Two-dimensional shock wave velocity measurement system and data processing method based on polarization interferometry

Abstract

The present invention provides a two-dimensional shock wave velocity measurement system and data processing method based on polarization interferometry. Based on the principle of polarization interferometry, two sets of 1 / 4 wave plates are used to obtain circularly polarized light with opposite rotation directions and synthesize interference. A polarization camera can be used to synchronously obtain a phase difference of 90 degrees through a single exposure. ° The four-phase image can be obtained by further solving the two-dimensional velocity field information. The present invention breaks through the limitation of one-dimensional measurement. The overall structure of the system is simple and easy to adjust. It can be achieved by using simple polarizers and wave plates. The data processing is accurate and efficient, which lays a good technical foundation for two-dimensional shock wave velocity diagnosis.

Description

Technical Field

[0001] The present invention relates to the technical field of laser interferometry velocity measurement, and more particularly to a two-dimensional shock wave velocity measurement system and a data processing method based on polarization interferometry. Background Art

[0002] Shock wave velocity diagnosis plays a vital role in numerous high-energy-density physics research fields. In laser inertial confinement fusion (ICF) research, precise diagnosis of ion velocities and shock wave velocities during microsecond to nanosecond transients enables the study of shock pressure, shock symmetry, and other indicators. Furthermore, to achieve the ideal compression state, the ICF process requires the shock wave to possess extremely high spherical symmetry. However, due to various non-ideal factors, the shock wave can form large-scale hydrodynamic instabilities, disrupting spherical compression. Therefore, diagnosing the inhomogeneity of two-dimensional shock waves is crucial.

[0003] The Velocity Interferometer System for Any Reflector (VISAR) is a widely used velocity diagnostic technique. It primarily exploits the optical Doppler effect, interfering two time-delayed light beams using an interferometer. This interferometer records the frequency variations of the light reflected from the wavefront being measured. A streak camera with high temporal resolution then captures the resulting streak image. By analyzing the fringe phase variations, the technique enables accurate diagnosis of shock wave velocity. Currently, the most mature method is one-dimensional line VISAR, which can measure the temporal evolution of shock wave velocity in one dimension but cannot accurately diagnose the spatial inhomogeneity of the two-dimensional velocity field. Summary of the Invention

[0004] In order to overcome the defect of the above-mentioned existing technology that it is impossible to accurately diagnose the non-uniform information of the spatial distribution of the two-dimensional velocity field, the present invention provides a two-dimensional shock wave velocity measurement system and data processing method based on polarization interferometry. Based on the principle of polarization interferometry, multi-step phase shift is adopted and recorded by a polarization camera. A two-dimensional interference image of the surface to be measured can be obtained. Combined with the corresponding data processing method, the spatial distribution information of the two-dimensional velocity field can be obtained.

[0005] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0006] A two-dimensional shock wave velocity measurement system based on polarization interferometry, comprising: a laser, a polarizer, a beam splitter BS1, a beam splitter BS2, a beam splitter BS3, a reflector M1, a reflector M2, a first quarter wave plate, a second quarter wave plate, a polarization camera, and a data processing module;

[0007] The detection light emitted by the laser passes through the polarizer and the beam splitter BS1 in sequence and is incident on the surface to be measured, and is reflected by the surface to be measured and then returns to the beam splitter BS1; the beam splitter BS1 injects the reflected light into the beam splitter BS2;

[0008] After the reflected light is split by the beam splitter BS2, a first beam split and a second beam split are obtained; the first beam split passes through the first 1 / 4 wave plate and the reflector M1 in sequence and then enters the beam splitter BS3; the second beam split passes through the reflector M2 and the second 1 / 4 wave plate in sequence and then enters the beam splitter BS3;

[0009] The fast axis directions of the first 1 / 4 wave plate and the second 1 / 4 wave plate are perpendicular to each other, and the two beams of light incident on the beam splitter BS3 are two beams of circularly polarized light with opposite rotation directions;

[0010] The two beams incident on the beam splitter BS3 are combined and interfered with each other before being incident on the polarization camera to obtain a two-dimensional interference image of the surface to be measured; the two-dimensional interference image of the surface to be measured includes the phases of the two beams that differ by 90 degrees in sequence. ° Four-phase image of

[0011] The data processing module is electrically connected to the polarization camera, and is used to receive the two-dimensional interference image of the surface to be measured and perform data processing to obtain the two-dimensional velocity field spatial distribution information of the surface to be measured.

[0012] Preferably, the detection light emitted by the laser is polarized to 0 after passing through the polarizer. ° Linearly polarized light;

[0013] The first split light becomes left-handed circularly polarized light after passing through the first quarter-wave plate;

[0014] The second split light becomes right-handed circularly polarized light after passing through the second quarter-wave plate.

[0015] Preferably, a polarizing film array is provided on the photosensitive surface of the polarization camera, and the polarizing film array is composed of repeated 2×2 square grid units, and each of the square grid units contains polarization directions of 0 ° , 45 ° , 90 ° and 135 ° Each of the micropolarizers corresponds to a pixel on the photosensitive surface, and each pixel records an interference image of a single polarization direction.

[0016] Preferably, the system further comprises a light receiving module, and the detection light emitted by the laser passes through the polarizer and the beam splitter BS1 in sequence and then enters the light receiving module, and is then focused on the surface to be measured;

[0017] The light receiving module includes at least one lens.

[0018] The present invention also provides a data processing method, based on the above-mentioned two-dimensional shock wave velocity measurement system based on polarization interferometry, applied to the data processing module, comprising the following steps:

[0019] The two-dimensional interference image of the surface to be measured and the light intensity of each pixel thereof are obtained from the polarization camera, and the light intensity expression of the four-phase image is constructed by using the four-step phase shift method. I 1. I 2. I 3 and I 4, among which, I 1. I 2. I 3 and I The phase offsets of 4 are 0, π / 2, π, and 3π / 2 respectively;

[0020] According to the light intensity expression of the four-phase image I 1. I 2. I 3 and I 4. Solve the truncated phase of each pixel ;

[0021] According to the truncated phase The spatial distribution information of the two-dimensional velocity field of the surface to be measured is further obtained by solving.

[0022] Preferably, the truncated phase is solved according to the following formula: :

[0023] .

[0024] Preferably, the truncated phase of each pixel Perform unwrapping operation to obtain continuous phase distribution ,in, is the horizontal and vertical coordinates of the pixel;

[0025] The spatial distribution information of the two-dimensional velocity field of the surface to be measured is solved according to the following formula:

[0026]

[0027] in, Indicates the location The speed at which is the laser wavelength; is the delay time caused by interference.

[0028] Preferably, the light intensity expression of the four-phase image is I 1. I 2.I 3 and I 4 is represented by:

[0029]

[0030]

[0031]

[0032]

[0033] in, is the background light intensity; For the modulation system.

[0034] Preferably, the background light intensity is calculated according to the following formula :

[0035]

[0036] Calculate the modulation degree according to the following formula :

[0037]

[0038] According to the background light intensity Extract noise information according to the modulation Obtain the intensity distribution information of the surface to be measured.

[0039] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0040] The present invention provides a two-dimensional shock wave velocity measurement system and data processing method based on polarization interferometry. Based on the principle of polarization interferometry, multi-step phase shift is adopted and recorded with a polarization camera to obtain a two-dimensional interference image of the surface to be measured. Combined with the corresponding data processing method, the spatial distribution information of the two-dimensional velocity field can be obtained.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] 1) Breaking through the limitations of one-dimensional measurement: This invention employs two sets of quarter-wave plates with orthogonal fast axes to convert linearly polarized light into left-handed and right-handed circularly polarized light with opposite handedness. After beam combining and interference, an interference field carrying two-dimensional phase information is formed. This fundamentally solves the problem that traditional linear VISAR cannot obtain the spatial distribution of the two-dimensional velocity field.

[0043] 2) Single-exposure efficient acquisition: The present invention can synchronously capture four interference images with a phase difference of strictly π / 2 in a single exposure, completely avoiding the timing error caused by multiple exposures in the time-sharing phase shift method, and significantly improving the temporal resolution and spatial synchronization of transient shock wave measurements;

[0044] 3) Simplified and reliable system structure: The present invention only requires conventional polarizers, wave plates and beam splitters to form the core optical path, without the need for complex mechanical phase shifters or multiple laser pulse triggering, which greatly reduces the complexity of optical path debugging and system cost, while improving anti-interference capabilities.

[0045] 4) Accurate and efficient data processing: Based on a four-step phase-shift algorithm, the present invention can quickly reconstruct the continuous phase distribution by solving the truncated phase of each pixel and combining it with an unwrapping operation. The continuous phase distribution is finally converted into a two-dimensional velocity field with high computational accuracy.

[0046] 5) Outstanding application value: This invention is particularly suitable for diagnosing shock wave symmetry in laser inertial confinement fusion (ICF). It can quantify fluid dynamics instabilities through two-dimensional velocity field inhomogeneity analysis, providing irreplaceable technical support for high-energy-density physics research. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 This is a structural diagram of a two-dimensional shock wave velocity measurement system based on polarization interferometry provided in Example 1.

[0048] Figure 2 This is a flow chart of a data processing method provided in Example 2. DETAILED DESCRIPTION

[0049] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting the present application;

[0050] In order to better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product size;

[0051] It is understandable to those skilled in the art that some well-known structures and descriptions thereof may be omitted in the drawings.

[0052] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0053] Example 1

[0054] like Figure 1 As shown, this embodiment provides a two-dimensional shock wave velocity measurement system based on polarization interferometry, including: a laser, a polarizer, a beam splitter BS1, a light receiving module, a beam splitter BS2, a beam splitter BS3, a reflector M1, a reflector M2, a first quarter wave plate, a second quarter wave plate, a polarization camera, and a data processing module;

[0055] The detection light emitted by the laser passes through the polarizer and beam splitter BS1 in sequence and is incident on the light receiving module, then is focused on the surface to be measured, and returns to the beam splitter BS1 after being reflected by the surface to be measured; the beam splitter BS1 injects the reflected light into the beam splitter BS2;

[0056] After the reflected light is split by the beam splitter BS2, a first beam split and a second beam split are obtained; the first beam split passes through the first 1 / 4 wave plate and the reflector M1 in sequence and then enters the beam splitter BS3; the second beam split passes through the reflector M2 and the second 1 / 4 wave plate in sequence and then enters the beam splitter BS3;

[0057] The fast axis directions of the first 1 / 4 wave plate and the second 1 / 4 wave plate are perpendicular to each other, and the two beams of light incident on the beam splitter BS3 are two beams of circularly polarized light with opposite rotation directions;

[0058] The two beams incident on the beam splitter BS3 are combined and interfered with each other before being incident on the polarization camera to obtain a two-dimensional interference image of the surface to be measured; the two-dimensional interference image of the surface to be measured includes the phases of the two beams that differ by 90 degrees in sequence. ° Four-phase image of

[0059] The data processing module is electrically connected to the polarization camera, and is used to receive the two-dimensional interference image of the surface to be measured and perform data processing to obtain the two-dimensional velocity field spatial distribution information of the surface to be measured;

[0060] The detection light emitted by the laser is polarized to 0 after passing through the polarizer. ° Linearly polarized light;

[0061] The first split light becomes left-handed circularly polarized light after passing through the first quarter-wave plate;

[0062] The second split light becomes right-handed circularly polarized light after passing through the second quarter-wave plate;

[0063] A polarizing plate array is provided in front of the photosensitive surface of the polarization camera. The polarizing plate array is composed of repeated 2×2 square grid units. Each of the square grid units contains polarization directions of 0 ° , 45 ° , 90 ° and 135 ° Each of the micro-polarizers corresponds to a pixel on the photosensitive surface, and each pixel records an interference image in a single polarization direction;

[0064] The light receiving module includes at least one lens. In this embodiment, the light receiving module includes a lens L1 and a lens L2 that are sequentially arranged.

[0065] In the specific implementation process, the detection light emitted from the laser is polarized to 0 after passing through the polarizer. °The linearly polarized light then passes through the beam splitter BS1 and enters the light receiving module and is focused on the surface to be measured. The detection light is reflected by the surface to be measured and returns along the original optical path, and is reflected by BS1 and enters the interferometer.

[0066] In this embodiment, the interferometer consists of beam splitters BS2 and BS3 and reflectors M1 and M2. The reflected light enters the two arms of the interferometer through the beam splitter BS2. A first quarter-wave plate is placed in one arm, and the optical axis is precisely adjusted to convert the polarized light in this branch into left-handed (or right-handed) circularly polarized light. Simultaneously, a second quarter-wave plate is placed in the other arm, and the polarized light in this branch is precisely adjusted to convert the polarized light into right-handed (or left-handed) circularly polarized light. The key here is to ensure that the circularly polarized light in the two arms rotates in opposite directions.

[0067] The light from the two arms is combined and interfered after passing through the beam splitter BS3, and then enters the final polarization camera for recording;

[0068] Polarization camera has a polarizer array (such as Figure 1 As shown in the figure, every four micro-polarizers form a square unit, distributed in a 2×2 pattern, with polarization angles of 0°, 45°, 90°, and 135°, respectively. Each micro-polarizer corresponds to a pixel on the photosensitive surface.

[0069] After the interference light formed by left-handed (or right-handed) circularly polarized light and right-handed (or left-handed) circularly polarized light passes through the polarization camera, four phase images with phase differences of 90° can be obtained through a single exposure. The specific mathematical derivation and theoretical verification process are as follows:

[0070] Assume that the original linearly polarized light is x Directional polarization:

[0071]

[0072] in, represents the reflected light field entering the interferometer; represents the detection light field; Represents the unit vector in the x direction (horizontal direction);

[0073] This embodiment is described by taking the example of the two paths of light after being split by the beam splitter BS2 into left-handed circularly polarized light and right-handed circularly polarized light:

[0074] The first split light passes through the first quarter wave plate with the fast axis in the y direction to obtain LCP;

[0075] The second split light passes through the second quarter wave plate with the fast axis in the x direction to obtain the RCP;

[0076] Circularly polarized light is expressed in the form of a complex vector, and the light field of left-handed circularly polarized light (LCP) is expressed as:

[0077]

[0078] in, represents the light field of left-handed circularly polarized light; represents the unit vector in the y direction (vertical direction); i is the imaginary unit; k is the wave number, which represents the number of cycles of the wave per unit distance; z is the propagation direction coordinate (light propagates along the z direction); is the angular frequency, which indicates the number of fluctuation cycles per unit time; t indicates time;

[0079] The light field of right-handed circularly polarized light (RCP) is expressed as:

[0080]

[0081] in, is the light field of right-handed circularly polarized light; is the initial phase difference between the two beams;

[0082] Considering interference, and adding a linear polarizer with an angle of θ after the interference, the light field after interference is derived as follows:

[0083] Add two lights together:

[0084]

[0085] in, is the superimposed light field;

[0086] Expand the second item:

[0087]

[0088] So the total field is:

[0089]

[0090] After passing through the linear polarizer with an angle of θ, assuming that the transmission axis direction of the linear polarizer is , its effect on the electric field can be expressed using the projection operator:

[0091] Assume that the polarization of the total electric field in the xy plane is:

[0092]

[0093] in, represents the component of the total electric field in the x direction (complex amplitude); represents the component of the total electric field in the y direction (complex amplitude);

[0094] Then the light field after passing through the polarizer is the projection of the original electric field in that direction:

[0095] make:

[0096]

[0097] so:

[0098]

[0099] in, represents the output electric field after passing through the polarizer (i.e. the electric field after projection);

[0100] This embodiment focuses on the interference intensity, that is:

[0101]

[0102] in, It represents the intensity of the interference light captured by the polarization camera, which is the angle and phase difference function;

[0103] The next step is to calculate the light intensity:

[0104] make:

[0105]

[0106] in, It is a custom parameter. To simplify the formula, this formula refers to the projection expression of the total electric field in the direction of the polarizer.

[0107] Calculate the square of the modulus :

[0108]

[0109] in, express conjugation of;

[0110] First write the conjugate:

[0111]

[0112] get:

[0113]

[0114] Simplify each one:

[0115]

[0116]

[0117] The cross term is zero (because the imaginary part is multiplied by the real part, and the imaginary parts cancel out after the multiplication);

[0118] so:

[0119]

[0120] Arranged:

[0121]

[0122] Using the identity , and noted ,then:

[0123]

[0124] Therefore, when the polarizer is rotated by an angle of θ, the phase of the interference fringes will shift by 2θ, so the polarization camera can obtain four phase images with phases that differ by 90° at a time;

[0125] Finally, the two-dimensional interference image of the surface to be measured obtained by the polarization camera is input into the data processing module for data processing to obtain the two-dimensional velocity field spatial distribution information of the surface to be measured;

[0126] The system obtains left-hand polarized light and right-hand polarized light by setting 1 / 4 wave plates on the two arms of the interferometer and synthesizing interference. The polarization camera can obtain a phase difference of 90 degrees through a single exposure. ° The four-phase image is obtained and the velocity field information is further solved. The overall structure of the system is simple and easy to adjust. It can be realized by using simple polarizers and wave plates, laying a good technical foundation for two-dimensional shock wave velocity diagnosis.

[0127] Example 2

[0128] like Figure 2 As shown, this embodiment provides a data processing method, which is based on the two-dimensional shock wave velocity measurement system based on polarization interferometry described in Example 1 and is applied to the data processing module, including the following steps:

[0129] S1: Obtain the two-dimensional interference image of the surface to be measured and the light intensity of each pixel from the polarization camera, and use the four-step phase shift method to construct the light intensity expression of the four-phase image I 1. I 2. I 3 and I 4, among which, I 1. I 2. I 3 and I The phase offsets of 4 are 0, π / 2, π, and 3π / 2 respectively;

[0130] S2: Light intensity expression based on four-phase image I 1. I2. I 3 and I 4. Solve the truncated phase of each pixel ;

[0131] S3: According to the truncated phase Further solving to obtain the spatial distribution information of the two-dimensional velocity field of the surface to be measured;

[0132] Specifically, the truncated phase is solved according to the following formula: :

[0133]

[0134] The truncated phase of each pixel Perform unwrapping operation to obtain continuous phase distribution ,in, is the horizontal and vertical coordinates of the pixel;

[0135] The spatial distribution information of the two-dimensional velocity field of the surface to be measured is solved according to the following formula:

[0136]

[0137] in, Indicates the location The speed at which is the laser wavelength; The delay time caused by the interference;

[0138] In this embodiment, the light intensity expression of the four-phase image is I 1. I 2. I 3 and I 4 is represented by:

[0139]

[0140]

[0141]

[0142]

[0143] in, is the background light intensity; For the modulation system;

[0144] Calculate the background light intensity according to the following formula :

[0145]

[0146] Calculate the modulation degree according to the following formula :

[0147]

[0148] According to the background light intensity Extract noise information according to the modulation Obtain the intensity distribution information of the surface to be measured.

[0149] In the specific implementation process, after the four-phase interference image is obtained using the polarization camera, the image needs to be further processed. This embodiment adopts a four-step phase shift method, and the process is as follows:

[0150] A point on the fringe image The corresponding fringe light intensity can be written as the following formula:

[0151]

[0152] Where: I(x,y,t) is the fringe image at the t-th step phase shift A(x,y) represents the light intensity at The background light intensity (i.e., average light intensity) at ; B(x,y) represents The modulation degree at (i.e., fringe contrast); For those who are waiting The truncated phase at ; is the phase shift introduced in step t;

[0153] For the image obtained in this embodiment, the phase shift sequence is:

[0154]

[0155] Therefore, the expressions for the four images are as follows:

[0156]

[0157] Use trigonometric formulas to make substitutions:

[0158]

[0159] Substituting into the above formula we get:

[0160]

[0161] Next, use I 1. I 2. I 3 and I 4 Solve the background light intensity , adjustment system and truncated phase :

[0162] 1) Solve the background light intensity :

[0163] Add the four equations together:

[0164]

[0165] All containing The terms of cancel each other out, leaving:

[0166]

[0167] Solved background light intensity :

[0168]

[0169] 2) Find the solution to the modulation system :

[0170] Construct two difference terms:

[0171]

[0172] So we have:

[0173]

[0174] Square these two expressions and add them together:

[0175]

[0176] So we can get the adjustment system :

[0177]

[0178] 3) Solve the truncated phase :

[0179] Depend on It can be seen that:

[0180]

[0181] Use the inverse tangent function to express the phase:

[0182]

[0183] therefore,

[0184]

[0185] Noise information can be extracted from the background light intensity, intensity distribution information of the target surface can be obtained from the modulation index, and distribution information of the two-dimensional velocity field can be obtained from the truncated phase.

[0186] Specifically, the truncated phase of each pixel Perform unwrapping operation to obtain continuous phase distribution ,in, is the horizontal and vertical coordinates of the pixel;

[0187] The spatial distribution information of the two-dimensional velocity field of the surface to be measured is solved according to the following formula:

[0188]

[0189] in, Indicates the location The speed at which is the laser wavelength; The delay time caused by the interference;

[0190] This embodiment is based on a four-step phase shift algorithm. By solving the truncated phase of each pixel and combining it with an unwrapping operation, it can quickly reconstruct the continuous phase distribution and ultimately convert it into a two-dimensional velocity field with high calculation accuracy.

[0191] In addition, based on the extracted noise information, further denoising can be performed to improve the image signal-to-noise ratio; based on the extracted intensity distribution information of the surface to be measured itself, the uneven intensity distribution of the two-dimensional surface to be measured at different spatial positions can be obtained; since the surface to be measured is not an ideal smooth plane, there will be scratches, defects and other traces during the processing process, or there may be marks deliberately set on the surface to be measured in experimental research. This information can be obtained by calculating the modulation index B.

[0192] The same or similar reference numerals correspond to the same or similar components;

[0193] The terms used in the drawings to describe positional relationships are for illustrative purposes only and are not to be construed as limiting the present application.

[0194] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A two-dimensional shock wave velocity measurement system based on polarization interferometry, characterized in that: include: Laser, polarizer, beam splitter BS1, beam splitter BS2, beam splitter BS3, reflector M1, reflector M2, first quarter wave plate, second quarter wave plate, polarization camera and data processing module; The detection light emitted by the laser passes through the polarizer and the beam splitter BS1 in sequence and is incident on the surface to be measured, and is reflected by the surface to be measured and then returns to the beam splitter BS1; the beam splitter BS1 injects the reflected light into the beam splitter BS2; After the reflected light is split by the beam splitter BS2, a first beam split and a second beam split are obtained; the first beam split passes through the first 1 / 4 wave plate and the reflector M1 in sequence and then enters the beam splitter BS3; the second beam split passes through the reflector M2 and the second 1 / 4 wave plate in sequence and then enters the beam splitter BS3; The fast axis directions of the first 1 / 4 wave plate and the second 1 / 4 wave plate are perpendicular to each other, and the two beams of light incident on the beam splitter BS3 are two beams of circularly polarized light with opposite rotation directions; The two beams incident on the beam splitter BS3 are combined and interfered with each other before being incident on the polarization camera to obtain a two-dimensional interference image of the surface to be measured; the two-dimensional interference image of the surface to be measured includes the phases of the two beams that differ by 90 degrees in sequence. ° Four-phase image of The data processing module is electrically connected to the polarization camera, and is used to receive the two-dimensional interference image of the surface to be measured and perform data processing to obtain the two-dimensional velocity field spatial distribution information of the surface to be measured.

2. A two-dimensional shock wave velocity measurement system based on polarization interferometry according to claim 1, characterized in that: The detection light emitted by the laser is polarized to 0 after passing through the polarizer. ° Linearly polarized light; The first split light becomes left-handed circularly polarized light after passing through the first quarter-wave plate; The second split light becomes right-handed circularly polarized light after passing through the second quarter-wave plate.

3. The two-dimensional shock wave velocity measurement system based on polarization interferometry according to claim 1, characterized in that: A polarizing plate array is provided in front of the photosensitive surface of the polarization camera. The polarizing plate array is composed of repeated 2×2 square grid units. Each of the square grid units contains polarization directions of 0 ° , 45 ° , 90 ° and 135 ° Each of the micropolarizers corresponds to a pixel on the photosensitive surface, and each pixel records an interference image of a single polarization direction.

4. A two-dimensional shock wave velocity measurement system based on polarization interferometry according to any one of claims 1 to 3, characterized in that: The system further includes a light receiving module. The detection light emitted by the laser passes through the polarizer and the beam splitter BS1 in sequence and then enters the light receiving module, and then focuses on the surface to be measured. The light receiving module includes at least one lens.

5. A data processing method, based on the two-dimensional shock wave velocity measurement system based on polarization interferometry as described in any one of claims 1 to 4, applied to the data processing module, characterized in that: The following steps are involved: The two-dimensional interference image of the surface to be measured and the light intensity of each pixel thereof are obtained from the polarization camera, and the light intensity expression of the four-phase image is constructed by using the four-step phase shift method. I 1. I 2. I 3 and I 4, among which, I 1. I 2. I 3 and I The phase offsets of 4 are 0, π / 2, π, and 3π / 2 respectively; According to the light intensity expression of the four-phase image I 1. I 2. I 3 and I 4. Solve the truncated phase of each pixel ; According to the truncated phase The spatial distribution information of the two-dimensional velocity field of the surface to be measured is further obtained by solving.

6. A data processing method according to claim 5, characterized in that: The truncated phase is solved according to the following formula : 。 7. A data processing method according to claim 5, characterized in that: Truncated phase for each pixel Perform unwrapping operation to obtain continuous phase distribution ,in, is the horizontal and vertical coordinates of the pixel; The spatial distribution information of the two-dimensional velocity field of the surface to be measured is solved according to the following formula: in, Indicates the location The speed at which is the laser wavelength; is the delay time caused by interference.

8. A data processing method according to claim 5, characterized in that: The light intensity expression of the four-phase image I 1. I 2. I 3 and I 4 is represented by: in, is the background light intensity; For the modulation system.

9. A data processing method according to claim 8, characterized in that: Calculate the background light intensity according to the following formula : Calculate the modulation degree according to the following formula : According to the background light intensity Extract noise information according to the modulation Obtain the intensity distribution information of the surface to be measured.

Images