Strain measurement sensitivity calibration method of a shear speckle interferometry measurement system
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-06-08
- Publication Date
- 2026-08-11
AI Technical Summary
针对现有技术的不足，本发明提供了一种剪切散斑干涉测量系统的应变测量灵敏度标定方法，解决了目前尚无可靠的检测方法对剪切散斑干涉测量系统的应变测量灵敏度进行测量标定的问题
通过设置直接验证方法和间接外推方法，先利用直接验证法验证应变产生标准物质最小驱动步进偏转角度是否满足应变测量灵敏度测量要求，之后，依据验证结果判定选择直接验证法或者间接外推法对剪切散斑干涉测量系统的应变测量灵敏度进行测量，有效解决了目前尚无可靠的检测方法对剪切散斑干涉系统的应变测量灵敏度进行测量标定的问题，实现对剪切散斑干涉测量系统应变测量灵敏度的有效测量。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of calibration technology for shear speckle interferometry systems, and specifically to a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system. Background Technology
[0002] Shear speckle interferometry is an optical measurement technique based on laser speckle phenomena and the principle of interference. It is primarily used to measure the displacement derivatives of an object's surface, such as the first derivative of out-of-surface displacement. When coherent light (such as a laser) illuminates a rough surface, due to the surface's microscopic irregularities, the scattered light interferes in space, forming a random intensity distribution pattern. After passing through an optical shearing device, this object light field causes a certain lateral displacement in the speckle pattern on the object's surface, i.e., lateral shearing. The original object light field and the sheared object light field interfere on the imaging plane, i.e., shear speckle interferometry. By acquiring laser shear speckle interferometry images using photoelectric detection imaging devices, analyzing the data to obtain the phase difference distribution, and combining this with measurements of the laser wavelength and shearing amount, the strain distribution of the object under test can be obtained.
[0003] Strain measurement sensitivity is one of the important indicators for evaluating the performance of shear speckle interferometry systems, but there is currently no reliable testing method for measuring and calibrating this indicator.
[0004] Therefore, how to effectively calibrate the strain measurement sensitivity of the shear speckle interferometry system is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention
[0005] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system, solving the problem that there is currently no reliable detection method for calibrating the strain measurement sensitivity of a shear speckle interferometry system.
[0006] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: In a first aspect of this invention, a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system includes: The strain-generating standard material was selected as the observation object of the shear speckle interferometry system during the strain measurement sensitivity calibration process. After verifying and measuring the observed object, the sensitivity of the strain measurement is calibrated. The specific steps are as follows: S10. Verify, using the direct verification method, whether the minimum driving step deflection angle of the strain-generating standard material meets the strain measurement sensitivity requirements. Specifically: A rough planar component capable of precise, small-angle deflection is used as a strain-generating standard material, and the strain-generating standard material is controlled from a certain initial angle. Deflection angle by minimum drive step D min Small angle deflection occurs i (Pick θ= D min ); in, i This represents the angle of deflection. In-situ verification and monitoring of strain-generating standard materials were performed using a shear speckle interferometry system. The average strain value was obtained when the strain-generating standard material did not undergo small-angle deflection after multiple measurements. The standard deviation σ, and the average strain after a small-angle deflection. ; Compare and Determine the value of +3σ to obtain the verification result; S11. Based on the verification results of the direct verification method, determine whether to choose the direct verification method or the indirect extrapolation method for measurement, specifically as follows: like > +3σ indicates that the shear speckle interferometry system can clearly distinguish speckle patterns at the minimum driving step deflection angle. and The strain measurement sensitivity of the shear speckle interferometry system is then measured using the indirect extrapolation method. like ≤ +3σ indicates that the shear speckle interferometry system cannot clearly distinguish at the minimum driving step deflection angle. and Continue to increase the deflection angle i Subsequently, the strain measurement sensitivity of the shear speckle interferometry system was measured using the direct verification method until... > +3σ, the shear speckle interferometry system can clearly distinguish... and until.
[0007] Furthermore, in step S11, the sensitivity of the strain measurement obtained by the direct verification method is... s sin i .
[0008] Furthermore, a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system, specifically the indirect extrapolation method, is as follows: A rough planar component capable of precise small-angle deflection is used as a strain-generating standard material, and the strain-generating standard material is controlled to undergo a series of equally spaced small-angle deflections. For the known out-of-plane displacement caused by the angular changes, the phase difference information before and after the out-of-plane displacement of the strain-generating standard material is measured using a shear speckle interferometry system. ; By combining the strain value to be measured, the standard deviation σ of the phase difference measurement result of the shear speckle interferometry system and the phase difference measurement value are obtained. - The slope of the calibration curve for the strain value to be measured, sinθ m The strain measurement sensitivity of the shear speckle interferometry system is calculated according to the following formula. s : In the formula: s —Strain measurement sensitivity; k—confidence factor, take k≥3; σ—The standard deviation of the phase difference measurement in the shear speckle interferometry system when the strain is zero; m —The slope of the calibration curve of “phase difference measurement value - strain value to be measured”.
[0009] Furthermore, the strain-generating standard material is driven by piezoelectric ceramics or rotated by a precision turntable.
[0010] Furthermore, the design of the strain-generating standard material must meet the following conditions: Condition 1: Within the strain observation area of the strain-generating standard material, the strain value generated is the same at all points, that is, uniform strain generation is achieved. Condition 2: Within the strain observation area of the standard material for strain generation, the strain value generated at each location is within 10. -6 At or below the order of magnitude, i.e., achieving microscale strain generation.
[0011] Secondly, a strain measurement sensitivity calibration system for a shear speckle interferometry system includes: The verification module is used to verify whether the minimum drive step deflection angle meets the strain measurement sensitivity measurement requirements. The comparison module is used for comparison. and Determine the value of +3σ to obtain the verification result; The measurement module is used to obtain the strain measurement sensitivity.
[0012] Thirdly, a computer-readable storage medium storing a computer program for strain measurement sensitivity calibration, wherein the computer program causes a computer to perform strain measurement sensitivity calibration of the shear speckle interferometry system.
[0013] Fourthly, an electronic device comprising: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the programs including a strain measurement sensitivity calibration method for performing the shear speckle interferometry system.
[0014] (III) Beneficial Effects This invention provides a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system. Compared with existing technologies, it has the following advantages: By setting up direct verification and indirect extrapolation methods, the direct verification method is first used to verify whether the minimum driving step deflection angle of the strain-generating standard material meets the requirements for strain measurement sensitivity. Then, based on the verification results, the direct verification method or the indirect extrapolation method is selected to measure the strain measurement sensitivity of the shear speckle interferometry system. This effectively solves the problem that there is currently no reliable detection method to measure and calibrate the strain measurement sensitivity of the shear speckle interferometry system, and realizes the effective measurement of the strain measurement sensitivity of the shear speckle interferometry system. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 This is a schematic diagram of laser shear speckle interferometry. Figure 2 This is a schematic diagram of in-situ strain monitoring based on deflection angle. Figure 3 The strain measurement results are those of the strain-generating standard material in Example 1 before it undergoes a small-angle deflection. Figure 4 The strain measurement results are those obtained after the strain-generating standard material in Example 1 undergoes a small-angle deflection. Figure 5 This is the calibration curve of "phase difference measurement value - strain value to be measured" in Example 2; Figure 6 The results show the phase difference measurement at different deflection angles in Example 2. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0018] This application provides a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system, which solves the problem that there is currently no reliable detection method for calibrating the strain measurement sensitivity of a shear speckle interferometry system, and achieves effective measurement of the strain measurement sensitivity of the shear speckle interferometry system.
[0019] The specific design for strain-generated standard materials is as follows: Strain-generating standard materials are used as the observation object of the shear speckle interferometry system during the strain measurement sensitivity calibration process. They are used to generate minute strains, which are then measured using the shear speckle interferometry system. The measurement results are then evaluated and analyzed to obtain the strain measurement sensitivity. The design of the strain-generating standard material needs to meet two conditions: First, the strain value generated at all points within the strain observation area of the strain-generating standard material should be the same, i.e., uniform strain generation should be achieved; second, the strain value generated at all points within the strain observation area of the strain-generating standard material should be sufficiently small (10⁻⁶). -6 (At or below the order of magnitude), that is, achieving microscale strain generation. If condition one is not met, the strain values will differ at different locations within the observation area, making it impossible to effectively quantitatively evaluate the strain distribution of the entire observation area using a single strain value (usually the average of the strain distributions at different locations within the observation area). If condition two is not met, the lower limit of the generated strain value may be too large, exceeding the minimum strain value that the shear speckle interferometry system can detect and identify, making it impossible to obtain strain measurement sensitivity through direct observation of the strain-generating standard material.
[0020] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.
[0021] like Figure 1-Figure 6 As shown, a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system includes: The strain-generating standard material was selected as the observation object of the shear speckle interferometry system during the strain measurement sensitivity calibration process. After verifying and measuring the observed object, the sensitivity of the strain measurement is calibrated. The specific steps are as follows: S10. Verify, using the direct verification method, whether the minimum driving step deflection angle of the strain-generating standard material meets the sensitivity requirements for strain measurement. Specifically: A rough planar component capable of precise, small-angle deflection is used as a strain-generating standard material, and the strain-generating standard material is controlled from a certain initial angle. Deflection angle by minimum drive step D min Small angle deflection occurs i (Pick θ= D min ); in, i This represents the angle of deflection. In-situ verification and monitoring of strain-generating standard materials were performed using a shear speckle interferometry system. The average strain value was obtained when the strain-generating standard material did not undergo small-angle deflection after multiple measurements. The standard deviation σ, and the average strain after a small-angle deflection. ; Compare and Determine the value of +3σ to obtain the verification result; S11. Based on the verification results of the direct verification method, determine whether to choose the direct verification method or the indirect extrapolation method for measurement, specifically as follows: like > +3σ indicates that the shear speckle interferometry system can clearly distinguish speckle patterns at the minimum driving step deflection angle. and The strain measurement sensitivity of the shear speckle interferometry system is then measured using the indirect extrapolation method. like ≤ +3σ indicates that the shear speckle interferometry system cannot clearly distinguish at the minimum driving step deflection angle. and After further increasing the deflection angle, the strain measurement sensitivity of the shear speckle interferometry system was measured using the direct verification method until... > +3σ, the shear speckle interferometry system can clearly distinguish... and Until then; where, if the deflection angle is i When, satisfy > +3σ indicates the strain measurement sensitivity of the shear speckle interferometry system. s sin i .
[0022] Specifically, based on the principle of shear speckle interferometry, when verifying and measuring using direct verification or indirect extrapolation methods, laser illumination is applied to the object, and after shearing, two points... , Interference at the image plane coincidence: like Figure 1 As shown, when Small deformation under external stimulation Arriving late ,light source To the image Change in optical path Represented as: (1) Displacement to point ,light source To the image Change in optical path Represented as: (2) in, R S This represents the straight-line distance from the light source to the observation point on the surface of the object being measured. R c It represents the straight-line distance from the observation point on the surface of the object being measured to the image plane; u、v、w for P 1 o'clock at x、y、z Absolute displacement components in three directions; δu、δv、δw For optical shearing P 1 point and P The relative displacement gradient components between the two points.
[0023] Before and after object deformation P 1. P The relative phase change between two points is expressed as: (3) Where λ is the laser wavelength, and the coefficients A, B, and C can be represented by the following formula: (4) If the beam illumination direction and observation direction are defined to lie within the XOZ plane, then we can obtain... (5) Where α is the angle between the illumination direction and the observation direction of the beam. The interference is sheared along the x and y directions, with shearing amounts of respectively... L x , L y The phase difference before and after deformation is expressed as: (6) (7) For out-of-plane first-order displacement derivative measurements, paraxial illumination or coaxial illumination perpendicular to the object surface is generally used. The angle α between the illumination direction and the observation direction can be approximated as 0. The above formula simplifies to obtain the shear strain components (hereinafter referred to as "strain"): (8) We can obtain: When a surface of an object undergoes minute deformation, its strain (i.e., the first derivative of the out-of-surface displacement) can be calculated using the following formula: (9) In the formula, e For strain measurement results, To measure the laser wavelength for shear interferometry, L Shearing amount This represents the phase difference distribution obtained before and after the out-of-plane displacement. Therefore, using equation (9), the phase difference distribution can be calculated separately during the direct verification method measurement process. and .
[0024] When the strain driven on the test object causes a small-angle deflection of the standard material: like Figure 2 As shown, taking horizontal shear measurement as an example, this illustrates the process of calibrating strain measurement sensitivity by generating optical path difference due to changes in deflection angle. After the target surface rotates horizontally, point a rotates to point a′, and point b rotates to point b′. The rotation angle... i Recorded as i x The coordinate relationship of each point before and after the rotation is as follows: (10) In the formula, and Let a and b be the coordinates of point a and point b before rotation, respectively. and Let a and b be the coordinates of points a′ and b′ after rotation, respectively.
[0025] After the observation plane is deflected, the height difference between point a′ and point b′ in the Z direction can be expressed as: (11) The phase difference caused by the change in optical path difference is expressed as: (12) The change in out-of-plane displacement gradient was measured using a shear speckle interferometry system. Based on the change in optical path caused by the height difference, the rotation angle was determined. xThe resulting strain value can be expressed as (13) Similarly, rotation angle y The resulting strain value can be expressed as (14) From equations (13) and (14), we can obtain: In the direct verification method, if the strain causes the standard substance to deflect by an angle of _____ i At that time, the shear speckle interferometry system can distinguish and Then its strain measurement sensitivity s sin i In the indirect extrapolation method, the phase difference measurement value sin i The two are linearly related, and the slope of their calibration curve can be obtained through data fitting.
[0026] The specific steps of using the direct verification method are as follows: Test Step 1: Control the strain-generating standard material to rotate to a certain initial angle. The strain-generating standard material was monitored in situ using a shear speckle interferometry measurement system as a reference standard for strain measurement. Test step 2: Repeat the measurement M times using a shear speckle interferometry system to obtain the strain value relative to the reference standard for each measurement. e j (j=1, 2...M); Test step 3: Controlling strain to generate standard material from the initial angle Small angle deflection occurs i (Deflection angle) i First take D min , D min To determine the minimum driving step deflection angle of the strain-generating standard material, an in-situ monitoring system using shear speckle interferometry was employed. This was repeated N times to obtain the strain value relative to the reference standard after rotation. e' j (j=1, 2, ..., N); Test step 4, calculate { e j The average value of} Standard deviation σ; Test step 5, calculate { e' j The average value of} ; Test step 6: If the minimum drive step deflection angle is used for verification, then... > +3σ indicates that the shear speckle interferometry system can distinguish... and Then, the indirect extrapolation method is needed to measure the strain measurement sensitivity s; like ≤ +3σ indicates that the shear speckle interferometry system cannot clearly distinguish at the minimum driving step deflection angle. and After further increasing the deflection angle, the strain measurement sensitivity of the shear speckle interferometry system was measured using the direct verification method until... > +3σ, the shear speckle interferometry system can clearly distinguish... and Until then. Where, if the deflection angle is... i When, satisfy > +3σ indicates the strain measurement sensitivity of the shear speckle interferometry system. s sin i .
[0027] Specific embodiments, Example 1, are as follows: Figure 3-Figure 4 As shown in Table 1 (the minimum driving step deflection angle for the strain-generating standard material is 0.1″, starting from an initial angle of 0″, the strain measurement sensitivity of the shear speckle interferometry system is verified using the direct verification method at a deflection angle of 0.1″. The measurement results show that at a deflection angle of 0.1″, the system cannot effectively distinguish the strain values before and after the deflection of the strain-generating standard material; increasing the deflection angle to 0.2″, the direct verification method results show that the system still cannot effectively distinguish the strain values before and after the deflection of the strain-generating standard material; increasing the deflection angle to 0.3″, the direct verification method results show that the system can effectively distinguish the strain values before and after the deflection of the strain-generating standard material. Taking a deflection angle of 0.3″ as an example, the measurement process of the direct verification method is explained): (1) Control the strain-generating standard material to rotate to the initial angle 0″, and use the shear speckle interferometry measurement system to perform in-situ monitoring of the calibration components as a reference for strain measurement; (2) The strain values relative to the reference standard were obtained by repeating the measurement nine times using a shear speckle interferometry system. e j (j=1, 2……9); (3) Control the calibration component to deflect by a small angle of 0.3″ from the initial angle 0″, and use the shear speckle interferometry measurement system to monitor the strain-generating standard material in situ. Repeat the measurement 9 times to obtain the strain value relative to the reference reference after rotation. e' j (j=1, 2……9); (4) Calculate and obtain { e j The average value of} =6.81×10 -8 Standard deviation σ = 7.88 × 10 -8 ; (5) Calculate and obtain { e' j The average value of} =1.52×10 -6 ; (6) It can be calculated that > +3σ indicates that the shear speckle interferometry system can distinguish... and Then the strain measurement sensitivity s sin i =1.45×10 -6 .
[0028] Table 1 - Record of Strain Measurement Sensitivity Test Results (Direct Verification Method) In another scenario, when the strain measurement sensitivity of the shear speckle interferometry system is high (the value is below the lower limit of the strain value range that the strain-generating standard material can produce), i.e., when verified by the direct verification method at the minimum driving step deflection angle... > +3σ indicates that the shear speckle interferometry system can clearly distinguish the parameters at the minimum driving step deflection angle. and If a direct measurement method is used, the strain measurement sensitivity will be relatively low, and the strain-generating standard material will not be able to produce a value equivalent to the small strain to be measured. In summary, for shear speckle interferometry systems with high strain measurement sensitivity, direct verification methods are insufficient to effectively measure the instrument's strain measurement sensitivity. Therefore, an indirect extrapolation method can be used to measure the strain measurement sensitivity of the shear speckle interferometry system. Based on the phase difference measurements at various angles and the corresponding strain values to be measured, a calibration curve of "phase difference measurement value - strain value to be measured" is fitted, and the strain measurement sensitivity is calculated by extrapolation from this curve. like Figure 5-Figure 6As shown, a method for calibrating the strain measurement sensitivity of a shear speckle interferometry system is proposed, which uses an indirect extrapolation method to measure the strain measurement sensitivity of the shear speckle interferometry system. The indirect extrapolation method is as follows: A rough planar component capable of precise small-angle deflection is used as a strain-generating standard material, and the strain-generating standard material is controlled to undergo a series of equally spaced small-angle deflections; for the known out-of-plane displacement caused by the angle change, the phase difference information before and after the out-of-plane displacement of the strain-generating standard material is measured using a shear speckle interferometry system. ; By combining the strain value to be measured, the standard deviation σ of the phase difference measurement result of the shear speckle interferometry system and the phase difference measurement value are obtained. -The strain value to be measured sin i "Slope of the calibration curve" m The strain measurement sensitivity of the shear speckle interferometry system is calculated according to the following formula. s : (15) In the formula: s —Strain measurement sensitivity; k — confidence factor, take k≥3; σ—The standard deviation of the phase difference measurement in the shear speckle interferometry system when the strain is zero; m — The slope of the calibration curve of “phase difference measurement value - strain value to be measured”.
[0029] It should be noted that when using the indirect extrapolation method for measurement, the strain-generating standard material can be offset at a small angle by using a actuator such as a piezoelectric ceramic drive or a precision turntable rotation.
[0030] The specific measurement steps of the indirect extrapolation method are as follows: Measurement Step 1: Set the strain-generating standard material to the zero-position reference state (deflection angle of 0″), measure it using the shear speckle interferometry measurement system, and set the phase measurement result at this time as the phase measurement reference. Measurement Step 2: Control the shear speckle interferometry measurement system to measure the strain-generating standard material and obtain the phase difference measurement results (relative to the phase measurement reference) within the effective area. 0-i (i=1, 2...M); Measurement Step 3: Control the strain-generating standard material to rotate at equal intervals (each rotation step is Δ, and the number of rotations is N (corresponding to an angle deflection range of NΔ); after each rotation of the strain-generating standard material (the deflection angle is denoted as Δ), The shear speckle interferometry system is controlled to measure the strain-generating standard material, obtaining the phase difference measurement results (relative to the phase measurement reference) within the effective region. -i ( =Δ, 2Δ, 3Δ……NΔ, i =1, 2, ..., N); Measurement Step 4: Calculate the phase difference measurement result when the standard material deflection angle is 0″ due to strain. 0-i ( i Standard deviation of (=1, 2...M) s ; Measurement step 5: Calculate the deflection angle of the standard material caused by strain. hour( Phase difference measurement results of (Δ, 2Δ, 3Δ...NΔ) The average value Δ of (i=1, 2, ..., N) The phase difference measurement (Δ) is obtained through least squares linear fitting. - The strain value to be measured (sin) "Calibrate the curve and obtain the curve slope" m ; Measurement Step 6: Calculate the strain measurement sensitivity according to formula (15). s .
[0031] Specific embodiment, embodiment 2, as follows: Figure 5-Figure 6 And as shown in Table 2 (the minimum driving step deflection angle for strain-generating standard material is 0.1″, starting from the initial angle of 0″, the strain measurement sensitivity of the shear speckle interferometry system is first verified by the direct verification method at a deflection angle of 0.1″. The results show that at a deflection angle of 0.1″, the system can effectively distinguish the strain values before and after the deflection of the strain-generating standard material. Therefore, the indirect extrapolation method is used to measure the strain measurement sensitivity of the shear speckle interferometry system. The measurement process is described below): 1. After verifying the minimum drive step deflection angle using the direct verification method, the following results were obtained. > +3σ was measured using the indirect extrapolation method. Specifically, the strain-generating standard material was set to a zero-position reference state (deflection angle of 0″), and the shear speckle interferometry measurement system was used to measure it. The phase measurement result at this time was set as the phase measurement reference. 2. Control the shear speckle interferometry measurement system to measure the strain-generating standard material, and obtain the phase difference measurement results (relative to the phase measurement reference) of each measurement (10 times) within the effective area. 0-i ( i =1, 2...10); 3. Control the strain-generating standard material to rotate at equal intervals (each rotation step is 0.2″, and the number of rotations is 10 (corresponding to an angle deflection range of 2″); after each rotation of the strain-generating standard material (the deflection angle is recorded as...), The shear speckle interferometry system is controlled to measure the calibration components, obtaining the phase difference measurement results (relative to the phase measurement reference) within the effective area. ( =0.2″, 0.4″, ..., 2″, i =1, 2...10); 4. Calculate the phase difference measurement results when the standard material deflection angle is 0″ due to strain. 0-i ( i The standard deviation σ of (=1, 2……10) is σ. 5. The angle of deflection of the standard material caused by strain is calculated as follows: hour( Phase difference measurement results (=0.2″, 0.4″, ..., 2″) ( i The average value of (=1, 2, ..., 10) is used to obtain the phase difference measurement (Δ) through least squares linear fitting. - The strain value to be measured (sin) The calibration curve is as follows: Figure 6 As shown, the slope of the curve is obtained. m ; 6. Phase difference measurement results at different rotation angles obtained by combining the shear speckle interferometry system (as shown in Table 2): When the strain is zero, the standard deviation of the phase difference measurement value of the shear speckle interferometry system is calculated to be σ=0.0090 based on the data in the table; the slope of the calibration curve of "phase difference measurement value - strain value to be measured" is calculated to be m=193018 based on the data in the table; the strain measurement sensitivity is calculated according to formula (15). s , can be obtained s =1.40 10 -7 ; Table 2 - Record of Strain Measurement Sensitivity Test Results (Indirect Extrapolation Method) In summary, compared with existing technologies, it has the following beneficial effects: 1. By setting up direct verification and indirect extrapolation methods, the direct verification method is first used to verify whether the minimum driving step deflection angle of the strain-generating standard material meets the strain measurement sensitivity requirements. Then, based on the verification results, the direct verification method or the indirect extrapolation method is selected to measure the strain measurement sensitivity of the shear speckle interferometry system. This effectively solves the problem that there is currently no reliable detection method to measure and calibrate the strain measurement sensitivity of the shear speckle interferometry system, and realizes the effective measurement of the strain measurement sensitivity of the shear speckle interferometry system.
[0032] 2. The strain measurement sensitivity of the shear speckle interferometry system is measured by setting an indirect extrapolation method. The strain-generating standard material is controlled to undergo a series of equally spaced small-angle deflections. Based on the phase difference measurement value at each angle and the corresponding strain value to be measured, a calibration curve of "phase difference measurement value - strain value to be measured" is fitted, and the strain measurement sensitivity is obtained by extrapolation. This method can solve the problem that the applicability of the direct verification method is limited by the control accuracy of the strain-generating standard material: when the strain measurement sensitivity value of the shear speckle interferometry system is small, the strain-generating standard material is difficult to generate a small strain value comparable to its value, so the strain measurement sensitivity cannot be directly measured.
[0033] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0034] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A method for calibrating the strain measurement sensitivity of a shear speckle interferometry system, characterized in that, include: The strain-generating standard material was selected as the observation object of the shear speckle interferometry system during the strain measurement sensitivity calibration process. After verifying and measuring the observed object, the sensitivity of the strain measurement is calibrated. The specific steps are as follows: S10. Verify, using the direct verification method, whether the minimum driving step deflection angle of the strain-generating standard material meets the strain measurement sensitivity requirements. Specifically: A rough planar component capable of precise, small-angle deflection is used as a strain-generating standard material, and the strain-generating standard material is controlled from a certain initial angle. Deflection angle by minimum drive step Δ min Small angle deflection occurs θ (Pick θ=Δ min ); in, θ This represents the angle of deflection. In-situ verification and monitoring of strain-generating standard materials were performed using a shear speckle interferometry system. The average strain value was obtained when the strain-generating standard material did not undergo small-angle deflection after multiple measurements. The standard deviation σ, and the average strain after a small-angle deflection. ; Compare and Determine the value of +3σ to obtain the verification result; S11. Based on the verification results of the direct verification method, determine whether to choose the direct verification method or the indirect extrapolation method for measurement, specifically as follows: like > +3σ indicates that the shear speckle interferometry system can clearly distinguish speckle patterns at the minimum driving step deflection angle. and The strain measurement sensitivity of the shear speckle interferometry system is then measured using the indirect extrapolation method. like ≤ +3σ indicates that the shear speckle interferometry system cannot clearly distinguish at the minimum driving step deflection angle. and Continue to increase the deflection angle θ Subsequently, the strain measurement sensitivity of the shear speckle interferometry system was measured using the direct verification method until... > +3σ, meaning the shear speckle interferometry system can clearly distinguish... and until.
2. The strain measurement sensitivity calibration method for a shear speckle interferometry system as described in claim 1, characterized in that, The strain measurement sensitivity measured by the direct verification method in step S11 s sin θ .
3. The strain measurement sensitivity calibration method for a shear speckle interferometry system as described in claim 1, characterized in that, The indirect extrapolation method is as follows: A rough planar component capable of precise small-angle deflection is used as a strain-generating standard material, and the strain-generating standard material is controlled to undergo a series of equally spaced small-angle deflections. For the known out-of-plane displacement caused by the angular changes, the phase difference information before and after the out-of-plane displacement of the strain-generating standard material is measured using a shear speckle interferometry system. ; By combining the strain value to be measured, the standard deviation σ of the phase difference measurement result of the shear speckle interferometry system and the phase difference measurement value are obtained. - The slope of the calibration curve for the strain value to be measured, sinθ m The strain measurement sensitivity of the shear speckle interferometry system is calculated according to the following formula. s : ； In the formula: s —Strain measurement sensitivity; k—confidence factor, take k≥3; σ—The standard deviation of the phase difference measurement in the shear speckle interferometry system when the strain is zero; m —The slope of the calibration curve of "phase difference measurement value - strain value to be measured".
4. The strain measurement sensitivity calibration method for a shear speckle interferometry system as described in any one of claims 1-3, characterized in that, The strain-generating standard material is rotated by a piezoelectric ceramic drive or a precision turntable.
5. A method for calibrating the strain measurement sensitivity of a shear speckle interferometry system as described in any one of claims 1-3, characterized in that, The design of the strain-generating standard material must meet the following conditions: Condition 1: Within the strain observation area of the strain-generating standard material, the strain value generated is the same at all points, that is, uniform strain generation is achieved. Condition two: the strain value produced in each place in the strain observation area of the standard strain producing material is 10 -6 orders of magnitude or below, i.e. micro-scale strain production is achieved.