Binocular camera calibration method and system based on laser interference and two-dimensional grating diffraction

Abstract

The invention discloses a binocular camera calibration method based on laser interference and two-dimensional grating diffraction, and the method comprises the steps: S1, configuring an interference light path: equally dividing a laser beam into two beams, transmitting the two beams through two interference arms, carrying out the beam combination, enabling the diffraction light spots to generate interference, and forming an interference image; s2, calibrating an interference light path: adjusting a light guide system until it is observed that an interference ring continuously diverges outwards from the center; and S3, binocular camera matching: the binocular cameras are placed on the light guide paths of the two interference arms respectively, it is ensured that the light path distances from the binocular cameras to the observation equipment are equal, the positions and angles of the binocular cameras are adjusted, the positions of diffraction spots coincide, and round bright spots are formed in the center. A laser interference measurement method is adopted, the measurement precision can reach one thousandth wavelength magnitude, the matching calibration precision is high, a sensor target surface pixel two-dimensional periodic distribution structure is used as a two-dimensional grating to diffract a measurement laser beam, no additional measurement device is needed, and the equipment cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of spatial matching calibration of two image sensors of a binocular camera, and in particular to a binocular camera calibration method and system based on laser interference and two-dimensional grating diffraction. Background Art

[0002] Binocular cameras simulate the way people see the world. They estimate the distance of pixels in space by comparing the difference between the images taken by the left and right cameras (similar to the human eye). There is a 6-7 cm gap between the left and right eyes of a person. The images seen by the left eye and the right eye will be slightly different, so that the distance of objects and the front and back relationship of multiple objects can be judged. Binocular cameras are also based on this principle. Two cameras at different positions or one camera is used to shoot the same scene through translation or rotation to obtain a stereo image pair, and then the three-dimensional information of the object is calculated. The two image sensors of the binocular camera need to match in space to measure the distance, shape and other physical quantities of the same target. The spatial matching accuracy of the two sensors will affect the measurement results.

[0003] The existing technology mainly uses Zhang Zhengyou calibration method to calibrate a pair of image sensors of an already formed binocular vision system. Zhang Zhengyou calibration method is a camera calibration method based on calibration objects. It uses the known chessboard calibration plate image to obtain the coordinates of the corner points in the image through corner point detection, solves the camera's intrinsic parameter matrix and extrinsic parameter matrix, as well as distortion parameters, and then performs de-distortion processing and three-dimensional scene reconstruction on the captured image.

[0004] However, the calibration equipment of this method is complex in structure, high in cost, and cannot be tracked during the production and deployment process. In addition, the matching accuracy is limited by multiple factors such as the spatial resolution of the acquired image and the measurement distance. At the same time, the method of using a six-dimensional adjustment system for correction is limited by the manufacturing accuracy, stability, and repeatability of the measuring tool, and it is difficult to achieve sub-pixel matching calibration accuracy. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention aims to provide a binocular camera calibration method based on laser interference and two-dimensional grating diffraction to solve the problems of high equipment cost and insufficient matching calibration accuracy of the two sensors of the binocular camera in the prior art. The specific technical solution is as follows: A binocular camera calibration method based on laser interference and two-dimensional grating diffraction comprises the following steps: S1: Configure the interference optical path: a laser beam is divided into two equal beams, which are respectively propagated along a preset path through two interference arms through a light guide system. After the two interference arms combine the beams, the diffracted light spots interfere with each other to form an interference image, and the interference image is observed through an observation device; S2: Calibrate the interference light path: adjust the light guide system until interference rings are observed to continuously diverge from the center outward, indicating that the calibration of the interference light path is completed; S3: Matching binocular cameras: Place the binocular cameras on the light guiding paths of the two interference arms respectively for projecting light beams, and ensure that the light path distances from the binocular cameras to the observation device are equal. By adjusting the position and angle of the binocular cameras, the diffraction spots generated by the first interference arm and the second interference arm are overlapped in position and shape, and a circular bright spot is formed in the center, indicating that the binocular camera matching is completed.

[0006] As a preferred implementation, the specific steps of configuring the interference light path in step S1 are: Place a plane mirror and a beam splitter prism so that the light beam emitted by the laser is split into two beams by the beam splitter prism A and propagates through the first interference arm and the second interference arm respectively; The light beam of the first interferometer arm is reflected by plane mirror A to beam splitter prism B. Spectral prism B splits the incident light beam into two beams, one of which is beam A and is split to beam splitter prism C. The other beam B is split along the normal direction to plane mirror B, and is reflected back to beam splitter prism B by plane mirror B, and is reflected by beam splitter prism B to beam splitter prism C. Light beam A and light beam B are split by beam splitter prism C and pass through the double convex lens to reach the sensor target surface of camera A. The light beam of the second interferometer arm passes through the beam splitter prism D, which splits the incident light beam into two beams, one of which is a beam C that is split to the plane mirror C, and the other beam D that is split along the normal direction to the plane mirror B, and is reflected back to the beam splitter prism D by the plane mirror B, and is reflected by the beam splitter prism D to the plane mirror C. The beams C and D are split by the beam splitter prism C and pass through the double convex lens to reach the sensor target surface of the camera A; The light path from the beam splitter prism D to the plane mirror C is parallel to the light path from the beam splitter prism B to the beam splitter prism C and has the same length.

[0007] As a preferred implementation, the specific steps of step S2 for calibrating the interference light path are: Assemble plane mirror A on the piezoelectric ceramic transducer, drive the piezoelectric ceramic transducer to cause plane mirror A to produce micro-displacement, collect the continuously changing interference pattern through camera A, adjust the position and / or angle of each plane mirror and dichroic prism, until interference rings are observed to continuously diverge from the center to the outside through camera A, indicating that the interference light path calibration is completed.

[0008] As a preferred implementation, the specific steps of step S3 matching the binocular camera are: Replace camera A with an observation screen, and replace plane mirror B with camera B and camera C, ensuring that the sensor target surfaces of camera B and camera C are in the same plane as plane mirror B, and that the light beams split from beam splitter prism B and beam splitter prism D can reach the sensor target surfaces of camera B and camera C respectively. By adjusting the positions and angles of camera B and camera C, the diffraction spots generated by the first interferometer arm and the second interferometer arm are made to coincide in position and shape, and form a circular bright spot in the center, indicating that the binocular camera matching is completed.

[0009] As a preferred implementation manner: the splitting ratios of the beam splitter prism A, the beam splitter prism B, the beam splitter prism C and the beam splitter prism D are all 50:50.

[0010] As a preferred implementation manner: the laser is a helium-neon laser.

[0011] As a preferred implementation manner: the camera B and the camera C are respectively mounted on a six-dimensional adjustment frame, and the left-right position, front-back distance, vertical height, and Euler angle of the camera B and the camera C are adjusted by the six-dimensional adjustment frame.

[0012] As a preferred implementation, the specific steps of adjusting the camera B and the camera C by the six-dimensional adjustment frame are as follows: By adjusting the horizontal position, vertical displacement and Euler angle of the six-dimensional adjustment frame, the corresponding positions of the two groups of light spots on the observation screen are made to coincide, which indicates that the horizontal and vertical coordinates of camera B and camera C have basically matched; Adjust the front-to-back displacement to make the two groups of light spots the same size and completely overlap, and interference fringes appear at the spots. This indicates that the front-to-back distances of camera B and camera C are basically matched. Continue to adjust the six-dimensional adjustment frame and observe that the stripe shapes at several spots on the screen gradually become consistent; Continue to adjust the six-dimensional adjustment frame, and the interference fringes will become interference concentric rings. At this time, the three Euler angles of camera B and camera C are almost the same. By adjusting the forward and backward displacement of the six-dimensional adjustment frame, the number of interference concentric rings decreases, and the central bright spot becomes larger and brighter, indicating that the two spherical waves are coaxial, and the centers of the spherical waves gradually approach to nearly coincide. Continue to fine-tune until the central bright spot is stable. At this time, the lateral position, front-to-back distance, vertical height, and three Euler angles of the image sensor target surfaces of camera B and camera C have been matched and calibrated. At this time, the binocular camera matching is completed.

[0013] As a preferred implementation manner: in step S2, after placing plane mirror B, place camera B and camera C close to the back of plane mirror B. When plane mirror B is replaced with camera B and camera C in step S3, remove plane mirror B, and then adjust the positions of camera B and camera C according to the thickness compensation of plane mirror B.

[0014] The present invention also provides a binocular camera calibration system based on laser interference and two-dimensional grating diffraction, which is applied to implement the above calibration method, including: Light guide system: used to divide a laser beam into two equal beams, which are transmitted along a preset path through two interference arms through the light guide system respectively, so that the diffracted light spots after the two interference arms are combined will interfere and form an interference image; Binocular camera: placed on the light guide path of the light guide system, used to observe the interference image; Adjustment device: used to adjust the position and placement angle of the binocular camera.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention utilizes the two-dimensional grating structure on the surface of the camera sensor to diffract the light beam, and the 0th and ±1st order energies in the diffraction spot are relatively strong. Since the two sensors of the binocular camera have the same structure and the same grating period, the diffraction angles of the ±1st order light beams are the same. After diffraction occurs, if the propagation distance is the same, the lateral displacement from the 0th order light beam is also the same. In this way, the light beams diffracted by the two sensor surfaces are combined after the same propagation distance, and the light spots of the same order will produce interference. Only when the six degrees of freedom of the positions and angles of the two cameras are the same, will concentric rings of coaxial interference appear, indicating that the binocular camera matching is complete, otherwise only stripes will appear, or the matching will fail and no interference pattern will be generated.

[0016] By adopting the laser interferometry method, the measurement accuracy can reach one thousandth of the wavelength, and the matching calibration accuracy is high. At the same time, the two-dimensional periodic distribution structure of the sensor target surface pixels is used as a two-dimensional grating to diffract the measurement laser beam. No additional measurement device is required, the structure is simple, and the equipment cost is saved. In addition, due to the use of spherical wave coaxial interference technology, the interference image is a concentric ring, which is easy to observe and adjust; the method of pre-calibration with a calibrated optical path is used to determine the key parameters of the optical system, and there is no need to repeat the calibration every time matching and calibration is performed. The operation is simple and convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the calibration optical path in the first embodiment of the present invention; Figure 2 is a schematic diagram of the optical path of the binocular camera group spatial matching calibration in the first embodiment of the present invention; Figure 3 is a schematic diagram of diffraction spot distribution in Embodiment 1 of the present invention; Figure 4 yes Figure 1 Schematic diagram of the interference ring captured by camera A.

[0018] In the figure, 1. laser; 2. beam splitter prism A; 3. plane mirror A; 4. beam splitter prism D; 5. plane mirror C; 6. beam splitter prism B; 7. beam splitter prism C; 8. double convex lens; 9. camera A; 10. plane mirror B; 11. observation screen; 12. camera C; 13. camera B. DETAILED DESCRIPTION

[0019] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0020] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0021] Embodiment 1 In this system, the incident direction of the light on the target surface of the binocular camera sensor is the positive z direction. The direction perpendicular to the z direction in the horizontal plane is the x direction, and the plane where the laser 1 and the binocular camera are located is the xoz plane. The direction perpendicular to the xoz plane is the y direction. x, y, and z form a right-handed system.

[0022] A binocular camera calibration method based on laser interference and two-dimensional grating diffraction, such as Figure 1 As shown, the following steps are included: S1: Configure the interference optical path and build Figure 1 The light guide system in Figure 1 It includes multiple beam splitting prisms: beam splitting prism A2, beam splitting prism D4, beam splitting prism B6 and beam splitting prism C7, and the beam splitting ratio of the above beam splitting prisms is 50:50; it includes multiple plane mirrors: plane mirror A3, plane mirror C5 and plane mirror B10; it also includes a double convex lens 8 and a camera A9.

[0023] In this embodiment, the laser 1 is a helium-neon laser that emits red laser light. In some other embodiments, the laser 1 may also be of other wavelengths, such as emitting a 532nm green laser light, which can reduce the diffraction angle but requires a smaller beam splitter prism C7.

[0024] The laser light emitted by the laser 1 is split into two identical light beams by the beam splitter prism A2, and propagates through the first interference arm and the second interference arm respectively.

[0025] Among them, the propagation path of the first interferometer arm: the light beam transmitted through the beam splitter prism A2 is first reflected by the plane mirror A3, and then reaches the beam splitter prism B6. The light reflected by the beam splitter prism B6 is no longer used by the system, and the light transmitted through the beam splitter prism B6 is reflected by the plane reflector B10 and reaches the beam splitter prism B6 again. At this time, the light transmitted through the beam splitter prism 6 again is no longer used by the system, and the light reflected by the beam splitter prism 6 again continues to propagate to the beam splitter prism C7. The light transmitted through the beam splitter prism 7 is no longer used by the system.

[0026] Among them, the propagation path of the second interference arm: the light beam reflected by the beam splitter prism A2 reaches the beam splitter prism D4. The light reflected by the beam splitter prism D4 is no longer used by the system. The light transmitted through the beam splitter prism D4 is reflected by the plane reflector B10 and reaches the beam splitter prism D4 again. At this time, the light transmitted through the beam splitter prism 4 is no longer used by the system, and the light reflected by the beam splitter prism D4 again continues to propagate and is reflected by the plane reflector C5. The reflected light beam propagates to the beam splitter prism C7. The light reflected by the beam splitter prism C7 is no longer used by the system.

[0027] After the first interference arm and the second interference arm are combined by the beam splitter prism C7, they reach the biconvex lens 8, which is used to transform the wavefront of the light beam into a spherical surface. Therefore, the light beams passing through the first interference arm and the second interference arm respectively form an interference field on the sensor target surface of the camera 9.

[0028] In the light guiding system, the light path split by the beam splitter prism D4 to the plane mirror C5 is parallel to the light path split by the beam splitter prism B6 to the beam splitter prism C7 and has the same length, that is, Figure 1 The distances between D1 and D2 are equal, so that the optical path distances from the binocular cameras to the observation device are equal.

[0029] S2: Calibrate the interference optical path: Fine Adjustment Figure 1 The positions and angles of all the beam splitters and plane mirrors in the image are such that the beams transmitted by the first interference arm and the second interference arm are coaxial after being combined by the beam splitter prism C7. At this time, the two spherical waves will form concentric interference rings, as shown in Figure 4 shown.

[0030] Plane mirror A3 is mounted on PZT (piezoelectric ceramic transducer), which drives PZT to produce micro displacement, that is, drives plane reflector 3 to micro displacement. At the same time, the camera A9 collects the continuously changing interference pattern, and observes that the continuous interference ring diverges from the center to the outside. At this point, the interference light path calibration is completed.

[0031] It should be noted that Figure 1Where D1 and D2 are the distances of the light path from the beam splitter prism D4 to the plane mirror C5 and the light path from the beam splitter prism B6 to the beam splitter prism C7, respectively, and L is the distance of the light path from the plane mirror B10 to the beam splitter prism B6. The grating formula is: , where θ is the diffraction angle, k is the diffraction order, λ is the wavelength (for example, the wavelength of the red laser emitted by the helium-neon laser is 632.8 nanometers), and d is the grating period (i.e., the pixel size of the image sensor, such as 5 microns). Generally, k=±1, because the diffraction spot energy of the corresponding order is stronger and easier to observe. The diffraction angle of the ±1-order diffraction beam can be calculated by the grating formula . Figure 1 In the figure, the ±1st order diffracted beams propagate to the exit surface of the beam splitter C7, and their lateral distance from the 0th order beam is To ensure that the beam splitter C7 can pass the ±1 diffracted beams, its side length must be greater than Therefore, when configuring the optical path, L and D1 (or D2) should be as small as possible to reduce the cost of the beam splitter C7.

[0032] S3: Matching the Stereo Camera The binocular camera includes a camera B13 and a camera C12. In step S2, the camera B13 and the camera C12 can be placed close to the back of the plane mirror B10. The camera B13 and the camera C12 are both set on a six-dimensional adjustment frame, which can independently adjust the horizontal (x direction), up and down (y direction), front and back (z direction) and three Euler angles (rotation angles around the x, y, and z axes, respectively), a total of six dimensions.

[0033] like Figure 2 As shown, the plane mirror B10 is removed, and the positions of the cameras B13 and C12 are adjusted according to the thickness of the plane mirror B10 through the six-position adjustment frame to ensure that the sensor target surface of the cameras B13 and C12 and the plane mirror B10 are in the same plane, and the light beam split from the beam splitter prism B6 is incident on the sensor target surface of the camera B13 along the normal direction, and the light beam split from the beam splitter prism D4 is incident on the sensor target surface of the camera C12 along the normal direction. Since the distances of D1 and D2 are equal, the optical path distances reflected by the cameras B13 and C12 to the beam splitter prism C7 are the same, and the lateral displacements deviating from the 0-order light beam are also the same. In this way, the light beams diffracted by the surface of the binocular camera are combined after the same propagation distance, and the light spots of the same order will produce interference.

[0034] Since the field of view of the camera A9 is limited and not all the diffraction spots can be observed, it is necessary to replace the camera A9 with the observation screen 11 to observe the interference image on the observation screen 11.

[0035] The laser beams of the first interferometer arm and the second interferometer arm are incident on the target surface of the binocular camera image sensor respectively, and each produces diffraction. The light spot distribution is as follows: Figure 3As shown, two groups of diffraction spots are projected onto the observation screen 11.

[0036] At this time, by adjusting the horizontal position, vertical displacement and Euler angle of the six-dimensional adjustment frame, the corresponding positions of the two groups of light spots on the observation screen 11 are made to coincide, indicating that the horizontal and vertical coordinates of the camera B13 and the camera C12 are basically matched.

[0037] Then adjust the front-to-back displacement to make the two groups of light spots the same size, the two groups of light spots completely overlap, and interference fringes appear at the spots, which indicates that the front-to-back distances of camera B13 and camera C12 are basically matched. Continue to adjust the six-dimensional adjustment frame, and observe that the stripe shapes at several spots on the screen 11 gradually become consistent.

[0038] Continue to adjust the six-dimensional adjustment frame, and the interference fringes will become interference concentric rings. At this time, the three Euler angles of camera B13 and camera C12 are almost the same, and fine-tuning is required in the next step.

[0039] By adjusting the forward and backward displacement of the six-dimensional adjustment frame, the number of interference concentric rings decreases and the central bright spot becomes larger and brighter, indicating that the two spherical waves are coaxial and the centers of the spherical waves gradually approach to approximately coincide.

[0040] Continue to fine-tune until the central bright spot is stable. At this time, the lateral position, front-to-back distance, vertical height, and three Euler angles of the target surface of the image sensors of cameras 12 and 13 have been matched and calibrated. The six degrees of freedom of camera B13 and camera C12 are exactly the same, indicating that the binocular camera matching is completed.

[0041] Since the present embodiment adopts the laser interferometry measurement method, the measurement accuracy can reach one thousandth of a wavelength, while the pixel size of the image sensor is generally in the micron range. The optical interferometry measurement method can easily obtain an accuracy better than the pixel size, thereby achieving sub-pixel matching calibration.

[0042] At the same time, this embodiment adopts a two-dimensional periodic distribution structure of pixels on the sensor target surface, and uses it as a two-dimensional grating to diffract the measuring laser beam. No additional measuring device is needed, the structure is simple, and the cost is saved.

[0043] Since the present embodiment adopts the spherical wave coaxial interference technology, the interference image is a concentric ring, which is easy to observe and adjust. In addition, the present embodiment adopts the method of pre-calibration of the calibration light path to determine the key parameters of the optical system. There is no need to repeat the calibration every time the matching calibration is performed. The operation is simple, convenient and fast, and it is suitable for popularization and use.

[0044] In the description of the present invention, it is necessary to understand that the terms "middle", "length", "up", "down", "front", "back", "vertical", "horizontal", "inside", "outside", "radial", "circumferential" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0045] In the present invention, unless otherwise clearly specified and limited, the first feature "on" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. "Multiple" means at least two, such as two, three, etc., unless otherwise clearly and specifically limited.

[0046] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] The above is only for explaining the implementation mode of the present invention and is not intended to limit the present invention. For those skilled in the art, any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention without creative work should be included in the protection scope of the present invention.

Claims

1. A binocular camera calibration method based on laser interference and two-dimensional grating diffraction, characterized in that: The following steps are involved: S1: Configure the interference optical path: a laser beam is divided into two equal beams, which are respectively propagated along a preset path through two interference arms through a light guide system. After the two interference arms combine the beams, the diffracted light spots interfere with each other to form an interference image, and the interference image is observed through an observation device; S2: Calibrate the interference light path: adjust the light guide system until interference rings are observed to continuously diverge from the center outward, indicating that the calibration of the interference light path is completed; S3: Matching binocular cameras: Place the binocular cameras on the light guiding paths of the two interference arms respectively for projecting light beams, and ensure that the light path distances from the binocular cameras to the observation device are equal. By adjusting the position and angle of the binocular cameras, the diffraction spots generated by the first interference arm and the second interference arm are overlapped in position and shape, and a circular bright spot is formed in the center, indicating that the binocular camera matching is completed.

2. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction as claimed in claim 1, characterized in that: The specific steps of step S1 to configure the interference optical path are: Placing a plane mirror and a beam splitter prism so that the light beam emitted by the laser (1) is split into two beams by the beam splitter prism A (2), and the two beams are propagated through the first interference arm and the second interference arm respectively; The light beam of the first interferometer arm is reflected by the plane mirror A (3) to the beam splitter prism B (6), and the beam splitter prism B (6) splits the incident light beam into two beams, one of which is a beam A and is split to the beam splitter prism C (7), and the other beam B is split along the normal direction to the plane mirror B (10), and is reflected back to the beam splitter prism B (6) by the plane mirror B (10), and is reflected by the beam splitter prism B (6) to the beam splitter prism C (7); the light beam A and the light beam B are split by the beam splitter prism C (7) and pass through the double convex lens (8) to reach the sensor target surface of the camera A (9); The light beam of the second interferometer arm passes through the beam splitter prism D (4), and the beam splitter prism D (4) splits the incident light beam into two beams, one of which is a beam C that is split to a plane mirror C (5), and the other beam D that is split along the normal direction to a plane mirror B (10), and is reflected back to the beam splitter prism D (4) by the plane mirror B (10), and is reflected by the beam splitter prism D (4) to the plane mirror C (5), and the beams C and D are split by the beam splitter prism C (7), pass through the double convex lens (8), and reach the sensor target surface of the camera A (9); The light path split by the beam splitter prism D (4) to the plane mirror C (5) is parallel to the light path split by the beam splitter prism B (6) to the beam splitter prism C (7) and has the same length.

3. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction as claimed in claim 2, characterized in that: The specific steps of step S2 for calibrating the interference light path are: The plane mirror A (3) is mounted on the piezoelectric ceramic transducer, and the piezoelectric ceramic transducer is driven to cause the plane mirror A (3) to produce a micro-displacement. The continuously changing interference pattern is collected by the camera A (9), and the position and / or angle of each plane mirror and the dichroic prism are adjusted until interference rings are observed to continuously diverge from the center to the outside through the camera A (9), indicating that the interference light path calibration is completed.

4. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction as claimed in claim 3, characterized in that: The specific steps of step S3 matching the binocular camera are: Camera A (9) is replaced by an observation screen (11), and plane mirror B (10) is replaced by camera B (13) and camera C (12), ensuring that the sensor target surfaces of camera B (13) and camera C (12) are in the same plane as plane mirror B (10), and that the light beams split from beam splitter prism B (6) and beam splitter prism D (4) can reach the sensor target surfaces of camera B (13) and camera C (12), respectively. By adjusting the positions and angles of camera B (13) and camera C (12), the diffraction spots generated by the first interferometer arm and the second interferometer arm are made to coincide in position and shape, and to form a circular bright spot in the center, indicating that the binocular camera matching is completed.

5. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction according to any one of claims 2 to 4, characterized in that: The splitting ratios of the beam splitter prism A (2), the beam splitter prism B (6), the beam splitter prism C (7) and the beam splitter prism D (4) are all 50:

50.

6. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction according to any one of claims 2 to 4, characterized in that: The laser (1) is a helium-neon laser.

7. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction as claimed in claim 4, characterized in that: The camera B (13) and the camera C (12) are respectively mounted on a six-dimensional adjustment frame, and the left-right position, front-back distance, vertical height, and Euler angle of the camera B (13) and the camera C (12) are adjusted by the six-dimensional adjustment frame.

8. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction as claimed in claim 7, characterized in that: The specific steps of adjusting the camera B (13) and the camera C (12) by the six-dimensional adjustment frame are as follows: By adjusting the horizontal position, vertical displacement and Euler angle of the six-dimensional adjustment frame, the corresponding positions of the two groups of light spots on the observation screen (11) are made to coincide with each other, which indicates that the horizontal and vertical coordinates of the camera B (13) and the camera C (12) are basically matched. Adjust the front-to-back displacement so that the two groups of light spots have the same size and completely overlap, and interference fringes appear at the spots. This indicates that the front-to-back distances of camera B (13) and camera C (12) are basically matched. Continue to adjust the six-dimensional adjustment frame, and observe that the stripe shapes at several spots on the screen (11) gradually become consistent; Continue to adjust the six-dimensional adjustment frame, and the interference fringes will become interference concentric rings. At this time, the three Euler angles of camera B (13) and camera C (12) are almost the same. By adjusting the forward and backward displacement of the six-dimensional adjustment frame, the number of interference concentric rings decreases, and the central bright spot becomes larger and brighter, indicating that the two spherical waves are coaxial, and the centers of the spherical waves gradually approach to nearly coincide. Continue fine-tuning until the central bright spot is stable. At this time, the lateral position, front-to-back distance, vertical height, and three Euler angles of the image sensor target surfaces of camera B (13) and camera C (12) have been matched and calibrated. At this time, the binocular camera matching is completed.

9. The binocular camera calibration method based on laser interference and two-dimensional grating diffraction as claimed in claim 4, characterized in that: In step S2, after the plane mirror B (10) is placed, the camera B (13) and the camera C (12) are placed close to the back of the plane mirror B (10). In step S3, when the plane mirror B (10) is replaced by the camera B (13) and the camera C (12), the plane mirror B (10) is removed, and then the positions of the camera B (13) and the camera C (12) are adjusted according to the thickness compensation of the plane mirror B (10).

10. A binocular camera calibration system based on laser interference and two-dimensional grating diffraction, characterized in that: Applied to implement the calibration method according to any one of claims 1 to 9, comprising: Light guide system: used to divide a laser beam into two equal beams, which are transmitted along a preset path through two interference arms through the light guide system respectively, so that the diffracted light spots after the two interference arms are combined will interfere and form an interference image; Binocular camera: placed on the light guide path of the light guide system, used to observe the interference image; Adjustment device: used to adjust the position and placement angle of the binocular camera.

Images