Annular common-path shearing speckle interference system and method

Abstract

The invention provides an annular common-path shearing speckle interference system and method, and relates to an optical measurement system, and the system comprises a light beam generation device which generates light which irradiates the surface of a measured object and forms reflected light; part of the reflected light sequentially penetrates through the imaging objective lens and the Fourier lens I, then irradiates the polarization splitting prism and is divided into reflected light and transmission light; part of the reflected light is reflected by the reflector I, the adjustable reflector, the reflector II and the polarization splitting prism in sequence, and then passes through the 1 / 4 wave plate and the Fourier lens II in sequence to irradiate the imaging surface of the polarization camera; part of the transmission light is reflected by the reflector II, the adjustable reflector and the reflector I in sequence, and then passes through the polarization splitting prism, the 1 / 4 wave plate and the Fourier lens II in sequence to irradiate the imaging surface of the polarization camera; according to the method, the shear amount can be effectively adjusted at will.

Description

Technical Field

[0001] The present invention relates to an optical measurement system, and in particular to an annular common-path shearing speckle interferometry system and method. Background Art

[0002] Shear speckle interferometry is an optical measurement technique based on the laser speckle phenomenon and the principle of interference. It is primarily used to measure surface displacement derivatives, such as the first-order derivative (slope) of out-of-plane displacement. The principle is as follows: when coherent light (such as a laser) is irradiated on a rough surface, it is scattered due to the microscopic irregularities of the rough surface. The scattered light interferes with each other in space to form a random intensity distribution pattern, namely the speckle field. Passing a portion of the speckle field through an optical shearing device causes a certain lateral displacement (i.e., lateral shear). This lateral displacement is then superimposed on another portion of the speckle field (not lateral displacement) in the imaging plane, causing interference (i.e., shear speckle interferometry). The resulting interference field changes phase, and the phase change of the measured object before and after deformation is related to the surface displacement derivative.

[0003] Common optical paths include shearing devices based on Michelson interferometers and Mach-Zehnder interferometers. These shearing devices split the object light into two independently propagating optical paths, independently adjusting the lateral displacement of each optical path through optical elements such as reflectors. In these shearing devices, factors such as vibrations in the propagation path can produce inconsistent optical path difference disturbances between the original object light field and the sheared object light field, thus affecting the measurement effect. Common-path shearing devices, on the other hand, can avoid this problem. Currently, common-path shearing methods include those based on flat plates, gratings, and Wollaston prisms. However, the disadvantage of these common-path shearing devices is that the shearing amount is difficult to adjust. The shearing amount of flat-plate shearing devices is determined by the thickness of the plate, the shearing amount of Wollaston prism-based shearing devices is determined by the size of the prism and its birefringence characteristics, and the shearing amount cannot be continuously adjusted. The shearing amount of grating-based shearing devices is determined by the grating position. Although the shearing amount can be continuously adjusted, it requires changing the grating position over a large range, and the adjustment range is limited, and the minimum shearing amount cannot be close to zero. In addition, the above three common-path shearing devices require the overall rotation of the plate, grating, and Wollaston prism when changing the shearing direction, which makes adjustment inconvenient. Summary of the Invention

[0004] (1) Technical problems solved

[0005] In view of the shortcomings of the prior art, the present invention provides an annular common-path shearing speckle interferometry system and method to solve the technical problem in the prior art that the shearing amount cannot be continuously adjusted.

[0006] (2) Technical solution

[0007] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0008] A first aspect of the present invention provides an annular common-path shearing speckle interferometry system, comprising a light beam generating device, the light generated by the light beam irradiating the surface of the object to be measured and forming reflected light;

[0009] Part of the reflected light passes through the imaging objective lens and Fourier lens in sequence and then shines on the polarization beam splitter prism, and is divided into reflected light and transmitted light;

[0010] Part of the reflected light is reflected by the first reflector, the adjustable reflector, the second reflector and the polarization beam splitter in sequence, and then passes through the quarter wave plate and the second Fourier lens in sequence to illuminate the imaging surface of the polarization camera;

[0011] Part of the transmitted light is reflected by the second reflector, the adjustable reflector and the first reflector in sequence, and then passes through the polarization beam splitter prism, the quarter wave plate and the second Fourier lens in sequence to illuminate the imaging surface of the polarization camera;

[0012] in:

[0013] Fourier lens 1 and Fourier lens 2 form a 4f system, and the back focal plane of the imaging objective lens coincides with the front focal plane of Fourier lens 1, and the back focal plane of Fourier lens 2 coincides with the imaging plane of the polarization camera;

[0014] The adjustable reflector can be rotated arbitrarily around point A on its reflecting surface, and point A is located on the optical axis and spectrum surface of the 4f system.

[0015] Furthermore, the adjustable reflector includes a reflector 3 and a driving structure. The reflector 3 is mounted on the driving structure. The driving structure is used to drive the reflector 3 to perform arbitrary rotational motion around point A.

[0016] Furthermore, the light beam generating device includes a laser and a beam expander, and the light beam generated by the laser is irradiated onto the surface of the object to be measured through the beam expander.

[0017] Furthermore, the polarization splitter prism is replaced by a semi-transparent and semi-reflective prism, and a polarizer 1 is arranged between the semi-transparent and semi-reflective prism and the reflector 1, a polarizer 2 is arranged between the semi-transparent and semi-reflective prism and the reflector 2, and a 1 / 2 wave plate is arranged between the reflector 1 and the adjustable reflector.

[0018] A second aspect of the present invention further provides a method for measuring object surface deformation using the annular common-path shearing speckle interferometry system, the method comprising:

[0019] Obtain the speckle interferogram corresponding to the deformation before the object is deformed out of the plane, obtained on the imaging surface of the polarization camera And record it as

[0020] Obtain the corresponding speckle interferogram after deformation on the imaging surface of the polarization camera after the object under test undergoes out-of-plane deformation. And record it as

[0021] Depend on Get the deformation derivative of the point (x, y) in the z-axis direction Used for calculation of out-of-plane deformation;

[0022] Among them, before and after the object is deformed, the shear between the two beams of light irradiated on the imaging surface of the polarization camera is δ s , is the phase difference between the reflected light and the transmitted light in the corresponding speckle interferogram I(x,y), and Obtained by the following formula:

[0023] I m (x, y) is the modulated light intensity in the corresponding speckle interferogram, (x, y) is the coordinate of the point on the imaging surface of the polarization camera, i is the imaginary unit, is the carrier phase introduced by the polarizer array in the polarization camera at point (x, y), λ is the wavelength of the light emitted by the beam generator, is δ s The corresponding shear direction vector.

[0024] (3) Beneficial effects

[0025] The present invention provides an annular common-path shearing speckle interferometry system and method. Compared with the prior art, the system has the following advantages:

[0026] 1. By setting an adjustable reflector, the shearing position can be adjusted arbitrarily according to needs, which improves the adjustment efficiency.

[0027] 2. The object light and the sheared object light are transmitted on the same path, which is beneficial to resist the influence of environmental disturbance on the measurement effect.

[0028] 3. Use polarization phase shift technology to introduce phase shift between two object lights transmitted in the same path to achieve high-precision phase measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0030] Figure 1FIG1 shows a schematic diagram of the optical path structure of an annular common-path shearing speckle interferometer system provided in Example 1;

[0031] Figure 2 A schematic diagram of the light propagation path in the annular common-path shearing speckle interferometer system shown in Example 1 is shown;

[0032] Figure 3 A schematic structural diagram of the polarizer array in the polarization camera shown in Example 1 is shown;

[0033] Figure 4 A schematic diagram of the optical path structure of an annular common-path shearing speckle interferometer system provided in Example 2 is shown.

[0034] In the picture:

[0035] 1. Light beam generator; 2. Imaging objective lens; 3. Polarization beam splitter; 4. Reflector 1; 5. Adjustable reflector; 6. Reflector 2; 7. Quarter wave plate; 8. Fourier lens 2; 9. Polarization camera; 10. Semi-transparent and semi-reflective prism; 11. Polarizer 1; 12. Polarizer 2; 13. Half wave plate; 14. Fourier lens 1. DETAILED DESCRIPTION

[0036] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0037] Example 1

[0038] Combined with attachment Figure 1 This embodiment provides an annular common-path shearing speckle interferometry system, which includes a light beam generating device 1, an imaging objective lens 2, a Fourier lens 14, a polarization beam splitter prism 3, a reflector 1 4, an adjustable reflector 5, a reflector 2 6, a quarter-wave plate 7, a Fourier lens 2 8 and a polarization camera 9.

[0039] in:

[0040] 1. The imaging objective lens 2 and the Fourier lens 14 are coaxially arranged, and the back focal plane of the imaging objective lens 2 coincides with the front focal plane of the Fourier lens 14. The surface where the two coincide is the intermediate image plane. Light emitted from any point on the intermediate image plane is parallel light after passing through the Fourier lens 14.

[0041] 2. The polarizing beam splitter prism 3, the first reflector 4, the adjustable reflector 5 and the second reflector 6 form a ring light path;

[0042] 3. The quarter wave plate 7, the second Fourier lens 8 and the polarization camera 9 are coaxially distributed, and the outgoing light of the annular optical path passes through the quarter wave plate 7 and the second Fourier lens 8 in sequence and then illuminates the imaging surface of the polarization camera 9;

[0043] 4. The back focal plane of the Fourier lens 8 coincides with the imaging plane of the polarization camera 9;

[0044] 5. Fourier lens 14 and Fourier lens 2 8 form a 4f system, and point A on the reflection surface of the adjustable reflector 5 is located on the spectrum surface of the 4f system and also on the optical axis of the 4f system;

[0045] 6. The adjustable reflector 5 can perform arbitrary rotational motion around point A.

[0046] Based on the position distribution of the above-mentioned system components, this embodiment forms the following optical path:

[0047] The light generated by the light beam generating device 1 first irradiates the surface of the object to be measured, forming scattered light;

[0048] Part of the scattered light passes through the imaging objective lens 2 and the Fourier lens 14 in sequence and then illuminates the polarization beam splitter prism 3, and is divided into reflected light and transmitted light, where the reflected light is S light and the transmitted light is P light;

[0049] Part of the reflected light is reflected by the reflector 1 4 , the adjustable reflector 5 , the reflector 2 6 and the polarization beam splitter prism 3 in sequence, and then passes through the 1 / 4 wave plate 7 and the Fourier lens 2 8 in sequence before being irradiated on the imaging surface of the polarization camera 9 .

[0050] Part of the transmitted light is reflected by the second reflector 6, the adjustable reflector 5 and the first reflector 4 in sequence, and then passes through the polarization beam splitter prism 3, the 1 / 4 wave plate 7 and the second Fourier lens 8 in sequence before being irradiated on the imaging surface of the polarization camera 9.

[0051] The two beams of light irradiated on the imaging surface of the polarization camera 9 are both emitted by the polarization beam splitter prism 3, and are first converted into two circularly polarized beams with opposite rotation directions by the 1 / 4 wave plate 7. They are then imaged on the imaging surface of the polarization camera 9 by the Fourier lens 8, and interfere with each other to form an annular common-path shearing speckle interferometer system, which is used for relevant measurements.

[0052] In this embodiment, the polarization beam splitter prism 3 causes the polarization states of the reflected light and the transmitted light entering the annular optical path to be perpendicular to each other. Adjustment of the adjustable reflector 5 allows for lateral misalignment of the reflected and transmitted light in the annular optical path, thereby enabling adjustment of the shearing amount. This adjustment amount can be arbitrarily adjusted as needed, greatly enhancing the ease of adjustment. Furthermore, point A of the adjustable reflector 5 is located both on the spectrum plane and on the optical axis of the 4f system. This ensures that, during any rotation of the reflector, the principal ray of the object light in the system remains perpendicular to the imaging plane of the polarization camera 9. This eliminates the generation of additional spatial carriers, thereby helping to improve subsequent spectrum utilization.

[0053] In this embodiment, the light beam generating device 1 is used to generate a light beam to illuminate the surface of the object to be measured. Its composition may include a laser and a beam expander. The light beam generated by the laser is irradiated on the surface of the object to be measured through the beam expander to form reflected light.

[0054] In this embodiment, the adjustable reflector 5 may include a reflector 3 and a driving structure. The reflector 3 is mounted on the driving structure. The driving structure is used to drive the reflector 3 to perform arbitrary rotational motion around point A.

[0055] The principle of measuring object surface deformation based on the annular common-path shearing speckle interferometry system provided in this embodiment is as follows:

[0056] Reference Attachment Figure 2 , when the adjustable reflector 5 is not rotated (at this time, the reflected light undergoes a displacement with a shear amount of 0):

[0057] The propagation path of the transmitted light is 0→1→2→3→0 in the figure, and the propagation path of the reflected light is 0→3→2→1 in the figure. At this time, the transmitted light and the reflected light are imaged to the same position through Fourier lens 8.

[0058] When the adjustable reflector 5 is rotated (at this time, the reflected light undergoes a displacement in which the shear amount is not 0):

[0059] The propagation path of the transmitted light is 0→1→2→4→5→6 in the figure, and the propagation path of the reflected light is 0→3→2→7→8→9 in the figure. At this time, the reflected light and the transmitted light are imaged in opposite directions by Fourier lens 8 and are staggered by the same distance.

[0060] Based on the above, the phase measurement principle is:

[0061] The adjustable reflector 5 is rotated so that the shear between the two beams of light irradiated on the imaging surface of the polarization camera is δ s , δ s The components in the x-axis direction and the y-axis direction are δ x and δ y , in order to simplify the derivation process, let δ y = 0, only retain δx , then the complex amplitude of the reflected light A1(x,y) and the complex amplitude of the transmitted light A2(x,y) incident on the imaging surface of the polarization camera are respectively:

[0062]

[0063] Among them, i is the imaginary unit, (x, y) is the coordinate of the point on the imaging surface of the polarization camera, the origin of the coordinate system of the point is located on the optical axis of the 4f system, A0(x, y), are δ x = 0, the complex amplitude and phase of the reflected light irradiated on the imaging surface of the polarization camera;

[0064] After the reflected light and the transmitted light interfere on the imaging surface of the polarization camera, the resulting speckle interference pattern I(x,y) is:

[0065]

[0066] I0(x,y) is the background light intensity, which does not carry carrier information and is always δ before and after the object is deformed (where the shear amount of the reflected light is always δ s ) will not change, so it is a fixed value and is not affected by whether the object is deformed, and I0(x,y)=|A0(x-δ x ,y)| 2 +|A0(x+δ x ,y)| 2 ;

[0067] I m (x,y) is the modulated light intensity, I m (x,y)=2|A0(v-δ x ,y)A0(x+δ x ,y)|;

[0068] is the phase difference between the reflected light and the transmitted light incident on the imaging surface of the polarization camera, and:

[0069]

[0070] The carrier phase is introduced by the polarizer array in the polarization camera. The polarizer array in the polarization camera consists of four polarization directions of 0°, 45°, 90° and 135° (2×2, reference Figure 3) The structure of the polarizer array composed of micro-polarizers is obtained by arranging the polarizers in a matrix. Since the interference of right-handed and left-handed circularly polarized light through the polarizer array produces a phase shift twice the polarizer rotation angle, an additional carrier phase is introduced. Therefore, the two object beams entering the polarization camera imaging plane have different rotation directions. The carrier phase introduced by the polarizer array in the polarization camera is as follows:

[0071]

[0072] (m,n) are the coordinates of the micro-polarizer in the polarizer array of the polarization camera;

[0073] In order to separate the modulated light spectrum from the background light spectrum, the speckle interferogram collected by the polarization camera needs to be processed as follows:

[0074] make

[0075] visible It consists of three parts, including Part of the spectrum does not carry any carrier phase and is located in the center of the spectrum, that is, the low-frequency part, while the other two parts carry carrier phase and are located in the four sides of the spectrum. The Fourier transform combined with the bandpass filter can be used to extract this part of the information. That is:

[0076]

[0077] And then obtain

[0078] The above formula specifically expresses: the obtained speckle interferogram is first Fourier transformed to obtain a spectrum diagram, then filtered with a low-pass filter, and finally subjected to an inverse Fourier transform to obtain intensity information without any carrier phase; among them, FFT is used to calculate the Fourier transform, converting the image from the spatial domain (time domain) to the frequency domain. After applying FFT, the center of the image spectrum is low frequency and the surrounding is high frequency. IFFT is the inverse transform of FFT, which converts the frequency domain data back to the spatial domain so that the processed data can be restored to an image. LPF represents a low-pass filter, which allows low-frequency signals to pass through while suppressing high-frequency signals.

[0079] Then collect a speckle interferogram before and after deformation, and extract the corresponding The data collected before the object is deformed for The data collected after the object is deformed for The subtraction of the two values can be used to obtain the phase difference Δψ between the reflected light and the transmitted light on the imaging plane of the polarization camera before and after the object is deformed. In this embodiment, the angle between the illumination direction and the observation direction is close to zero (the default is 0). Therefore, Δψ is only related to the first-order derivatives of the out-of-plane deformation function w(x,y) of the object in the x-axis and y-axis directions, and is:

[0080] λ is the wavelength of light emitted by the light beam generating device 1;

[0081] In the above derivation process, in order to simplify the derivation process, let δ s The component δ in the y-axis direction y = 0 and the component δ in the x-axis direction x ≠0, however, in the actual shearing process, δ y It can be set according to the needs, and it is not continuously zero. When the shear between the two beams of light irradiated on the imaging surface of the polarization camera is δ s When , the relationship between Δψ obtained at the point (x, y) before and after the deformation of the object and the deformation function w(x, y) of the point in the z-axis direction is as follows:

[0082]

[0083] Among them, δ s The modulus and the corresponding shear direction vector The relationship is as follows:

[0084]

[0085] Based on the above, in order to obtain the out-of-plane deformation of the object under test, the following methods can be used:

[0086] Step 1: Before the object undergoes out-of-plane deformation, obtain the shear amount δ between the two beams of light irradiated on the imaging surface of the polarization camera. s (δ s When the polarization camera is used to obtain the speckle interference pattern before deformation, the corresponding speckle interference pattern is obtained from the speckle interference pattern before deformation. And record it as

[0087] Step 2: After the object undergoes out-of-plane deformation, the shear between the two beams of light irradiated on the imaging surface of the polarization camera is obtained as δ s (δ s When the image is obtained directly by the adjustment device of the adjustable reflector, the deformed speckle interferogram obtained on the imaging surface of the polarization camera is obtained, and the corresponding And record it as

[0088] By Available Used for calculation of out-of-plane deformation.

[0089] Based on the above, this embodiment further provides a method for measuring object surface deformation using the annular common-path shearing speckle interferometry system. The method is specifically as follows:

[0090] Step 1: Obtain the speckle interferogram corresponding to the pre-deformation speckle pattern on the imaging surface of the polarization camera before the object undergoes out-of-plane deformation. And record it as

[0091] Step 2: Obtain the corresponding speckle interferogram after deformation on the imaging surface of the polarization camera after the object undergoes out-of-plane deformation. And record it as

[0092] Step 3: Get the deformation derivative of the point (x, y) in the z-axis direction Used for calculation of out-of-plane deformation;

[0093] Among them, before and after the object is deformed, the shear between the two beams of light irradiated on the imaging surface of the polarization camera is δ s , is the phase difference between the reflected light and the transmitted light in the corresponding speckle interferogram I(x,y), and Obtained by the following formula:

[0094] I m (x, y) is the modulated light intensity in the corresponding speckle interferogram, (x, y) is the coordinate of the point on the imaging surface of the polarization camera, i is the imaginary unit, is the carrier phase introduced by the polarizer array in the polarization camera at point (x, y), λ is the wavelength of the light emitted by the beam generator, is δ s The corresponding shear direction vector.

[0095] Example 2

[0096] like Figure 4 This embodiment provides an annular common-path shearing speckle interferometry system. The main differences between this system and embodiment 1 are:

[0097] The polarization splitter prism 3 in Example 1 is replaced by a semi-transparent semi-reflective prism 10, and a polarizer 11 is further provided between the semi-transparent semi-reflective prism 10 and the reflector 1 4, a polarizer 2 12 is further provided between the semi-transparent semi-reflective prism 10 and the reflector 2 6, and a 1 / 2 wave plate 13 is further provided between the reflector 1 4 and the adjustable reflector 5.

[0098] In this embodiment, the optical path formed is:

[0099] The light generated by the light beam generating device 1 first irradiates the surface of the object to be measured, forming scattered light;

[0100] Part of the scattered light passes through the imaging objective lens 2 and the Fourier lens 14 in sequence and then illuminates the semi-transparent and semi-reflective prism 10, and is divided into reflected light and transmitted light;

[0101] Part of the reflected light first passes through polarizer 11 and is reflected by mirror 1 4, then passes through half-wave plate 13 and is reflected in sequence by adjustable mirror 5 and mirror 2 6, then passes through polarizer 2 12 and is reflected by semi-transparent and semi-reflective prism 10, and passes through quarter-wave plate 7 and Fourier lens 2 8 in sequence before being irradiated on the imaging surface of polarization camera 9.

[0102] The partially transmitted light first passes through the polarizer 2 12, is reflected by the reflector 2 6 and the adjustable reflector 5 in sequence, passes through the 1 / 2 wave plate 13 and is reflected by the reflector 1 4, then passes through the polarizer 1 11, the semi-transparent and semi-reflective prism 10, the 1 / 4 wave plate 7 and the Fourier lens 2 8 in sequence, and is irradiated on the imaging surface of the polarization camera 9.

[0103] The optical axes of polarizers 11 and 12 are perpendicular, and the angle between the optical axis of half-wave plate 13 and both polarizers 11 and 12 is 45°. This structure ensures that the polarization states of the two light beams (reflected light and transmitted light) emitted by the semi-transparent and semi-reflective prism 10 are perpendicular to each other. Adjusting the adjustable reflector 5 allows for lateral misalignment of the two light beams entering the annular optical path, thereby adjusting the shear amount. Furthermore, point A on the adjustable reflector 5 lies on the spectrum plane and optical axis of the 4f system. Therefore, regardless of the shear amount adjustment, the principal ray of the object light remains perpendicular to the polarization camera imaging plane, thus eliminating the introduction of additional spatial carriers and improving spectrum utilization. The two light beams emitted from the semi-transparent and semi-reflective prism 10 are converted into two circularly polarized beams of opposite handing after passing through the quarter-wave plate. These beams are then imaged onto the imaging plane of the polarization camera 9 by Fourier lens 2 8, where they interfere with each other, forming a common-path shear speckle interferometry system in a circular interferometer.

[0104] The remaining principles are the same as those in Example 1 and will not be described again here.

[0105] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0106] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. An annular common-path shearing speckle interferometry system, characterized in that: It includes a light beam generating device, the light generated by the light is irradiated on the surface of the object to be measured and forms reflected light; Part of the reflected light passes through the imaging objective lens and Fourier lens in sequence and then shines on the polarization beam splitter prism, and is divided into reflected light and transmitted light; Part of the reflected light is reflected by the first reflector, the adjustable reflector, the second reflector and the polarization beam splitter in sequence, and then passes through the quarter wave plate and the second Fourier lens in sequence to illuminate the imaging surface of the polarization camera; Part of the transmitted light is reflected by the second reflector, the adjustable reflector and the first reflector in sequence, and then passes through the polarization beam splitter prism, the quarter wave plate and the second Fourier lens in sequence to illuminate the imaging surface of the polarization camera; in: Fourier lens 1 and Fourier lens 2 form a 4f system, and the back focal plane of the imaging objective lens coincides with the front focal plane of Fourier lens 1, and the back focal plane of Fourier lens 2 coincides with the imaging plane of the polarization camera; The adjustable reflector can be rotated arbitrarily around point A on its reflecting surface, and point A is located on the optical axis and spectrum surface of the 4f system.

2. The annular common-path shearing speckle interferometry system according to claim 1, characterized in that: The adjustable reflector includes a reflector 3 and a driving structure. The reflector 3 is mounted on the driving structure. The driving structure is used to drive the reflector 3 to perform arbitrary rotational motion around point A.

3. The annular common-path shearing speckle interferometry system according to claim 1, characterized in that: The light beam generating device comprises a laser and a beam expander. The light beam generated by the laser is irradiated onto the surface of the object to be measured via the beam expander.

4. The annular common-path shearing speckle interferometry system according to claim 1, characterized in that: The polarization splitter prism is replaced with a semi-transparent semi-reflective prism, and a polarizer 1 is set between the semi-transparent semi-reflective prism and the reflector 1, a polarizer 2 is set between the semi-transparent semi-reflective prism and the reflector 2, and a 1 / 2 wave plate is set between the reflector 1 and the adjustable reflector.

5. A method for measuring object surface deformation using the annular common-path shearing speckle interferometry system according to claim 1, characterized in that: The method comprises: Obtain the speckle interferogram corresponding to the deformation before the object is deformed out of the plane, obtained on the imaging surface of the polarization camera And record it as Obtain the corresponding speckle interferogram after deformation on the imaging surface of the polarization camera after the object under test undergoes out-of-plane deformation. And record it as Depend on Get the deformation derivative of the point (x, y) in the z-axis direction Used for calculation of out-of-plane deformation; Among them, before and after the object is deformed, the shear between the two beams of light irradiated on the imaging surface of the polarization camera is δ s , is the phase difference between the reflected light and the transmitted light in the corresponding speckle interferogram I(x,y), and Obtained by the following formula: I m (x, y) is the modulated light intensity in the corresponding speckle interferogram, (x, y) is the coordinate of the point on the imaging surface of the polarization camera, i is the imaginary unit, is the carrier phase introduced by the polarizer array in the polarization camera at point (x, y), λ is the wavelength of the light emitted by the beam generator, is δ s The corresponding shear direction vector; FFT stands for Fourier transform, IFFT is the inverse transform of FFT, and LPF stands for low-pass filter.

Images