Pre-compensation flexible assembling and adjusting mechanism of large-aperture transmission reflector

Abstract

The invention relates to a pre-compensation flexible assembling and adjusting mechanism of a large-diameter transmission reflector. The pre-compensation flexible assembling and adjusting mechanism comprises the large-diameter transmission reflector, a glue joint mandrel, an isolation telecentric flexible hinge, an isolation plate, a hooke flexible hinge, an adjusting flexible branch chain, an anti-rotation flexible branch chain, a back plate and a driving assembly. The large-aperture transmission reflector is provided with three blind holes for glue joint, and is connected with the isolation plate through three groups of glue joint mandrels and isolation telecentric flexible hinges, so that isolation of load deformation interference of the isolation plate is realized; the driving ends of the two adjusting flexible branch chains are correspondingly connected with two driving assemblies installed on the back plate, and the connecting ends of the adjusting flexible branch chains are connected with the isolation plate. One ends of the Hooke flexible hinges and the anti-rotation flexible branch chains are connected with the isolation plate, and the other ends are connected with the back plate; the device has the advantages of being simple in structural form, stable in movement and high in precision, meanwhile, the return clearance caused by axial load reversing under heavy loads can be avoided, the additional surface shape caused by assembling and adjusting stress is effectively isolated, and the additional surface shape caused by gravity is compensated.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of precision optical machines, and particularly relates to a pre-compensation flexible adjustment mechanism for a large-aperture transmission mirror of a high-power fixed laser device. BACKGROUND

[0002] In a high-power solid laser device, the main responsibility of the transmission mirror is to accurately divert the laser beam from the amplifier to the target chamber direction from the linear array, complete the spatial diversion from the horizontal optical path to the radial incidence of the target field, and ensure that each beam line has a strictly matched optical path and arrival timing. Since the transmission mirror is located at the end of the optical link, its surface error and angle error have little room for subsequent correction, so the error margin allowed in error distribution is extremely small.

[0003] When the large-aperture transmission mirror is used in laser deflection or imaging path turning scenarios, it is mostly in a 45° inclined attitude with the optical axis. The existing installation form mostly adopts peripheral clamping, which has the advantages of good stability and low adjustment additional deformation, but has limited compensation capability for the surface deformation of the central area of the mirror caused by gravity, and it is difficult to meet the high surface accuracy requirement. On the other hand, the existing back support method has a better surface shape in a specific attitude, but the adjustment stress generated during the attitude adjustment process will be directly transmitted to the mirror body, resulting in additional surface error and affecting the final surface accuracy.

[0004] Therefore, it is urgent to develop a new type of adjustment mechanism that can effectively isolate the adjustment stress and compensate for the mirror deformation caused by gravity while ensuring the support rigidity and adjustment accuracy, so as to meet the stringent application requirements of large-aperture transmission mirrors in high-precision optical systems. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the existing large-aperture transmission mirror support and adjustment technology, and to provide a pre-compensation flexible adjustment mechanism for a large-aperture transmission mirror. The mechanism aims to effectively isolate the stress generated during the adjustment process and avoid its impact on the mirror surface accuracy. At the same time, it can actively compensate for the additional surface of the mirror caused by gravity, and maintain high-precision surface shape in 45° overhead and overhead and other inclined attitudes. Through precise flexible design, the return gap in the movement process is eliminated, ensuring high precision and high stability of the attitude adjustment.

[0006] To achieve the above purpose, the present application adopts the following technical solutions: A pre-compensation flexible adjustment mechanism for a large-aperture transmission mirror, characterized in that it comprises: A large-aperture transmission mirror, the back of the lens is provided with three blind holes in an inverted isosceles triangle distribution; Three adhesive mandrels are fixed in the three blind holes respectively by adhesive, and gaps are reserved between the end of each adhesive mandrel and the bottom of the corresponding blind hole to avoid the adjustment stress affecting the surface accuracy directly through the bottom of the blind hole. An isolation plate is arranged parallel to the back of the large-aperture transmission mirror. Three isolated remote flexible hinges are fixed at one end to the three adhesive mandrels respectively and at the other end to the isolation plate, so as to flexibly connect the large-aperture transmission mirror to the isolation plate in a three-point support manner and form a first-level flexible isolation structure for isolating the adjustment stress and the deformation of the isolation plate. A back plate is arranged opposite to the isolation plate. A hooke flexible hinge is fixed at both ends to the isolation plate and the back plate respectively to provide the isolation plate with the rotation freedom around two orthogonal axes. Two drive assemblies are fixedly installed on the back plate. Two adjustment flexible branches each include a connection end and a drive end, the connection end is fixedly connected to the isolation plate, and the drive end is connected to the output end of the corresponding drive assembly, so that the adjustment flexible branch is driven to produce axial displacement by the drive assembly to push the isolation plate together with the large-aperture transmission mirror to perform pitch and yaw attitude adjustment around the hooke flexible hinge. A rotation-prevention flexible branch is fixed at both ends to the isolation plate and the back plate respectively to limit the in-plane rotation freedom of the isolation plate relative to the back plate.

[0007] Further, the isolated remote flexible hinge is composed of four thin segments with the same parameters and interacting with the same remote common intersection line, and the remote common intersection line is parallel to the short side of the front surface of the large-aperture transmission mirror during installation.

[0008] Further, the hooke flexible hinge is composed of two remote flexible hinge structures with the same structure fixed orthogonally at the proximal end, and the common intersection lines of the two remote flexible hinge structures are perpendicular to each other; during installation, one of the common intersection lines of the hooke flexible hinge is ensured to be parallel to the short side of the front surface of the large-aperture transmission mirror.

[0009] Further, the hooke flexible hinge and the two adjustment flexible branches are distributed in an inverted isosceles triangle, forming three flexible support points, wherein the support point at the top corner is the hooke flexible hinge, and the two support points at the two ends of the bottom side are the connection ends of the two adjustment flexible branches.

[0010] Further, the central axis of the anti-rotation flexible branch is located in a common plane formed by two mutually perpendicular common intersection lines of the hook flexible hinge.

[0011] Further, when installed obliquely, a normal line of a front surface of the large-aperture transmission mirror forms a predetermined inclination angle with a horizontal plane, and the hook flexible hinge is located at an upper vertex of the isosceles triangle distribution for gravity pre-compensation in a downward-looking posture, or the hook flexible hinge is located at a lower vertex of the isosceles triangle distribution for gravity pre-compensation in an upward-looking posture.

[0012] Compared with the prior art, the present application has the following beneficial effects: 1. The parallel flexible mechanism based on the hook flexible hinge reduces the adjustment stress of the mechanism while ensuring stability, avoids the backstroke gap of the driving assembly caused by the axial load reversal due to excessively high rigidity during posture adjustment, and improves the adjustment accuracy. 2. The deformation characteristics of the telecentric flexible hinge are isolated to pre-compensate the transmission mirror for gravity, complement the additional surface shape caused by gravity, and effectively improve the surface shape accuracy of the transmission mirror in the downward-looking and upward-looking postures by using the same structure.

[0013] 3. The large-aperture transmission mirror is isolated from the isolation plate by the telecentric flexible hinge, which reduces the influence of the mechanism stress and the strain of the isolation plate on the surface shape of the transmission mirror during posture adjustment. Based on finite element simulation, the overall additional surface shape is less than 200 nm within the range of ±15 mrad of the pitch and yaw postures from the initial position. 4. The anti-rotation flexible branch is coplanar with the rotation plane of the hook flexible hinge, which further improves the in-plane stability while reducing the motion coupling during adjustment.

[0014] In addition to the technical problems solved by the present application, the technical features constituting the technical solutions, and the advantages brought by these technical features as described above, other technical problems solved by the present application, other technical features included in the technical solutions, and the advantages brought by these technical features will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be considered as limiting the scope of protection of the present application.

[0016] Figure 1 The structural schematic diagram of the embodiment of the present application; Figure 2 The structural explosion schematic diagram of the embodiment of the present application; Figure 3 This is a schematic diagram of the large-aperture transmission reflector and its partial assembly relationship according to an embodiment of the present invention; Figure 4 This is an intermediate sectional view and a partial sectional view of an embodiment of the present invention; Figure 5 This is a schematic diagram of the adjustable flexible branch in an embodiment of the present invention; Figure 6 This is a schematic diagram of an isolated telecentric flexible hinge according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the Hooke flexible hinge according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the mechanism deformation according to an embodiment of the present invention; (enlarged deformation scale) Figure 9 This describes the initial angle and additional surface shape under some extreme attitudes of the embodiments of the present invention; In the picture: 1-Large-aperture transmission mirror: 11-Blind aperture, 111-Single-aperture side blind aperture, 112-Double-aperture side blind aperture, front surface short side 12 parallel; 2-Glued mandrel; 3-Isolated telecentric flexible hinge: 301-Telecentric common intersection line, 302-Thin segment, 31-Proximal end of isolated telecentric flexible hinge, 32-Telecentric end of isolated telecentric flexible hinge; 4-Separation plate; 5-Hooke flexible hinge: 51-Telecentric flexible hinge structure, 511-Common intersection line, 512-Thin segment, 513-Proximal end of telecentric flexible hinge structure, 514-Common plane; 6-Adjusting flexible branch: 61-Adjusting flexible branch connection end, 62-Adjusting flexible branch drive end; 7-Anti-spin flexible branch chain; 71-Central axis; 8-Back plate; 9-Drive assembly; Detailed Implementation

[0017] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the scope of protection of the present invention.

[0018] like Figures 1 to 7 As shown, this embodiment provides a pre-compensation flexible assembly and adjustment mechanism for a large-aperture transmission reflector. Through the coordinated operation of two-stage flexible systems, it achieves isolation of assembly and adjustment stress and pre-compensation of the gravity surface shape. The first-stage flexible system consists of an isolating telecentric flexible hinge 3, used to isolate downstream assembly and adjustment stress and deformation of the isolation plate. The second-stage flexible system is a parallel mechanism consisting of a Hooke flexible hinge 5, an adjusting flexible branch 6, and an anti-rotation flexible branch 7, used to achieve high-precision attitude adjustment and transmit pre-compensation deformation. The specific structure is as follows: The large aperture transmission mirror 1 has a caliber of 610mm*440mm*85mm, and three blind holes 11 with the same depth and size are arranged in an inverted isosceles triangle on the back of the large aperture transmission mirror 1.

[0019] The outer diameter of the glued mandrel 2 and the inner diameter of the blind hole 11 are kept at a gap of 0.02-0.05mm for adhesive filling. The glued mandrel 2 is fixed in the blind hole 11 by gluing, and the space between the end of the three glued mandrels 2 and the bottom of the blind hole 11 is 4mm±0.1mm, which is used as a stress isolation layer to avoid the local stress in the subsequent adjustment affecting the surface shape of the large aperture transmission mirror 1.

[0020] The three isolated telecentric flexible hinges 3 are respectively fixedly connected with the glued mandrels 2 in the three blind holes 11. That is, the glued mandrel on the single-hole side blind hole 111 at the top angle of the inverted isosceles triangle is connected with the telecentric end 32 of the corresponding isolated telecentric flexible hinge 3, and the glued mandrel on the double-hole side blind hole 112 at the two ends of the bottom is connected with the near-center end 31 of the corresponding isolated telecentric flexible hinge 3. The asymmetric connection mode of "one telecentric and two near-center" lays a mechanical foundation for subsequent gravity pre-compensation. The other end of all the isolated telecentric flexible hinges 3 is connected with the isolation plate 4 through a precision screw. During installation, it is necessary to ensure that the telecentric common intersection line 301 of each isolated telecentric flexible hinge 3 is parallel to the short side 12 of the front surface of the large aperture transmission mirror 1, and all the intersection lines are coplanar or have a small preset angle (<0.5°) to ensure that the flexibility of the three hinges in the same direction is consistent.

[0021] One end of the hooke flexible hinge 5 is fixed on the isolation plate 4 by a screw, and the installation position corresponds to the top angle position of the aforementioned inverted isosceles triangle. During installation, it is necessary to ensure that one of the common intersection lines 511 of the hooke flexible hinge 5 is parallel to the short side 12 of the front surface of the large aperture transmission mirror 1.

[0022] The connection ends 61 of the two adjustment flexible branches 6 are symmetrically fixed on the isolation plate 4 by screws, corresponding to the two end points of the bottom of the aforementioned isosceles triangle. The adjustment flexible branch 6 can adopt a parallel leaf spring type or a double-axis orthogonal hinge type flexible mechanism, and the axial stiffness should be much larger than the bending stiffness of the hooke flexible hinge 5 to provide effective driving force.

[0023] The two ends of the anti-rotation flexible branch 7 are respectively connected with the isolation plate 4 and the back plate 8. During installation, the central axis 71 of the anti-rotation flexible branch 7 must be located in the common plane 514 formed by the two mutually perpendicular common intersection lines 511 of the hooke flexible hinge 5. The deviation of the central axis 71 from the plane can be measured and adjusted by a laser tracker or an electronic autocollimator to ensure that the deviation is not greater than 0.1mm. Thus, the constraint coupling of the anti-rotation branch to the attitude adjustment movement is reduced.

[0024] Two driving components 9 (such as piezoelectric ceramic actuators or precision micro-differential heads) are installed on the back plate 8, and their output ends are connected with the driving ends 62 of the adjusting flexible branch chain 6. The driving components 9 should be equipped with high-resolution position sensors (such as capacitive sensors or grating rulers) to form a closed-loop control.

[0025] The assembled "mirror-isolation plate" assembly is integrally installed on the back plate 8 through the Hooke flexible hinge 5, the adjusting flexible branch chain 6 and the anti-rotation flexible branch chain 7.

[0026] As shown in Figure 6 The isolation remote center flexible hinge 3 is composed of four thin segments 302 with the same parameters and interacting with the same remote center common intersection line 301 in parallel, which has the supporting ability while providing the rotation freedom around the remote center common intersection line 301. The remote center common intersection line 301 of the isolation remote center flexible hinge 3 is ensured to be parallel to the short side 12 of the front surface of the large-aperture transmission mirror 1 during installation.

[0027] As shown in Figure 7 The Hooke flexible hinge 5 is composed of two remote center flexible hinge structures 51 in orthogonal; the remote center flexible hinge structure 51 is composed of four thin segments 512 with the same parameters and interacting with the same common intersection line 511 in parallel; the Hooke flexible hinge 5 is fixedly connected through the proximal ends 513 of the two remote center flexible hinge structures during assembly, and the common intersection lines 511 are ensured to be perpendicular to each other; when the Hooke flexible hinge 5 is fixedly connected with the isolation plate 4, the horizontal common intersection line 5111 of the remote center flexible hinge structure 51 close to the isolation plate 4 should be parallel to the short side 12 of the front surface of the large-aperture transmission mirror 1. The central axis 71 of the anti-rotation flexible branch chain 7 should be located in the common plane 514 composed of the two perpendicular common intersection lines 511 of the Hooke flexible hinge 5, which improves the in-plane stability while reducing the motion coupling during assembly and adjustment.

[0028] When used in a 45° overhead posture (the light beam irradiates the mirror from top to bottom), the Hooke flexible hinge 5 is ensured to be located above the entire mechanism (i.e. the upper vertex of the isosceles triangle).

[0029] When used in a 45° overhead posture (the light beam irradiates the mirror from top to bottom), the Hooke flexible hinge 5 is ensured to be located above the entire mechanism (i.e. the upper vertex of the isosceles triangle).

[0030] The pre-compensation working mechanism is as follows: As shown in Figure 8As shown, for 45° top view posture, the gravity can be decomposed into a component perpendicular to the mirror normal and a component parallel to the tangent. The normal component will cause a convex deformation tendency of the large aperture transmission mirror 1. At this time, the upper Hook flexible hinge 5 will have a tendency of small lateral shift and rotation along the tangent direction of the gravity, and is supported by the two adjustment flexible branches 6 to achieve balance, which causes the isolation plate 4 to have a concave micro-deformation towards the back plate 8. The concave micro-deformation is transmitted to the large aperture transmission mirror 1 through the three isolation telecentric flexible hinges 3, so that the large aperture transmission mirror 1 also has a concave pre-deformation towards the back plate 8. This concave pre-deformation is opposite to the convex deformation tendency caused by the normal component of the gravity, thereby realizing the gravity pre-compensation. It should be noted that the deformation degree of the isolation plate 4 is much larger than the concave micro-deformation of the large aperture transmission mirror 1.

[0031] Similarly, for 45° top view posture, the lower Hook flexible hinge 5 will have a tendency of small lateral shift and rotation along the tangent direction of the gravity, and is supported by the two adjustment flexible branches 6 to achieve balance, which causes the isolation plate 4 to have a convex micro-deformation towards the large aperture transmission mirror 1, and is transmitted to the large aperture transmission mirror 1 through the three isolation telecentric flexible hinges 3, so that the large aperture transmission mirror 1 also has a convex micro-deformation towards the back plate 8, thereby realizing the compensation of the concave micro-deformation of the large aperture transmission mirror 1 caused by the normal component of the gravity.

[0032] Therefore, the proximal end 31 of the isolation telecentric flexible hinge 3 on the same side of the Hook flexible hinge 5 is opposite to the proximal end 513 of the telecentric flexible hinge structure 51 on the side of the Hook flexible hinge 5 close to the isolation plate 4, thereby realizing the relief of the concave micro-deformation tendency.

[0033] As shown in Figure 9 , based on finite element simulation analysis, the surface shape of the large aperture transmission mirror 1 at the initial zero position under 45° top view posture is shown in Figure 9 a and Figure 9 d. As a comparison, the surface shape simulation after the posture adjustment based on the initial zero position, the surface shape change in the preset pitch limit adjustment range (±15 mrad) is shown in Figure 9 b and Figure 9 c; the surface shape change in the yaw limit adjustment range (±15 mrad) is shown in Figure 9 e and Figure 9 f. The simulation structure shows that the pre-compensation flexible adjustment mechanism can not only effectively compensate the surface shape precision deterioration caused by the gravity, but also provide excellent surface shape keeping ability to isolate the adjustment stress from affecting the surface shape precision.

[0034] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto. Any changes or replacements within the technical scope disclosed by the present application can be easily conceived by those skilled in the art, and shall be covered within the protection scope of the present application.

Claims

1. A pre-compensation flexible assembly and adjustment mechanism for a large-aperture transmission reflector, characterized in that, include: A large-aperture transmission mirror (1) has three blind holes (11) arranged in an inverted isosceles triangle on the back of its lens. Three adhesive mandrels (2) are respectively fixed in the three blind holes (11) by adhesive bonding, and a gap is maintained between the end of each adhesive mandrel (2) and the bottom of the corresponding blind hole (11) to avoid the installation and adjustment stress directly affecting the surface accuracy through the bottom of the blind hole (11); An isolation plate (4) is arranged parallel to the back of the large-aperture transmission reflector (1); Three isolation telecentric flexible hinges (3), one end of the three isolation telecentric flexible hinges (3) are fixedly connected to the three adhesive mandrels (2) respectively, and the other end is fixedly connected to the isolation plate (4), so that the large-diameter transmission reflector (1) is flexibly connected to the isolation plate (4) in a three-point support manner, and forms a first-level flexible isolation structure for isolating stress and deformation of the isolation plate; A back plate (8) is disposed opposite to the isolation plate (4); A Hooke flexible hinge (5) is fixedly connected at both ends to the isolation plate (4) and the back plate (8) respectively, providing the isolation plate (4) with rotational degrees of freedom about two orthogonal axes; Two drive components (9) are fixedly mounted on the back plate (8); Two adjustable flexible branches (6), each adjustable flexible branch (6) includes a connecting end (61) and a driving end (62). The connecting end (61) is fixedly connected to the isolation plate (4), and the driving end (62) is connected to the output end of the corresponding driving component (9). The driving component (9) drives the adjustable flexible branch (6) to generate axial displacement, so as to push the isolation plate (4) together with the large-aperture transmission reflector (1) to adjust the pitch and yaw attitude around the Hooke flexible hinge (5). An anti-rotation flexible branch (7) is fixedly connected at both ends to the isolation plate (4) and the back plate (8) respectively, and is used to restrict the in-plane rotational freedom of the isolation plate (4) relative to the back plate (8).

2. The pre-compensation flexible adjustment mechanism for the large-aperture transmission reflector according to claim 1, characterized in that, The isolated telecentric flexible hinge (3) is composed of four thin segments (302) with the same parameters and all interacting on the same telecentric common intersection line (301) connected in parallel, and its telecentric common intersection line (301) is parallel to the short side (12) of the front surface of the large-aperture transmission reflector (1) during installation.

3. The pre-compensation flexible assembly mechanism for the large-aperture transmission reflector according to claim 1, characterized in that, The Hooke flexible hinge (5) is formed by two identical telecentric flexible hinge structures (51) orthogonally fixedly connected at their proximal ends (513), and the common intersection line (511) of the two telecentric flexible hinge structures (51) is perpendicular to each other; during installation, ensure that one of the common intersection lines (511) of the Hooke flexible hinge (5) is parallel to the short side (12) of the front surface of the large-aperture transmission reflector (1).

4. The pre-compensation flexible adjustment mechanism for the large-aperture transmission reflector according to claim 1, characterized in that, The Hooke flexible hinge (5) and the two adjustable flexible branches (6) are arranged in an inverted isosceles triangle to form three flexible support points. The support point located at the apex is the Hooke flexible hinge (5), and the two support points located at the two ends of the bottom edge are the connection ends (61) of the two adjustable flexible branches (6).

5. The pre-compensation flexible adjustment mechanism for the large-aperture transmission reflector according to claim 1, characterized in that, The central axis (71) of the anti-rotation flexible branch (7) is located in the common plane (514) formed by the two mutually perpendicular common intersection lines (511) of the Hooke flexible hinge (5).

6. The pre-compensation flexible assembly mechanism for a large-aperture transmission reflector according to any one of claims 1-5, characterized in that, When installed at an angle, the normal to the front surface of the large-aperture transmission mirror (1) will form a predetermined angle with the horizontal plane, and the Hooke flexible hinge (5) will be located at the upper vertex of the isosceles triangle distribution for gravity pre-compensation in the downward orientation; or, the Hooke flexible hinge (5) will be located at the lower vertex of the isosceles triangle distribution for gravity pre-compensation in the upward orientation.

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