Calibration-free double-optical-wedge high-precision direction adjusting device and method

Abstract

The invention relates to an uncalibrated double-optical-wedge high-precision pointing adjustment device and method, and the device comprises a first optical wedge adjustment mechanism, a second optical wedge adjustment mechanism, a beam expander, a corner reflection light guide prism, a diffraction beam splitting module, a pointing monitoring lens, a pointing monitoring focal plane, and a processing and control module. Laser sequentially enters the first optical wedge adjusting mechanism, the second optical wedge adjusting mechanism, the beam expander, the corner reflection light guide prism, the diffraction beam splitting module, the pointing monitoring lens and the pointing monitoring focal plane, the detector of the pointing monitoring focal plane records focal plane light spot information, and finally the processing and control module calculates laser pointing information according to focal plane light spots. And the two optical wedge adjusting mechanisms are controlled to rotate, so that the direction of the laser reaches an adjusting target value. The optical wedge does not need to be absolutely calibrated, scales do not need to be calibrated, the pointing monitoring precision is multiplied through diffraction beam splitting, and the environment adaptability and reliability are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of laser remote sensing and relates to a non-calibrated double optical wedge high-precision pointing adjustment device and method. Background Art

[0002] In laser remote sensing technology, using dual optical wedges to adjust laser pointing is a common method. After the target direction is given, the dual optical wedge adjustment mechanism needs to adjust a certain rotation angle each to make the synthesized laser aim at the target.

[0003] At present, the use of dual optical wedges for adjustment often requires absolute calibration of the optical wedge rotation angle. After the dual optical wedges are installed, the scales are marked on the structures of the two optical wedges through absolute calibration, and then the rotation angle is calculated based on the target pointing from the calibrated scales. Although this method of use is simple to calculate, it places high demands on calibration accuracy and structural stability in many working conditions where high pointing accuracy is required and there are mechanical shocks, vibrations, etc. When the optical wedge hardware parameters change due to shocks, vibrations, changes in gravity conditions, etc., the rotation angle calculated by the absolute calibration parameters will have large errors, and may even fail to point to the target direction.

[0004] In addition, the adjustment angle resolution of the dual optical wedge is closely related to its vertex angle and rotation angle resolution. High-precision pointing angle adjustment often requires high rotation angle resolution and high-precision rotation angle control. High rotation angle control accuracy places extremely high requirements on the accuracy and cost of the control mechanism, increasing the cost and reliability requirements of the solution implementation. Summary of the invention

[0005] The technical problem solved by the present invention is to overcome the deficiencies of the prior art and propose a non-calibrated double optical wedge high-precision pointing adjustment device and method, which does not require absolute calibration of the optical wedges and improves environmental adaptability and reliability.

[0006] The technical solution of the present invention is: a non-calibrated double-optical wedge high-precision pointing adjustment device, which emits a single-wavelength collimated laser from a laser, and includes a first optical wedge adjustment mechanism, a second optical wedge adjustment mechanism, a beam expander, an angle reflection light guide prism, a diffraction beam splitting module, a pointing monitoring lens, a pointing monitoring focal plane and a processing and control module;

[0007] The first optical wedge adjustment mechanism and the second optical wedge adjustment mechanism have the same structure, and the direction of the collimated laser is deflected around the light output axis of the laser in three-dimensional space through refraction and rotation;

[0008] The beam expander is used to thicken the laser beam and compress the divergence angle;

[0009] Corner reflective light guide prism is used to flip a laser beam in the completely opposite direction;

[0010] The diffraction beam splitting module is used to split a laser beam into multiple laser beams according to a specific angle distribution;

[0011] The pointing monitoring lens is used to focus the laser beams in multiple different directions onto the pointing monitoring focal plane;

[0012] The pointing monitoring focal plane is a planar array detector installed on the focal plane of the pointing monitoring lens, and is capable of detecting a laser spot image corresponding to the laser beam;

[0013] The processing and control module extracts the centroid according to the laser spot on the pointing monitoring focal plane, calculates the pointing data of the laser emitted from the beam expander, calculates the deviation between the pointing data and the target according to the pointing adjustment target input to the processing and control module, and then calculates the adjustment amount of the first optical wedge adjustment mechanism and the second optical wedge adjustment mechanism to rotate, controls the first optical wedge adjustment mechanism and the second optical wedge adjustment mechanism to rotate, so that the pointing direction of the laser reaches the adjustment target value.

[0014] Furthermore, the angle-reflecting light-guiding prism supports full-aperture light collection or partial light collection.

[0015] Furthermore, the first optical wedge adjustment mechanism and the second optical wedge pointing adjustment mechanism can be replaced by a pointing scanning mirror.

[0016] Furthermore, the beam expander is a transmission beam expander or a reflection beam expander.

[0017] Furthermore, the corner reflection light-guiding prism is a corner reflection or a special-shaped corner reflection mirror with a cut-off top angle.

[0018] Furthermore, the diffraction beam splitting module is any one of a DOE element, a birefringent beam splitting element, and a metasurface lens element.

[0019] A method for high-precision pointing adjustment of double optical wedges without calibration, comprising the following steps:

[0020] The processing and control module (8) extracts the initial average position of the laser spot on the pointing monitoring focal plane (7) as A(x mA ,y mA ), the main optical axes of the two optical wedge rotating mechanisms are at the corresponding positions Z(x Z ,y Z ) is unknown, the adjustment target of the laser spot on the monitoring focal plane (7) is O(x O ,y O );

[0021] The first optical wedge adjustment mechanism (1) and the second optical wedge adjustment mechanism (2) are rotated 180° clockwise to emit laser light. At this time, the processing and control module (8) extracts the average position of the laser light spot on the pointing monitoring focal plane (7) as B(x mB ,ymB ), according to A(x mA ,y mA ) and B(x mB ,y mB ) to calculate the corresponding position Z(x) of the main optical axis of the two optical wedge rotating mechanisms on the pointing monitoring focal plane (7) Z ,y Z );

[0022] Turn the first wedge adjustment mechanism (1) clockwise. At the same time, the second optical wedge adjustment mechanism (2) rotates counterclockwise The laser is emitted. At this time, the processing and control module (8) extracts the average position of the laser spot on the pointing monitoring focal plane (7) as C(x mC ,y mC );

[0023] Calculate the rotation angle required to adjust B to Z The rotation angle required from B to O The rotation angle required from Z to O

[0024] The following judgment criteria are calculated:

[0025]

[0026] x O ′=x O (y mB -y Z )+y O (x Z -x mB )+x mB y Z -x Z y mB

[0027] Calculate the clockwise rotation angle of the first wedge adjustment mechanism (1) The second optical wedge adjustment mechanism (2) rotates clockwise by an angle Rotate the two optical wedge adjustment mechanisms to move the center of the laser spot pointing to the monitoring focal plane (7) to the target position O(x O ,y O ):

[0028]

[0029] Furthermore, the

[0030] Furthermore, Z(x Z ,y Z ) is calculated as:

[0031]

[0032] Furthermore, the rotation angle The calculation method is as follows:

[0033]

[0034] Where n is the refractive index of the optical wedge, α is the apex angle of the optical wedge, K is the beam expansion factor, F is the focal length of the monitoring lens (6), and L is AB , L OZ , L BZ , L OB is the straight-line distance between the centers of the light spots in the monitoring focal plane (7), which are respectively expressed as:

[0035]

[0036] The beneficial effects of the present invention compared with the prior art are:

[0037] (1) The present invention does not require absolute calibration of the optical wedge, and does not require calibration of the scale, thereby improving environmental adaptability and reliability;

[0038] (2) The present invention improves the pointing monitoring accuracy by multiples through diffraction beam splitting, thereby reducing the pointing recording error. times, M is the number of laser beam splitting by the diffraction beam splitting module, thereby reducing the difficulty and cost of monitoring cameras;

[0039] (3) The present invention improves the pointing accuracy exponentially with low rotational resolution, thereby reducing the difficulty in developing a high-precision pointing adjustment system and the cost of the mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 A schematic diagram of a non-calibrated double-optical wedge high-precision pointing adjustment device of the present invention;

[0041] Figure 2 A schematic diagram of the three-dimensional coordinates formed by the optical axis z of the pointing monitoring lens and the pointing monitoring focal plane;

[0042] Figure 3 This is a schematic diagram of the position relationship of each point in step 1;

[0043] Figure 4 This is a schematic diagram of the position relationship of each point in step 2;

[0044] Figure 5 This is a schematic diagram of a high-precision pointing adjustment device without calibration double optical wedges according to Example 1;

[0045] Figure 6 This is the diffraction beam splitting and monitoring of the spot distribution on the focal plane in Example 1. DETAILED DESCRIPTION

[0046] like Figure 1 As shown, the present invention proposes a calibration-free double-wedge high-precision pointing adjustment device, which includes a first wedge adjustment mechanism 1, a second wedge adjustment mechanism 2, a beam expander 3, an angle reflection light guide prism 4, a diffraction beam splitting module 5, a pointing monitoring lens 6, a pointing monitoring focal plane 7 and a processing and control module 8; a single-wavelength collimated laser is emitted by a laser.

[0047] The first optical wedge adjustment mechanism 1 and the second optical wedge adjustment mechanism 2 have the same structure, and the direction of the collimated laser is deflected around the light output axis of the laser in three-dimensional space through refraction and rotation;

[0048] The beam expander 3 is used to thicken the laser beam and compress the divergence angle;

[0049] The corner reflection light-guiding prism 4 is used to flip a laser beam in a completely opposite direction;

[0050] The diffraction beam splitting module 5 is used to split a laser beam into multiple laser beams according to a specific angle distribution;

[0051] The pointing monitoring lens 6 is used to focus the laser beams in multiple different directions on the pointing monitoring focal plane 7;

[0052] The pointing monitoring focal plane 7 is a planar array detector installed on the focal plane of the pointing monitoring lens 6, and is capable of detecting a laser spot image corresponding to the laser beam;

[0053] The processing and control module 8 extracts the centroid according to the laser spot on the pointing monitoring focal plane 7, calculates the pointing data of the laser emitted from the beam expander 3, calculates the deviation between the pointing data and the target according to the pointing adjustment target input to the processing and control module 8, and then calculates the adjustment amount of the first optical wedge adjustment mechanism 1 and the second optical wedge adjustment mechanism 2, controls the rotation of the first optical wedge adjustment mechanism 1 and the second optical wedge adjustment mechanism 2, so that the pointing direction of the laser reaches the adjustment target value.

[0054] The optical path process is:

[0055] The laser enters the first optical wedge adjustment mechanism 1, the second optical wedge adjustment mechanism 2, the beam expander 3, the corner reflection light guide prism 4, the diffraction beam splitting module 5, the pointing monitoring lens 6, and the pointing monitoring focal plane 7 in sequence. The detector pointing to the monitoring focal plane 7 records the focal plane spot information. Finally, the processing and control module 8 calculates the laser pointing information according to the focal plane spot.

[0056] The laser enters the subsequent optical path after passing through the fixed optical wedge adjustment mechanism 1 and the optical wedge adjustment mechanism 2, and finally obtains a pointing monitoring image containing M light spots distributed on the pointing monitoring focal plane 7 through the optical path. The processing and control module 8 extracts the positions of the M light spots {(x1, y1), (x2, y2)…(x M ,y M )}, and then calculate the average spot position (x m ,y m ), the calculation formula is:

[0057]

[0058] Assume that the three-dimensional coordinates formed by the optical axis z pointing to the monitoring lens 6 and the monitoring focal plane 7 are as follows: Figure 2 As shown, the three-dimensional coordinate system is established as follows: the optical axis z pointing to the monitoring lens 6 is consistent with the optical axis direction of the laser, and the x direction is any direction in the plane perpendicular to the optical axis z, and the x direction is determined by the right-hand rule. Assuming the focal length of the monitoring lens 6 is F, the angle θ between the laser pointing to the z axis after the beam expander 3 is z The calculation formula is:

[0059]

[0060] The laser beam emitted by the beam expander 3 points to the azimuth angle θ on the xy projection plane. x The calculation formula is:

[0061]

[0062] Assuming that the pointing measurement error of a single light spot is Δθ, the pointing jitter measurement error measured by M light spots is:

[0063]

[0064] Therefore, the laser pointing measurement value range of the processing and control module 8 is θ z ±Δθ m , the pointing jitter measurement error is reduced to the existing adjustment mechanism M is the number of laser beam splittings performed by the diffraction beam splitting module.

[0065] In the device of the present invention, the corner reflective light-guiding prism 4 can take in light at full aperture, in which case it needs to be coated with a semi-reflective and semi-transparent film; or take in light partially, in which case it does not need to be coated with a semi-reflective and semi-transparent film.

[0066] The first optical wedge adjustment mechanism 1 and the second optical wedge pointing adjustment mechanism 2 can be replaced by other mechanisms such as pointing scanning mirrors that can realize light beam pointing adjustment.

[0067] The beam expander 3 can be a transmission beam expander or a reflection beam expander.

[0068] The corner reflection light guide prism 4 is a special-shaped corner reflection mirror with corner reflection or cut-off top angle.

[0069] The diffraction beam splitting module 5 can be a DOE element, a birefringent beam splitting element, a metasurface lens element, or the like, which has the function of splitting a single beam of light into multiple beams with overlapping exit light spots.

[0070] The present invention provides a high-precision pointing adjustment method for double optical wedges without calibration, comprising the following steps:

[0071] Step 1: Figure 3 As shown, the processing and control module 8 extracts the initial average position of the laser spot on the pointing monitoring focal plane 7 as A(x mA ,y mA ), the main optical axes of the two optical wedge rotating mechanisms are pointing to the corresponding position Z (x Z ,y Z ) is unknown, the adjustment target of the laser spot on the monitoring focal plane 7 is O(x O ,y O ).

[0072] Step 2: Rotate the first optical wedge adjustment mechanism 1 and the second optical wedge adjustment mechanism 2 clockwise by 180° to emit laser. At this time, the processing and control module 8 extracts the average position of the laser spot on the pointing monitoring focal plane 7 as B(x mB ,y mB ).like Figure 4 As shown, at this time, the main optical axes of the two optical wedge rotating mechanisms are pointing to the corresponding position Z (x Z ,y Z ) is calculated as:

[0073]

[0074] Step 3: The first optical wedge adjustment mechanism 1 rotates clockwise At the same time, the second optical wedge adjustment mechanism 2 rotates counterclockwise The laser is emitted. At this time, the processing and control module 8 extracts the average position of the laser spot on the pointing monitoring focal plane 7 as C(x mC ,y mC ).

[0075] Step 4: Calculate the angle according to formulas (6), (7), and (8)

[0076]

[0077] in, are the rotation angles required for adjusting B to Z, B to O, and Z to O, respectively. n is the refractive index of the optical wedge, α is the vertex angle of the optical wedge, K is the beam expansion factor, F is the focal length of the monitoring lens 6, and L AB , L OZ , L BZ , L OB is the straight-line distance between the centers of the light spots in the monitoring focal plane 7, respectively expressed as:

[0078]

[0079] Step 5: Calculate the following judgment criteria:

[0080]

[0081] x O ′=x O (y mB -y Z )+y O (x Z -x mB )+x mB y Z -x Z y mB (11)

[0082] Step 6: Calculate the clockwise rotation angle of the first optical wedge adjustment mechanism 1 according to formulas (12) and (13): The second optical wedge adjustment mechanism 2 rotates clockwise by an angle Rotate the two optical wedge adjustment mechanisms to move the center of the laser spot pointing to the monitoring focal plane 7 to the target position O(x O ,y O ).

[0083]

[0084] The present invention will be further described below in conjunction with the embodiments.

[0085] Example 1

[0086] like Figure 5 As shown, the calibration-free double-optical wedge high-precision pointing adjustment device in this embodiment is composed of a first optical wedge adjustment mechanism 1, a second optical wedge adjustment mechanism 2, a beam expander 3, an angle reflection light guide prism 4, a diffraction beam splitting module 5, a pointing monitoring lens 6, a pointing monitoring focal plane 7 and a processing and control module 8.

[0087] The working wavelength of the laser is 1064nm. The laser it emits passes through the wedge adjustment mechanism 1, the wedge adjustment mechanism 2, the beam expander 3, the angle reflection light guide prism 4, the diffraction beam splitting module 5, and the pointing monitoring lens 6 in sequence before reaching the pointing monitoring focal plane 7, forming a laser spot on the pointing monitoring focal plane 7. The diffraction beam splitting module 5 splits the single laser beam into 9 laser beams with an angle of 0.1° between each other. The focal length of the pointing monitoring lens 6 is 350mm. The angular distribution of the 9 laser beams and their spot distribution on the array detector 7 are shown in Figure 6 .

[0088] According to formula (1), the centroid distribution of the monitoring focal spot is extracted, and the pointing information of the laser to be measured can be obtained by formula (2) and formula (3). If the laser pointing angle error corresponding to the calculation of the centroid of a single spot is Δθ, then it can be seen from formula (4) that the laser pointing angle error corresponding to the calculation of the centroid of 9 spots is Δθ / 3.

[0089] The vertex angles of the first optical wedge adjustment mechanism 1 and the second optical wedge adjustment mechanism 2 are both 1.2°, and the refractive index for the wavelength of 1064nm is 1.45. The beam expansion factor K of the beam expander 3 is 10. It is known that the rotation angle control resolution is 0.5°, so the double optical wedge adjustment resolution can be better than 200urad at most, and the adjustment accuracy of the system is better than 20urad.

[0090] At this time, the position O(x O ,y O ), then the laser spot can be adjusted to the target position O(x O ,y O ).

[0091] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0092] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A high-precision pointing adjustment device with double optical wedges without calibration, which emits single-wavelength collimated laser light from a laser, characterized in that: It comprises a first optical wedge adjustment mechanism (1), a second optical wedge adjustment mechanism (2), a beam expander (3), an angle reflection light guide prism (4), a diffraction beam splitting module (5), a pointing monitoring lens (6), a pointing monitoring focal plane (7) and a processing and control module (8); The first optical wedge adjustment mechanism (1) and the second optical wedge adjustment mechanism (2) have the same structure and deflect the direction of the collimated laser light around the light output axis of the laser in three-dimensional space through refraction and rotation; The beam expander (3) is used to thicken the laser beam and compress the divergence angle; The corner reflection light-guiding prism (4) is used to flip a laser beam in a completely opposite direction; The diffraction beam splitting module (5) is used to split a laser beam into multiple laser beams according to a specific angle distribution; The pointing monitoring lens (6) is used to focus the laser beams in multiple different directions onto the pointing monitoring focal plane (7); The pointing monitoring focal plane (7) is a planar array detector installed on the focal plane of the pointing monitoring lens (6), and is capable of detecting a laser spot image corresponding to the laser beam; The processing and control module (8) extracts the centroid according to the laser spot on the pointing monitoring focal plane (7), calculates the pointing data of the laser emitted from the beam expander (3), calculates the deviation between the pointing data and the target according to the pointing adjustment target input to the processing and control module (8), and further calculates the adjustment amount of the first optical wedge adjustment mechanism (1) and the second optical wedge adjustment mechanism (2) to rotate, and controls the first optical wedge adjustment mechanism (1) and the second optical wedge adjustment mechanism (2) to rotate so that the pointing direction of the laser reaches the adjustment target value.

2. The high-precision pointing adjustment device without calibration double optical wedge according to claim 1, characterized in that: The corner reflection light-guiding prism (4) supports full-aperture light extraction or partial light extraction.

3. The high-precision pointing adjustment device without calibration double optical wedge according to claim 1, characterized in that: The first optical wedge adjustment mechanism (1) and the second optical wedge pointing adjustment mechanism (2) can both be replaced by pointing scanning mirrors.

4. The high-precision pointing adjustment device without calibration double optical wedge according to claim 1, characterized in that: The beam expander (3) is a transmission beam expander or a reflection beam expander.

5. The high-precision pointing adjustment device without calibration double optical wedge according to claim 1, characterized in that: The corner reflection light-guiding prism (4) is a corner reflection or a special-shaped corner reflection mirror with the top angle cut off.

6. The high-precision pointing adjustment device without calibration double optical wedge according to claim 1, characterized in that: The diffraction beam splitting module (5) is any one of a DOE element, a birefringent beam splitting element, and a super-surface lens element.

7. A method for high-precision pointing adjustment of double optical wedges without calibration based on the device according to any one of claims 1 to 6, characterized in that: The following steps are involved: The processing and control module (8) extracts the initial average position of the laser spot on the pointing monitoring focal plane (7) as A(x mA ,y mA ), the main optical axes of the two optical wedge rotating mechanisms are at the corresponding positions Z(x Z ,y Z ) is unknown, the adjustment target of the laser spot on the monitoring focal plane (7) is O(x O ,y O ); The first optical wedge adjustment mechanism (1) and the second optical wedge adjustment mechanism (2) are rotated 180° clockwise to emit laser light. At this time, the processing and control module (8) extracts the average position of the laser light spot on the pointing monitoring focal plane (7) as B(x mB ,y mB ), according to A(x mA ,y mA ) and B(x mB ,y mB ) to calculate the corresponding position Z(x) of the main optical axis of the two optical wedge rotating mechanisms on the pointing monitoring focal plane (7) Z ,y Z ); Turn the first wedge adjustment mechanism (1) clockwise. At the same time, the second optical wedge adjustment mechanism (2) rotates counterclockwise The laser is emitted. At this time, the processing and control module (8) extracts the average position of the laser spot on the pointing monitoring focal plane (7) as C(x mC ,y mC ); Calculate the rotation angle required to adjust B to Z The rotation angle required from B to O The rotation angle required from Z to O The following judgment criteria are calculated: x O ′=x O (and mB -and Z )+y O (x Z -x mB )+x mB and Z -x Z and mB Calculate the clockwise rotation angle of the first wedge adjustment mechanism (1) The second optical wedge adjustment mechanism (2) rotates clockwise by an angle Rotate the two optical wedge adjustment mechanisms to move the center of the laser spot pointing to the monitoring focal plane (7) to the target position O(x O ,y O ):

8. The method for high-precision pointing adjustment of double optical wedges without calibration according to claim 7, characterized in that: Said 9. The method for high-precision pointing adjustment of double optical wedges without calibration according to claim 7, characterized in that: Z(x Z ,y Z ) is calculated as:

10. The method for high-precision pointing adjustment of double optical wedges without calibration according to claim 7, characterized in that: Rotation Angle The calculation method is as follows: Where n is the refractive index of the optical wedge, α is the apex angle of the optical wedge, K is the beam expansion factor, F is the focal length of the monitoring lens (6), and L is AB , L OZ , L BZ , L OB is the straight-line distance between the centers of the light spots in the monitoring focal plane (7), which are respectively expressed as:

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