Displacement measuring device and displacement measuring method

Abstract

The present application provides a displacement measurement device and a displacement measurement method. The displacement measurement device includes a laser, a beam splitter, a spatial light modulator, a camera and an image processing module. The beam splitter divides the laser emitted by the laser into two beams of light, which are used as a detection light field and a reference light field for displacement measurement; the spatial light modulator is used to modulate the reference light field and selectively generate a vortex light field and / or a plane wave light field. The vortex light field and the plane wave light field have different energies and are spatially separated. The vortex light field is combined with the detection light field reflected by the measured object through the beam splitter to generate an optical Ferris wheel array light field; the generated optical Ferris wheel array light field interferes with the plane wave light field to generate an interference field; the camera successively images the optical Ferris wheel array light field and the interference field respectively; the image processing module locates the position of the optical singularity in the optical Ferris wheel array light field based on the first image and the second image of the imaging, so as to measure the displacement of the measured object.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of displacement sensing technology, and in particular to a displacement measuring device and a displacement measuring method. Background Art

[0002] With the development of modern science and technology, people are no longer satisfied with the cognition of things at the classical spatial scale, but are constantly exploring the microscopic world. In this process, the first problem to be solved is the measurement of smaller spatial scales. As a highly coherent light source, laser-induced structured light field has attracted widespread attention as a high-precision optical metrology ruler. However, due to the limitation of the diffraction limit, the characteristic size of the traditional structured light field cannot be further compressed, which greatly affects the obtainable measurement accuracy. To this end, some new types of nanoscale light fields such as optical surface waves and optical super-oscillation fields with deep subwavelength scale characteristics have been proposed. The former exists on the surface of an object, such as the propagation of surface plasmon polaritons along the metal surface. There are many limitations on the measurement scene, making it difficult to achieve far-field measurement. The latter forms a deep subwavelength focus in the far field through a metasurface structure, and has a very high local wave vector surrounded by a dark field area. In recent years, it has been proven that the displacement measurement accuracy of λ / 4000 (~0.2 nm) can be theoretically achieved. However, the super-oscillation signal is easily suppressed by the strong surrounding side lobes, and the accuracy is difficult to further improve. In addition, the transverse and longitudinal superoscillation characteristics are in a competitive relationship, making it difficult to achieve high-precision measurements in three-dimensional full-space scenarios. However, with the development of modern materials science and information science, higher and higher requirements are placed on the accuracy of imaging and detection systems, especially the measurement of atomic spatial scales and displacements, which requires sub-nanometer or even picometer optical metrology accuracy. Therefore, how to obtain higher-precision optical metrology remains a major challenge and demand. Summary of the invention

[0003] The purpose of the embodiments of the present application is to provide a displacement measurement device and a displacement measurement method, which can perform high-precision displacement measurement.

[0004] One aspect of an embodiment of the present application provides a displacement measurement device for measuring the displacement of an object to be measured. The displacement measurement device includes a laser, a beam splitter, a spatial light modulator, a camera, and an image processing module, wherein the laser is used to emit laser light; the beam splitter is used to split the laser light emitted by the laser into two beams of light as a detection light field and a reference light field for displacement measurement, wherein the detection light field is reflected to the object to be measured and reflected back to the beam splitter through the object to be measured, and the reference light field is transmitted to the spatial light modulator; the spatial light modulator is used to modulate the reference light field and selectively generate a vortex light field and / or a plane wave light field, wherein the vortex light field and the plane wave light field have different energies and are spatially separated, wherein when generating the vortex light field, the vortex light field and the plane wave light field are generated. In the case of a light field, the vortex light field is combined with the detection light field reflected by the object to be measured through the beam splitter to generate an optical Ferris wheel array light field; in the case of simultaneously generating the vortex light field and the plane wave light field, the generated optical Ferris wheel array light field further interferes with the plane wave light field to generate an interference field; the camera is used to successively image the optical Ferris wheel array light field and the interference field, respectively, to obtain a first image and a second image, respectively; the image processing module is used to locate the position of the optical singularity in the optical Ferris wheel array light field based on the first image and the second image, so as to measure the displacement of the object to be measured.

[0005] Furthermore, the camera includes a CCD camera, the first image includes a first light intensity distribution, and the second image includes a second light intensity distribution.

[0006] Furthermore, the displacement measuring device also includes a first polarizer and a half glass plate, wherein the first polarizer is used to adjust the energy of the laser to obtain a linearly polarized laser with adjustable energy; and the half glass plate is used to change the polarization direction of the linearly polarized laser to meet the incident condition of the spatial light modulator.

[0007] Furthermore, the displacement measuring device also includes a beam expansion system, and the beam expansion system is used to expand the laser light emitted by the laser and irradiate it onto the first polarizer.

[0008] Furthermore, the displacement measuring device also includes a first reflector, and the first reflector is used to irradiate the laser modulated by the first polarizer and the half glass plate onto the beam splitter.

[0009] Furthermore, the displacement measuring device also includes a convex lens, and the convex lens is used to focus the plane wave light field reflected by the beam splitter and the optical Ferris wheel array light field.

[0010] Furthermore, the displacement measuring device also includes a second polarizer, which is used to analyze the light field generated by the spatial light modulator to make the plane wave light field interfere with the optical Ferris wheel array light field on the focal plane of the convex lens.

[0011] Furthermore, the displacement measuring device also includes an amplification system, which is used to amplify the interference fringes generated by the interference between the plane wave light field and the optical Ferris wheel array light field, and the camera is used to image the amplified interference fringes.

[0012] Another aspect of the embodiment of the present application provides a displacement measurement method. The method includes: dividing a laser into two beams of light as a detection light field and a reference light field for displacement measurement, wherein the detection light field is irradiated to the object to be measured; modulating the reference light field and selectively generating a vortex light field and / or a plane wave light field, wherein the vortex light field and the plane wave light field have different energies and are spatially separated; combining the vortex light field with the detection light field reflected from the object to be measured to generate an optical Ferris wheel array light field; interfering the optical Ferris wheel array light field with the plane wave light field to generate an interference field; imaging the optical Ferris wheel array light field generated when only the vortex light field is modulated to generate the interference field and the interference field generated when the vortex light field and the plane wave light field are modulated to generate the interference field, respectively, to obtain a first image and a second image, respectively; locating the position of an optical singular point in the optical Ferris wheel array light field based on the first image and the second image; and measuring the displacement of the object to be measured based on the position of the optical singular point.

[0013] Furthermore, the optical Ferris wheel array light field generated when only the vortex light field is modulated to generate the vortex light field and the interference field generated when the vortex light field and the plane wave light field are simultaneously modulated to generate the vortex light field are respectively imaged to obtain a first image and a second image, respectively, including: using a CCD camera to image the optical Ferris wheel array light field generated when only the vortex light field is modulated to generate the vortex light field and the interference field generated when the vortex light field and the plane wave light field are simultaneously modulated to generate the vortex light field, respectively, to obtain a first image and a second image, respectively, the first image includes a first light intensity distribution; the second image includes a second light intensity distribution.

[0014] Furthermore, locating the position of the optical singularity in the optical Ferris wheel array light field based on the first image and the second image includes: performing image processing on the second image to obtain a light field phase distribution; and locating the position of the optical singularity in the optical Ferris wheel array light field based on the first light intensity distribution and the light field phase distribution.

[0015] Furthermore, the image processing of the second image to obtain the light field phase distribution includes: performing Fourier transform on the second light intensity distribution to obtain the light intensity spectrum information of the interference field; modifying the data except the positive first order in the light intensity spectrum information of the interference field to 0 to obtain the modified light intensity spectrum information; and performing inverse Fourier transform on the modified light intensity spectrum information to obtain the light field phase distribution.

[0016] Furthermore, locating the position of the optical singularity in the optical Ferris wheel array light field based on the first light intensity distribution and the light field phase distribution includes: calculating the complex amplitude distribution of the light field based on the first light intensity distribution and the light field phase distribution; obtaining the angular momentum distribution of the light field based on the complex amplitude distribution to obtain different angular momentum dividing lines; solving the intersection of different angular momentum dividing lines to locate the center of mass of the angular momentum, and the position of the center of mass of the angular momentum is the position of the optical singularity.

[0017] The displacement measurement device and displacement measurement method based on the centroid method of one or more embodiments of the present application use an infinitesimal optical singular point as an optical ruler for interference measurement, which greatly reduces the spatial size of the traditional interference measurement optical ruler that relies on sinusoidal fringes, thereby obtaining an interference measurement technology with higher measurement accuracy; compared with extreme light field optical rulers such as super oscillations and surface wave fringes, the optical ruler of the optical singular point has a smaller optical structure, and its measurement accuracy will be higher. Therefore, the displacement measurement device and method of the present application will have higher measurement accuracy for the displacement measurement of the measured object. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic structural diagram of a displacement measuring device according to an embodiment of the present application.

[0019] Figure 2 The intensity distribution of the optical Ferris wheel array light field measured by a CCD camera according to one embodiment of the present application.

[0020] Figure 3 The intensity distribution of the interference field measured by a CCD camera according to one embodiment of the present application.

[0021] Figure 4 This is a flow chart of a displacement measurement method according to an embodiment of the present application.

[0022] Figure 5 A schematic diagram showing the result of measuring the displacement of an object to be measured by controlling the translation of a reflector used to simulate the object to be measured using the displacement measurement method of the present application. DETAILED DESCRIPTION

[0023] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of devices consistent with some aspects of the present application as detailed in the appended claims.

[0024] The following is a detailed description of the displacement measurement device and displacement measurement method of each embodiment of the present application in conjunction with the accompanying drawings. In the absence of conflict, the features of the following embodiments and implementations can be combined with each other.

[0025] The present application provides a displacement measuring device which can be used to measure the displacement of a measured object with high precision. Figure 1 The structural diagram of a displacement measuring device 100 according to an embodiment of the present application is disclosed. Figure 1 As shown, a displacement measuring device 100 according to an embodiment of the present application includes a laser 101 , a beam splitter 102 , a spatial light modulator 103 and a camera. The camera may include a CCD camera 104 , for example.

[0026] The laser 101 can be used to emit laser light. In one embodiment, the laser 101 is a linearly polarized continuous light laser that can emit continuous linearly polarized laser light.

[0027] The beam splitter 102 can be used to split the laser light emitted by the laser 101 into two beams of light, which are used as a detection light field and a reference light field for displacement measurement, respectively. The detection light field is reflected to the object to be measured 140 and reflected back to the beam splitter 102 through the object to be measured 140, and the reference light field is transmitted to the spatial light modulator 103.

[0028] The spatial light modulator 103 can modulate the reference light field and can selectively generate a vortex light field and / or a plane wave light field. The vortex light field and the plane wave light field have different energies and are spatially separated. Among them, when the spatial light modulator 103 generates a vortex light field, the vortex light field can be combined with the detection light field reflected back by the measured object 140 through the beam splitter 102 to generate an optical Ferris wheel array light field. The topological charge of the vortex light field used in the embodiment of the present application is 6, so the dark core number of the generated optical Ferris wheel light field is 6. This numerical selection is only an illustrative embodiment of the present application, however, the present application is not limited to this, and the selection of other topological charges is also within the scope of protection of the present invention.

[0029] Each dark core of the optical Ferris wheel array light field is an optical singular point, and when the measured object 140 moves, the optical Ferris wheel array rotates due to the change in the light field phase. Therefore, the present application can measure the displacement of the measured object 140 by locating the position of the optical singular point.

[0030] When the spatial light modulator 103 generates a vortex light field and a plane wave light field simultaneously, the plane wave light field generated by the spatial light modulator 103 can be reflected by the beam splitter 102 and further interfere with the generated optical Ferris wheel array light field to generate an interference field.

[0031] The CCD camera 104 can image the optical Ferris wheel array light field and the interference field respectively to obtain a first image and a second image respectively. The first image includes a first light intensity distribution, that is, an intensity distribution of the optical Ferris wheel array light field, such as Figure 2 The second image includes a second light intensity distribution, that is, the intensity distribution of the interference field, as shown in Figure 3 shown.

[0032] In some embodiments, the displacement measurement device 100 of the present application further includes a first polarizer 111 and a half glass plate 112. The first polarizer 111 can adjust the energy of the laser. In this process, the energy of the transmitted light field of the first polarizer 111 can be controlled by rotating the first polarizer 111, and energy-adjustable linearly polarized laser light is obtained. Then, the energy-adjustable linearly polarized laser light further passes through a half glass plate 112, and the half glass plate 112 can change the polarization direction of the linearly polarized laser light. In this process, the direction of the half glass plate 112 is rotated so that the polarization direction of the linearly polarized laser light meets the incident condition of the spatial light modulator 103.

[0033] In some embodiments, the displacement measuring device 100 of the present application may further include a beam expansion system 113. The beam expansion system 113 may be used to expand the laser emitted by the laser 101 and irradiate it onto the first polarizer 111. In the embodiment illustrated in the present application, the beam expansion system 113 of the present application is composed of two convex lenses with different focal lengths. In other embodiments, the beam expansion system 113 of the present application may also include a pinhole filter, and the beam expansion of the light field is achieved through the pinhole filter.

[0034] In some embodiments, the displacement measuring device 100 of the present application may further include a first reflector 114. The first reflector 114 may irradiate the laser modulated by the first polarizer 111 and the half glass plate 112 onto the beam splitter 102 for beam splitting.

[0035] In some embodiments, the displacement measurement device 100 of the present application may further include a convex lens 131. The plane wave light field reflected by the beam splitter 102 and the optical Ferris wheel array light field are irradiated on the convex lens 131 together, and the convex lens 131 can focus the plane wave light field reflected by the beam splitter 102 and the optical Ferris wheel array light field.

[0036] In some embodiments, the displacement measurement device 100 of the present application may further include a second polarizer 132, which is used to polarize the light field generated by the spatial light modulator 103, thereby causing the plane wave light field to interfere with the optical Ferris wheel array light field on the focal plane of the convex lens 131 and obtain clear interference fringes.

[0037] In some embodiments, the displacement measurement device 100 of the present application may further include an amplification system 133, such as a 12-fold amplification system as shown in the figure. The amplification system 133 may amplify the interference fringes generated by the interference between the plane wave light field and the optical Ferris wheel array light field, and use the CCD camera 104 to image the amplified interference fringes.

[0038] It can be understood that the above interference optical path of the displacement measuring device 100 of the present application is only an illustrative embodiment of the present application. However, the interference optical path of the displacement measuring device 100 of the present application is not limited to Figure 1 As shown, for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the present application, which will all be included in the protection scope of the present application.

[0039] The displacement measuring device 100 of the present application may further include an image processing module (not shown). The image processing module may use the centroid method data processing method of the present application to be introduced below to locate the position of the optical singular point in the optical Ferris wheel array light field based on the first image and the second image, so as to measure the displacement of the measured object 140.

[0040] The present application also provides a displacement measurement method, which can use the centroid method to calculate the interference fringes of the interference field imaged by the CCD camera 104, and to locate the optical singularity in the optical Ferris wheel array light field with high precision, so that the displacement of the measured object 140 can be measured with high precision through the optical singularity located with high precision. The centroid method described in the present application is a high-precision optical singularity positioning technology based on the distribution of light field energy flow or angular momentum density, and its core idea is to accurately determine the optical singularity by calculating the "centroid" position of the angular momentum in the light field.

[0041] The following will be combined Figure 4 A displacement measurement method according to an embodiment of the present application is described in detail.

[0042] Figure 4 The following is a flow chart of a displacement measurement method according to an embodiment of the present application. Figure 4 As shown, a displacement measurement method according to an embodiment of the present application may include steps S1 to S7.

[0043] In step S1 , the laser light may be divided into two beams of light, which are used as a detection light field and a reference light field for displacement measurement, respectively. The detection light field is irradiated onto the object 140 to be measured.

[0044] In step S2, the reference light field may be modulated to selectively generate a vortex light field and a plane wave light field, wherein the vortex light field and the plane wave light field have different energies and are spatially separated.

[0045] In step S3, the vortex light field may be combined with the detection light field reflected by the object to be measured 140 to generate an optical Ferris wheel array light field.

[0046] In step S4, the optical Ferris wheel array light field may be further interfered with the plane wave light field to generate an interference field.

[0047] In step S5, the optical Ferris wheel array light field generated when only the vortex light field is modulated and the interference field generated when the vortex light field and the plane wave light field are modulated and generated simultaneously can be imaged to obtain a first image and a second image respectively.

[0048] In some embodiments, the optical Ferris wheel array light field and the interference field can be imaged by a CCD camera to obtain a first image and a second image respectively. The first image includes: Figure 2 The first light intensity distribution shown; the second image includes Figure 3 The second light intensity distribution is shown. Thus, the light field data required by the centroid method of the present application can be obtained.

[0049] Optionally, the acquired light field data may be subjected to denoising, normalization and other processing to ensure that the environmental noise is suppressed to the greatest extent possible.

[0050] In step S6, the position of the optical singular point in the optical Ferris wheel array light field may be located based on the first image and the second image obtained in step S5.

[0051] In some embodiments, locating the position of the optical singular point in the optical Ferris wheel array light field based on the first image and the second image in step S6 may further include step S61 and step S62.

[0052] In step S61, image processing is performed on the second image to obtain a light field phase distribution.

[0053] In some embodiments, the second light intensity distribution can be Fourier transformed to obtain the light intensity spectrum information of the interference field; the data except the positive first order in the light intensity spectrum information of the interference field can be modified to 0 using a data processing method to obtain the modified light intensity spectrum information; then, the modified light intensity spectrum information can be inverse Fourier transformed to obtain the light field phase distribution.

[0054] In step S62, the position of the optical singular point in the optical Ferris wheel array light field may be located based on the first light intensity distribution and the light field phase distribution.

[0055] In some embodiments, step S62 may further include steps S621 to S623.

[0056] In step S621, the complex amplitude distribution of the light field may be calculated based on the first light intensity distribution and the light field phase distribution.

[0057] Specifically, according to the formula of complex amplitude distribution of light field, it is as follows:

[0058] (1)

[0059] Where E represents the complex amplitude distribution of the light field, I1 represents the first light intensity distribution, represents the phase distribution of the light field, Represents the vibration direction of the light field (i.e. polarization direction).

[0060] The first light intensity distribution can be used Obtained light intensity information and light field phase distribution The obtained phase information is used to calculate the complex amplitude distribution E of the light field according to the above formula (1).

[0061] In step S622, the angular momentum distribution of the light field may be obtained based on the complex amplitude distribution obtained in step S621 to obtain different angular momentum boundary lines.

[0062] Furthermore, according to the formula of the energy flow of the light field and the formula of the angular momentum of the light field, it is as follows:

[0063] (2)

[0064] (3)

[0065] Among them, p represents the energy flow of the light field, represents the vacuum dielectric constant, represents the circular frequency of light, represents the angular momentum of the light field, is the position vector with the singular point as the origin of the coordinate system, is the position vector from the reference axis to the singularity position for calculating angular momentum.

[0066] The energy flux p and angular momentum of the light field can be further calculated based on the complex amplitude distribution E of the light field using the above formulas (2) and (3): .

[0067] In step S623, the intersection points of different angular momentum dividing lines are solved to locate the center of mass of the angular momentum. The position of the center of mass of the angular momentum is the position of the optical singular point.

[0068] Specifically, the reference axis of the angular momentum calculation is shifted, that is, the position vector is changed in the above formula (3). The magnitude and direction of angular momentum can be used to locate the boundary between the positive and negative angular momentum regions.

[0069] For example, 1920 reference axes can be selected at equal intervals of 360° around the singularity, and the angular momentum distribution can be repeatedly calculated using the above formula (3), thereby obtaining different angular momentum dividing lines; solving the intersection points of different angular momentum dividing lines can locate the center of mass of the angular momentum, that is, the location of the optical singularity.

[0070] In the stage of locating the optical singularity, the centroid method of the present application successfully locates the optical singularity by accurately calculating the centroid position of the energy flow or angular momentum distribution of the light field. Since the optical singularity is often in the region of sudden change of the light field phase, the centroid offset directly reflects the precise position of the optical singularity. In order to improve the accuracy of the algorithm, the calculation error can also be optimized, such as increasing the sampling density, improving the light field resolution, etc., to further effectively improve the positioning accuracy of the optical singularity.

[0071] In step S7, the displacement of the object 140 to be measured may be measured based on the position of the optical singular point obtained in step S6.

[0072] Next, a reflector will be used to simulate the measured object 140 to experimentally verify the displacement measurement method based on the centroid method proposed in the application.

[0073] In this experiment, a reflector is used to simulate Figure 1The measured object 140 shown in the figure is translated by controlling the reflector used to simulate the measured object 140 using the P-733.3 piezoelectric displacement stage produced by PI. The P-733.3 displacement stage used can generate a standard displacement signal with a minimum step length of 100 pm. With the step length introduced as a displacement signal, the displacement signal is detected using the displacement measurement device 100 based on the centroid method of the present application. Each time the displacement stage moves a step length, the CCD camera 104 successively records a first image of the optical Ferris wheel array light field generated when the spatial light modulator 103 only modulates to generate a vortex light field and a second image of the interference fringes of the interference field generated when the spatial light modulator 103 simultaneously modulates to generate a vortex light field and a plane wave light field.

[0074] Then, the centroid method data processing method mentioned in the displacement measurement method based on the centroid method of the present application is used to perform high-precision positioning of the optical singularity in each second image. Thus, the rotation of the optical Ferris wheel array light field can be measured based on the movement of the optical singularity displacement, and then the displacement change of the reflector of the simulated object 140 can be measured.

[0075] Figure 5 The schematic diagram discloses the result of measuring the displacement of the measured object by controlling the translation of the reflector used to simulate the measured object 140 using the displacement measurement method of the present application. Figure 5 As shown, through linear fitting, it is found that the standard error of the offset between the measured value and the actual value obtained by the displacement measurement method of the present application is about 1.2 pm, thereby verifying the feasibility of the displacement measurement method based on the centroid method proposed in the present application.

[0076] The displacement measurement device 100 and method of one or more embodiments of the present application have at least the following beneficial technical effects:

[0077] Compared with the prior art, the displacement measurement device 100 and method based on the centroid method of the present application uses an infinitesimal optical singular point as an optical ruler for interference measurement, which greatly reduces the spatial size of the traditional interference measurement optical ruler that relies on sinusoidal fringes, thereby obtaining an interference measurement technology with higher measurement accuracy; compared with extreme light field optical rulers such as super oscillations and surface wave fringes, the optical ruler of the optical singular point has a smaller optical structure, and its measurement accuracy will be higher. Therefore, the displacement measurement device 100 and method of the present application will have higher measurement accuracy for the displacement measurement of the measured object.

[0078] The displacement measuring device and the displacement measuring method provided in the embodiments of the present application are introduced in detail above. Specific examples are used herein to illustrate the displacement measuring device and the displacement measuring method in the embodiments of the present application. The description of the above embodiments is only used to help understand the core idea of ​​the present application and is not intended to limit the present application. It should be pointed out that for ordinary technicians in this technical field, without departing from the spirit and principles of the present application, several improvements and modifications can be made to the present application, and these improvements and modifications should also fall within the scope of protection of the claims attached to the present application.

Claims

1. A displacement measuring device for measuring the displacement of an object to be measured, characterized in that: It includes a laser, a beam splitter, a spatial light modulator, a camera and an image processing module, wherein: The laser is used to emit laser light; The beam splitter is used to split the laser light emitted by the laser into two beams of light as a detection light field and a reference light field for displacement measurement, wherein the detection light field is reflected to the object to be measured and reflected back to the beam splitter through the object to be measured, and the reference light field is transmitted to the spatial light modulator; The spatial light modulator is used to modulate the reference light field and selectively generate a vortex light field and / or a plane wave light field, wherein the vortex light field and the plane wave light field have different energies and are spatially separated, wherein, in the case of generating the vortex light field, the vortex light field is combined with the detection light field reflected from the measured object through the beam splitter to generate an optical Ferris wheel array light field; in the case of generating the vortex light field and the plane wave light field at the same time, the generated optical Ferris wheel array light field further interferes with the plane wave light field to generate an interference field; The camera is used to successively image the optical Ferris wheel array light field and the interference field to obtain a first image and a second image respectively; The image processing module is used to locate the position of the optical singular point in the optical Ferris wheel array light field based on the first image and the second image, so as to measure the displacement of the measured object.

2. The displacement measuring device according to claim 1, characterized in that: The camera includes a CCD camera, the first image includes a first light intensity distribution, and the second image includes a second light intensity distribution.

3. The displacement measuring device according to claim 1, characterized in that: It also includes a first polarizer and a half glass plate, wherein: The first polarizer is used to adjust the energy of the laser to obtain linearly polarized laser with adjustable energy; The half glass slide is used to change the polarization direction of the linearly polarized laser to meet the incident condition of the spatial light modulator.

4. The displacement measuring device according to claim 3, characterized in that: It also includes a beam expansion system, which is used to expand the laser light emitted by the laser and irradiate it onto the first polarizer.

5. The displacement measuring device according to claim 3, characterized in that: It also includes a first reflector, which is used to irradiate the laser modulated by the first polarizer and the half glass plate onto the beam splitter.

6. The displacement measuring device according to claim 1, characterized in that: It also includes a convex lens, which is used to focus the plane wave light field reflected by the beam splitter and the optical Ferris wheel array light field.

7. The displacement measuring device according to claim 6, characterized in that: It also includes a second polarizer, which is used to analyze the light field generated by the spatial light modulator to make the plane wave light field interfere with the optical Ferris wheel array light field on the focal plane of the convex lens.

8. The displacement measuring device according to claim 1, characterized in that: It also includes an amplification system, which is used to amplify the interference fringes generated by the interference between the plane wave light field and the optical Ferris wheel array light field, and the camera is used to image the amplified interference fringes.

9. A displacement measurement method, characterized in that: include: Splitting the laser into two beams of light as a detection light field and a reference light field for displacement measurement, wherein the detection light field is irradiated onto the object to be measured; Modulating the reference light field and selectively generating a vortex light field and / or a plane wave light field, wherein the vortex light field and the plane wave light field have different energies and are spatially separated; Combining the vortex light field with the detection light field reflected by the measured object to generate an optical Ferris wheel array light field; interfering the optical Ferris wheel array light field with the plane wave light field to generate an interference field; Imaging the optical Ferris wheel array light field generated when only the vortex light field is modulated and generated, and the interference field generated when the vortex light field and the plane wave light field are modulated and generated simultaneously, respectively, to obtain a first image and a second image; Locating the position of an optical singular point in the optical Ferris wheel array light field based on the first image and the second image; The displacement of the measured object is measured based on the position of the optical singular point.

10. The displacement measurement method according to claim 9, characterized in that: The optical Ferris wheel array light field generated when only the vortex light field is modulated and generated and the interference field generated when the vortex light field and the plane wave light field are modulated and generated simultaneously are imaged to obtain a first image and a second image respectively, including: The optical Ferris wheel array light field generated when only the vortex light field is modulated to generate the optical Ferris wheel array light field and the interference field generated when the vortex light field and the plane wave light field are simultaneously modulated to generate the optical Ferris wheel array light field are imaged by a CCD camera to obtain a first image and a second image, respectively. The first image includes a first light intensity distribution; the second image includes a second light intensity distribution.

11. The displacement measurement method according to claim 10, characterized in that: The locating the position of the optical singular point in the optical Ferris wheel array light field based on the first image and the second image comprises: Performing image processing on the second image to obtain a light field phase distribution; The position of the optical singular point in the optical Ferris wheel array light field is located based on the first light intensity distribution and the light field phase distribution.

12. The displacement measurement method according to claim 11, characterized in that: The performing image processing on the second image to obtain a light field phase distribution includes: Performing Fourier transform on the second light intensity distribution to obtain light intensity spectrum information of the interference field; Modify the data except the positive first level in the light intensity spectrum information of the interference field to 0, so as to obtain modified light intensity spectrum information; The modified light intensity spectrum information is subjected to inverse Fourier transformation to obtain the light field phase distribution.

13. The displacement measurement method according to claim 11, characterized in that: The method of locating the position of the optical singular point in the optical Ferris wheel array light field based on the first light intensity distribution and the light field phase distribution comprises: Calculating a complex amplitude distribution of the light field based on the first light intensity distribution and the light field phase distribution; Obtaining the angular momentum distribution of the light field based on the complex amplitude distribution to obtain different angular momentum dividing lines; The intersection points of different angular momentum dividing lines are solved to locate the center of mass of the angular momentum, and the position of the center of mass of the angular momentum is the position of the optical singular point.

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