Stress detection method based on X-ray diffraction residual stress meter

Abstract

The invention discloses a stress detection method based on an X-ray diffraction residual stress meter, and the method comprises the steps: S1, obtaining the measurement data of the internal residual stress of a material through X-ray diffraction detection, carrying out the interpolation and smoothing of stress values in different depths and directions, and constructing the data of a continuous three-dimensional stress field model; s2, selecting a micro-lens array as a display device and configuring a fill factor; s3, phase modulation is carried out by using a computer generated hologram algorithm, and phase distribution parameters of the spatial light modulator are adjusted through an iterative optimization algorithm; s4, a rotary diffusion sheet is arranged in an optical path to serve as a dynamic scatterer, the rotating speed is controlled to range from 100 rpm to 500 rpm, and meanwhile the voltage standing wave ratio of the IDT is reduced to 1.5 or below through an impedance matching network; a double-layer orthogonally rotating polycarbonate diffusion sheet is used as a dynamic scatterer in S4, so that a fixed speckle pattern formed by laser interference can be effectively broken, and the generated three-dimensional stress field model is clearer and smoother.

Description

Technical Field

[0001] The present invention relates to the technical field of stress detection, and in particular to a stress detection method based on an X-ray diffraction residual stress instrument. Background Art

[0002] In the field of materials science, accurately obtaining and displaying the residual stress distribution inside the material is crucial for evaluating material properties, optimizing manufacturing processes, and predicting the service life of structural components. The residual stress state inside the material can significantly affect its mechanical properties, such as strength, fatigue life, and corrosion resistance. Therefore, accurately measuring and effectively displaying this stress information is a key step to ensure the reliability and safety of the material.

[0003] As a non-destructive testing tool, the X-ray diffraction residual stress instrument can provide stress data at different depths and directions inside the material. However, when visualizing the residual stress measurement data, the traditional two-dimensional image or chart method is difficult to fully and intuitively display the stress state inside the three-dimensional structure. Traditional visualization methods can only provide information in limited directions or levels, and lack a comprehensive understanding of the stress distribution in the entire three-dimensional space. For example, a two-dimensional chart cannot fully express the changes in stress at different depths, nor can it clearly show the distribution characteristics of stress inside materials of complex shapes. These limitations make it difficult for users to obtain a complete view of the true distribution of stress inside the material, thereby limiting the in-depth analysis of material behavior and its response mechanism.

[0004] In addition, "speckle" occurs when trying to use 3D holographic display technology to visualize these complex data sets. Speckle is a random pattern of bright or dark spots formed by laser interference, which seriously affects the quality of the hologram, reduces the viewing experience, and obscures important details. Since high-coherence lasers are used as light sources in the holographic imaging process, multiple scattering occurs when the light passes through rough surfaces or inhomogeneous media. This multiple scattering causes the light to form a complex interference pattern during propagation, and is ultimately projected onto the viewing surface to form the so-called "speckle". Speckle not only destroys the clarity and smoothness of the image, but also causes important stress distribution features to be obscured or blurred, greatly affecting the effectiveness of holograms in practical applications.

[0005] Therefore, it is necessary to provide a stress detection method based on an X-ray diffraction residual stress instrument to solve the above technical problems. Summary of the invention

[0006] The present invention overcomes the deficiencies of the prior art and provides a stress detection method based on an X-ray diffraction residual stress instrument.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a stress detection method based on an X-ray diffraction residual stress instrument, comprising the following steps:

[0008] S1: Obtain the residual stress measurement data inside the material through X-ray diffraction detection, interpolate and smooth the stress values ​​at different depths and directions, and construct continuous three-dimensional stress field model data;

[0009] S2: Select a microlens array as the display device, configure a lens group with a fill factor of 0.6-0.8 and a focal length of 10-50 mm, and set the SAW frequency in the range of 10-100 MHz;

[0010] S3: Based on the three-dimensional stress field model data in S1, a computer-generated hologram algorithm is used for phase modulation, and the phase distribution parameters of the spatial light modulator are adjusted by an iterative optimization algorithm;

[0011] S4: A rotating diffuser is set in the optical path as a dynamic scatterer, and the rotation speed is controlled at 100-500rpm. At the same time, an impedance matching network is used to reduce the voltage standing wave ratio of the IDT to below 1.5.

[0012] In a preferred embodiment of the present invention, in S4, the dynamic scatterer adopts a double-layer orthogonally rotated polycarbonate diffuser, and the surface roughness Ra of the dynamic scatterer is in the range of 0.2-0.8 μm.

[0013] In a preferred embodiment of the present invention, in S4, the IDT uses an inclined electrode.

[0014] In a preferred embodiment of the present invention, the ratio of the width to the spacing of the electrode fingers is 1:1.2-1.5, the thickness of the electrode is 200-500 nm of the aluminum film, and the tilt angle is 5-15°.

[0015] In a preferred embodiment of the present invention, in S3, the computer generated hologram algorithm adopts a weighted angular spectrum method, and optimizes the amplitude constraint and the phase modulation depth simultaneously during the iteration process, and the number of iterations is set to 8-12 times.

[0016] In a preferred embodiment of the present invention, in said S1, in the X-ray diffraction detection link, a multi-axis goniometer is set to synchronize the spatial coordinates with the holographic display system, and a mapping relationship between the incident angle θ and the diffraction angle 2θ scanning angle and the holographic pixel points is established, and the mapping accuracy reaches 0.01°.

[0017] In a preferred embodiment of the present invention, in S2, the lens group has a filling factor of 0.6-0.8 and a focal length of 10-50 mm, and the SAW frequency is set in the range of 10-100 MHz.

[0018] In a preferred embodiment of the present invention, the three-dimensional holographic stress detection system of the X-ray diffraction residual stress instrument includes: a three-dimensional holographic display module and a user interaction module, wherein the three-dimensional holographic display module integrates a real-time monitoring module, including a temperature sensor array and a photodetector array, with a sampling frequency of not less than 1kHz, and real-time feedback adjustment of the IDT driving power and the working status of the radiator.

[0019] In a preferred embodiment of the present invention, the user interaction module provides a gesture recognition interface for interactive sectioning display of the three-dimensional stress field.

[0020] In a preferred embodiment of the present invention, a three-dimensional holographic stress detection device of an X-ray diffraction residual stress instrument includes: an X-ray generator, an acousto-optic modulator, a dynamic scatterer module and a photoelectric detection module, and the X-ray generator, acousto-optic modulator, a dynamic scatterer module and a photoelectric detection module are integrated on a shock-proof platform.

[0021] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0022] (1) The present invention provides a stress detection method based on an X-ray diffraction residual stress meter. By combining X-ray diffraction detection and three-dimensional holographic display in S1, data on residual stress distribution inside the material can be obtained, and a continuous three-dimensional stress field model can be constructed. In the X-ray diffraction detection link, a multi-axis goniometer is set to synchronize spatial coordinates with the holographic display system to ensure that the mapping relationship between the incident angle θ and the diffraction angle 2θ scanning angle and the holographic pixel point reaches an accuracy of 0.01°, so that this high-precision measurement method, compared with traditional stress detection methods, not only improves the accuracy of the data, but also can more comprehensively display the stress state inside the material.

[0023] (2) The present invention provides a stress detection method based on an X-ray diffraction residual stress meter, which uses a dynamic scatterer to solve the speckle phenomenon in the three-dimensional holographic display process. By using a double-layer orthogonally rotating polycarbonate diffuser as a dynamic scatterer in S4, the surface roughness Ra range is controlled between 0.5μm and the rotation speed is set at 300rpm, which effectively breaks the fixed speckle pattern formed by laser interference, making the generated three-dimensional stress field model clearer and smoother. In addition, the voltage standing wave ratio of the IDT is reduced to below 1.5 through an impedance matching network, further improving the image quality and ensuring the richness of details, so that the observer can obtain a more delicate and realistic three-dimensional stress field view.

[0024] (3) The present invention provides a stress detection method based on an X-ray diffraction residual stress instrument, which uses a computer-generated hologram algorithm to simultaneously optimize the amplitude constraint and the phase modulation depth during the iteration process, and the number of iterations is set to 8-12 times to ensure high-quality hologram generation. In addition, the sampling frequency of the temperature sensor array and the photodetector array in the real-time monitoring module is not less than 1kHz, which can provide real-time feedback to adjust the IDT drive power and the working state of the radiator to ensure the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0026] Figure 1 It is a schematic diagram of a preferred embodiment of the present invention;

[0027] Figure 2 Schematic diagram of speckle of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments 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 creative work are within the scope of protection of the present invention.

[0029] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0030] Traditional two-dimensional images or charts are difficult to fully display the complex three-dimensional stress state inside the material, while 3D holographic display technology can present these stress distributions from an all-round perspective, enhance the understanding of the internal stress of complex-shaped materials, and as a non-destructive detection method, it can obtain its internal stress information without damaging the sample.

[0031] However, when using 3D holographic display technology, the problem of "speckle" phenomenon will be encountered. Speckle is a random pattern of bright or dark spots formed by laser interference, which seriously affects the quality of the hologram. Since 3D holographic imaging uses high-coherence laser as the light source, multiple scattering will occur when the light passes through a rough surface or an inhomogeneous medium, forming a complex interference pattern and projecting it onto the observation surface to form speckle. In addition, if the surface roughness of the dynamic scatterer is not appropriate or the rotation speed is not appropriate, the fixed speckle pattern cannot be effectively broken, thus affecting the image quality.

[0032] like Figure 1-Figure 2 As shown, the present invention provides a stress detection method based on an X-ray diffraction residual stress instrument, comprising the following steps:

[0033] S1: Obtain the residual stress measurement data inside the material through X-ray diffraction detection, interpolate and smooth the stress values ​​at different depths and directions, and construct continuous three-dimensional stress field model data. In the X-ray diffraction detection link, set up a multi-axis goniometer and holographic display system to synchronize spatial coordinates, establish the mapping relationship between the incident angle θ and the diffraction angle 2θ scanning angle and the holographic pixel point, and the mapping accuracy reaches 0.01°;

[0034] It should be noted that X-ray diffraction technology is used to non-destructively obtain residual stress data at different depths and directions inside the material, interpolate the collected data to fill in the gaps, and eliminate noise through smoothing to ensure that continuous and accurate stress distribution information can be obtained at different depths and directions. During the X-ray diffraction process, a high-precision 0.01° mapping relationship between the incident angle θ and the diffraction angle 2θ and the holographic pixel point is established through synchronization of the multi-axis goniometer and the holographic display system. This improves data acquisition accuracy and supports accurate three-dimensional stress field modeling.

[0035] Where: X-ray diffraction angle (Bragg's law): nλ = 2dsinθ

[0036] n is the reflection order, λ is the wavelength of the X-ray, d is the interplanar spacing, and θ is the angle of incidence or diffraction.

[0037] Among them: interpolation and smoothing will use interpolation algorithms such as linear interpolation to fill data gaps, and use smoothing filters such as Gaussian filters to reduce noise;

[0038] Linear interpolation is one of the simplest interpolation methods and is used to estimate the value between two known data points. and To estimate the value y at x, the following formula can be used:

[0039]

[0040] Gaussian filtering is a commonly used image smoothing technique that aims to reduce noise and blur the image. The two-dimensional Gaussian function is defined as follows:

[0041]

[0042] Among them, σ controls the width of the Gaussian distribution and determines the strength of the filtering effect to achieve a smoothing effect.

[0043] S2: Select a microlens array as the display device, configure a lens group with a fill factor of 0.6-0.8 and a focal length of 10-50 mm, and set the SAW frequency in the range of 10-100 MHz;

[0044] It should be noted that the microlens array is an optical element composed of many tiny lens units, each of which can form an image independently, which can achieve high-resolution image display and effectively improve the clarity and detail expression of the three-dimensional hologram. The fill factor is the ratio of the actual lens area to the total area in the lens array. A higher fill factor means that more light can be imaged through the lens array, thereby improving the brightness and contrast of the image while reducing unnecessary light loss. The focal length of the lens group is set in the range of 10-50mm to provide sufficient depth of field to ensure that information at different depths can be accurately reproduced in the hologram. SAW can effectively interact with light to achieve efficient phase modulation, and the SAW frequency can enhance the stability of the image.

[0045] Where: Fill factor:

[0046] A lens is the area of ​​a single lens, A total is the total area.

[0047] Depth of field (DOF): for a given focal length f, aperture value NN, magnification m;

[0048] The depth of field is approximately: DOF≈2Nυ 2 / m 2 ;

[0049] where υ is the object distance.

[0050] S3: Use a computer-generated hologram algorithm for phase modulation, and adjust the phase distribution parameters of the spatial light modulator through an iterative optimization algorithm. The computer-generated hologram algorithm uses a weighted angular spectrum method to simultaneously optimize the amplitude constraint and the phase modulation depth during the iteration process. The number of iterations is set to 8-12 times;

[0051] It should be noted that after obtaining the three-dimensional stress field model data, the computer-generated hologram algorithm is used to process these data to achieve phase modulation, which can convert complex three-dimensional stress information into a three-dimensional hologram that can be used for display, thereby displaying the internal stress state of the material in an intuitive way, and using an iterative optimization algorithm to adjust the phase distribution parameters of the spatial light modulator (SLM). By continuously adjusting and optimizing the phase distribution on the SLM, the final generated holographic image is clearer and more stable. In the process of generating the hologram, the weighted angular spectrum method is particularly used. In this way, the amplitude constraint conditions and phase modulation depth can be optimized simultaneously during the iteration process, ensuring that the hologram has both high resolution and good contrast and detail expression. In order to balance the computational efficiency and image quality, the number of iterations is set to 8-12 times, which can not only ensure the optimization effect, but also avoid the waste of time caused by excessive calculation. Each iteration will be adjusted according to the previous result, gradually approaching the optimal solution, thereby generating a high-quality hologram.

[0052] Among them, the weighted angular spectrum method is used to generate holograms. Its core idea is to process the propagation process of light waves through Fourier transform.

[0053] For a given light field Its any position The complex amplitude distribution at can be obtained by the angular spectrum method:

[0054]

[0055] in,

[0056] and denote two-dimensional Fourier transform and inverse Fourier transform respectively;

[0057] is the propagation function, defined as:

[0058]

[0059] where j is the imaginary unit, λ is the wavelength, and are the frequency domain coordinates.

[0060] Iterative optimization algorithm: refers to the Gerchberg-Saxton algorithm, which approximates the target image by iteratively adjusting the phase information. The following is a simplified example of the iterative process:

[0061] Initialization: Setting the initial phase Combined with the given amplitude constraint A target (i.e., the amplitude of the target hologram), forming an initial estimate

[0062] Iterative updates:

[0063] For the current estimate E n Perform Fourier transform to get the frequency domain representation F(E n );

[0064] In the frequency domain, constraints are imposed on the depth of phase modulation, such as keeping the amplitude unchanged and only modifying the phase part P(F(E n ));

[0065] Perform an inverse Fourier transform on the modified frequency domain representation back to the spatial domain I(P(F(E n )));

[0066] Adjust the results in the spatial domain according to actual requirements (such as amplitude constraints) and update the phase distribution

[0067] Termination condition: Repeat the above steps until the predetermined number of iterations is met (8-12 times in this example).

[0068] S4: A rotating diffuser is set in the optical path as a dynamic scatterer. The dynamic scatterer adopts a double-layer orthogonally rotating polycarbonate diffuser. The surface roughness Ra of the dynamic scatterer is in the range of 0.2-0.8μm. The rotation speed is controlled at 100-500rpm. At the same time, an impedance matching network is used to reduce the voltage standing wave ratio of the IDT to below 1.5. The IDT adopts an inclined electrode, the ratio of the electrode finger width to the spacing is 1:1.2-1.5, the electrode thickness is an aluminum film of 200-500nm, and the inclination angle is 5-15°;

[0069] It should be noted that the spatial coherence of the light field is increased by introducing an element that can randomly change the light path, thereby improving the quality of the final holographic image. A double-layer orthogonally rotating polycarbonate diffuser is used, each layer rotates at a different speed or direction to ensure that the change is continuous and uniform, further improving the uniformity of the light field and reducing the appearance of interference fringes.

[0070] Among them: the surface roughness Ra is controlled between 0.2-0.8μm: the surface roughness Ra is defined as:

[0071]

[0072] Where L is the evaluation length and f(x) is the height deviation function relative to the ideal plane. The roughness within this range can ensure sufficient light scattering while avoiding image blur caused by excessive scattering, ensuring a proper balance.

[0073] Where: The speed is set within the range of 100-500rpm: (Unit: rpm) and angular velocity (Unit: rad / s) The conversion relationship between them is:

[0074]

[0075] Adjustment within this range can optimize the scattering effect according to specific needs, avoiding the problem of too low a speed not being enough to produce an ideal scattering effect, and preventing mechanical stability problems caused by too high a speed.

[0076] Impedance matching network

[0077] Reduce the voltage standing wave ratio of IDT to below 1.5: The voltage standing wave ratio (VSWR) calculation formula is:

[0078]

[0079] The reflection coefficient Γ is defined as:

[0080]

[0081] Among them, Z L is the load impedance, and Z0 is the characteristic impedance of the transmission line. By optimizing, the VSWR is as close to 1 as possible, with the goal of reducing it to below 1.5, ensuring that more energy is effectively converted into the required sound or light waves rather than being reflected back to the source, thereby improving the overall efficiency of the system.

[0082] like Figure 1 As shown, the three-dimensional holographic stress detection system of the X-ray diffraction residual stress instrument includes: a three-dimensional holographic display module and a user interaction module. The three-dimensional holographic display module is integrated with a real-time monitoring module, which includes a temperature sensor array and a photodetector array. The sampling frequency is not less than 1kHz, and real-time feedback is provided to adjust the IDT driving power and the working state of the radiator. The user interaction module provides a gesture recognition interface for interactive sectioning display of the three-dimensional stress field.

[0083] It should be noted that the real-time monitoring module integrates a temperature sensor array and a photodetector array, with a sampling frequency of no less than 1kHz. This enables the system to respond quickly to environmental changes and perform real-time feedback adjustments to ensure the optimization of the IDT drive power and the working state of the radiator, thereby maintaining image quality and system stability. Through real-time monitoring data, the system can automatically adjust the scatterer rotation speed and the refresh rate of the spatial light modulator, effectively reducing interference factors in the image, such as speckle noise, to ensure high-quality hologram generation. And through the user interaction module, a gesture recognition interface is provided, allowing users to interact with the three-dimensional stress field model in a natural way and perform interactive sectioning display.

[0084] like Figure 1As shown, the three-dimensional holographic stress detection device of the X-ray diffraction residual stress instrument includes: an X-ray generator, an acousto-optic modulator, a dynamic scatterer module and a photoelectric detection module, and the X-ray generator, the acousto-optic modulator, the dynamic scatterer module and the photoelectric detection module are integrated on a shockproof platform.

[0085] It should be noted that the X-ray generator non-destructively obtains the internal stress data of the material, and the photoelectric detection module monitors and feedbacks information in real time to ensure the high accuracy of data acquisition. The dynamic scatterer breaks the fixed speckle pattern through a double-layer orthogonal rotating diffuser to improve image clarity and smoothness. Integration on the anti-vibration platform effectively reduces the impact of external vibration and enhances the stability of the system. The real-time monitoring module adjusts the IDT drive power and the working status of the radiator at a sampling frequency of not less than 1kHz to ensure the stable operation of the system. The user interaction module provides a gesture recognition interface.

[0086] Embodiment 1:

[0087] S1: Obtain the residual stress measurement data inside the material through X-ray diffraction detection, interpolate and smooth the stress values ​​at different depths and directions, and construct continuous three-dimensional stress field model data. In the X-ray diffraction detection link, set up a multi-axis goniometer and holographic display system to synchronize spatial coordinates, establish the mapping relationship between the incident angle θ and the diffraction angle 2θ scanning angle and the holographic pixel point, and the mapping accuracy reaches 0.01°;

[0088] S2: Select a microlens array as the display device, configure a lens group with a fill factor of 0.7 and a focal length of 30 mm, and set the SAW frequency to 50 MHz;

[0089] S3: Use the computer-generated hologram algorithm for phase modulation, and adjust the phase distribution parameters of the spatial light modulator through an iterative optimization algorithm. The computer-generated hologram algorithm uses a weighted angular spectrum method to simultaneously optimize the amplitude constraint and the phase modulation depth during the iteration process. The number of iterations is set to 10 times;

[0090] S4: A rotating diffuser is set in the optical path as a dynamic scatterer. The dynamic scatterer adopts a double-layer orthogonally rotating polycarbonate diffuser. The surface roughness Ra of the dynamic scatterer is 0.5μm, and the rotation speed is controlled at 300rpm. At the same time, an impedance matching network is used to reduce the voltage standing wave ratio of the IDT to below 1.5. The IDT adopts an inclined electrode, the ratio of the electrode finger width to the spacing is 1:1.3, the electrode thickness is 300nm of aluminum film, and the tilt angle is 10°.

[0091] Embodiment 2:

[0092] This embodiment is basically the same as the first embodiment, with the difference being that in step S4, the dynamic scatterer uses a double-layer orthogonally rotated polycarbonate diffuser, the surface roughness Ra of the dynamic scatterer is 0.2 μm, and the rotation speed is controlled at 300 rpm.

[0093] Embodiment three:

[0094] This embodiment is basically the same as the first embodiment, except that in step S4, the dynamic scatterer uses a double-layer orthogonally rotated polycarbonate diffuser, the surface roughness Ra of the dynamic scatterer is 0.8 μm, and the rotation speed is controlled at 300 rpm.

[0095] Embodiment 4:

[0096] This embodiment is basically the same as the first embodiment, except that in step S4, the dynamic scatterer uses a double-layer orthogonally rotated polycarbonate diffuser, the surface roughness Ra of the dynamic scatterer is 0.5 μm, and the rotation speed is controlled at 100 rpm.

[0097] Embodiment five:

[0098] This embodiment is basically the same as the first embodiment, except that in step S4, the dynamic scatterer uses a double-layer orthogonally rotated polycarbonate diffuser, the surface roughness Ra of the dynamic scatterer is 0.5 μm, and the rotation speed is controlled at 500 rpm.

[0099] Embodiment six:

[0100] This embodiment is basically the same as the first embodiment, except that in step S4, the surface roughness Ra of the dynamic scatterer is 0.5 μm, the rotation speed is controlled at 300 rpm, and no impedance matching network is used.

[0101] Embodiment seven:

[0102] This embodiment is basically the same as the first embodiment, except that step S4 is deleted.

[0103] Experiment 1:

[0104] Experimental method: An X-ray diffraction residual stress instrument was set according to the specific parameters of Examples 1 to 7, and each Example was tested repeatedly at least 5 times.

[0105] Evaluation Metrics:

[0106] Speckle density (number of speckles per unit area / cm 2 ).

[0107] Image clarity (using peak signal-to-noise ratio PSNR as the evaluation standard / dB).

[0108] Data analysis: Use statistical analysis tools to calculate mean values ​​and standard deviations and compare differences between different embodiments;

[0109] Table 1:

[0110]

[0111] According to Table 1:

[0112] Example 1: By adjusting the surface roughness of the dynamic scatterer to 0.5 μm and setting the rotation speed to 300 rpm, the speckle phenomenon is effectively reduced. The impedance matching network is used to further optimize the performance of the system, so that the voltage standing wave ratio is reduced to below 1.5, improving the energy conversion efficiency and image quality. This example has the lowest average speckle density (10.14 / cm 2 ) and the highest PSNR value (45.23dB), indicating that it performs best in reducing speckle and improving image clarity.

[0113] Example 2: The same rotation speed of 300 rpm and impedance matching network as in Example 1 are used, but the surface roughness of the dynamic scatterer is reduced to 0.2 μm, resulting in a higher speckle density (15.27 / cm 2 ) and a lower PSNR value (40.15dB). This indicates that although too low surface roughness can provide a certain scattering effect, it is not enough to effectively break the fixed speckle pattern formed by laser interference, thus affecting the image quality.

[0114] Example 3: The surface roughness of the dynamic scatterer is increased to 0.8 μm, which improves the speckle phenomenon to a certain extent, but is still not as significant as the effect of Example 1. The average speckle density is 12.36 / cm 2 , the PSNR value is 42.45dB. This means that excessive surface roughness will introduce additional scattering noise, and although it still helps to destroy the fixed speckle pattern, the overall effect is not as good as moderate surface roughness.

[0115] Example 4: Maintaining the surface roughness (0.5 μm) and the application of the impedance matching network, but reducing the rotation speed to 100 rpm. The results show a higher speckle density (18.54 / cm 2 ) and a lower PSNR value (38.67dB), indicating that the too low rotation speed is not enough to provide enough dynamics to disrupt the fixed speckle pattern, thus affecting the image quality.

[0116] Example 5: The same surface roughness (0.5 μm) and impedance matching network are used, but the rotation speed is increased to 500 rpm. Although high-speed rotation helps to destroy the fixed speckle pattern, too high a rotation speed may cause mechanical stability problems, resulting in a higher speckle density (16.78 / cm2 ) and PSNR values ​​are low (39.89dB), indicating that the higher the speed, the better.

[0117] Example 6: The surface roughness (0.5 μm) and the rotation speed of 300 rpm are still used, but the impedance matching network is not used, which leads to an increase in the voltage standing wave ratio and a decrease in system performance. The results show that the speckle density is as high as 20.89 / cm 2 , the PSNR value is only 37.56dB, proving that the impedance matching network is crucial to optimizing system performance and improving image quality.

[0118] Example 7: The dynamic scatterer module is completely removed, resulting in the inability to effectively eliminate the fixed speckle pattern caused by laser interference. The results show an extremely high speckle density (50.98 / cm 2 ) and the lowest PSNR value (30.12 dB), indicating that without a dynamic scatterer, the quality of the hologram is severely impaired and difficult to meet the needs of practical applications. Therefore, the presence of a dynamic scatterer is essential to reduce speckle and improve image clarity.

[0119] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A stress detection method based on an X-ray diffraction residual stress instrument, characterized in that: The following steps are involved: S1: Obtain the residual stress measurement data inside the material through X-ray diffraction detection, interpolate and smooth the stress values ​​at different depths and directions, and construct continuous three-dimensional stress field model data; S2: Select a microlens array as the display device and configure the fill factor; S3: Phase modulation using a computer-generated hologram algorithm and adjusting the phase distribution parameters of the spatial light modulator through an iterative optimization algorithm; S4: A rotating diffuser is set in the optical path as a dynamic scatterer, and the rotation speed is controlled at 100-500rpm. At the same time, an impedance matching network is used to reduce the voltage standing wave ratio of the IDT to below 1.

5.

2. The stress detection method based on X-ray diffraction residual stress instrument according to claim 1, characterized in that: In S4, the dynamic scatterer adopts a double-layer orthogonally rotated polycarbonate diffuser, and the surface roughness Ra of the dynamic scatterer is in the range of 0.2-0.8 μm.

3. The stress detection method based on X-ray diffraction residual stress instrument according to claim 1, characterized in that: In the S4, the IDT uses an inclined electrode.

4. The stress detection method based on X-ray diffraction residual stress instrument according to claim 3 is characterized in that: The ratio of the electrode finger width to the spacing is 1:1.2-1.5, the electrode thickness is 200-500nm of aluminum film, and the tilt angle is 5-15°.

5. The stress detection method based on X-ray diffraction residual stress instrument according to claim 1, characterized in that: In S3, the computer generated hologram algorithm adopts a weighted angular spectrum method, and optimizes the amplitude constraint and the phase modulation depth simultaneously during the iteration process, and the number of iterations is set to 8-12 times.

6. The stress detection method based on X-ray diffraction residual stress instrument according to claim 1, characterized in that: In the S1, in the X-ray diffraction detection link, a multi-axis goniometer is set to synchronize the spatial coordinates with the holographic display system, and a mapping relationship between the incident angle θ and the diffraction angle 2θ scanning angle and the holographic pixel points is established, and the mapping accuracy reaches 0.01°.

7. The stress detection method based on X-ray diffraction residual stress instrument according to claim 1, characterized in that: In S2, the lens group has a filling factor of 0.6-0.8 and a focal length of 10-50 mm, and the SAW frequency is set in the range of 10-100 MHz.

8. A three-dimensional holographic stress detection system based on the X-ray diffraction residual stress instrument according to any one of claims 1 to 7, characterized in that: include: A three-dimensional holographic display module and a user interaction module, wherein the three-dimensional holographic display module integrates a real-time monitoring module, including a temperature sensor array and a photodetector array, with a sampling frequency of not less than 1kHz, and real-time feedback to adjust the IDT driving power and the working status of the radiator.

9. The three-dimensional holographic stress detection system of the X-ray diffraction residual stress instrument according to claim 8, characterized in that: The user interaction module provides a gesture recognition interface for interactive sectioning display of a three-dimensional stress field.

10. A three-dimensional holographic stress detection device based on the X-ray diffraction residual stress instrument according to any one of claims 1 to 9, characterized in that: include: An X-ray generator, an acousto-optic modulator, a dynamic scatterer module and a photoelectric detection module are integrated on a shockproof platform.

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