Method for measuring phase deflection of near-optical coaxial double-mirror-surface object

Abstract

The invention discloses a near-optical coaxial double-mirror-surface object phase deflection measurement method. The method comprises the following steps: 1) establishing a near-optical coaxial double-mirror-surface object phase deflection measurement system; 2) replacing a to-be-measured double-mirror object with a double-mirror calibration plate to obtain calibration parameters of the system; 3) calculating to obtain an absolute phase of the double-mirror calibration plate; 4) replacing the double-mirror-surface calibration plate with a to-be-measured double-mirror-surface object to obtain an absolute phase of the to-be-measured double-mirror-surface object; 5) solving the three-dimensional surface shape data of the A-side mirror surface and the B-side mirror surface of the to-be-measured double-mirror-surface object in the corresponding coordinate system; according to the double-mirror-surface object three-dimensional shape data fusion method, light path folding is achieved and a near-optical coaxial light path is constructed through collaborative layout of the double semi-transparent and semi-reflecting mirrors and the double display screens, so that a camera can directly capture virtual images reflected by the mirror surfaces, and the shielding and shadow effects caused by mirror surface curvature or structural characteristics in a traditional off-axis light path are avoided.

Description

Technical Field

[0001] This invention relates to the field of optical three-dimensional topography measurement, specifically a method for measuring the phase deflection of near-optical coaxial dual-mirror objects. Background Technology

[0002] Phase deflection measurement is an optical three-dimensional topography measurement technique applicable to mirror surfaces. Based on the principle of fringe reflection, a computer generates standard sinusoidal fringes and transmits them to a display screen. The mirror under test and a mirror calibration plate are reflected sequentially to form images. The standard sinusoidal fringes displayed on the screen are deformed by the modulation of the mirror surface topography. A CCD camera then captures a virtual image of the deformed fringes from another direction, which is transmitted back to the computer for demodulation and calculation. By calculating and comparing the phase information in the sinusoidal fringes reflected from the mirror calibration plate and the sinusoidal fringes reflected from the mirror under test, the depth of each point on the mirror under test relative to the reference position on the calibration plate is determined, thereby reconstructing the three-dimensional topography of the mirror.

[0003] Traditional phase deflection measurement techniques can only measure a single mirror in principle. However, many important double-mirror components exist in high-end equipment such as aerospace remote sensing beam splitters and astronomical telescope mirror assemblies. Furthermore, for some double-mirror components with distinct surface structures, the off-axis optical path in traditional phase deflection measurement can cause shadows from the structured mirrors during camera capture, reducing measurement accuracy. To ensure the functionality of such components, it is necessary to simultaneously acquire the surface shape of both mirrors, as well as the position and orientation between them, posing a significant challenge to existing precision measurement techniques. Effective deflection measurement theories and methods are needed for the simultaneous measurement of the surface shape and orientation of such double-mirror components. Existing measurement techniques are detailed below: The paper "Gao F, Xu Y, and Jiang X. Near optical coaxial phase measuring deflectometry for measuring structured specular surfaces[J]. Optics Express, 2022, 30(10): 17554-17566" describes a collaborative optical path phase deflection measurement system consisting of two cameras, a semi-transparent mirror, and a display screen. The semi-transparent mirror reflects the display screen as an equivalent vertical virtual light source, and the deformed fringes reflected from the surface of the specular object are simultaneously acquired by the two cameras. The absolute phase is calculated using the phase-shifting method, and the surface normal gradient is derived. Then, 3D reconstruction is achieved by deeply fusing the gradient field with stereo matching point cloud data. This method effectively solves the shadow problem when the camera captures large curvature or structured specular objects. However, the data fusion relies on an iterative optimization algorithm, and its convergence speed limits the measurement accuracy. Furthermore, it cannot simultaneously measure both surfaces of the dual-mirror element.

[0004] The paper "Liu Y, Huang, S, Zhang Z, et al. Full-field 3D shape measurement of discontinuous specular objects by direct phase measuring deflectometry[J]. Scientific Reports, 2017, 7(1), 10293." describes a three-dimensional measurement system for specular objects composed of a computer, two LCD screens, a semi-transparent mirror, and a CCD camera. The system uses two LCD screens to generate sinusoidal fringes, which are modulated by the mirror under test and then captured by the camera through mirror reflection. The data is then transmitted back to the computer to calculate the phase information of the reflected fringes, obtaining a direct relationship between the phase and depth of the fringe reflection system. This method eliminates the need for integration and can measure large-gradient, discontinuous specular objects. However, this method can only measure the three-dimensional shape of the specular portion illuminated by the sinusoidal fringe light on the screens and cannot simultaneously measure the overall three-dimensional shape of both surfaces of the dual-mirror element.

[0005] In the paper "He Wenjing, Ni Yubo, Gao Nan, et al. Common reference form and position measurement of dual-mirror objects [J]. Optics and Precision Engineering, 2025, (6): 850-861," a dual-mirror calibration plate is used to perform depth and lateral calibration on the two subsystems constituting the dual-mirror object form and position measurement system, establishing the relationship between absolute phase and depth, pixel coordinates and spatial X, Y coordinates. Then, the spatial constraint relationship is used to perform common reference calibration, transforming the 3D point cloud located in the two coordinate systems into a reference coordinate system to achieve 3D reconstruction. This method enables simultaneous measurement of the upper and lower surfaces of the dual-mirror element, but it suffers from the problem that the form and position measurement accuracy of the dual-mirror object is lower than that of the subsystem measurement accuracy, and it cannot solve the shadow problem of the structured mirror, requiring further improvement.

[0006] As can be seen from the above literature, phase deflection measurement based on fringe reflection is a suitable technique for measuring the surface shape of mirrors. It has been widely studied and applied to the three-dimensional topography measurement of complex mirrors such as freeform surfaces, high curvature, and discontinuous surfaces. However, most methods can only measure the three-dimensional topography of a single mirror surface. There are few methods that can simultaneously measure the three-dimensional surface shape of high-curvature, opposing double-mirror elements, and the shading problem of structured mirrors is not well solved. Therefore, further research is needed on the simultaneous measurement of the surface shape and relative pose of the two surfaces of a double-mirror element. Summary of the Invention

[0007] To address the shortcomings of existing technologies, this invention provides a method for measuring the phase deflection of near-optical coaxial dual-mirror objects.

[0008] The technical solution of this invention to solve the aforementioned technical problem is to provide a method for measuring the phase deflection of a near-optical coaxial dual-mirror object, characterized in that the method includes the following steps: Step 1: Construct a near-optical coaxial dual-mirror object phase deflection measurement system; The system includes a computer, a first CCD camera, a second CCD camera, a transparent display screen, an LCD display screen, a first semi-transparent mirror, and a second semi-transparent mirror. The transparent display screen and the liquid crystal display screen are respectively fixed vertically on the optical platform, and the transparent display screen and the liquid crystal display screen are parallel to each other and the distance is Δd; the first CCD camera, the second CCD camera, the first semi-transparent and semi-reflective mirror and the second semi-transparent and semi-reflective mirror are respectively fixed on the optical platform, the first CCD camera and the first semi-transparent and semi-reflective mirror are fixed on side A of the double mirror object to be tested, and the second CCD camera and the second semi-transparent and semi-reflective mirror are fixed on side B of the double mirror object to be tested. The dual-mirror object under test is slidably mounted on an optical platform, sliding along a path perpendicular to the transparent display screen and the liquid crystal display screen. The dual-mirror object can rotate, such that the virtual images of the liquid crystal display screen and the transparent display screen reflected by the first semi-transparent mirror and then reflected by the A-side mirror of the dual-mirror object are within the depth of field of the first CCD camera, and the virtual images of the liquid crystal display screen and the transparent display screen reflected by the second semi-transparent mirror and then reflected by the B-side mirror of the dual-mirror object are within the depth of field of the second CCD camera. The first CCD camera, the first semi-transparent mirror, and the A-side mirror form a triangular measurement relationship in space; the second CCD camera, the second semi-transparent mirror, and the B-side mirror also form a triangular measurement relationship in space. The transparent display screen and the liquid crystal display screen are mirrored about the first semi-transparent and semi-reflective mirror, respectively, as the first equivalent virtual display screen on side A and the second equivalent virtual display screen on side A. The transparent display screen and the liquid crystal display screen are mirrored about the second semi-transparent and semi-reflective mirror, respectively, as the first equivalent virtual display screen on side B and the second equivalent virtual display screen on side B. The computer, the first CCD camera, the A-side mirror, the first semi-transparent mirror, the transparent display screen, and the liquid crystal display screen constitute the A-side subsystem; the computer, the second CCD camera, the B-side mirror, the second semi-transparent mirror, the transparent display screen, and the liquid crystal display screen constitute the B-side subsystem. The computer is communicatively connected to the transparent display screen, the liquid crystal display screen, the first CCD camera, and the second CCD camera; the computer controls the precise movement of the double-mirror object under test or the double-mirror calibration plate. Step 2: Replace the dual-mirror object to be measured with a dual-mirror calibration plate, ensuring that the dual-mirror calibration plate is within the depth of field of the first CCD camera and the second CCD camera, and that its pose conforms to the triangle measurement relationship, and obtain the calibration parameters of the system. The plane containing side A of the dual-mirror calibration plate is the first reference plane, and the plane containing side B of the dual-mirror calibration plate is the second reference plane; the coordinate system defined by the annular array on the surface of side A of the dual-mirror calibration plate is set as the reference coordinate system O. A -X A Y A Z A The coordinate system defined by the annular array on the B-side surface of the dual-mirror calibration plate is set as the coordinate system O to be calibrated. B -X B Y B Z B ; Calibration parameters include the reference coordinate system O A -X A Y A Z A With the coordinate system to be calibrated O B -X B Y B Z B Transformation matrix between The distance d between the first equivalent virtual display screen on side A and the first reference plane A In the A-side subsystem, the X and Y coordinates of each point with respect to the pixel coordinates (u A ,v A The coefficient a of the quadratic nonlinear function of the Z-coordinate A0 a A1 a A2 b A0 b A1 and b A The distance d between the first equivalent virtual display screen on side B and the second reference plane B And the X and Y coordinates of each point in the B-side subsystem with respect to the pixel coordinates (u B ,v B The coefficient a of the quadratic nonlinear function of the Z-coordinate B0 a B1 a B2 b B0 b B1 and b B2 ; Step 3: Calculate the absolute phase value φ of the transparent display screen reflected from side A of the double-mirror calibration plate. Ar1 The absolute phase value φ of the liquid crystal display screen reflected from side A of the dual-mirror calibration plate. Ar2 The absolute phase value φ of the transparent display screen reflected from the B side of the double-mirror calibration plate. Br1 And the absolute phase value φ of the liquid crystal display screen reflected from the B side of the dual-mirror calibration plate. Br2 ; Step 4: Replace the dual-mirror calibration plate with the object to be tested, ensuring that the object is within the depth of field of the first CCD camera and the second CCD camera, and that its pose conforms to the triangle measurement relationship. Calculate the absolute phase value φ of the transparent display screen reflected by the mirror on side A. Am1 The absolute phase value φ of the mirror-reflected liquid crystal display on side A. Am2 The absolute phase value φ of the transparent display screen reflected by the B-side mirror. Bm1 And the absolute phase value φ of the liquid crystal display screen reflected by the B-side mirror. Bm2 ; Step 5: Solve for the three-dimensional surface data of the A-side mirror and the B-side mirror in the corresponding coordinate system; For the A-side subsystem, the relationship between the phase and the depth information of the A-side mirror is established as shown in equation (3), thus obtaining the depth information h of the A-side mirror relative to the first reference plane. A : (3) Then, based on the coefficient a obtained in step 2 A0 a A1 a A2 b A0 b A1 and b A2 Calculate the coordinates of each pixel in the reference coordinate system O A -X A Y A Z A The X and Y coordinates of the mirror surface on side A are obtained in the reference coordinate system O. A -X A Y A Z A The three-dimensional coordinates (X) A ,Y A Z A ); For the B-side subsystem, the relationship between the phase and the depth information of the B-side mirror is established as shown in Equation (4), thus obtaining the depth information h of the B-side mirror relative to the second reference plane. B : (4) Then, based on the coefficient a obtained in step 2 B0 a B1 a B2 b B0 b B1 and b B2 Calculate the coordinate system O for each pixel. B -X B Y B Z B The X and Y coordinates of the B-side mirror are obtained in the coordinate system O to be calibrated.B -X B Y B Z B The three-dimensional coordinates (X) B ,Y B Z B ); Step 6: Fusion of 3D topographic data of dual-mirror objects; Based on the transformation matrix obtained in step 2 Using equation (5), a point on the B-side mirror is placed in the coordinate system O to be calibrated. B -X B Y B Z B The three-dimensional coordinates (X) B ,Y B Z B Converted to the reference coordinate system O A -X A Y A Z A The three-dimensional coordinates below ( ); (5) At this time, the three-dimensional coordinates (X) A ,Y A Z A ) and three-dimensional coordinates ( All are located in the reference coordinate system O. A -X A Y A Z A This allows us to obtain the overall three-dimensional morphological data of the double-mirror object under test.

[0009] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The measurement system of this invention is simple and ingenious: through the coordinated layout of two semi-transparent and semi-reflective mirrors and two displays, the optical path is folded and a near-optical coaxial optical path is constructed, enabling the camera to directly capture the virtual image reflected by the mirror surface, avoiding the occlusion and shadow effects caused by the curvature or structural features of the mirror surface in the traditional off-axis optical path. Secondly, the introduction of the equivalent virtual display screen optimizes the optical path propagation path, ensuring that the measurement light field covers the entire mirror surface area, thereby significantly improving the measurability of complex mirror surfaces. This design not only simplifies the system debugging process, but also enhances the measurement stability, and is especially suitable for scenarios with extremely high requirements for surface integrity, such as beam splitters in spacecraft.

[0010] (2) High measurement accuracy: This method uses a fixed dual display screen as the light source of the direct phase deflection measurement system, which eliminates the system error introduced by moving the display screen and improves the system measurement accuracy.

[0011] (3) Non-destructive testing: This method belongs to the optical three-dimensional surface shape measurement method. It does not contact the surface being measured and will not cause damage to the surface being measured.

[0012] (4) This invention is mainly applicable to the precise measurement of the three-dimensional surface shape and relative pose of high-curvature, opposing double-mirror components. In practical applications, it plays an important role in the precise measurement of the surface shape and pose of complex double-mirror components in high-end equipment such as aerospace remote sensing beam splitting systems, laser weapon dual-reflection cavities, and astronomical telescope reflector groups. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the measurement system of the present invention; Figure 2 This is a schematic diagram of the calibration structure of the measurement system of the present invention; Figure 3 This is a schematic diagram illustrating the measurement principle of the present invention.

[0014] In the diagram, 1 is a computer, 2 is a first CCD camera, 3 is a second CCD camera, 4 is a transparent display screen, 5 is a liquid crystal display screen, 6 is a double-mirror object to be tested, 7 is the A-side mirror of the double-mirror object to be tested, 8 is the B-side mirror of the double-mirror object to be tested, 9 is a first semi-transparent and semi-reflective mirror, 10 is a second semi-transparent and semi-reflective mirror, 11 is a double-mirror calibration plate, 12 is a first reference plane, 13 is a second reference plane, 14 is a first equivalent virtual display screen on side A, 15 is a second equivalent virtual display screen on side A, 16 is a first equivalent virtual display screen on side B, and 17 is a second equivalent virtual display screen on side B. Detailed Implementation

[0015] Specific embodiments of the present invention are given below. These specific embodiments are only used to further illustrate the present invention in detail and do not limit the scope of protection of the present invention.

[0016] This invention provides a method for measuring the phase deflection of near-optical coaxial dual-mirror objects (hereinafter referred to as the method), characterized in that the method includes the following steps: Step 1: Construct a near-optical coaxial dual-mirror object phase deflection measurement system (hereinafter referred to as the system); The system includes a computer 1, a first CCD camera 2, a second CCD camera 3, a transparent display screen 4, an LCD display screen 5, a first semi-transparent mirror 9, and a second semi-transparent mirror 10; The transparent display screen 4 and the liquid crystal display screen 5 are respectively vertically fixed on the optical platform, and the transparent display screen 4 and the liquid crystal display screen 5 are parallel to each other and the distance between them is Δd; the first CCD camera 2, the second CCD camera 3, the first semi-transparent mirror 9 and the second semi-transparent mirror 10 are respectively fixed on the optical platform. The first CCD camera 2 and the first semi-transparent mirror 9 are fixed to side A of the double mirror object 6 to be tested (in this embodiment, side A is the left side), and the second CCD camera 3 and the second semi-transparent mirror 10 are fixed to side B of the double mirror object 6 to be tested (in this embodiment, side B is the right side). The dual-mirror object 6 under test is slidably mounted on an optical platform, sliding along a path perpendicular to the transparent display screen 4 and the liquid crystal display screen 5. The dual-mirror object 6 can rotate, so that the virtual images of the liquid crystal display screen 5 and the transparent display screen 4, reflected by the first semi-transparent mirror 9 and then by the mirror 7 on the A side of the dual-mirror object 6 (hereinafter referred to as mirror 7 on the A side), are within the depth of field of the first CCD camera 2. Similarly, the virtual images of the liquid crystal display screen 5 and the transparent display screen 4, reflected by the second semi-transparent mirror 10 and then by the mirror 8 on the B side of the dual-mirror object 6 (hereinafter referred to as mirror 8 on the B side), are within the depth of field of the second CCD camera 3. The first CCD camera 2, the first semi-transparent mirror 9, and mirror 7 on the A side are in a triangular measurement relationship in space. The second CCD camera 3, the second semi-transparent mirror 10, and mirror 8 on the B side are also in a triangular measurement relationship in space. The mirror images of the transparent display screen 4 and the liquid crystal display screen 5 about the first semi-transparent and semi-reflective mirror 9 are respectively the first equivalent virtual display screen 14 and the second equivalent virtual display screen 15 on the A side; the mirror images of the transparent display screen 4 and the liquid crystal display screen 5 about the second semi-transparent and semi-reflective mirror 10 are respectively the first equivalent virtual display screen 16 and the second equivalent virtual display screen 17 on the B side. The computer 1, the first CCD camera 2, the A-side mirror 7, the first semi-transparent mirror 9, the transparent display screen 4, and the liquid crystal display screen 5 constitute the A-side subsystem (i.e., the A-side phase deflection measurement subsystem); the computer 1, the second CCD camera 3, the B-side mirror 8, the second semi-transparent mirror 10, the transparent display screen 4, and the liquid crystal display screen 5 constitute the B-side subsystem (i.e., the B-side phase deflection measurement subsystem); the structures on both sides of the double-mirror object 6 under test are arranged in a mirror-symmetric manner through its midsection, and the structures on both sides share the computer 1, the transparent display screen 4, and the liquid crystal display screen 5; Computer 1 communicates with transparent display screen 4 and LCD display screen 5 via HDMI interface, and controls transparent display screen 4 and LCD display screen 5 to display three sets of sinusoidal stripes that conform to the optimal three-stripe selection method; Computer 1 communicates with first CCD camera 2 and second CCD camera 3 via USB 3.0 interface, and controls first CCD camera 2 and second CCD camera 3 to acquire stripe images; Computer 1 controls the precise movement of the double mirror object 6 under test or the double mirror calibration plate 11. Preferably, in step 1, the high-precision horizontal moving guide rail is fixed on the optical platform and is perpendicular to the transparent display screen 4 and the liquid crystal display screen 5. The double mirror object 6 to be tested is slidably mounted on the high-precision horizontal moving guide rail and can rotate. The computer 1 is connected to the high-precision horizontal moving guide rail to control the precise movement of the double mirror object 6 to be tested or the double mirror calibration plate 11.

[0017] Preferably, in step 1, the high-precision horizontal moving guide rail is perpendicular to the liquid crystal display screen 5 and the transparent display screen 4 and is located on the vertical line between the liquid crystal display screen 5 and the transparent display screen 4.

[0018] Step 2: Replace the double mirror object 6 to be measured with the double mirror calibration plate 11 (i.e., remove the double mirror object 6 from the high-precision horizontal guide rail, and then install the double mirror calibration plate 11 on the high-precision horizontal guide rail), ensuring that the double mirror calibration plate 11 is located within the depth of field of the first CCD camera 2 and the second CCD camera 3, and that its pose conforms to the triangle measurement relationship, and obtain the calibration parameters of the system; The plane containing side A of the dual-mirror calibration plate 11 is the first reference plane 12, and the plane containing side B of the dual-mirror calibration plate 11 is the second reference plane 13; the coordinate system defined by the annular array on the surface of side A of the dual-mirror calibration plate 11 is set as the reference coordinate system O. A -X A Y A Z A The coordinate system defined by the annular array on the B-side surface of the dual-mirror calibration plate 11 is set as the coordinate system O to be calibrated. B -X B Y B Z B ; Calibration parameters include the reference coordinate system O A -X A Y A Z A With the coordinate system to be calibrated O B -X B Y B Z B Transformation matrix between The distance d between the first equivalent virtual display screen 14 on side A and the first reference plane 12 A The coefficients a of the quadratic nonlinear function of the X and Y coordinates of each point in the A-side subsystem with respect to the pixel coordinates (u,v) and Z coordinates. A0 a A1 a A2 b A0 b A1 and b A The distance d between the first equivalent virtual display screen 16 on side B and the second reference plane 13 BAnd the coefficients a of the quadratic nonlinear functions of the X and Y coordinates of each point in the B-side subsystem with respect to the pixel coordinates (u,v) and Z coordinates. B0 a B1 a B2 b B0 b B1 and b B2 ; Preferably, in step 2, when the dual-mirror calibration plate 11 calibrates the A-side subsystem, the virtual image reflected by the first semi-transparent mirror 9 through the first reference plane 12 and the first reference plane 12 are both within the depth of field of the first CCD camera 2, and the first CCD camera 2, the first semi-transparent mirror 9 and the A-side of the dual-mirror calibration plate 11 are in a triangular measurement relationship in space.

[0019] Preferably, in step 2, when the dual-mirror calibration plate 11 calibrates the B-side subsystem, the virtual image reflected by the second semi-transparent mirror 10 through the second reference plane 13 and the second reference plane 13 are both within the depth of field of the second CCD camera 3, and the B-side of the second CCD camera 3, the second semi-transparent mirror 10 and the dual-mirror calibration plate 11 are in a triangular measurement relationship in space.

[0020] Preferably, in step 2, given the pose transformation method between the first reference plane 12 and the second reference plane 13, the reference coordinate system O is calculated using the rigid body transformation method. A -X A Y A Z A With the coordinate system to be calibrated O B -X B Y B Z B Transformation matrix between .

[0021] Preferably, in step 2, for the A-side subsystem, since the transparent display screen 4, the liquid crystal display screen 5, and the first equivalent virtual display screen 14 and the second equivalent virtual display screen 15 on the A-side are symmetrical about the first semi-transparent mirror 9, the distance between the first equivalent virtual display screen 14 and the second equivalent virtual display screen 15 on the A-side is equal to the distance between the transparent display screen 4 and the liquid crystal display screen 5, which is Δd. A circular array with known spatial distance and radius is displayed on the transparent display screen 4 using software. The first CCD camera 2 respectively acquires the circular array on the A-side of the dual-mirror calibration plate 11 and the circular array displayed on the transparent display screen 4 after reflection by the dual-mirror calibration plate 11. The boundary of the ring is extracted, and the center of the ring is determined by ellipse fitting. Using Zhang Zhengyou's camera-based machine vision calibration method, the distance d between the first equivalent virtual display screen 14 on the A-side and the first reference plane 12 is calculated. A Furthermore, the first reference plane 12 is parallel to the first equivalent virtual display screen 14 on side A.

[0022] Preferably, in step 2, for the A-side subsystem, the dual-mirror calibration plate 11 is moved n along a path perpendicular to the liquid crystal display 5 and the transparent display 4 within the depth of field of the first CCD camera 2. A There are n positions. A ≥6 (n in this embodiment) A =11), at each position, the first CCD camera 2 acquires the circular array of the first reference plane 12, and records the center of each ring in the circular array in the reference coordinate system O. A -X A Y A Z A The three-dimensional coordinates (X) Ab ,Y Ab Z Ab Then, based on the pixel coordinates of the center of each ring in the circular array extracted by the first CCD camera 2, the pixel coordinates (u) of each pixel point of the first CCD camera 2 are calculated. A ,v A The coefficient a of the quadratic nonlinear function of the Z-coordinate A0 a A1 a A2 b A0 b A1 and b A2 Complete the calibration of the X and Y coordinates of the A-side subsystem, i.e., the lateral calibration, where X... Ab and Y Ab The calibration formula is shown in equation (1): (1).

[0023] Preferably, in step 2, for the B-side subsystem, the distance between the first equivalent virtual display screen 16 and the second equivalent virtual display screen 17 on the B-side can be obtained as Δd. A circular array with known spatial distance and radius is displayed on the transparent display screen 4 using software. The second CCD camera 3 acquires the circular array on the second reference plane 13 on the dual-mirror calibration plate 11 and the circular array displayed on the transparent display screen 4 after reflection from the dual-mirror calibration plate 11. The boundary of the ring is extracted, and the center of the ring is determined by ellipse fitting. Using Zhang Zhengyou's camera-based machine vision calibration method, the distance d between the first equivalent virtual display screen 16 and the second reference plane 13 on the B-side is calculated. B Furthermore, the second reference plane 13 is parallel to the first equivalent virtual display screen 16 on side B.

[0024] Preferably, in step 2, for the B-side subsystem, the dual-mirror calibration plate 11 is moved n along a path perpendicular to the liquid crystal display 5 and the transparent display 4 within the depth of field of the second CCD camera 3. B There are n positions. B≥6 (n in this embodiment) B =11), at each position, the second CCD camera 3 acquires the circular array of the second reference plane 13, and records the center of each ring in the circular array in the coordinate system O to be calibrated. B -X B Y B Z B The three-dimensional coordinates (X) Bb ,Y Bb Z Bb Then, based on the pixel coordinates of the center of each ring in the circular array extracted by the second CCD camera 3, the pixel coordinates (u) of each pixel point of the second CCD camera 3 are calculated. B ,v B The coefficient a of the quadratic nonlinear function of the Z-coordinate B0 a B1 a B2 b B0 b B1 and b B2 Complete the calibration of the X and Y coordinates of the B-side subsystem, i.e., the lateral calibration. and The calibration formula is shown in equation (2): (2).

[0025] Step 3: Calculate the absolute phase value φ of the transparent display screen 4 reflected from side A of the double-mirror calibration plate 11. Ar1 The absolute phase value φ of the liquid crystal display 5 reflected from the A-side of the dual-mirror calibration plate 11. Ar2 The absolute phase value φ of the transparent display screen 4 reflected from the B side of the double-mirror calibration plate 11. Br1 And the absolute phase value φ of the liquid crystal display 5 reflected from the B side of the dual-mirror calibration plate 11. Br2 ; Preferably, step 3 specifically involves: using computer 1 to select three sets of sinusoidal straight stripes to be displayed in the measurement field based on the size of the measurement field and the requirements of measurement accuracy, according to the existing stripe generation method; and the number of stripes in these three sets of sinusoidal straight stripes satisfies the optimal three-stripe selection method; each set of sinusoidal straight stripes contains four sinusoidal straight stripe images (referred to as sinusoidal straight stripe images) with a 90-degree phase shift between each other. For the A-side subsystem, sinusoidal straight fringe images are displayed on the transparent display screen 4 and the liquid crystal display screen 5, respectively. After reflection from the A-side of the dual-mirror calibration plate 11, no distortion occurs. The first CCD camera 2 acquires the zero-distortion fringe images of the sinusoidal straight fringe images of the transparent display screen 4 and the liquid crystal display screen 5 after reflection from the A-side of the dual-mirror calibration plate 11, and stores them in the computer 1. The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen 4 reflected from the A-side of the dual-mirror calibration plate 11 is obtained. Ar1 The absolute phase value φ of the liquid crystal display 5 reflected from the A side of the dual-mirror calibration plate 11 Ar2 ; For the B-side subsystem, sinusoidal straight fringe images are displayed on the transparent display screen 4 and the liquid crystal display screen 5, respectively. After reflection from the B-side of the dual-mirror calibration plate 11, no distortion occurs. The second CCD camera 3 acquires the zero-distortion fringe images of the sinusoidal straight fringe images of the transparent display screen 4 and the liquid crystal display screen 5 after reflection from the B-side of the dual-mirror calibration plate 11, and stores them in the computer 1. The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen 4 reflected from the B-side of the dual-mirror calibration plate 11 is obtained. Br1 The absolute phase value φ of the liquid crystal display 5 reflected from the B side of the dual-mirror calibration plate 11 Br2 .

[0026] Step 4: Replace the dual-mirror calibration plate 11 with the dual-mirror object 6 to be tested (i.e., remove the dual-mirror calibration plate 11 from the high-precision horizontal guide rail, and then install the dual-mirror object 6 to be tested on the high-precision horizontal guide rail), ensuring that the dual-mirror object 6 to be tested is within the depth of field of the first CCD camera 2 and the second CCD camera 3, and that its pose conforms to the triangle measurement relationship, and calculate the absolute phase value φ of the transparent display screen 4 reflected by the mirror 7 on side A. Am1 The absolute phase value φ of the liquid crystal display screen 5 reflected by the mirror surface 7 on side A. Am2 The absolute phase value φ of the transparent display screen 4 reflected by mirror 8 on side B. Bm1 And the absolute phase value φ of the liquid crystal display screen 5 reflected by the B-side mirror 8. Bm2 ; Preferably, step 4 specifically involves: for the A-side subsystem, sinusoidal straight-line fringe images are displayed on the transparent display screen 4 and the liquid crystal display screen 5, respectively. These images are then modulated and deformed by the A-side mirror 7. The first CCD camera 2 acquires the deformed fringe images reflected from the transparent display screen 4 and the liquid crystal display screen 5 by the A-side mirror 7, and stores them in the computer 1. The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen 4 reflected by the A-side mirror 7 is obtained. Am1 The absolute phase value φ of the liquid crystal display screen 5 reflected by the mirror surface 7 on side A. Am2; For the B-side subsystem, sinusoidal straight fringe images are displayed on the transparent display screen 4 and the liquid crystal display screen 5, respectively. These images are then modulated and deformed by the B-side mirror 8. The second CCD camera 3 captures the deformed fringe images reflected from the transparent display screen 4 and the liquid crystal display screen 5 by the B-side mirror 8, and stores them in the computer 1. The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen 4 reflected by the B-side mirror 8 is obtained. Bm1 The absolute phase value φ of the liquid crystal display screen 5 reflected by the B-side mirror 8 Bm2 .

[0027] Step 5: Solve for the three-dimensional surface data of mirror surface 7 on side A and mirror surface 8 on side B in the corresponding coordinate system; For the A-side subsystem, the relationship between the phase and the depth information of the A-side mirror 7 is established as shown in equation (3), thus obtaining the depth information h of the A-side mirror 7 relative to the first reference plane 12. A : (3) Then, based on the coefficient a obtained in step 2 A0 a A1 a A2 b A0 b A1 and b A2 Calculate the coordinates of each pixel in the reference coordinate system O A -X A Y A Z A The X and Y coordinates of the mirror surface 7 on side A are obtained in the reference coordinate system O. A -X A Y A Z A The three-dimensional coordinates (X) A ,Y A Z A ); For the B-side subsystem, the relationship between the phase and the depth information of the B-side mirror 8 is established as shown in equation (4), and the depth information h of the B-side mirror 8 relative to the second reference plane 13 is obtained. B : (4) Then, based on the coefficient a obtained in step 2 B0 a B1 a B2 b B0 b B1 and b B2 Calculate the coordinate system O for each pixel. B -X B Y B ZB The X and Y coordinates of the B-side mirror 8 are used to obtain the coordinates of the B-side mirror 8 in the coordinate system O to be calibrated. B -X B Y B Z B The three-dimensional coordinates (X) B ,Y B Z B ); Step 6: Fusion of 3D topographic data of dual-mirror objects; Based on the transformation matrix obtained in step 2 Using equation (5), a point on the B-side mirror 8 is placed in the coordinate system O to be calibrated. B -X B Y B Z B The three-dimensional coordinates (X) B ,Y B Z B Converted to the reference coordinate system O A -X A Y A Z A The three-dimensional coordinates below ( ); (5) At this time, the three-dimensional coordinates (X) A ,Y A Z A ) and three-dimensional coordinates ( All are located in the reference coordinate system O. A -X A Y A Z A The overall three-dimensional shape data of the double-mirror object 6 to be tested are obtained.

[0028] Example: In step 1, computer 1 is equipped with software for generating stripe images and image processing (MATLAB software in this embodiment), as well as software for controlling the camera to acquire and store images. This software is known technology and can be commercially available.

[0029] In step 2, the reference coordinate system O is calculated using the rigid body transformation method. A -X A Y A Z A With the coordinate system to be calibrated O B -X B Y B Z B Transformation matrix between ; The rigid body transformation method described is a well-known method, and the reference is "LaValle S M. Planning algorithms [M]. Cambridge University Press, 2006"; The camera-based machine vision calibration method proposed by Zhang Zhengyou is a well-known method. The reference is "Zhang Z. A flexible new technique for camera calibration[J].IEEE Transactions on Pattern Analysis and Machine Intelligence,2000,22(11):1330-1334"; In step 3, the number of sinusoidal stripes generated in the three sets are 81, 80, and 72, respectively. The absolute phase unfolding diagram was calculated using the optimal three-fringe selection method; the optimal three-fringe selection method is a well-known method in the field, and the reference is "Zhang Z. Time efficient color fringe projection system for simultaneous 3D shape and color using optimum 3frequency selection. Optics Express, 2006, 14(14):6444-6455". Any aspects not covered in this invention are applicable to existing technologies.

Claims

1. A method for measuring the phase deflection of a near-optical coaxial double-mirror object, characterized in that, The method includes the following steps: Step 1: Construct a near-optical coaxial dual-mirror object phase deflection measurement system; The system includes a computer (1), a first CCD camera (2), a second CCD camera (3), a transparent display screen (4), a liquid crystal display screen (5), a first semi-transparent mirror (9), and a second semi-transparent mirror (10). The transparent display screen (4) and the liquid crystal display screen (5) are respectively fixed vertically on the optical platform, and the transparent display screen (4) and the liquid crystal display screen (5) are parallel to each other and the distance is Δd; the first CCD camera (2), the second CCD camera (3), the first semi-transparent and semi-reflective mirror (9) and the second semi-transparent and semi-reflective mirror (10) are respectively fixed on the optical platform, the first CCD camera (2) and the first semi-transparent and semi-reflective mirror (9) are fixed on side A of the double mirror object (6) to be tested, and the second CCD camera (3) and the second semi-transparent and semi-reflective mirror (10) are fixed on side B of the double mirror object (6) to be tested; The dual-mirror object (6) to be tested is slidably mounted on the optical platform and slides along a path perpendicular to the transparent display screen (4) and the liquid crystal display screen (5). The dual-mirror object (6) to be tested can rotate so that the virtual images of the liquid crystal display screen (5) and the transparent display screen (4) reflected by the first semi-transparent mirror (9) and reflected by the A-side mirror (7) of the dual-mirror object (6) to be tested are within the depth of field of the first CCD camera (2). The virtual images of the liquid crystal display screen (5) and the transparent display screen (4) reflected by the second semi-transparent mirror (10) and reflected by the B-side mirror (8) of the dual-mirror object (6) to be tested are within the depth of field of the second CCD camera (3). The first CCD camera (2), the first semi-transparent mirror (9) and the A-side mirror (7) are in a triangular measurement relationship in space. The second CCD camera (3), the second semi-transparent mirror (10) and the B-side mirror (8) are in a triangular measurement relationship in space. The mirror images of the transparent display screen (4) and the liquid crystal display screen (5) about the first semi-transparent mirror (9) are respectively the first equivalent virtual display screen (14) on side A and the second equivalent virtual display screen (15) on side A. The mirror images of the transparent display screen (4) and the liquid crystal display screen (5) about the second semi-transparent mirror (10) are respectively the first equivalent virtual display screen (16) on side B and the second equivalent virtual display screen (17) on side B. The computer (1), the first CCD camera (2), the A-side mirror (7), the first semi-transparent mirror (9), the transparent display screen (4), and the liquid crystal display screen (5) constitute the A-side subsystem; the computer (1), the second CCD camera (3), the B-side mirror (8), the second semi-transparent mirror (10), the transparent display screen (4), and the liquid crystal display screen (5) constitute the B-side subsystem; The computer (1) is connected to the transparent display screen (4), the liquid crystal display screen (5), the first CCD camera (2), and the second CCD camera (3) respectively; the computer (1) controls the precise movement of the double mirror object (6) or the double mirror calibration plate (11) to be tested; Step 2: Replace the double mirror object (6) to be measured with a double mirror calibration plate (11) to ensure that the double mirror calibration plate (11) is located within the depth of field of the first CCD camera (2) and the second CCD camera (3) and that its pose conforms to the triangle measurement relationship, and obtain the calibration parameters of the system. The plane containing side A of the dual-mirror calibration plate (11) is the first reference plane (12), and the plane containing side B of the dual-mirror calibration plate (11) is the second reference plane (13); the coordinate system defined by the annular array on the surface of side A of the dual-mirror calibration plate (11) is set as the reference coordinate system O. A -X A Y A Z A The coordinate system defined by the annular array on the B side surface of the double-mirror calibration plate (11) is set as the coordinate system O to be calibrated. B -X B Y B Z B ; Calibration parameters include the reference coordinate system O A -X A Y A Z A With the coordinate system O to be calibrated B -X B Y B Z B Transformation matrix between The distance d between the first equivalent virtual display screen (14) on side A and the first reference plane (12) A In the A-side subsystem, the X and Y coordinates of each point with respect to the pixel coordinates (u A ,v A The coefficient a of the quadratic nonlinear function of the Z-coordinate A0 a A1 a A2 b A0 b A1 and b A The distance d between the first equivalent virtual display screen (16) on side B and the second reference plane (13) B And the X and Y coordinates of each point in the B-side subsystem with respect to the pixel coordinates (u B ,v B The coefficient a of the quadratic nonlinear function of the Z-coordinate B0 a B1 a B2 b B0 b B1 and b B2 ; Step 3: Calculate the absolute phase value φ of the transparent display screen (4) reflected from the A side of the double-mirror calibration plate (11). Ar1 The absolute phase value φ of the liquid crystal display screen (5) reflected from the A side of the dual-mirror calibration plate (11) Ar2 The absolute phase value φ of the transparent display screen (4) reflected from the B side of the double-mirror calibration plate (11) Br1 And the absolute phase value φ of the liquid crystal display (5) reflected from the B side of the dual-mirror calibration plate (11). Br2 ; Step 4: Replace the double-mirror calibration plate (11) with the double-mirror object (6) to be tested, ensuring that the double-mirror object (6) is within the depth of field of the first CCD camera (2) and the second CCD camera (3), and that its pose conforms to the triangle measurement relationship. Calculate the absolute phase value φ of the transparent display screen (4) reflected by the mirror (7) on side A. Am1 The absolute phase value φ of the liquid crystal display screen (5) reflected by the mirror surface (7) on side A. Am2 The absolute phase value φ of the transparent display screen (4) reflected by the B-side mirror (8) Bm1 And the absolute phase value φ of the liquid crystal display screen (5) reflected by the B-side mirror (8). Bm2 ; Step 5: Solve for the three-dimensional surface data of mirror A (7) and mirror B (8) in the corresponding coordinate system; For the A-side subsystem, the relationship between the phase and the depth information of the A-side mirror (7) is established as shown in Equation (3), thus obtaining the depth information h of the A-side mirror (7) relative to the first reference plane (12). A : （3） Then, based on the coefficient a obtained in step 2 A0 a A1 a A2 b A0 b A1 and b A2 Calculate the coordinates of each pixel in the reference coordinate system O A -X A Y A Z A The X and Y coordinates of the mirror surface (7) on side A are obtained in the reference coordinate system O. A -X A Y A Z A The three-dimensional coordinates (X) below A ,Y A Z A ); For the B-side subsystem, the relationship between the phase and the depth information of the B-side mirror (8) is established as shown in Equation (4), and the depth information h of the B-side mirror (8) relative to the second reference plane (13) is obtained. B : （4） Then, based on the coefficient a obtained in step 2 B0 a B1 a B2 b B0 b B1 and b B2 Calculate the coordinate system O for each pixel. B -X B Y B Z B The X and Y coordinates of the B-side mirror (8) are obtained in the coordinate system O to be calibrated. B -X B Y B Z B The three-dimensional coordinates (X) below B ,Y B Z B ); Step 6: Fusion of 3D topographic data of dual-mirror objects; Based on the transformation matrix obtained in step 2 Using equation (5), a point on the B-side mirror (8) is placed in the coordinate system O to be calibrated. B -X B Y B Z B The three-dimensional coordinates (X) below B ,Y B Z B Converted to the reference coordinate system O A -X A Y A Z A The three-dimensional coordinates below ( ); （5） At this time, the three-dimensional coordinates (X) A ,Y A Z A ) and three-dimensional coordinates ( All are located in the reference coordinate system O. A -X A Y A Z A The overall three-dimensional morphology data of the double-mirror object (6) to be tested are obtained.

2. The method for measuring the phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, In step 1, the high-precision horizontal moving guide rail is fixed on the optical platform and is perpendicular to the transparent display screen (4) and the liquid crystal display screen (5). The double mirror object (6) to be tested is slidably mounted on the high-precision horizontal moving guide rail and can rotate on its own. The computer (1) is connected to the high-precision horizontal moving guide rail and controls the precise movement of the double mirror object (6) or the double mirror calibration plate (11).

3. The method for measuring the phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, In step 2, when the dual-mirror calibration plate (11) calibrates the A-side subsystem, the virtual image reflected by the first semi-transparent mirror (9) through the first reference plane (12) and the first reference plane (12) are both within the depth of field of the first CCD camera (2). The A-side of the first CCD camera (2), the first semi-transparent mirror (9) and the dual-mirror calibration plate (11) are in a triangular measurement relationship in space. When the dual-mirror calibration plate (11) calibrates the B-side subsystem, the virtual image reflected by the second semi-transparent mirror (10) through the second reference plane (13) and the second reference plane (13) are both within the depth of field of the second CCD camera (3). The B-side of the second CCD camera (3), the second semi-transparent mirror (10) and the dual-mirror calibration plate (11) are in a triangular measurement relationship in space.

4. The method for measuring the phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, In step 2, given the pose transformation method between the first reference plane (12) and the second reference plane (13), the reference coordinate system O is calculated using the rigid body transformation method. A -X A Y A Z A With the coordinate system O to be calibrated B -X B Y B Z B Transformation matrix between .

5. The method for measuring the phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, In step 2, for the A-side subsystem, since the transparent display screen (4), the liquid crystal display screen (5), the first equivalent virtual display screen (14) and the second equivalent virtual display screen (15) on the A-side are symmetrical about the first semi-transparent and semi-reflective mirror (9), the distance between the first equivalent virtual display screen (14) and the second equivalent virtual display screen (15) on the A-side is equal to the distance between the transparent display screen (4) and the liquid crystal display screen (5), which is Δd. A circular array with known spatial distance and radius is displayed on the transparent display screen (4). The first CCD camera (2) respectively collects the circular array on the A-side of the double mirror calibration plate (11) and the circular array displayed on the transparent display screen (4) reflected by the double mirror calibration plate (11). The boundary of the circular array is extracted, the center of the circular array is determined by ellipse fitting, and the distance d between the first equivalent virtual display screen (14) on the A-side and the first reference plane (12) is calculated using Zhang Zhengyou's camera-based machine vision calibration method. A Furthermore, the first reference plane (12) is parallel to the first equivalent virtual display screen (14) on side A.

6. The method for measuring the phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, In step 2, for the A-side subsystem, the dual-mirror calibration plate (11) is moved n along a path perpendicular to the liquid crystal display (5) and the transparent display (4) within the depth of field of the first CCD camera (2). A There are n positions. A ≥6, at each position, the first CCD camera (2) acquires the circular array of the first reference plane (12), and records the center of each ring in the circular array in the reference coordinate system O. A -X A Y A Z A The three-dimensional coordinates (X) below Ab ,Y Ab Z Ab Then, based on the pixel coordinates of the center of each ring in the circular array extracted by the first CCD camera (2), the pixel coordinates (u) of each pixel point of the first CCD camera (2) are calculated. A ,v A The coefficient a of the quadratic nonlinear function of the Z-coordinate A0 a A1 a A2 b A0 b A1 and b A2 Complete the calibration of the X and Y coordinates of the A-side subsystem, where X... Ab and Y Ab The calibration formula is shown in equation (1): （1）。 7. The method for measuring the phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, In step 2, for the B-side subsystem, the distance between the first equivalent virtual display screen (16) and the second equivalent virtual display screen (17) on the B-side can be obtained as Δd. A circular array with known spatial distance and radius is displayed on the transparent display screen (4). The second CCD camera (3) respectively acquires the circular array on the second reference plane (13) on the double mirror calibration plate (11) and the circular array displayed on the transparent display screen (4) reflected by the double mirror calibration plate (11). The boundary of the circular array is extracted, and the center of the circular array is determined by ellipse fitting. Using Zhang Zhengyou's camera-based machine vision calibration method, the distance d between the first equivalent virtual display screen (16) and the second reference plane (13) on the B-side is calculated. B Furthermore, the second reference plane (13) is parallel to the first equivalent virtual display screen (16) on side B.

8. The method for measuring the phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, In step 2, for the B-side subsystem, the dual-mirror calibration plate (11) is moved n along a path perpendicular to the liquid crystal display (5) and the transparent display (4) within the depth of field of the second CCD camera (3). B There are n positions. B ≥6, at each position, the second CCD camera (3) acquires the circular array of the second reference plane (13), and records the center of each ring in the circular array in the coordinate system to be calibrated O. B -X B Y B Z B The three-dimensional coordinates (X) below Bb ,Y Bb Z Bb Then, based on the pixel coordinates of the center of each ring in the circular array extracted by the second CCD camera (3), the pixel coordinates (u) of each pixel point of the second CCD camera (3) are calculated. B ,v B The coefficient a of the quadratic nonlinear function of the Z-coordinate B0 a B1 a B2 b B0 b B1 and b B2 Complete the calibration of the X and Y coordinates of the B-side subsystem, among which... and The calibration formula is shown in equation (2): （2）。 9. The method for measuring the phase deflection of a near-optical coaxial double-mirror object according to claim 1, characterized in that, Step 3 specifically involves: using a computer (1) to select three sets of sinusoidal straight stripes to be displayed in the measurement field based on the size of the measurement field and the requirements of measurement accuracy, according to the existing stripe generation method; and the number of stripes in these three sets of sinusoidal straight stripes satisfies the optimal three-stripe selection method. Each set of sinusoidal stripes contains four sinusoidal stripe images with a 90-degree phase shift between them; For the A-side subsystem, sinusoidal straight fringe images are displayed on the transparent display screen (4) and the liquid crystal display screen (5), respectively. After being reflected by the A-side of the double mirror calibration plate (11), no deformation occurs. The first CCD camera (2) acquires the zero-deformation fringe images of the sinusoidal straight fringe images of the transparent display screen (4) and the liquid crystal display screen (5) after being reflected by the A-side of the double mirror calibration plate (11), and stores them in the computer (1). The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen (4) reflected by the A-side of the double mirror calibration plate (11) is obtained. Ar1 The absolute phase value φ of the liquid crystal display (5) reflected from the A side of the dual-mirror calibration plate (11) and the double-mirror calibration plate (11) Ar2 ; For the B-side subsystem, sinusoidal straight fringe images are displayed on the transparent display screen (4) and the liquid crystal display screen (5), respectively. After being reflected by the B-side of the double-mirror calibration plate (11), no deformation occurs. The second CCD camera (3) acquires the zero-deformation fringe images of the sinusoidal straight fringe images of the transparent display screen (4) and the liquid crystal display screen (5) after being reflected by the B-side of the double-mirror calibration plate (11), and stores them in the computer (1). The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen (4) reflected by the B-side of the double-mirror calibration plate (11) is obtained. Br1 The absolute phase value φ of the liquid crystal display (5) reflected from the B side of the dual-mirror calibration plate (11) Br2 .

10. The method for measuring phase deflection of a near-optical coaxial dual-mirror object according to claim 1, characterized in that, Step 4 is as follows: For the A-side subsystem, sinusoidal straight fringe images are displayed on the transparent display screen (4) and the liquid crystal display screen (5), respectively. Then, after being modulated and deformed by the A-side mirror (7), the first CCD camera (2) acquires the sinusoidal straight fringe images of the transparent display screen (4) and the liquid crystal display screen (5) and the deformed fringe images reflected by the A-side mirror (7), and stores them in the computer (1). The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen (4) reflected by the A-side mirror (7) is obtained. Am1 The absolute phase value φ of the liquid crystal display (5) reflected by the mirror (7) on side A Am2 ; For the B-side subsystem, sinusoidal straight fringe images are displayed on the transparent display screen (4) and the liquid crystal display screen (5), respectively. Then, after being modulated and deformed by the B-side mirror (8), the second CCD camera (3) acquires the sinusoidal straight fringe images of the transparent display screen (4) and the liquid crystal display screen (5) and the deformed fringe images reflected by the B-side mirror (8), and stores them in the computer (1). The absolute phase unfolding diagram is calculated using the optimal three-fringe selection method, and then the absolute phase value φ of the transparent display screen (4) reflected by the B-side mirror (8) is obtained. Bm1 The absolute phase value φ of the liquid crystal display screen (5) reflected by the B-side mirror (8) Bm2 .

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