Two-frame random phase shift method and device for resisting phase shift plane distortion, and storage medium

Abstract

The present invention discloses a two-frame random phase shift method and device, system, and storage medium for resisting phase shift plane distortion, including: step S1, obtaining two adjacent frames of interference graph; step S2, normalizing the two adjacent frames of interference graph; step S3, linearly fitting the distorted phase shift plane by the least square method according to the normalized two adjacent frames of interference graph, to obtain the tilted phase shift plane; step S4, according to the tilted phase shift plane, obtaining the phase restored by the two frames of interference graph. The technical solution of the present invention is adopted to solve the problem of high-quality demodulation phase in the case of two types of situations that are difficult to be compatible with parallel phase shift and tilt phase shift, and has the characteristics of high precision, high robustness and immunity to potential tilt.

Description

Technical Field

[0001] The invention belongs to the technical field of quantitative phase detection, and in particular relates to a two-frame random phase shift method and device for resisting phase shift plane distortion, and a storage medium. Background Art

[0002] Phase shift interferometry is a widely used technology in the field of optical precision metrology. The measurement error of this technology mainly comes from the difference in the quality of the interference pattern and the principle error of the algorithm. The former is affected by many factors such as mechanical device errors, nonlinear signal response, and stray light pollution in the experiment. Compared with the use of expensive precision phase shifters at the hardware level, algorithm research on random phase shift interferograms with few data models to reduce the principle error of the algorithm will become a development trend in the field of phase demodulation. Most of the existing time random phase shift algorithms believe that the interferograms between adjacent frames are ideally parallel phase shifted. In real scenes, errors that are easy to ignore, such as eccentric manufacturing of phase shifters, poor installation of optical path devices, and nonlinear response of piezoelectric effects, will cause the inter-frame phase shift to be a small linear tilt phase shift problem along two dimensions on the plane. This conflicts with the assumption that the in-plane phase shift is consistent in most time phase shift algorithms, resulting in the inability to obtain truly accurate wrapped phase results.

[0003] The tilt of the micro-phase shift plane will produce a coupling relationship with factors such as noise, translational phase shift, background terms and modulation terms. Within a certain tilt range, the algorithm designed based on the consistency of the phase shift plane will still have good demodulation characteristics. However, some algorithms that assume tilt will strengthen the possibility of tilt, and then add a significant tilt factor to the phase shift plane, causing the demodulation result to deviate from the true value. Existing research on tilt factor extraction in the frequency domain can be effectively applied to vibration phase shift interferometry experiments. However, in experiments, the coupling of the micro-tilt component with the low-frequency term makes the tilt insufficient to be reflected in the spectrum. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a two-frame random phase shift method and device, and a storage medium that are resistant to phase shift plane distortion, so as to solve the problem of high-quality demodulation phase in situations where parallel phase shift and tilt phase shift are difficult to be compatible, and the method has the characteristics of high precision, high robustness and immunity to potential tilt.

[0005] To achieve the above object, the present invention adopts the following technical solution:

[0006] A two-frame random phase shifting method for resisting phase shift plane distortion, comprising:

[0007] Step S1, obtaining two adjacent frames of interference patterns;

[0008] Step S2, normalizing the interference graphs of two adjacent frames;

[0009] Step S3, performing linear fitting on the distortion phase shift plane by the least square method according to the normalized interference patterns of two adjacent frames to obtain the tilted phase shift plane;

[0010] Step S4: Obtain the phase restored by the two interferograms according to the tilted phase shift plane.

[0011] Preferably, in step S2, a maximum-minimum value method is used to normalize the interference graphs of two adjacent frames.

[0012] Preferably, step S3 comprises:

[0013] Select the first frame interference graph after normalization The point with the largest light intensity value is taken as the initial point;

[0014] Interference diagram of the first frame after normalization Select the normalized second frame interference pattern The points with the same light intensity values ​​as the initial points are taken as the equivalent points of the light intensity difference between frames;

[0015] Using the equivalent point position in the second frame interference diagram after normalization The linear phase shift plane is fitted with the light intensity value in to obtain the inclined phase shift plane; wherein, the linear phase shift plane fitting adopts the least square method to linearly fit the distorted phase shift plane.

[0016] The present invention also provides a two-frame random phase shift device for resisting phase shift plane distortion, comprising:

[0017] An acquisition module, used for acquiring two adjacent frames of interference patterns;

[0018] A normalization module is used to normalize the interference graphs of two adjacent frames;

[0019] A fitting module is used to perform linear fitting on the distorted phase shift plane by the least square method according to the normalized interference patterns of two adjacent frames to obtain a tilted phase shift plane;

[0020] The calculation module is used to obtain the phase restored by the two-frame interference pattern according to the tilted phase shift plane.

[0021] Preferably, the normalization module uses a maximum and minimum value method to normalize the interference graphs of two adjacent frames.

[0022] Preferably, the fitting module comprises:

[0023] The first processing unit is used to select the first frame interference image after normalization The point with the largest light intensity value is taken as the initial point;

[0024] The second processing unit is used to obtain the first frame interference image after normalization. Select the normalized second frame interference pattern The points with the same light intensity values ​​as the initial points are taken as the equivalent points of the light intensity difference between frames;

[0025] The third processing unit is used to use the equivalent point position to obtain the normalized second frame interference image. The linear phase shift plane is fitted with the light intensity value in to obtain the inclined phase shift plane; wherein, the linear phase shift plane fitting adopts the least square method to linearly fit the distorted phase shift plane.

[0026] The present invention also provides a two-frame random phase shift system for resisting phase shift plane distortion, comprising: a memory and a processor, wherein the memory stores a computer program run by the processor, and the computer program executes a two-frame random phase shift method for resisting phase shift plane distortion when run by the processor.

[0027] The present invention also provides a storage medium, on which a computer program is stored, and when the computer program is running, a two-frame random phase shift method for resisting phase shift plane distortion is executed.

[0028] The present invention uses interference pattern normalization and least squares fitting to propose a light intensity expression form on a circle to screen pixel points suitable for demodulation. By introducing a new equation in the phase equivalence relationship between two frames of interference patterns, the linear phase shift plane is fitted with high precision, and finally phase recovery is achieved. The present invention has the following characteristics: ① The calculation principle is simple and direct, and only reasonable screening of points is required to provide accuracy guarantee for the fitting of the linear random phase shift plane; ② The demodulation accuracy and robustness are high, and points can be selected multiple times for least squares fitting to stably solve the phase shift plane; ③ No iteration is required, and the solution speed is much faster than the iterative algorithm. ④ Accurate demodulation can still be achieved when the number of fringes is less than 1, and it is insensitive to the number of fringes. The present invention can be extended to the situation where there is no need to consider the tilt distortion of the phase shift plane, and the small tilt factor can be ignored for least squares fitting. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] 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 will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying creative work.

[0030] Figure 1 It is a flow chart of a two-frame random phase shifting method for resisting phase shift plane distortion according to an embodiment of the present invention;

[0031] Figure 2 It is the relationship between the pixel light intensity of each point in the two interference patterns of the present invention at different positions;

[0032] Figure 3 This is the light intensity circle expression form in the present invention, in which the change of light intensity value caused by phase change explains the principle of ambiguous point screening;

[0033] Figure 4 are simulation parameters in comparative example 1 of the present invention; wherein, taking the case of tilted phase shift as an example, (a) and (b) are two frames of initial interference patterns; (c) and (d) are two frames of normalized interference patterns; (e) is an estimated background term; (f) is an estimated modulation term; (g) is a preset phase; and (h) is a tilted phase shift plane;

[0034] Figure 5 It is a schematic diagram of phase distribution and phase residual distribution results calculated by different algorithms in comparative example 1 of the present invention;

[0035] Figure 6 It is an experimental principle diagram of comparative example 2 of the present invention, wherein the box represents the relationship between SLM grayscale and phase modulation;

[0036] Figure 7 Schematic diagram of the phase distribution and phase residual distribution results calculated by different algorithms in comparative example 2 of the present invention; wherein, (a) is the phase obtained by GS solution; (b) is the phase obtained by EVI solution; (c) is the phase obtained by the three-step iterative algorithm; (d) is the phase obtained by AIA solution; (e) is the phase obtained by the method of the present invention; and (f) is the phase shift plane fitted by the method of the present invention. DETAILED DESCRIPTION

[0037] 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.

[0038] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0039] Embodiment 1:

[0040] Due to the assumption of consistency of phase shift between frames in phase shift interferometry, many algorithms cannot cope with the situation of phase shift plane distortion caused by slight tilt. Some algorithms that intentionally consider the tilt factor have certain requirements for the tilt amount. In order to solve the problem that the algorithm is difficult to be compatible with high-quality demodulation phase in the two types of situations of parallel phase shift and tilt phase shift, an embodiment of the present invention provides a two-frame random phase shift method that is resistant to phase shift plane distortion, aiming to improve the versatility of phase shift interferometry in the cases of parallel phase shift and tilt phase shift and the accuracy of phase demodulation.

[0041] like Figure 1 As shown, an embodiment of the present invention provides a two-frame random phase shift method for resisting phase shift plane distortion, comprising:

[0042] Step S1, obtaining two adjacent frames of interference patterns;

[0043] Step S2, normalizing the interference graphs of two adjacent frames;

[0044] Step S3, performing linear fitting on the distortion phase shift plane by the least square method according to the normalized interference patterns of two adjacent frames to obtain the tilted phase shift plane;

[0045] Step S4: According to the tilted phase shift plane, an inverse tangent operation is performed using two frames of interference patterns to achieve phase recovery.

[0046] As an implementation of an embodiment of the present invention, in step S1, based on the laser interference optical path of the Michelson structure, the polarizer 11 is installed in the incident optical path, and the reflective pure phase spatial light modulator 2 replaces the reference plane mirror in the interference experiment. Figure 6 As shown, the laser is emitted by the laser 7, and the linear polarized light is obtained by modulating the polarizer 11, and then the laser is horizontally collimated and incident on the spatial filter module 8 under the action of the first reflector 9 and the second reflector 10 to achieve laser beam expansion. After entering the beam splitting cube 5, a beam of test light is irradiated to the surface 6 of the object to be tested, and a beam of reference light is irradiated to the spatial light modulator 2. The reference light wavefront is modulated by the spatial light modulator 2. Then, the reference light and the test light enter the imaging light path through the beam combining action of the cube. The combined light is weakened by the filter 4 and then irradiated to the target surface of the camera 3. In the grayscale mapping mode of the spatial light modulator, image format files of different grayscales are input into the computer 1 to achieve random parallel phase shift, and then the camera end 3 collects the interference pattern. When the input image format file is a grayscale image that gradually changes in a certain direction or periodically changes in a sawtooth shape, the interference pattern under the inclined phase shift plane between frames is correspondingly obtained. The interference diagrams of two adjacent frames under the phase shifter tilt error caused by experimental environment vibration, electromagnetic interference and installation of optical path components are expressed as:

[0047]

[0048] Among them, x and y represent the horizontal and vertical coordinates of the interference pattern, I1(x, y), I2(x, y) are the image intensity collected by the camera, A(x, y) is the background light intensity term, and B(x, y) is the modulation amplitude term. is the phase to be measured, δ is the principal component of the phase shift plane perpendicular to the optical axis, and u, v are the tilt factors of the tilted phase shift plane along the x, y directions.

[0049] As an implementation of the embodiment of the present invention, in step S2, there is a coupling relationship between the in-plane non-uniformity of the background light intensity term and the modulation amplitude term and the phase shift plane error, and the tilt error of the phase shift plane is visualized by normalizing the interference pattern.

[0050] The present invention adopts the maximum and minimum value method, assuming that the background light intensity and modulation amplitude at the corresponding pixel coordinates between adjacent frames are constant, and sufficient N The frame interference graph approximately satisfies the following relationship:

[0051] I max (x,y)=A(x,y)+B(x,y)

[0052] I min (x,y)=A(x,y)-B(x,y)

[0053] Then we can get the estimated background light intensity and the estimated modulation amplitude term

[0054]

[0055] The result of normalized interference pattern is:

[0056]

[0057] As an implementation of the embodiment of the present invention, step S3 includes:

[0058] Select the first frame interference graph after normalization The point with the largest light intensity value is taken as the initial point;

[0059] Interference diagram of the first frame after normalization Select the normalized second frame interference pattern The points with the same light intensity values ​​as the initial points are taken as the equivalent points of the light intensity difference between frames;

[0060] Using the equivalent point position in the second frame interference diagram after normalization The linear phase shift plane is fitted with the light intensity value in to obtain the inclined phase shift plane; wherein, the linear phase shift plane fitting adopts the least square method to linearly fit the distorted phase shift plane.

[0061] Furthermore, in step S3, in the normalized interference graph, the light intensity value of each pixel is only affected by the phase change in the cosine term. A point is selected as a1, which corresponds to the second frame interference pattern after normalization The pixel point with the same coordinates is a2. From the perspective of the continuous change of the light intensity value of the interference pattern, You can always find Light intensity at point a2 The point where they are equal is recorded as b.

[0062] Due to the even function property of the cosine function, points with equal light intensity values ​​may not be consistent in phase information. Therefore, the present invention proposes a light intensity circle to classify points with equal light intensity values ​​of unequal pixel points in two frames, and select the correct pixel points for accurate phase demodulation. Figure 2 is the normalized two-frame interference pattern and The connection between the same and different pixels. Figure 3 It is the geometric relationship between phase change and light intensity.

[0063] like Figure 2 and Figure 3 As shown, in Find and Among all the points of light intensity matching, taking point b as an example, these points are divided into two categories: b1 and b1′. The specific expression can be written as:

[0064]

[0065] Therefore, b1, b1′ are equivalent to the inter-frame phase shift of point a with different phase differences to be measured, thus showing equal light intensity, that is, and Equal value, and then As the unused light intensity information, the light intensity equation under the new inter-frame phase shift is provided. At this time, the problem of random tilt phase shift between two frames has an additional known quantity. The light intensities are:

[0066]

[0067] Among them, due to the inhomogeneity of the phase shifter surface, the phase shift at the coordinates a, b, and b′ cannot be guaranteed to be constant. Under a certain angle of tilt error, it can be seen that the light intensity at each point will be Figure 3 Swinging around a fixed point on the middle circle, Then keep a larger numerical difference, where and The approximately equal values ​​cannot be used as new meaningful data for phase demodulation.

[0068] Furthermore, in the embodiment of the present invention, This type has intra-frame heterogeneous phase difference Equivalent inter-frame co-location phase difference δ a The point is called the correct point, and This type of point with similar light intensity to the initially selected point a1 is called an ambiguous point. According to the selection of the initial point and the tilt amplitude of the phase shift plane, a reasonable and specific ambiguous point screening standard is established in the algorithm, and a set of correct points can be obtained.

[0069] The pixel points after filtering out ambiguous points are recorded as a set P = {p1, p2···p m}, considering the random error of the phase shift plane, a linear tilt plane can usually be used to fit the actual phase shift plane. The light intensity in the second frame in the set P can be expressed as follows:

[0070]

[0071] Further rewritten as:

[0072]

[0073] Based on this, the embodiment of the present invention uses the similar light intensity data in the set P to perform the least square method to solve the constant phase shift plane principal component δ and the tilt factor estimation u,v, and the phase of the point to be measured Calculate using the light intensity at the initial point, that is:

[0074]

[0075] Will It can be expressed in matrix form as:

[0076] A P X=B P

[0077] in,

[0078]

[0079] Therefore, the tilted phase shift plane obtained by least squares fitting is:

[0080]

[0081] Among them, δ P(x, y) is the fitted tilt phase shift plane. In order to improve the accuracy and robustness of the fitted plane, multiple initial points can be selected to perform multiple least squares fittings to obtain the average value of the tilt factor or the equation group corresponding to each initial point can be simultaneously combined to perform a least squares fitting.

[0082] As an implementation of the embodiment of the present invention, in step S4, the phase recovered from the two frames of interference patterns can be calculated by the following formula:

[0083]

[0084] The embodiment of the present invention utilizes two frames of random phase shift interference images after normalization preprocessing, and then uses the equivalence of the inter-frame phase shift and the intra-frame phase difference to mine the light intensity value of the pixel point carrying the new phase shift from the second frame interference image; finally, the least squares method is used to fit the linear random phase shift plane, and the high-precision phase distribution can be obtained through the inverse tangent relationship. In the simulation, the phase distribution obtained by fitting the linear phase shift plane is more accurate than the iterative algorithm. In addition, in the significant range of the maximum inclination of 0-1rad in the plane, it has excellent performance in both tilted and non-tilted conditions. Finally, the accurate control of the in-plane phase shift by the spatial light modulator verifies the effectiveness of the method of the embodiment of the present invention in the tilt phase shift interference technology. The simulation and experimental results demonstrate the high precision, high robustness and immunity to potential tilt phase shift planes of the embodiment of the present invention.

[0085] Comparative Example 1:

[0086] In order to verify the performance of the method of the embodiment of the present invention and demonstrate its superiority, a numerical simulation comparison is performed; the interference pattern with noise generated by the simulation is:

[0087]

[0088] Among them, n t is additive white noise that follows a Gaussian distribution.

[0089] The background light intensity and modulation amplitude terms are set according to the Gaussian distribution characteristics of the light source and the contrast characteristics of the collected image. The simulation image size is 256×256, and the phase to be measured is preset to

[0090] In order to verify the feasibility of the method of the embodiment of the present invention and its high accuracy compared with other commonly used algorithms, the Gram–Schmidt orthogonalization algorithm (GS), the extreme value interference algorithm (EVI), the advanced iterative algorithm (AIA) and the three-step iterative algorithm are used as comparative algorithms for research. Figure 4 It is the relevant information of background term, modulation term, phase and interference pattern used in simulation.

[0091] When the signal-to-noise ratio (SNR) is 40 dB, the single-shot performance of the algorithm with and without tilt is initially presented. Figure 5 middle. Figure 5 The root mean square error and calculation time of the demodulation phase of the corresponding algorithm are presented in Table 1, which is the average result of five experiments repeated under the same environment.

[0092] Table 1

[0093]

[0094] Compared with the residual graph in the non-tilt simulation, the three-step iterative algorithm and the AIA algorithm are only slightly better than the proposed algorithm. However, the calculation time of the embodiment method of the present invention is significantly faster than that of the three-step iterative algorithm and the AIA algorithm. After the inter-frame phase shift of the interference pattern is applied with a maximum in-plane tilt phase shift error of 0.06 rad, the slight tilt has different degrees of influence on Liu's, AIA, GS and EVI algorithms. For the embodiment method of the present invention, the tilt of the phase shift plane does not change the phase demodulation effect of the algorithm. The simulation preliminarily verifies the correctness of the embodiment method of the present invention and gives the responses of various algorithms to the tilt factor of the phase shift plane.

[0095] Comparative Example 2:

[0096] In order to verify the feasibility of the invented method at the experimental level, the laser interferometer optical path was constructed using existing experimental instruments. In order to introduce the tilted phase shift plane, the reference plane mirror was replaced with a pure phase spatial light modulator (SLM). The principle of experimental measurement of the surface morphology of the convex lens is as follows: Figure 6 As shown, different grayscale images are input to the SLM through the display to adjust the wavefront phase of the reference beam corresponding to each pixel. The relationship between 0-255 grayscale and 0-π phase modulation is approximately proportional. When the grayscale in the plane is consistent, it is considered as an ideal parallel phase shift, and when the plane is preset as a gradient grayscale image, it is considered as an inclined phase shift.

[0097] In the process of adjusting the in-plane modulation phase of the SLM, 49 interferograms were collected, and the background term and modulation term distribution of this set of interferograms were calculated using the extreme value method. In order to obtain the reference phase benchmark, 13 interferograms with consistent grayscale changes in the plane were selected for AIA solution.

[0098] When the SLM introduces a tilt, compared with the reference phase distribution, the GS, EVI, three-step iterative algorithm and AIA algorithm show obvious ripple-shaped residuals in the tilt direction, which is caused by the tilt of the phase shift plane. Figure 7At the same time, it is verified that the iterative algorithm uses more oblique phase shift interference patterns, and in addition to the significant twill error, the accuracy after iterative convergence is poor. At this time, the method of the embodiment of the present invention is not affected by the oblique phase shift, and the demodulation result is similar to that of the parallel phase shift. And Table 2 shows that the method of the embodiment of the present invention can achieve the highest demodulation accuracy in only a short time.

[0099] Table 2

[0100] GS EVI Three-step iteration AIA Invention Method Root mean square error (rad) 0.3660 0.3907 0.7599 0.7580 0.1074 Calculation time(s) 0.0013 0.0048 6.4157 11.7039 0.0458

[0101] In the experiment, the maximum light intensity is selected as the initial point, and the tilt phase shift plane is obtained by least squares fitting after screening the correct point. for:

[0102]

[0103] Furthermore, the method of the embodiment of the present invention can also solve the fitting problem other than the inclined surface type. As long as the correct points within a certain range are selected, nonlinear fitting can be performed on any distorted phase shift plane. Combined with the single-frame normalization technology, the method of the embodiment of the present invention can be effectively applied to high-speed phase demodulation technology, and has considerable accuracy and anti-distortion capability.

[0104] The above example is selected to introduce in detail an accurate two-frame random phase shift algorithm for resisting phase shift plane distortion in an embodiment of the present invention. In the embodiment of the present invention, a liquid crystal spatial light modulator is used as a device for generating tilt phase shift, and a convex lens surface is selected as an experimental measurement object. This specific interference measurement system is intended to help relevant industry insiders better understand the idea and execution process of the method in the embodiment of the present invention.

[0105] At the same time, for specific application objects and scenarios, for example, the method of generating tilt phase shift is replaced by micro-nano platform drive, the interference pattern normalization method is replaced by Fourier transform, polynomial fitting and other normalization methods, etc.; improvements based on the above similar methods or application classes should be regarded as within the scope covered by the embodiment method of the present invention, and these changes should belong to the protection scope of the claims attached to the present invention.

[0106] Embodiment 2:

[0107] The embodiment of the present invention further provides a two-frame random phase shifting device for resisting phase shift plane distortion, comprising:

[0108] An acquisition module, used for acquiring two adjacent frames of interference patterns;

[0109] A normalization module is used to normalize the interference graphs of two adjacent frames;

[0110] A fitting module is used to perform linear fitting on the distorted phase shift plane by the least square method according to the normalized interference patterns of two adjacent frames to obtain a tilted phase shift plane;

[0111] The calculation module is used to obtain the phase restored by the two-frame interference pattern according to the tilted phase shift plane.

[0112] As an implementation method of the embodiment of the present invention, the normalization module uses a maximum and minimum value method to normalize two adjacent frames of interference graphs.

[0113] As an implementation of an embodiment of the present invention, the fitting module includes:

[0114] The first processing unit is used to select the first frame interference image after normalization The point with the largest light intensity value is taken as the initial point;

[0115] The second processing unit is used to obtain the first frame interference image after normalization. Select the normalized second frame interference pattern The points with the same light intensity values ​​as the initial points are taken as the equivalent points of the light intensity difference between frames;

[0116] The third processing unit is used to use the equivalent point position to obtain the normalized second frame interference image. The linear phase shift plane is fitted with the light intensity value in to obtain the inclined phase shift plane; wherein, the linear phase shift plane fitting adopts the least square method to linearly fit the distorted phase shift plane.

[0117] Embodiment 3:

[0118] An embodiment of the present invention also provides a two-frame random phase shift system for resisting phase shift plane distortion, comprising: a memory and a processor, wherein the memory stores a computer program executed by the processor, and the computer program executes a two-frame random phase shift method for resisting phase shift plane distortion when executed by the processor.

[0119] Embodiment 4:

[0120] An embodiment of the present invention further provides a storage medium, on which a computer program is stored. When the computer program is run, a two-frame random phase shift method for resisting phase shift plane distortion is executed.

[0121] The embodiments described above are only descriptions of the preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A two-frame random phase shift method for resisting phase shift plane distortion, characterized in that: include: Step S1, obtaining two adjacent frames of interference patterns; Step S2, normalizing the interference graphs of two adjacent frames; Step S3, performing linear fitting on the distortion phase shift plane by the least square method according to the normalized interference patterns of two adjacent frames to obtain the tilted phase shift plane; Step S4, obtaining the phase restored by the two frames of interference patterns according to the tilted phase shift plane; In step S2, the maximum and minimum value method is used to normalize the interference graphs of two adjacent frames; Step S3 includes: Select the first frame interference graph after normalization I1 The point with the largest light intensity value is taken as the initial point; Interference diagram of the first frame after normalization I1 Select the second frame interference pattern after normalization I2 The points with the same light intensity values ​​as the initial points are taken as the equivalent points of the light intensity difference between frames; Using the equivalent point position in the second frame interference diagram after normalization I2 The linear phase shift plane is fitted with the light intensity value in to obtain the inclined phase shift plane; wherein, the linear phase shift plane fitting uses the least square method to linearly fit the distorted phase shift plane.

2. A two-frame random phase shift device for resisting phase shift plane distortion, characterized in that: include: An acquisition module, used for acquiring two adjacent frames of interference patterns; A normalization module is used to normalize the interference graphs of two adjacent frames; A fitting module is used to perform linear fitting on the distorted phase shift plane by the least square method according to the normalized interference patterns of two adjacent frames to obtain a tilted phase shift plane; A calculation module, used for obtaining the phase restored from the two-frame interference pattern according to the tilted phase shift plane; The normalization module uses the maximum and minimum value method to normalize the interference graphs of two adjacent frames; The fitting module includes: The first processing unit is used to select the first frame interference image after normalization I1 The point with the largest light intensity value is taken as the initial point; The second processing unit is used to obtain the first frame interference image after normalization. I1 Select the second frame interference pattern after normalization I2 The points with the same light intensity values ​​as the initial points are taken as the equivalent points of the light intensity difference between frames; The third processing unit is used to use the equivalent point position to obtain the normalized second frame interference image. I2 The linear phase shift plane is fitted with the light intensity value in to obtain the inclined phase shift plane; wherein, the linear phase shift plane fitting uses the least square method to linearly fit the distorted phase shift plane.

3. A two-frame random phase shift system for resisting phase shift plane distortion, characterized in that: include: A memory and a processor, wherein the memory stores a computer program executed by the processor, and when the computer program is executed by the processor, the two-frame random phase shift method for resisting phase shift plane distortion as claimed in claim 1 is executed.

4. A storage medium, characterized in that: The storage medium stores a computer program, which executes the two-frame random phase shift method for resisting phase shift plane distortion as claimed in claim 1 when running.

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