Interferogram phase demodulation method, device and system

Abstract

The invention provides an interferogram phase demodulation method, device and system, and relates to the technical field of optical detection, and the method comprises the steps: obtaining first phase shift amounts corresponding to at least three interference images, and the phase shift between the adjacent interference images is an inclined plane; determining reference phases corresponding to the at least three interference images according to the first phase shift amount; determining second phase shift amounts respectively corresponding to the at least three interference images according to the reference phase; the difference value between the first phase shift amount and the second phase shift amount is calculated, and whether the difference value between the first phase shift amount and the second phase shift amount is smaller than a preset threshold value or not is judged; if not, determining the reference phase again according to the second phase shift amount; and if yes, outputting the reference phase as the target phase, so that the demodulation precision can be improved by assuming the phase shift between the adjacent interference images as the inclined plane and solving the phase shift amount and the target phase through the iteration method, and the method can be applied to a vibration test scene.

Description

Technical Field

[0001] The present application relates to the technical field of optical detection, and in particular, to an interferogram phase demodulation method, apparatus, and system. Background Art

[0002] The phase-shifting interference detection method is one of the important methods for optical surface shape detection. However, for high-precision measurement means represented by the phase-shifting interference measurement technology, random phase-shifting methods such as the advanced iterative algorithm are often used to assume that the phase shift between interferograms is planar. However, during the measurement process, environmental vibration will have a great impact on the phase demodulation accuracy, which will lead to inaccurate phase demodulation results. Summary of the Invention

[0003] In order to at least overcome the above deficiencies in the prior art, an object of the present application is to provide an interferogram phase demodulation method, apparatus, and system.

[0004] In a first aspect, an embodiment of the present application provides an interferogram phase demodulation method, and the interferogram phase demodulation method includes:

[0005] Obtain first phase shift amounts corresponding to at least three interferograms respectively, and the phase shift between adjacent interferograms is an inclined plane;

[0006] Determine reference phases corresponding to at least three interferograms according to the first phase shift amounts;

[0007] Determine second phase shift amounts corresponding to at least three interferograms respectively according to the reference phases;

[0008] Calculate the difference between the first phase shift amount and the second phase shift amount, and determine whether the difference between the first phase shift amount and the second phase shift amount is less than a preset threshold;

[0009] If the difference between the first phase shift amount and the second phase shift amount is not less than the preset threshold, re-determine the reference phase according to the second phase shift amount;

[0010] If the difference between the first phase shift amount and the second phase shift amount is less than the preset threshold, output the reference phase as the target phase.

[0011] In a possible implementation manner, the phase shift between adjacent interferograms satisfies the following constraint:

[0012] δ i =f x x+f y y+d

[0013] where f x represents the slope of the phase shift between adjacent interferograms in the x direction, fy represents the slope of the phase shift between adjacent interference images in the y direction, and d represents a constant.

[0014] In a possible implementation, the step of determining the second phase shift amounts corresponding to at least three of the interference images according to the reference phase includes:

[0015] Calculating energy functions corresponding to at least three of the interference images according to the reference phase;

[0016] Calculating the second phase shift amounts corresponding to at least three of the interference images according to the energy functions.

[0017] In a possible implementation, the step of calculating the second phase shift amounts corresponding to at least three of the interference images according to the energy functions includes:

[0018] Updating the slope of the phase shift between adjacent interference images according to the energy functions;

[0019] Calculating the second phase shift amounts corresponding to at least three of the interference images according to the updated slope.

[0020] In a possible implementation, the energy function E corresponding to the interference image i is:

[0021]

[0022] where N represents the number of pixel points in the interference image; j represents the j-th pixel point in the interference image; i represents the i-th interference image among at least three interference images; represents the phase; a, b, and c respectively represent the polynomial coefficients of the two-dimensional expression.

[0023] In a possible implementation, the step of determining the reference phase corresponding to at least three of the interference images according to the first phase shift amount includes:

[0024] Obtaining the light intensity expression of the interference image and converting the light intensity expression into a two-dimensional expression;

[0025] Calculating the polynomial coefficients of the two-dimensional expression according to the first phase shift amount by the least squares method;

[0026] Calculating the reference phase according to the polynomial coefficients of the two-dimensional expression.

[0027] In a possible implementation, the step of calculating the polynomial coefficients of the two-dimensional expression according to the first phase shift amount by the least squares method includes:

[0028] Calculating the polynomial coefficients of the two-dimensional expression corresponding to each pixel point in the interference image according to the first phase shift amount by the least square method;

[0029] The step of calculating the reference phase according to the polynomial coefficients of the two-dimensional expression includes:

[0030] Calculating the reference phase corresponding to each of the pixel points according to the polynomial coefficients of the two-dimensional expression.

[0031] In a possible implementation manner, the light intensity expression of the interference image is:

[0032]

[0033] where, I i (x, y) represents the light intensity; I0(x, y) represents the background light, I′(x, y) represents the modulation degree, and δ represents the phase shift amount; represents the phase; i represents the i-th interference image among at least three interference images; (x, y) represents the coordinates of the pixel point in the interference image;

[0034] The two-dimensional expression is:

[0035] I i =a + bcos(δ i ) + csin(δ i )

[0036] where, a(x, y) = I0(x, y), a, b, and c respectively represent the polynomial coefficients of the two-dimensional expression; I i represents the light intensity; δ represents the phase shift amount; represents the phase; i represents the i-th interference image among at least three interference images;

[0037] The least square matrix is:

[0038]

[0039] where, a, b, and c respectively represent the polynomial coefficients of the two-dimensional expression; I represents the light intensity; δ represents the phase shift amount; i represents the i-th interference image among at least three interference images; j represents the j-th pixel point in the interference image; M represents the number of interference images;

[0040] The reference phase corresponding to each of the pixel points is:

[0041]

[0042] wherein, represents the phase; j represents the j-th pixel point in the interference image; b and c respectively represent the polynomial coefficients of the two-dimensional expression.

[0043] In a second aspect, an interference pattern phase demodulation device provided by an embodiment of the present application includes:

[0044] An acquisition module, configured to acquire first phase shift amounts respectively corresponding to at least three interference images, and the phase shift between adjacent interference images is a ramp;

[0045] A first determination module, configured to determine a reference phase corresponding to at least three interference images according to the first phase shift amounts;

[0046] A second determination module, configured to determine second phase shift amounts respectively corresponding to at least three interference images according to the reference phase;

[0047] A judgment module, configured to calculate a difference between the first phase shift amount and the second phase shift amount, and judge whether the difference between the first phase shift amount and the second phase shift amount is less than a preset threshold;

[0048] An iteration module, if the difference between the first phase shift amount and the second phase shift amount is not less than the preset threshold, then configured to re-determine the reference phase according to the second phase shift amount;

[0049] An output module, if the difference between the first phase shift amount and the second phase shift amount is less than the preset threshold, then configured to output the reference phase as a target phase.

[0050] In a third aspect, an interference pattern phase demodulation system provided by an embodiment of the present application includes a processor and a machine-readable storage medium, the machine-readable storage medium stores machine-executable instructions, and when the machine-executable instructions are executed by the processor, the interference pattern phase demodulation method described in any of the above aspects is implemented.

[0051] Based on any of the above aspects, the interference pattern phase demodulation method, device, and system provided by the embodiments of the present application can assume that the phase shift between adjacent interference images is a ramp, and solve the phase shift amount and the target phase through an iterative method, which can improve the demodulation accuracy and be applied to the test scenario of vibration. Description of the Drawings

[0052] To more clearly illustrate the technical solutions of the embodiments of the present application, the accompanying drawings required to be invoked in the embodiments will be briefly introduced below. It should be understood that the following accompanying drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related accompanying drawings can also be obtained based on these drawings.

[0053] Figure 1 It is a schematic flowchart of the interference pattern phase demodulation method provided in this embodiment;

[0054] Figure 2 It is a schematic diagram of the sub-steps of step S300 provided in this embodiment;

[0055] Figure 3 It is a schematic diagram of the sub-steps of step S320 provided in this embodiment;

[0056] Figure 4 It is a schematic diagram of the sub-steps of step S200 provided in this embodiment;

[0057] Figure 5a It is a phase diagram of the interference phase shift measurement method in the prior art;

[0058] Figure 5b It is a residual diagram of the interference phase shift measurement method in the prior art;

[0059] Figure 6a It is a phase diagram of the interference pattern phase demodulation method provided in this embodiment;

[0060] Figure 6b It is a residual diagram of the interference pattern phase demodulation method provided in this embodiment;

[0061] Figure 7 It is a schematic structural diagram of the interference pattern phase demodulation system provided in this embodiment;

[0062] Figure 8 It is a schematic structural diagram of the interference pattern phase demodulation device provided in this embodiment.

[0063] Icons: 800 - Interference pattern phase demodulation system; 810 - Processor; 820 - Machine-readable storage medium; 830 - Interference pattern phase demodulation device; 831 - Acquisition module; 832 - First determination module; 833 - Second determination module; 834 - Judgment module; 835 - Iteration module; 836 - Output module. Detailed implementation manners

[0064] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the following will clearly and completely describe the technical solutions in the embodiments of this application in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, rather than all of them. The components of the embodiments of this application usually described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0065] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0066] It should be noted that similar reference numerals and letters indicate similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0067] In the description of this application, it should be noted that the orientation or positional relationship indicated by terms such as "upper" and "lower" is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed when in use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation to this application. In addition, terms such as "first" and "second" are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0068] In addition, terms such as "horizontal", "vertical", and "overhanging" do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0069] In the description of this application, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0070] It should be noted that, without conflict, the different features in the embodiments of this application can be combined with each other.

[0071] The following will describe the specific embodiments of the present application in detail with reference to the accompanying drawings.

[0072] Please refer to Figure 1 , Figure 1 a schematic flowchart of a method for demodulating the phase of an interference pattern provided by an example of this embodiment. The method may include the following steps.

[0073] Step S100: Obtain the first phase shift amounts respectively corresponding to at least three interference images, and the phase shift between adjacent interference images is a ramp.

[0074] In this embodiment, the number of the interference images may include three, or may be greater than three. At least three interference images may respectively correspond to at least three first phase shift amounts, and the first phase shift amount may be an initial phase shift amount or a phase shift amount obtained from the previous iterative calculation. Among them, the initial phase shift amount may be an empirical value or a random value.

[0075] For example, when the number of the interference images is three, the initial phase shift amounts respectively corresponding to the three interference images may be 0, π / 2, and π.

[0076] Step S200: Determine the reference phases corresponding to at least three interference images according to the first phase shift amounts.

[0077] In this embodiment, the reference phases corresponding to at least three interference images may be determined by the least squares fitting method according to the first phase shift amounts obtained in step S100. Among them, different pixel points in the interference images may correspond to different reference phases, and the reference phases corresponding to the pixel points at the same position in multiple interference images are equal.

[0078] Step S300: Determine the second phase shift amounts respectively corresponding to at least three interference images according to the reference phases.

[0079] In this embodiment, the second phase shift amounts respectively corresponding to at least three interference images may be determined by the gradient descent fitting method according to the reference phases obtained in step S300.

[0080] It should be noted that the method for calculating the second phase shift amount is not limited to the gradient descent fitting method, and may also include other optimization methods, such as genetic algorithm, particle swarm algorithm, quantum algorithm, etc., which are not specifically limited herein.

[0081] Step S400: Calculate the difference between the first phase shift amount and the second phase shift amount, and determine whether the difference between the first phase shift amount and the second phase shift amount is less than a preset threshold.

[0082] In this embodiment, the difference between the first phase shift amount obtained in step S100 and the second phase shift amount obtained in step S300 can be calculated, and it can be determined whether this difference is less than a preset threshold in the following manner:

[0083] max|(δ i k -δ1 k )-(δ i k-1 -δ1 k-1 )|<τ, i = 2…M

[0084] wherein, i represents the i-th interference image among at least three interference images; δ represents the phase shift amount; M represents the number of interference images; k represents the number of iterations, k≥1; τ represents the preset threshold.

[0085] Specifically, when the number of iterations k is equal to 1, it can be determined whether to output the reference phase obtained in step S200 as the target phase by the difference between the second phase shift amount and the initial phase shift amount. When the number of iterations k is greater than 1, it can be determined whether to output the reference phase obtained in step S200 as the target phase by the difference between the second phase shift amount and the phase shift amount of the previous iteration.

[0086] It should be noted that the preset threshold can be determined according to actual needs and is not specifically limited herein.

[0087] Step S500, if the difference between the first phase shift amount and the second phase shift amount is not less than the preset threshold, then re-determine the reference phase according to the second phase shift amount.

[0088] In this embodiment, if the difference between the first phase shift amount and the second phase shift amount is not less than the preset threshold, then iteration can be performed again, and the second phase shift amount obtained in step S300 is used as the first phase shift amount to determine the reference phase.

[0089] Step S600, if the difference between the first phase shift amount and the second phase shift amount is less than the preset threshold, then output the reference phase as the target phase.

[0090] In this embodiment, if the difference between the first phase shift amount and the second phase shift amount is less than the preset threshold, then the iteration can be ended, and the reference phase obtained in step S200 is directly output as the target phase.

[0091] It can be seen that based on the above design, an interference pattern phase demodulation method provided by an embodiment of the present application can improve the demodulation accuracy by assuming the phase shift between adjacent interference images as an inclined plane and solving the phase shift amount and the target phase by an iterative method, and can be applied to the test scenario of vibration.

[0092] In a possible implementation, assuming that the phase shift between adjacent interference images is an inclined plane, the phase shift between adjacent interference images can satisfy the following constraints:

[0093] δ i = f x x + f y y + d

[0094] where f x represents the slope of the phase shift between adjacent interference images in the x direction, and f y represents the slope of the phase shift between adjacent interference images in the y direction, and d represents a constant.

[0095] In a possible implementation, please refer to Figure 2 , step S300 may include the following sub-steps.

[0096] Step S310, calculate the energy function corresponding to at least three of the interference images according to the reference phase.

[0097] In this embodiment, the energy function corresponding to each of the interference images can be calculated according to the reference phase. The energy function E i corresponding to each of the interference images can be:

[0098]

[0099] where N represents the number of pixel points in the interference image; j represents the j-th pixel point in the interference image; i represents the i-th interference image among at least three interference images; represents the phase; a, b, and c respectively represent the polynomial coefficients of the two-dimensional expression.

[0100] Step S320, calculate the second phase shift amount corresponding to at least three of the interference images according to the energy function.

[0101] In this embodiment, the second phase shift amount corresponding to at least three of the interference images can be calculated according to the energy function obtained in step S310.

[0102] In a possible implementation, please refer to Figure 3 , step S320 may include the following sub-steps.

[0103] Step S321, update the slope of the phase shift between adjacent interference images according to the energy function.

[0104] In this embodiment, the slope f of the phase shift between adjacent interference imagesx2 , f y2 can be updated in the following manner:

[0105]

[0106] The constant d2 of the phase shift between adjacent interference images can be updated in the following manner:

[0107]

[0108] where f x represents the slope of the phase shift between adjacent interference images before update in the x direction, and f y represents the slope of the phase shift between adjacent interference images before update in the y direction, d represents the constant before update; E represents the energy function; t represents the step size.

[0109] Step S322, calculate the second phase shift amounts corresponding to at least three of the interference images according to the updated slopes.

[0110] In this embodiment, the second phase shift amount can be calculated in the following manner:

[0111] δ i = f x2 x + f y2 y + d2

[0112] where f x2 represents the slope of the phase shift between adjacent interference images after update in the x direction, and f y2 represents the slope of the phase shift between adjacent interference images after update in the y direction, and d2 represents the constant after update.

[0113] In a possible implementation manner, please refer to Figure 4 , step S200 may include the following sub-steps.

[0114] Step S210, obtain the light intensity expression of the interference image and convert the light intensity expression into a two-dimensional expression.

[0115] In this embodiment, the light intensity expression of the interference image may be:

[0116]

[0117] where I i (x, y) represents the light intensity; I0(x, y) represents the background light, I′(x, y) represents the modulation degree, and δ represents the phase shift amount; represents the phase; i represents the i-th interference image among at least three interference images; (x, y) represents the coordinates of a pixel point in the interference image.

[0118] Let a(x, y) = I0(x, y), Therefore, the two-dimensional expression converted from the light intensity expression can be:

[0119] I i = a + bcos(δ i ) + csin(δ i )

[0120] where a, b, and c respectively represent the polynomial coefficients of the two-dimensional expression; I i represents the light intensity; δ represents the phase shift amount; represents the phase; i represents the i-th interference image among at least three interference images.

[0121] Step S220, calculate the polynomial coefficients of the two-dimensional expression according to the first phase shift amount by the least squares method.

[0122] In this embodiment, the polynomial coefficients of the two-dimensional expression can be calculated according to the first phase shift amount obtained in step S100 by the least squares method.

[0123] Step S230, calculate the reference phase according to the polynomial coefficients of the two-dimensional expression.

[0124] In this embodiment, the reference phase can be calculated according to the polynomial coefficients of the two-dimensional expression obtained in step S220.

[0125] In a possible implementation manner, in step S220, when calculating the polynomial coefficients of the two-dimensional expression according to the first phase shift amount by the least squares method, the polynomial coefficients of the two-dimensional expression respectively corresponding to each pixel point in the interference image can be calculated according to the first phase shift amount by the least squares method.

[0126] In this embodiment, the polynomial coefficients of the two-dimensional expression respectively corresponding to each pixel point in the interference image can be obtained by calculating with a least squares matrix:

[0127]

[0128] where a, b, and c respectively represent the polynomial coefficients of the two-dimensional expression; I represents the light intensity; δ represents the phase shift amount; i represents the i-th interference image among at least three interference images; j represents the j-th pixel point in the interference image; M represents the number of interference images.

[0129] In step S230, when calculating the reference phase according to the polynomial coefficients of the two-dimensional expression, the reference phase corresponding to each pixel point can be calculated according to the polynomial coefficients of the two-dimensional expression.

[0130] In this embodiment, the reference phases corresponding to different pixels are different, and the reference phases corresponding to the pixels are It can be calculated as follows:

[0131]

[0132] in, represents the phase; j represents the jth pixel point in the interference image; b and c represent the polynomial coefficients of the two-dimensional expression respectively.

[0133] In order to verify the effectiveness of this application, an experimental verification was carried out on this application.

[0134] Please refer to Figure 5a and Figure 5b , Figure 5a and Figure 5b The phase diagram and residual diagram of the traditional interferometric phase shift measurement method are shown in Figure 2. Figure 6a and Figure 6b , Figure 6a and Figure 6b The phase diagram and residual diagram of the interferogram phase demodulation method provided by the present application are respectively illustrated. Compared with the traditional interferogram phase shift measurement method, the interferogram phase demodulation method provided by the present application can be applied to measurement scenarios with severe vibrations and can improve the solution accuracy.

[0135] This embodiment also provides an interference pattern phase demodulation system 800, please refer to Figure 7 , Figure 7 The block diagram of the interference pattern phase demodulation system 800 is shown as an example. The interference pattern phase demodulation system 800 includes a processor 810, a machine-readable storage medium 820, and an interference pattern phase demodulation device 830. The machine-readable storage medium 820 and the processor 810 are electrically connected to each other directly or indirectly to realize data transmission or interaction. For example, these elements can be electrically connected to each other through one or more communication buses or signal lines. The interference pattern phase demodulation device 830 includes a plurality of software function modules that can be stored in the machine-readable storage medium 820 in the form of software or firmware or solidified in the operating system (OS) of the interference pattern phase demodulation device 830. The processor 810 is used to execute the executable modules stored in the machine-readable storage medium 820, such as the software function modules and computer programs included in the interference pattern phase demodulation device 830.

[0136] Among them, the machine-readable storage medium 820 may be, but is not limited to, a Random Access Memory (RAM), a Read Only Memory (ROM), a Programmable Read-Only Memory (PROM), an Erasable Programmable Read-Only Memory (EPROM), an Electric Erasable Programmable Read-Only Memory (EEPROM), etc. Among them, the machine-readable storage medium 820 is used to store a program, and after receiving an execution instruction, the processor 810 executes the program.

[0137] The processor 810 may be an integrated circuit chip with signal processing capabilities. The above-mentioned processor 810 may be a general-purpose processor 810, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present application. The general-purpose processor 810 may be a microprocessor 810 or the processor 810 may also be any conventional processor 810, etc.

[0138] Please refer to Figure 8 , the embodiment of the present application further provides an interferogram phase demodulation device 830. The interferogram phase demodulation device 830 includes a plurality of functional modules that can be stored in the machine-readable storage medium 820 in software form. Functionally divided, the interferogram phase demodulation device 830 may include an acquisition module 831, a first determination module 832, a second determination module 833, a judgment module 834, an iteration module 835, and an output module 836. Among them:

[0139] The acquisition module 831 may be used to acquire the first phase shift amounts corresponding to at least three interferograms respectively, and the phase shift between adjacent interferograms is a slope.

[0140] In this embodiment, the acquisition module 831 may be used to execute Figure 1 the step S100 shown, and the specific description of the acquisition module 831 may refer to the description of the step S100.

[0141] The first determination module 832 may be configured to determine a reference phase corresponding to at least three of the interference images according to the first phase shift amount.

[0142] In this embodiment, the first determination module 832 may be configured to execute Figure 1 step S200 shown, and for a specific description of the first determination module 832, reference may be made to the description of step S200.

[0143] The second determination module 833 may be configured to determine a second phase shift amount corresponding to each of at least three of the interference images according to the reference phase.

[0144] In this embodiment, the second determination module 833 may be configured to execute Figure 1 step S300 shown, and for a specific description of the second determination module 833, reference may be made to the description of step S300.

[0145] The judgment module 834 may be configured to calculate a difference between the first phase shift amount and the second phase shift amount, and determine whether the difference between the first phase shift amount and the second phase shift amount is less than a preset threshold.

[0146] In this embodiment, the judgment module 834 may be configured to execute Figure 1 step S400 shown, and for a specific description of the judgment module 834, reference may be made to the description of step S400.

[0147] If the difference between the first phase shift amount and the second phase shift amount is not less than the preset threshold, the iteration module 835 may be configured to re-determine the reference phase according to the second phase shift amount.

[0148] In this embodiment, the iteration module 835 may be configured to execute Figure 1 step S500 shown, and for a specific description of the iteration module 835, reference may be made to the description of step S500.

[0149] If the difference between the first phase shift amount and the second phase shift amount is less than the preset threshold, the output module 836 may be configured to output the reference phase as a target phase.

[0150] In this embodiment, the output module 836 may be configured to execute Figure 1 step S600 shown, and for a specific description of the output module 836, reference may be made to the description of step S600.

[0151] In summary, this embodiment provides an interference pattern phase demodulation method, apparatus, and system. By assuming the phase shift between adjacent interference images as an inclined plane and solving for the phase shift amount and the target phase through an iterative method, the demodulation accuracy can be improved and applied to vibration test scenarios.

[0152] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article, or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or device. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article, or device comprising the element.

[0153] The foregoing is only a preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. An interference pattern phase demodulation method, characterized in that: The method comprises: Obtaining first phase shift amounts corresponding to at least three interference images respectively, wherein the phase shift between adjacent interference images is an inclined plane; Determine reference phases corresponding to at least three interference images according to the first phase shift amount; Determine second phase shift amounts respectively corresponding to at least three interference images according to the reference phase; Calculating a difference between the first phase shift and the second phase shift, and determining whether the difference between the first phase shift and the second phase shift is less than a preset threshold; If the difference between the first phase shift and the second phase shift is not less than a preset threshold, re-determining the reference phase according to the second phase shift; If the difference between the first phase shift and the second phase shift is smaller than a preset threshold, the reference phase is output as a target phase.

2. The interference pattern phase demodulation method according to claim 1, characterized in that: The phase shift between adjacent interference images satisfies the following constraints: δ i =f x x+f y y+d Among them, f x represents the slope of the phase shift between adjacent interference images in the x direction, f y represents the slope of the phase shift between adjacent interference images in the y direction, and d represents a constant.

3. The interference pattern phase demodulation method according to claim 1, characterized in that: The step of determining the second phase shift amounts respectively corresponding to at least three interference images according to the reference phase comprises: Calculate energy functions corresponding to at least three interference images respectively according to the reference phase; The second phase shift amounts respectively corresponding to at least three interference images are calculated according to the energy function.

4. The interference pattern phase demodulation method according to claim 3, characterized in that: The step of calculating the second phase shift amounts respectively corresponding to at least three interference images according to the energy function comprises: updating the slope of the phase shift between adjacent interference images according to the energy function; The second phase shift amounts respectively corresponding to at least three interference images are calculated according to the updated slope.

5. The interference pattern phase demodulation method according to claim 3, characterized in that: The energy function E corresponding to the interference image i for: Wherein, N represents the number of pixels in the interference image; j represents the jth pixel in the interference image; i represents the i-th interference image in at least three interference images; represents the phase; a, b, c represent the polynomial coefficients of the two-dimensional expression respectively.

6. The interference pattern phase demodulation method according to claim 1, characterized in that: The step of determining reference phases corresponding to at least three interference images according to the first phase shift comprises: Acquire a light intensity expression of the interference image, and convert the light intensity expression into a two-dimensional expression; Calculating the polynomial coefficients of the two-dimensional expression according to the first phase shift amount by the least square method; A reference phase is calculated based on the polynomial coefficients of the two-dimensional expression.

7. The interference pattern phase demodulation method according to claim 6, characterized in that: The step of calculating the polynomial coefficients of the two-dimensional expression according to the first phase shift amount by the least square method comprises: Calculate the polynomial coefficients of the two-dimensional expression corresponding to each pixel point in the interference image according to the first phase shift by using the least square method; The step of calculating the reference phase according to the polynomial coefficients of the two-dimensional expression comprises: The reference phase corresponding to each of the pixel points is calculated according to the polynomial coefficients of the two-dimensional expression.

8. The interference pattern phase demodulation method according to claim 6, characterized in that: The light intensity expression of the interference image is: Among them, I i (x, y) represents light intensity; I0(x, y) represents background light, I′(x, y) represents modulation, and δ represents phase shift; represents the phase; i represents the i-th interference image among at least three interference images; (x, y) represents the coordinates of the pixel point in the interference image; The two-dimensional expression is: I i =a+bcos(δ i )+csin(δ i ) Among them, a(x, y) = I0(x, y), a, b, c represent the polynomial coefficients of the two-dimensional expression respectively; i represents the light intensity; δ represents the phase shift; represents the phase; i represents the i-th interference image among the at least three interference images; The least squares matrix is: Wherein, a, b, and c represent the polynomial coefficients of the two-dimensional expression respectively; I represents the light intensity; δ represents the phase shift; i represents the i-th interference image among the at least three interference images; j represents the j-th pixel point in the interference image; and M represents the number of the interference images; The reference phase corresponding to each pixel point for: in, represents the phase; j represents the jth pixel point in the interference image; b and c represent the polynomial coefficients of the two-dimensional expression respectively.

9. An interference pattern phase demodulation device, characterized in that: include: An acquisition module, used for acquiring first phase shift amounts respectively corresponding to at least three interference images, wherein the phase shift between adjacent interference images is an inclined surface; A first determining module, configured to determine reference phases corresponding to at least three interference images according to the first phase shift; A second determination module, configured to determine second phase shift amounts respectively corresponding to at least three interference images according to the reference phase; A judging module, configured to calculate a difference between the first phase shift and the second phase shift, and judge whether the difference between the first phase shift and the second phase shift is less than a preset threshold; an iteration module, configured to re-determine the reference phase according to the second phase shift if the difference between the first phase shift and the second phase shift is not less than a preset threshold; The output module is configured to output the reference phase as a target phase if the difference between the first phase shift and the second phase shift is smaller than a preset threshold.

10. An interference pattern phase demodulation system, characterized in that: The interference pattern phase demodulation system includes a processor and a machine-readable storage medium, wherein the machine-readable storage medium stores machine-executable instructions, and when the machine-executable instructions are executed by the processor, the interference pattern phase demodulation method described in any one of claims 1-8 is implemented.

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