Coding line laser excitation method and device based on line laser scanning infrared nondestructive testing technology

Abstract

The invention provides a coding line laser excitation method and device based on a line laser scanning infrared nondestructive testing technology, and the method comprises the steps: employing a multi-channel coupling point light source laser, and outputting a plurality of point lasers through a plurality of channels; collimating the point laser output by each channel by using a collimating mirror to obtain homogenized point laser; converting the collimated homogenized point laser into Gaussian point laser through a plano-convex lens; stretching the Gaussian point laser or the homogenized point laser in one direction by using a Powell prism to form Gaussian line laser or homogenized line laser; performing specific light path arrangement and parameter adjustment on the point laser of the plurality of channels according to the required excitation waveform type so as to realize a similar phase lock waveform, a similar linear frequency modulation waveform or a similar phase coding excitation waveform; and irradiating the formed Gaussian line laser or homogenized line laser onto a test piece, and carrying out line laser scanning infrared nondestructive testing. The method is suitable for a line laser scanning infrared nondestructive testing scene, and can effectively detect the internal defects of the test piece.

Description

Technical Field

[0001] The present invention relates to the field of active infrared non-destructive testing technology, and more particularly to a thermal excitation method applied to dynamic scanning infrared non-destructive testing technology. Specifically, the present invention relates to a coded line laser excitation method and device based on line laser scanning infrared non-destructive testing technology, so as to realize an excitation waveform used in a variety of static infrared non-destructive testing technologies in the dynamic scanning infrared non-destructive testing technology. Background Art

[0002] Active infrared nondestructive testing (ANDIT) is an emerging NDT technology that has developed rapidly in recent years. Its main features include high speed, non-contact, safety, large single-test area, and clear and intuitive test results. This technology heats the specimen using a thermal excitation source and captures the temperature changes on the specimen surface using an infrared thermal imager, thereby enabling the detection of internal defects in the specimen. Common thermal excitation methods include pulse excitation, phase-locked excitation, linear frequency modulation excitation, and phase-coded excitation. Each of these excitation methods has its own advantages and disadvantages and is suitable for different testing scenarios. At present, active infrared non-destructive testing technology has developed a variety of excitation methods, including pulsed infrared non-destructive testing technology, phase-locked infrared non-destructive testing technology, thermal wave radar non-destructive testing technology and phase-coded non-destructive testing technology. Pulsed infrared non-destructive testing technology heats the test piece through a single-cycle square wave pulse. The detection speed is fast, but the detection capability of deep defects is limited. Phase-locked infrared non-destructive testing technology uses a digital power regulator to achieve phase-locked waveform excitation, which improves the detection capability of deep defects, but there is a blind frequency phenomenon. Thermal wave radar non-destructive testing technology introduces a linear frequency modulation waveform to overcome the blind frequency problem of phase-locked technology and further improve the detection depth. Phase-coded non-destructive testing technology uses a phase-coded excitation waveform, which has excellent energy saving and waveform autocorrelation characteristics. However, most of the above technologies are static detection methods, that is, the infrared thermal imager, the test piece and the thermal excitation source remain relatively stationary; In recent years, dynamic scanning infrared nondestructive testing (NDT) technology has gradually emerged, with line laser scanning NDT technology performing particularly well. This technology uses a line laser as an excitation source, homogenizing a point laser and stretching it into a line laser using a Powell prism to scan and inspect the specimen. However, current line laser scanning NDT technology often uses pulse-like excitation waveforms, failing to effectively utilize the diverse excitation waveforms used in static NDT technology. This limits its ability to detect deep defects. Although existing line laser scanning infrared nondestructive testing technology has certain advantages in dynamic detection, the single excitation waveform results in insufficient detection capabilities for deep defects. Phase-locked waveforms, linear frequency modulation waveforms, and phase-encoded excitation waveforms used in static infrared nondestructive testing have been proven to significantly improve defect detection capabilities, but these waveforms have not yet been effectively applied in line laser scanning infrared nondestructive testing technology. Therefore, existing line laser scanning infrared nondestructive testing technology has obvious limitations when detecting deep defects and cannot fully utilize the advantages of multiple excitation waveforms. A line laser excitation method that can realize multiple excitation waveforms is urgently needed to enhance the detection capabilities of dynamic scanning infrared nondestructive testing technology for deep defects. Summary of the Invention

[0003] To address the aforementioned technical issues, a method and device for coded line laser excitation based on line laser scanning infrared nondestructive testing technology is provided. By combining a multi-channel coupled point source laser with specific optical elements, this invention implements multiple excitation waveforms, including phase-locked waveforms, linear frequency modulation waveforms, and phase-coded excitation waveforms. This significantly enhances the ability of line laser scanning infrared nondestructive testing technology to detect deep defects while maintaining high detection efficiency.

[0004] The technical means adopted in the present invention are as follows: A coded line laser excitation method based on line laser scanning infrared nondestructive testing technology, comprising: S1, using a multi-channel coupled point light source laser to output multiple point lasers through its multiple channels; S2. Use a collimator to collimate the point laser output from each channel and obtain a homogenized point laser; S3, converting the collimated homogenized point laser into a Gaussian point laser through a plano-convex lens; S4. Using a Powell prism, the Gaussian point laser or the homogenized point laser is stretched in one direction to form a Gaussian line laser or a homogenized line laser; S5. Arrange the optical paths and adjust the parameters of the point lasers of multiple channels according to the required excitation waveform type to achieve a phase-locked waveform, a linear frequency modulation waveform, or a phase-encoded excitation waveform; S6. Irradiate the formed Gaussian line laser or homogenized line laser onto the test piece to perform line laser scanning infrared nondestructive testing.

[0005] Furthermore, in step S5, the process of implementing the quasi-phase-locked waveform includes: Assuming that the number of periods of the quasi-phase-locked waveform is N, the N channels of the multi-channel coupled point light source laser are used to output N homogenized point lasers; Ensure that the spot imaging size of the Gaussian point laser is consistent after the homogenized point lasers of N channels pass through the plano-convex lens; The spacing between the plano-convex lens and the Powell prism of all channels is set to be the same to ensure the line width of the N Gaussian line lasers is consistent; After arranging N Gaussian line lasers at regular intervals, a quasi-phase-locked waveform that is highly similar to the phase-locked waveform is formed.

[0006] Furthermore, in step S5, the process of implementing the linear frequency modulation-like waveform includes: Assuming that the linear frequency modulation waveform has M peaks, the M channels of the multi-channel coupled point light source laser are used to output M homogenized point lasers; After the homogenized point lasers of the M channels pass through the plano-convex lens, the spot imaging sizes of the Gaussian point lasers are ensured to be inconsistent, and the spot sizes of the M channels should gradually change from large to small; The spacing between the plano-convex lens and the Powell prism of all channels is set to be different to ensure that the line widths of the M Gaussian line lasers are different; After arranging M Gaussian line lasers at certain intervals, a quasi-linear frequency modulation waveform that is highly similar to a linear frequency modulation waveform is formed.

[0007] Furthermore, in step S5, the process of implementing the phase-coded excitation waveform includes: Assume that the phase-coded excitation waveform is similar to a specific Bark-coded pulse compression waveform, which has K square wave peaks; After the homogenized point lasers of the K channels pass through the collimator, the spot imaging sizes of the homogenized point lasers are ensured to be inconsistent, and the ratio of the spot sizes of the K channels is consistent with the width ratio of the K square waves in the Barker-coded pulse compression waveform; Adjusting the spacing between the collimating mirrors and the Powell prisms of all channels to ensure that the ratio of the line widths of the K homogenized line lasers is consistent with the width ratio of the K square waves in the Barker-coded pulse compression waveform; After K homogenized line lasers are arranged at certain intervals, a phase-encoded waveform highly similar to the Barker-encoded pulse compression waveform is formed.

[0008] Furthermore, the number of channels of the multi-channel coupled point light source laser is determined according to the number of peaks or cycles of the excitation waveform to be achieved.

[0009] Furthermore, depending on the different combinations of the collimating mirror, the plano-convex lens and the Powell prism, a variety of different excitation waveforms can be achieved, including but not limited to quasi-phase-locked, quasi-linear frequency modulation, and quasi-phase-coded excitation waveforms.

[0010] The present invention also provides a coding line laser excitation device implemented based on the above-mentioned coding line laser excitation method based on line laser scanning infrared non-destructive testing technology, comprising: a multi-channel coupled point light source laser, a collimating mirror, a plano-convex lens, a Powell prism and an optical path arrangement device, wherein: The multi-channel coupled point light source laser is used to output multiple point lasers through its multiple channels respectively; The collimating mirror is used to collimate and homogenize the point laser output from each channel; The plano-convex lens is used to convert the collimated homogenized point laser into a Gaussian point laser; The Powell prism is used to stretch the Gaussian point laser or the homogenized point laser in one direction to form a Gaussian line laser or the homogenized line laser; The optical path arrangement device is used to perform specific optical path arrangement and parameter adjustment on the point lasers of multiple channels according to the required excitation waveform type, so as to realize a quasi-phase-locked waveform, a quasi-linear frequency modulation waveform or a quasi-phase-encoded excitation waveform.

[0011] Furthermore, the coding line laser excitation device further includes: Mobile scanning platform, used to carry optical lens assembly, multi-channel coupled point light source laser and infrared thermal imager; Infrared thermal imager, used to collect infrared images of the test piece; The mobile terminal is used to collect images captured by the infrared thermal imager and control the output waveform style of the multi-channel coupled point light source laser through the signal acquisition card.

[0012] Compared with the prior art, the present invention has the following advantages: 1. The present invention combines a multi-channel coupled point light source laser, a collimating mirror, a plano-convex lens, and a Powell prism to achieve quasi-phase-locked waveform excitation in the line laser scanning infrared non-destructive testing technology. Compared with the line laser scanning infrared non-destructive testing technology excited by a single line laser light source, the defect detection capability can be improved.

[0013] 2. The present invention can realize linear frequency modulation waveform excitation in the line laser scanning infrared non-destructive testing technology by combining a multi-channel coupled point light source laser, a collimating mirror, a plano-convex lens and a Powell prism. Compared with the line laser scanning infrared non-destructive testing technology excited by a single line laser light source, the defect detection capability can be improved.

[0014] 3. The present invention can realize phase-coded waveform excitation in the line laser scanning infrared non-destructive testing technology by combining a multi-channel coupled point light source laser, a collimating mirror and a Powell prism. Compared with the line laser scanning infrared non-destructive testing technology excited by a single line laser light source, the defect detection capability can be improved.

[0015] 4. The present invention utilizes a wide range of different combinations of multi-channel coupled point source lasers, collimating lenses, plano-convex lenses, and Powell prisms to achieve a variety of different excitation waveforms in online laser scanning infrared nondestructive testing technology, including but not limited to the aforementioned phase-locked waveforms, linear frequency modulation waveforms, and coded pulse compression waveforms. Specific similar waveforms that can be generated include but are not limited to phase-locked, linear frequency modulation, and phase-coded excitation waveforms. Furthermore, these waveforms can be adjusted through various optical path arrangements and power adjustments, including but not limited to power modulation and phase modulation.

[0016] Based on the above reasons, the present invention can be widely promoted in the fields of active infrared non-destructive testing and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0018] Figure 1 Schematic diagram of the application scenario of the method of the present invention.

[0019] Figure 2 The present invention provides a comparison between the optical path for realizing the phase-locked waveform excitation in the coding line laser excitation method of the present invention and the phase-locked waveform in the static infrared non-destructive testing technology.

[0020] Figure 3 The present invention provides a comparison between the optical path for realizing the linear frequency modulation waveform excitation in the coded line laser excitation method of the present invention and the linear frequency modulation waveform in the static infrared non-destructive testing technology.

[0021] Figure 4 The present invention provides a comparison between the optical path for implementing the phase-coded waveform excitation in the coded line laser excitation method of the present invention and the 13-bit Barker coding waveform in the static infrared non-destructive testing technology.

[0022] Figure 5 A comparison diagram of the quasi-phase-locked waveform in the coded line laser excitation method provided in an embodiment of the present invention and the phase-locked waveform in the static infrared non-destructive testing technology.

[0023] Figure 6 A comparison diagram of the linear frequency modulation waveform in the coded line laser excitation method provided by the embodiment of the present invention and the linear frequency modulation waveform in the static infrared non-destructive testing technology.

[0024] Figure 7A comparison diagram of the phase-coded waveform in the coded line laser excitation method provided in an embodiment of the present invention and the 13-bit Barker coding waveform in the static infrared non-destructive testing technology.

[0025] Figure 8 A comparison chart of the defect center temperature results simulated when a phase-locked waveform is used for excitation in the coded line laser excitation method provided in an embodiment of the present invention and the defect center temperature results simulated when a phase-locked waveform is used for excitation in the static infrared nondestructive testing technology is provided.

[0026] Figure 9 A comparison chart of the defect center point temperature results simulated when a quasi-linear frequency modulation waveform is used for excitation in the coded line laser excitation method of the present invention provided in an embodiment of the present invention and the defect center point temperature results simulated when a linear frequency modulation waveform is used for excitation in the static infrared non-destructive testing technology is provided.

[0027] Figure 10 A comparison chart shows the defect center temperature results simulated when a phase-coded waveform is used for excitation in the coded line laser excitation method provided in an embodiment of the present invention, and the defect center temperature results simulated when a 13-bit Barker coded waveform is used for excitation in the static infrared nondestructive testing technology.

[0028] In the figure: 1. Mobile scanning platform; 2. Optical lens assembly; 3. Test piece; 4. Field of view of infrared thermal imager; 5. Line width of line laser; 6. Multi-channel coupled point light source laser; 7. Infrared thermal imager; 8. Computer; 9. Signal acquisition card; 10. Collimator; 11. Plano-convex lens; 12. Powell prism. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0030] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0031] The present invention provides a coded line laser excitation method based on line laser scanning infrared nondestructive testing technology, comprising: S1, using a multi-channel coupled point light source laser to output multiple point lasers through its multiple channels; S2. Use a collimator to collimate the point laser output from each channel and obtain a homogenized point laser; S3, converting the collimated homogenized point laser into a Gaussian point laser through a plano-convex lens; S4. Using a Powell prism, the Gaussian point laser or the homogenized point laser is stretched in one direction to form a Gaussian line laser or a homogenized line laser; S5. Arrange the optical paths and adjust the parameters of the point lasers of multiple channels according to the required excitation waveform type to achieve a phase-locked waveform, a linear frequency modulation waveform, or a phase-encoded excitation waveform; S6. Irradiate the formed Gaussian line laser or homogenized line laser onto the test piece to perform line laser scanning infrared nondestructive testing.

[0032] In this embodiment, the method of the present invention is applied to the scenario of using a mobile scanning platform to perform line laser scanning infrared non-destructive testing technology, and its application scenario examples are as follows: Figure 1 As shown. The application scenario generally includes a mobile scanning platform 1, an optical lens assembly 2, a test piece to be tested 3, a multi-channel coupled point light source laser 6, an infrared thermal imager 7, a computer 8, and a signal acquisition card 9. The mobile scanning platform 1 is used to carry the optical lens assembly 2, the multi-channel coupled point light source laser 6, and the infrared thermal imager 7. The optical lens assembly 2 mainly includes a collimator 10, a plano-convex lens 11, and a Powell prism 12. The computer 8 is used to collect the images captured by the infrared thermal imager 7, and to control the output waveform style of the multi-channel coupled point light source laser 6 through the signal acquisition card 9. The form of the mobile scanning platform 1 includes but is not limited to all implementation forms that can be used to perform the scanning function, such as a multi-degree-of-freedom robot and a truss-type manipulator.

[0033] In specific implementation, as a preferred embodiment of the present invention, in step S5, the process of realizing the quasi-phase-locked waveform includes: Assuming that the number of periods of the quasi-phase-locked waveform is N, the N channels of the multi-channel coupled point light source laser are used to output N homogenized point lasers; Ensure that the spot imaging size of the Gaussian point laser is consistent after the homogenized point lasers of N channels pass through the plano-convex lens; The spacing between the plano-convex lens and the Powell prism of all channels is set to be the same to ensure the line width of the N Gaussian line lasers is consistent; After arranging N Gaussian line lasers at regular intervals, a quasi-phase-locked waveform that is highly similar to the phase-locked waveform is formed.

[0034] In this embodiment, if Figure 2 As shown, in the process of implementing the quasi-phase-locked waveform excitation, a computer (mobile terminal) 8, a signal acquisition card 9, a multi-channel coupled point light source laser 6, and an optical lens assembly are mainly used. Among them, the optical lens assembly mainly includes four collimating lenses 10, four plano-convex lenses 11, and four Powell prisms 12. First, assuming that the number of quasi-phase-locked waveform cycles is 4, four channels of the multi-channel coupled point light source laser 6 are used, and the four channels output four point lasers. Taking one of the channels as an example, the point laser is output through one channel of the multi-channel coupled point light source laser 6, and then the optical path is collimated by the collimating lens 10. The collimated optical path will pass through the plano-convex lens 11, converting the homogenized point laser into a Gaussian point laser. Finally, the Gaussian point laser is stretched in one direction by the Powell prism 12 to obtain a Gaussian line laser. The above method can be used to generate four equal-width Gaussian laser lines from four channels of point laser light. After being regularly spaced, these four equal-width Gaussian laser lines exhibit a waveform highly similar to a phase-locked waveform, and are therefore referred to as quasi-phase-locked waveforms in the present invention. To achieve this quasi-phase-locked waveform, after the four channels of homogenized point laser light pass through the plano-convex lens 11, the spacing between the plano-convex lens 11 and the Powell prism 12 is set to the same for all channels to ensure a consistent imaging spot size. This ensures that the line width 5 of the four Gaussian laser lines is consistent.

[0035] In specific implementation, as a preferred embodiment of the present invention, in step S5, the process of realizing the linear frequency modulation waveform includes: Assuming that the linear frequency modulation waveform has M peaks, the M channels of the multi-channel coupled point light source laser are used to output M homogenized point lasers; After the homogenized point lasers of the M channels pass through the plano-convex lens, the spot imaging sizes of the Gaussian point lasers are ensured to be inconsistent, and the spot sizes of the M channels should gradually change from large to small; The spacing between the plano-convex lens and the Powell prism of all channels is set to be different to ensure that the line widths of the M Gaussian line lasers are different; After arranging M Gaussian line lasers at certain intervals, a quasi-linear frequency modulation waveform that is highly similar to a linear frequency modulation waveform is formed.

[0036] In this embodiment, if Figure 3 As shown, in the process of realizing the linear frequency modulation waveform excitation, a computer 8, a signal acquisition card 9, a multi-channel coupled point light source laser 6, and an optical lens assembly are mainly used. Among them, the optical lens assembly mainly includes 4 collimating lenses 10, 4 plano-convex lenses 11, and 4 Powell prisms 12. First, it is assumed here that the linear frequency modulation waveform has 4 peaks, so 4 channels of the multi-channel coupled point light source laser 6 are used, and the 4-channel laser outputs 4 point lasers. Taking one of the channels as an example, the point laser is output through one channel of the multi-channel coupled point light source laser 6, and then the optical path is collimated by the collimating lens 10. The collimated optical path will pass through the plano-convex lens 11 to convert the homogenized point laser into a Gaussian point laser. Finally, the Gaussian point laser is stretched in one direction by the Powell prism 12 to obtain a Gaussian line laser. The four-channel point laser can be converted into four Gaussian line lasers using the above method. After the four Gaussian line lasers are arranged at a certain interval, their waveform is highly similar to a linear frequency modulation waveform. Therefore, in the present invention, this waveform is referred to as a quasi-linear frequency modulation waveform. In the process of implementing the quasi-linear frequency modulation waveform, the four channels of homogenized point laser light must ensure that the spot imaging size of the Gaussian point laser light is inconsistent after passing through the plano-convex lens 11. In other words, the spot size of the four channels should gradually change from large to small. Therefore, the imaging distance between the plano-convex lens 11 and the Powell prism 12 of each channel is set to be different. This ensures that the line width 5 of the four Gaussian line lasers is different. The final effect is four Gaussian line lasers with widths varying from small to large.

[0037] In specific implementation, as a preferred embodiment of the present invention, in step S5, the process of implementing the phase-coded excitation waveform includes: Assume that the phase-coded excitation waveform is similar to a specific Bark-coded pulse compression waveform, which has K square wave peaks; After the homogenized point lasers of the K channels pass through the collimator, the spot imaging sizes of the homogenized point lasers are ensured to be inconsistent, and the ratio of the spot sizes of the K channels is consistent with the width ratio of the K square waves in the Barker-coded pulse compression waveform; Adjusting the spacing between the collimating mirrors and the Powell prisms of all channels to ensure that the ratio of the line widths of the K homogenized line lasers is consistent with the width ratio of the K square waves in the Barker-coded pulse compression waveform; After K homogenized line lasers are arranged at certain intervals, a phase-encoded waveform highly similar to the Barker-encoded pulse compression waveform is formed.

[0038] In this embodiment, if Figure 4 As shown, the implementation of a phase-encoded excitation waveform primarily involves a computer 8, a signal acquisition card 9, a multi-channel coupled point source laser 6, and an optical lens assembly. The optical lens assembly primarily comprises four collimators 10 and four Powell prisms 12. First, it is assumed that the phase-encoded excitation waveform is similar to a 13-bit Barker-encoded pulse compression waveform, which has four square wave peaks. In a 13-bit Barker-encoded pulse compression waveform, the width ratio of the four square waves is 5:2:1:1. Excitation of the four square waves requires the use of four channels of a multi-channel coupled point source laser, which output four point lasers. Taking one of these channels as an example, the point laser is output from one channel of the multi-channel coupled point source laser 6. The optical path is then collimated by a collimator 10. The collimated optical path is then stretched in one direction by a Powell prism 12 to produce a homogenized line laser. The above method can be used to generate four homogenized line lasers from four channels of point laser light. After being spaced apart, the waveform of these four homogenized line lasers is highly similar to the pulse compression waveform of a 13-bit Barker code. Therefore, this waveform is referred to as a phase-encoded waveform in the present invention. In implementing this phase-encoded excitation waveform, the spot sizes of the four channels of homogenized point laser light must be consistent after passing through the collimator 10. Specifically, the spot sizes of the four channels must be in a ratio of 5:2:1:1. Therefore, the spacing between the collimator 10 and the Powell prism 12 of each channel is adjusted, resulting in a line width ratio of 5:2:1:1 for the four homogenized line laser light.

[0039] In this embodiment, after the phase-locked waveform, linear frequency modulation waveform and phase-encoding waveform excitation are applied to the line laser scanning infrared non-destructive testing technology, the excitation experienced by a point on the scanned test piece in the time domain is similar to the phase-locked waveform excitation, linear frequency modulation waveform excitation and phase-encoding excitation waveform excitation in the static infrared non-destructive testing technology, thereby improving the defect detection capability of the dynamic scanning infrared non-destructive testing technology.

[0040] In specific implementation, as a preferred embodiment of the present invention, the number of channels of the multi-channel coupled point light source laser is determined according to the number of peaks or cycles of the excitation waveform to be achieved.

[0041] In specific implementation, as a preferred embodiment of the present invention, according to the different combinations of the collimating mirror, plano-convex lens and Powell prism, a variety of different excitation waveforms can be achieved, including unidirectional linear frequency modulation waveform, bidirectional linear frequency modulation waveform, two-phase coded pulse compression waveform, two-phase coded phase modulation waveform, chaotic coded pulse compression waveform, and chaotic coded phase modulation waveform.

[0042] Example The simulation test was carried out using the phase-locked waveform excitation, linear frequency modulation waveform, and phase-coded excitation waveform in the method of the present invention. The specimen was set as a carbon fiber composite reinforced material, the defect was set as a flat-bottom hole with a diameter of D=2mm, the depth of the flat-bottom hole defect was H=0.5mm, and the scanning speed was set to 10mm / s.

[0043] Use a phase-locked waveform stimulus to perform simulation tests, as follows: First, set the phase-locked waveform to: 0.5*(1+sin(2*pi*2*t-(pi / 2))), t∈(3,5) as a control; Figure 2 Arranging the collimator 10, plano-convex lens 11, and Powell prism 12 in the optical lens assembly 2 in the manner shown above yields four Gaussian line lasers with four identical line widths, whose cross-sectional waveforms are four regularly arranged Gaussian pulse waves. Phase-locked waveform excitation is used in static infrared nondestructive testing technology, and quasi-phase-locked waveform excitation is used in online laser scanning infrared nondestructive testing technology. The excitation peaks of the phase-locked waveform and the quasi-phase-locked waveform are set to the same 78250W / m 2 , the comparison between phase-locked waveform and quasi-phase-locked waveform is as follows Figure 5 shown.

[0044] The phase-locked waveform in the method of the present invention and the phase-locked waveform in the static infrared nondestructive testing technology are used to simulate the specimen. The temperature change at the center of the defect on the specimen surface is as follows: Figure 6 As shown in the figure, it can be seen that the excitation cycles of the phase-locked waveform and the quasi-phase-locked waveform are consistent and have the same peak value. At the center of the defect, the temperature change trends of the phase-locked waveform and the quasi-phase-locked waveform are consistent, but the integral area of ​​the phase-locked waveform excitation is larger than that of the quasi-phase-locked waveform excitation. Therefore, there is a difference in the temperature peak values ​​of the two, which can be compensated by increasing the excitation peak value of the quasi-phase-locked waveform.

[0045] Therefore, it can be concluded that the detection effect achieved by using quasi-phase-locked waveform excitation in the method of the present invention is almost equivalent to that achieved by using phase-locked waveform excitation in static infrared nondestructive testing technology. Given that the detection effects are nearly identical, the use of quasi-phase-locked waveform excitation in the method of the present invention is superior to static infrared nondestructive testing technology using phase-locked waveform excitation in terms of detection efficiency.

[0046] Use linear frequency modulation waveform excitation to perform simulation tests, as follows: First, set the linear frequency modulation waveform to: 0.5+0.5*sin(2*pi*0.001*t+pi*((ff-f0) / T)*t*t-3.25), t∈(1.5, 6). As a comparison, the starting frequency f0=0.001, the ending frequency ff=2.36, and the frequency modulation period T=10; Figure 3Arranging the collimator 10, plano-convex lens 11, and Powell prism 12 in the optical lens assembly 2 in the manner shown above yields four Gaussian line lasers with four different line widths, whose cross-sectional waveforms are four Gaussian pulse waves arranged in a certain pattern. Linear frequency modulation waveform excitation is used in static infrared nondestructive testing technology, and quasi-linear frequency modulation waveform excitation is used in online laser scanning infrared nondestructive testing technology. The excitation peak values ​​of the linear frequency modulation waveform and the quasi-linear frequency modulation waveform are set to the same 78250 W / m 2 , the comparison between linear FM waveform and quasi-linear FM waveform is as follows Figure 7 shown.

[0047] The linear frequency modulation waveform in the method of the present invention and the linear frequency modulation waveform in the static infrared non-destructive testing technology are used to simulate the specimen. The temperature change of the center point of the defect on the surface of the specimen is as follows: Figure 8 As shown in the figure, the excitation cycles of the linear FM waveform and the quasi-linear FM waveform are consistent, and the peak values ​​are the same. At the defect center, the temperature variation trends of the linear FM waveform and the quasi-linear FM waveform are consistent, but the integral area of ​​the quasi-linear FM waveform excitation is larger than that of the linear FM waveform excitation. Therefore, there is a difference in the temperature peak values ​​between the two, which can be compensated by reducing the excitation peak value of the linear FM waveform.

[0048] Therefore, it can be concluded that the detection results achieved using the quasi-linear FM waveform excitation in the present invention are almost equivalent to those achieved using the linear FM waveform excitation in static infrared nondestructive testing techniques. Given that the detection results are nearly identical, the quasi-linear FM waveform excitation in the present invention is superior to the static infrared nondestructive testing techniques using the linear FM waveform excitation in terms of detection efficiency.

[0049] Use a phase-encoded waveform stimulus to perform simulation tests, as follows: First, the phase encoding waveform is set to the 13-bit Barker encoding waveform {1, 1, 1, 1, 1, 0, 0, 1, 1, 1, 0, 0} which is shortened by half in equal proportion as a control; Figure 4 Arranging the collimator 10 and Powell prism 12 in the optical lens assembly 2 in the manner shown above yields four homogenized line lasers with four different line widths, each having a cross-sectional waveform consisting of four square wave pulses arranged in a certain pattern. Phase-encoded waveform excitation is used in static infrared nondestructive testing technology, while quasi-phase-encoded waveform excitation is used in online laser scanning infrared nondestructive testing technology. The excitation peak values ​​for both the phase-encoded waveform and the quasi-phase-encoded waveform are set to the same 39,000 W / m. 2 , the comparison between phase-encoded waveform and quasi-phase-encoded waveform is as follows Figure 9 shown.

[0050] The phase-encoding waveform in the method of the present invention and the phase-encoding waveform in the static infrared nondestructive testing technology are used to simulate the specimen. The temperature change of the center point of the defect on the surface of the specimen is as follows: Figure 10 As shown in the figure, it can be seen that the phase-encoding waveform and the quasi-phase-encoding waveform almost overlap, the excitation changes are consistent, and the peak values ​​are the same; at the center of the defect, the temperature changes of the phase-encoding waveform and the quasi-phase-encoding waveform are almost the same.

[0051] Therefore, it can be concluded that the detection effect achieved by using a phase-encoded waveform excitation in the present invention is almost equivalent to that achieved by using a phase-encoded waveform excitation in static infrared nondestructive testing technology. Given that the detection effects are nearly identical, the use of a phase-encoded waveform excitation in the present invention is superior to static infrared nondestructive testing technology using a phase-encoded waveform excitation in terms of detection efficiency.

[0052] In summary, the method of the present invention can realize excitation including but not limited to phase-locked waveforms, linear frequency modulation waveforms and phase-encoded waveforms in the online laser scanning infrared non-destructive testing technology through different optical path combinations. The application results are similar to the excitation of phase-locked waveforms, linear frequency modulation waveforms and phase-encoded excitation waveforms in static infrared non-destructive testing technology. It can improve the detection capability of defects while ensuring the detection efficiency of the linear laser scanning infrared non-destructive testing technology.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A coded line laser excitation method based on line laser scanning infrared non-destructive testing technology, characterized in that: include: S1, using a multi-channel coupled point light source laser to output multiple point lasers through its multiple channels; S2. Use a collimator to collimate the point laser output from each channel and obtain a homogenized point laser; S3, converting the collimated homogenized point laser into a Gaussian point laser through a plano-convex lens; S4. Using a Powell prism, the Gaussian point laser or the homogenized point laser is stretched in one direction to form a Gaussian line laser or a homogenized line laser; S5. Arrange the optical paths and adjust the parameters of the point lasers of multiple channels according to the required excitation waveform type to achieve a phase-locked waveform, a linear frequency modulation waveform, or a phase-encoded excitation waveform; S6. Irradiate the formed Gaussian line laser or homogenized line laser onto the test piece to perform line laser scanning infrared nondestructive testing.

2. The coded line laser excitation method based on line laser scanning infrared nondestructive testing technology according to claim 1 is characterized in that: In step S5, the process of implementing the quasi-phase-locked waveform includes: Assuming that the number of periods of the quasi-phase-locked waveform is N, the N channels of the multi-channel coupled point light source laser are used to output N homogenized point lasers; Ensure that the spot imaging size of the Gaussian point laser is consistent after the homogenized point lasers of N channels pass through the plano-convex lens; The spacing between the plano-convex lens and the Powell prism of all channels is set to be the same to ensure the line width of the N Gaussian line lasers is consistent; After N Gaussian line lasers are arranged at regular intervals, a quasi-phase-locked waveform similar to a phase-locked waveform is formed.

3. The coded line laser excitation method based on line laser scanning infrared nondestructive testing technology according to claim 1 is characterized in that: In step S5, the process of implementing the linear frequency modulation-like waveform includes: Assuming that the linear frequency modulation waveform has M peaks, the M channels of the multi-channel coupled point light source laser are used to output M homogenized point lasers; After the homogenized point lasers of the M channels pass through the plano-convex lens, the spot imaging sizes of the Gaussian point lasers are ensured to be inconsistent, and the spot sizes of the M channels should gradually change from large to small; The spacing between the plano-convex lens and the Powell prism of all channels is set to be different to ensure that the line widths of the M Gaussian line lasers are different; After arranging M Gaussian line lasers at certain intervals, a quasi-linear frequency modulation waveform that is highly similar to a linear frequency modulation waveform is formed.

4. The coded line laser excitation method based on line laser scanning infrared nondestructive testing technology according to claim 1 is characterized in that: In step S5, the process of implementing the phase-coded excitation waveform includes: Assume that the phase-coded excitation waveform is similar to a specific Bark-coded pulse compression waveform, which has K square wave peaks; After the homogenized point lasers of the K channels pass through the collimator, the spot imaging sizes of the homogenized point lasers are ensured to be inconsistent, and the ratio of the spot sizes of the K channels is consistent with the width ratio of the K square waves in the Barker-coded pulse compression waveform; Adjusting the spacing between the collimating mirrors and the Powell prisms of all channels to ensure that the ratio of the line widths of the K homogenized line lasers is consistent with the width ratio of the K square waves in the Barker-coded pulse compression waveform; After K homogenized line lasers are arranged at certain intervals, a phase-encoded waveform highly similar to the Barker-encoded pulse compression waveform is formed.

5. The coded line laser excitation method based on line laser scanning infrared nondestructive testing technology according to claim 1 is characterized in that: The number of channels of the multi-channel coupled point light source laser is determined according to the number of peaks or cycles of the excitation waveform to be realized.

6. The coded line laser excitation method based on line laser scanning infrared nondestructive testing technology according to claim 1 is characterized in that: Depending on the combination of the collimating mirror, the plano-convex lens and the Powell prism, a variety of different excitation waveforms can be achieved, including but not limited to quasi-phase-locked, quasi-linear frequency modulation, and quasi-phase-coded excitation waveforms.

7. A coding line laser excitation device implemented by the coding line laser excitation method based on line laser scanning infrared nondestructive testing technology according to any one of claims 1 to 6, characterized in that: include: Multi-channel coupled point light source laser, collimating lens, plano-convex lens, Powell prism and optical path arrangement device, wherein: The multi-channel coupled point light source laser is used to output multiple point lasers through its multiple channels respectively; The collimating mirror is used to collimate the point laser output by each channel; The plano-convex lens is used to convert the collimated point laser into a Gaussian point laser or a homogenized point laser; The Powell prism is used to stretch the Gaussian point laser or the homogenized point laser in one direction to form a Gaussian line laser or the homogenized line laser; The optical path arrangement device is used to perform specific optical path arrangement and parameter adjustment on the point lasers of multiple channels according to the required excitation waveform type, so as to realize a quasi-phase-locked waveform, a quasi-linear frequency modulation waveform or a quasi-phase-encoded excitation waveform.

8. The coding line laser excitation device according to claim 7, characterized in that: Also includes: Mobile scanning platform, used to carry optical lens assembly, multi-channel coupled point light source laser and infrared thermal imager; Infrared thermal imager, used to collect infrared images of the test piece; The mobile terminal is used to collect images captured by the infrared thermal imager and control the output waveform style of the multi-channel coupled point light source laser through the signal acquisition card.

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