror The mouth is aligned with the DMD digital microchip plate 10 .

Among them, the model of thermal imaging camera 3 is FLIR SC 7000, and the response wavelength is 3.6~5.2μm.

Embodiment 2: As shown in FIG. 1 , according to an infrared thermal wave imaging system based on time-space modulation described in Embodiment 1, the semiconductor laser 7 is an 808nm semiconductor laser.

Specific embodiment three: as shown in Figure 1, a kind of infrared thermal wave imaging system based on time-space modulation mode is realized by utilizing the system described in specific embodiment one or two, described DMD digital microchip plate 10 is provided with There are several DMD digital microchips, and at least 100,000 micromirrors are arrayed on each DMD digital microchip.

Specific embodiment four: as shown in Figure 1, a kind of detection method that utilizes the system described in specific embodiment three to realize the infrared thermal wave imaging based on time-space modulation mode, described detection method comprises the following steps:

Step 1: Clamp and fix the tested specimen 4; here, the tested specimen 4 is a cuboid shape as an example, the length of the tested specimen 4 × width × thickness = 10cm × 10cm × 4 mm, the tested specimen The material of 4 is CFRP material (test specimen 4 is prefabricated with micro-crack defects;

Step 2: Turn on the computer 1, thermal imaging camera 3, DMD controller 12, semiconductor laser 7 and DMD digital microchip plate 10 in the infrared thermal wave imaging system based on the time-space modulation mode;

Step 3: Set the peak power of the semiconductor laser 7 (according to the surface material and thickness of the test piece 4), set the laser power to 1W, and adjust the collimator 9 or the DMD digital microchip plate 10 Position, in order to realize the alignment of laser light path;

Step 4: By observing the display of the computer 1 in real time, adjust the focal length of the thermal imaging camera 3, so that the thermal imaging camera 3 has a reasonable focus and a clear image;

Step 5: Turn all micromirrors contained in each DMD digital microchip to OFF state, increase the power of semiconductor laser 7 to (7) power to 20W~50W (preferably 30W), computer 1 controls DMD Controller 12 makes the DMD digital microchip plate 10 controlled by the DMD controller 12 adopt a point-by-point and row-by-line opening mode, and now the laser beam reflected by the DMD digital microchip plate 10 is on the The surface of the tested sample 4 described above is scanned point by point or line by line; or, the micro-mirrors in different regions on the DMD digital microchip plate 10 controlled by the DMD controller 12 are switched to ON or OFF states at different frequencies, At this time, it is shown that the laser beam reflected by the DMD digital microchip is injected at different positions on the surface of the tested specimen 4 with heat flow at different frequencies;

Step 6: While the laser beam is irradiating the surface of the test piece 4, the computer 1 records the image sequence collected by the infrared thermal imager 3 through the Ethernet line 2, and performs image data processing and signal extraction through the control software of the computer 1, Further, the identification and judgment of the surface defects of the tested sample 4 are carried out, so far, the infrared thermal wave imaging detection of the tested sample 4 is completed.

In this embodiment, the point-by-point or line-by-line scanning rate and the multi-frequency, that is, the selection of frequency ranges in different frequency scanning are determined according to the material of the surface material of the test piece 4 and its structural parameters.

Specific embodiment five: a kind of detection method based on time-space modulation infrared thermal wave imaging described in specific embodiment four, in step one, step five and step six, the surface material of the tested test piece 4 It is a test piece with low reflectivity (such as ferrous metal, carbon fiber material, cast iron, etc.), if it is a material with high reflectivity (such as titanium alloy, aluminum alloy, stainless steel, etc.), the surface must be sprayed with matte paint , to increase its light absorption.

How it works: DMD digital microchips are now widely used in projection equipment. The side length of each DMD digital microchip is generally 0.55~0.95 inches (the chip is square), and there are hundreds of thousands to several million microreflectors arrayed on each DMD digital microchip. Each micro-mirror can reflect the laser light from two directions, and the actual reflection direction depends on the state of the underlying memory cell; when the memory cell is in the ON state, the micro-mirror will follow its axis When the hour hand rotates to +12°, the memory cell is in the OFF state, and the micro-mirror will rotate counterclockwise to -12° with its central axis as the reference axis. As long as the DMD digital microchip plate 10 is combined with an appropriate light source and projection optics, the microreflector will reflect incident light into or leave the light transmission hole of the infrared thermal imager 3, making the microreflector in the ON state look very Bright, off-state micromirrors look dark. The DMD digital microchip plate 10 can thus act as a plurality of acousto-optic modulators. The time-air-conditioning thermal wave nondestructive testing method is based on the principle of photothermal radiometry (PTR), using computer 1 to control the DMD controller 12, so that each micro-mirror in the DMD digital microchip changes according to the specified signal law, and the laser The light source irradiates the surface of the test piece 4 through the micro-mirror in the ON state of the DMD digital microchip. After the regularly changing laser light irradiates the test piece 4, due to the photothermal effect, the temperature of the test piece 4 rises. Falling and infrared radiation, the photothermal radiation signal is related to the photothermal characteristic parameters and structure of the tested test piece 4, the signal is received by the infrared thermal imager 3, and then the photothermal characteristics of the tested test piece 4 are extracted through the signal processing algorithm to achieve the detection Determination of surface defects of specimen 4.

Claims (5)

1. a kind of infrared thermal wave imaging system based on Space Time modulation system it is characterised in that：Its composition includes computer（1）、 Ethernet line（2）, thermal infrared imager（3）, power source of semiconductor laser（5）, power line（6）, semiconductor laser（7）, optical fiber （8）, collimating mirror（9）, DMD digital micro-analysis chip plate（10）, control line（11）, DMD controller（12）And VGA control line（13）；

Described computer（1）It is provided with two signal output parts, computer（1）One of described signal output part pass through VGA control line（13）With DMD controller（12）Signal input part connect, computer（1）Another signal output part pass through Ethernet line（2）With thermal infrared imager（3）Signal input part connect, described DMD controller（12）Signal output part lead to Cross control line（11）With DMD digital micro-analysis chip plate（10）Signal input part connect, described power source of semiconductor laser（5） Current output terminal pass through power line（6）With semiconductor laser（7）Current input terminal connect, described semiconductor laser （7）Laser emission end pass through optical fiber（8）With collimating mirror（9）Laser pick-off end connect, described collimating mirror（9）Jing Kou is aligned DMD digital micro-analysis chip plate（10）.

2. a kind of infrared thermal wave imaging system based on Space Time modulation system according to claim 1 it is characterised in that： Described semiconductor laser（7）For 808nm semiconductor laser.

3. a kind of infrared thermal wave imaging system based on Space Time modulation system according to claim 1 and 2, its feature exists In：Described DMD digital micro-analysis chip plate（10）It is provided with several DMD digital micro-analysis chips, each DMD digital micro-analysis chip Upper array at least 100,000 micro-reflectors.

4. the system described in a kind of utilization claim 3 realizes the detection side of the infrared thermal wave imaging based on Space Time modulation system Method it is characterised in that：Described detection method comprises the steps：

Step one：By tested test block（4）Carry out clamping to fix；

Step 2：Open the computer in the described infrared thermal wave imaging system based on Space Time modulation system（1）, infrared heat As instrument（3）, DMD controller（12）, semiconductor laser（7）With DMD digital micro-analysis chip plate（10）；

Step 3：The described semiconductor laser of setting（7）Peak power is 1W, the described collimating mirror of adjustment（9）Or DMD numeral Micro- chip plate（10）Position, to realize the calibration of laser optical path；

Step 4：By Real Time Observation computer（1）Display, the described thermal infrared imager of adjustment（3）Focal length, makes infrared heat As instrument（3）Focusing is reasonable, image imaging clearly；

Step 5：The all micro-reflectors comprising in each described DMD digital micro-analysis chip are adjusted to OFF state, increase half Conductor laser（7）Power is to 20W ~ 50W, computer（1）Control DMD controller（12）, make described DMD controller（12）Control The DMD digital micro-analysis chip plate of system（10）By the way of pointwise is opened line by line, now described DMD digital micro-analysis chip plate （10）The laser beam reflecting is then to described tested test block（4）Surface carries out pointwise or progressive scan；Or, make DMD Controller（12）The DMD digital micro-analysis chip plate controlling（10）The micro-reflector of upper zones of different by different frequency carry out ON or The conversion of OFF state, now then shows as laser beam that DMD digital micro-analysis chip reflects in tested test block（4）Surface Diverse location is injected with different frequency hot-fluid；

Step 6：Irradiate tested test block in laser beam（4）While surface, computer（1）By ethernet line（2）To red Outer thermal imaging system（3）The image sequence of collection is recorded, and passes through computer（1）Control software carry out image real time transfer with Signal extraction, and then carry out tested test block（4）The identification of surface defect and judgement, so far, complete to tested exemplar 4 Infrared thermal wave image checking.

5. the detection method of the infrared thermal wave imaging based on Space Time modulation system according to claim 4, its feature exists In：In step one, step 5 and step 6, described tested test block（4）Surfacing be the low material of reflectance.