A six-degree-of-freedom optical element precision control platform

Abstract

The present invention provides a six-degree-of-freedom optical element precision control platform, including a horizontal linear unit, a vertical linear unit, and a rotation unit connected by vertical coupling; the horizontal swing unit is fixed at the top, the horizontal linear unit completes horizontal movement in the x-axis and y-axis directions; the vertical linear unit completes vertical movement in the z-axis direction; the rotation unit completes rotation around the z-axis; the rotation unit drives the horizontal swing unit to complete circumferential rotation and angle adjustment; when the rotation unit moves, the three rotation axes of the rotation unit intersect at one point and are consistent with the center of the horizontal swing unit. The present invention uses a detachable assembly method, and the degree of freedom can be selected based on the mirror control requirements. When the mirror needs three degrees of freedom, it can be equipped with three degrees of freedom to reduce costs and improve stability. The three rotation axes of the rotation unit intersect at one point, and the center point can be adjusted vertically or horizontally, or the point can be fixed at the optical center of the mirror.

Description

Technical Field

[0001] The invention relates to the technical field of fast-reflection mirror motion control platform equipment, in particular to a six-degree-of-freedom optical element precision control platform. Background Art

[0002] In beamlines, we need to apply motion control with high resolution, high precision and high stability to optical components. Many different designs of optical component control platforms are used in traditional beamlines. Among them, the Hexapod six-degree-of-freedom displacement platform has become more popular in recent years.

[0003] For example, the six-axis platform motion simulation device disclosed in application number CN202011529062.3 for collecting and editing the driving parameters of the six-axis platform includes a base, a motion platform and six telescopic rods, wherein the six telescopic rods are installed between the base and the motion platform, and one end of each telescopic rod is hinged to the base ball, and the other end is hinged to the motion platform ball; the structure is simple, and when the control software drives the six telescopic rods to change their length, it can truly simulate the six-axis platform motion in the VR motion control system, and the operation is simple and easy, and the response sensitivity is high. The device achieves six degrees of freedom adjustment through 6 telescopic rods, but has the following shortcomings:

[0004] Movement in any one dimension requires complex control software to drive the six telescopic rods to move, and the six-dimensional movements are mutually restrained;

[0005] Unpredictable travel limits, limited trajectory range. The travel ranges listed for each dimension of the product are based on the premise that the other dimensions are in a neutral position (motion range is 0);

[0006] Speed ​​limitations;

[0007] The motion trajectory is not smooth and there are errors;

[0008] When six degrees of freedom are not required for some applications, the device cannot be streamlined.

[0009] In summary, the Hexapod six-degree-of-freedom displacement platform can realize the motion control of the six degrees of freedom (three translations and three rotations) of the mirror, and has the characteristics of high precision and high resolution. However, in practical applications, six degrees of freedom are not necessarily required, and it is hoped that the six movements will not restrain each other and can reach their motion limits at the same time; the use of traditional stacking displacement and angular displacement platforms is more economical and practical, but the performance parameters such as accuracy, resolution and stability do not meet the requirements. Moreover, the three rotation axes cannot intersect at one point, which brings about the mutual coupling of rotation and translation. Summary of the invention

[0010] The technical problem to be solved by the present invention is to provide an optical element precision control platform which can be arbitrarily combined and whose rotation center always intersects with a set center.

[0011] The present invention solves the above technical problems through the following technical means:

[0012] A six-degree-of-freedom optical element precision control platform comprises a horizontal linear unit (1), a vertical linear unit (2), and a rotation unit (3) connected in a vertical coupling manner; a horizontal swaying unit (4) is fixed at the top, the horizontal linear unit (1) completes horizontal movement in the x-axis and y-axis directions; the vertical linear unit (2) completes vertical movement in the z-axis direction; the rotation unit (3) completes rotation around the z-axis, and the horizontal swaying unit (4) completes rotation around the x-axis and the y-axis directions; the three rotation axes of the rotation unit (3) and the swaying unit (4) intersect at one point.

[0013] The present invention can be used for precise control of optical elements such as ordinary optical mirrors, fast-reflecting mirrors with piezoelectric motors or voice coil motors. The present invention uses a detachable assembly method, and the degree of freedom can be selected based on the mirror control requirements. According to the movement requirements of the optical element, three, four, five, or six degrees of freedom can be equipped to reduce costs and space and improve stability. Regardless of how the six movements change, the center of rotation remains constant relative to the top plane of the platform (optical element mounting surface) when necessary. The optical element can be properly installed on the top platform so that the pole of the optical element is consistent with the center of rotation. In this way, the six-dimensional motion of the optical element is decoupled from each other.

[0014] Furthermore, the vertical linear unit (2) comprises an upper wedge block (21) and a lower wedge block (22); the inclined surfaces of the upper wedge block (21) and the lower wedge block (22) are arranged relative to each other and slidably matched, and the bottom of the lower wedge block (22) is slidably fixed on the wedge block base (23); the lower wedge block (22) is provided with an elongated sliding hole (24) which passes through from top to bottom, and the length direction is consistent with the sliding direction of the lower wedge block (22); the upper wedge block (21) is provided with a limiting hole (26); a guide column (26') is fixed on the wedge block base (23), and the guide column (26') passes through the sliding hole (24) and the limiting hole (26) in sequence; when the lower wedge block (22) slides, the upper wedge block (21) moves up and down in the vertical direction along the guide column (26') under the limitation of the guide column (26').

[0015] Furthermore, the rotating unit (3) comprises a rotating base (31) and an angle adjustment mechanism; the rotating base (31) is detachably connected to the top of the lower unit; the upper surface of the inner ring of the rotating base (31) is rotatably connected to the bottom of the angle adjustment mechanism, and the rotating shaft coincides with the vertical center line of the fast reflex mirror.

[0016] Furthermore, the angle adjustment mechanism comprises a lower frame (32), an upper frame (33), and a central U-shaped frame (34); the upper frame (33) and the lower frame (32) are both U-shaped structures, and a hollow, contactless rectangular parallelepiped structure is formed after being buckled up and down, and the U-shaped frame (34) is located at the center of the rectangular parallelepiped, and the opening is in the vertical direction; the two side walls of the upper frame (33) and the two side walls opposite to the U-shaped frame (34) are slidably connected by a first pair of arc-shaped rails (35), and the two side walls of the lower frame (32) and the other two opposite side walls of the U-shaped frame (34) are slidably connected by a second pair of arc-shaped rails (36); the U-shaped frame (34) has no contact with the upper frame (33) and the lower frame (32); the lower frame (32) is rotatably connected to the rotating base (31).

[0017] Furthermore, the rotating unit (3) further comprises a rotating drive member (30), a rotating shaft is fixed at the bottom of the lower frame (32), the rotating shaft is vertically downward, and the output end of the rotating drive member (30) is rotatably connected to the rotating shaft fixed on the lower frame (32). The base of the rotating drive member (30) is fixed to a rotating frame (37), and the rotating frame (37) is rotatably connected to the side of the rotating base (31); the output end of the rotating frame (37) is rotatably connected to the rotating shaft. The output end of the rotating drive member (30) and the rotating shaft of the base are both parallel to the rotating shaft of the rotating base.

[0018] Furthermore, the angle adjustment mechanism also includes an upper frame driving member (38) and a lower frame driving member (39); the movable end of the upper frame driving member (38) is hinged to a first rotating ear (41) fixed to the upper frame (33), and the machine base is hinged to a second rotating ear fixed to the U-shaped frame (34); the movable end of the lower frame driving member (39) is hinged to a third rotating ear (42) of the U-shaped frame (34), and the machine base passes through the U-shaped frame (34) and is hinged to a fourth rotating ear fixed to the lower frame (32); the axis of the upper frame driving member (38) is perpendicular to a line connecting the hinge center of the first rotating ear (41) to the rotation center of the arc guide rail (35); the axis of the lower frame driving member (39) and a line connecting the axis center of the third rotating ear (42) to the axis of the arc guide rail (36) are mutually perpendicular.

[0019] Furthermore, the horizontal linear unit (1), the vertical linear unit (2), and the rotating unit (3) are all detachably fixed via a connecting plate (5).

[0020] Furthermore, the upper wedge block (21) and the lower wedge block (22) cooperate to form a rectangular parallelepiped structure.

[0021] Furthermore, a vertical guide column (26') is fixed on the upper wedge block 21, and a vertical guide sleeve (25) is fixed on the base 23. The guide column (26') and the guide sleeve (25) are precisely slidably matched to ensure that when the lower wedge block moves horizontally, the upper wedge block 21 only moves vertically. A waist-shaped groove is opened on the lower wedge block 22 to avoid being blocked by the guide sleeve (25). A hole (26) is opened on the upper wedge block 21 to prevent it from contacting the guide sleeve (25) when moving up and down.

[0022] The advantages of the present invention are:

[0023] The invention can be used for precise control of optical elements such as common optical mirrors, fast-reflecting mirrors with piezoelectric motors or voice coil motors, etc.

[0024] The present invention uses a detachable assembly method, and the degrees of freedom can be selected based on the mirror control requirements. According to the movement requirements of the optical element, it can be equipped with three, four, or five degrees of freedom, thereby reducing cost and space and improving stability. When it needs six degrees of freedom, it can operate with six degrees of freedom like Hexapod;

[0025] When necessary, the three rotation axes of the rotation unit can intersect at one point. When the optical center of an optical element such as a mirror is installed to coincide with the rotation center, when the mirror is rotated and adjusted, the light beam will only produce an angle change without a displacement change.

[0026] Each actuator can operate independently, controlling one degree of freedom, making it easy and straightforward to constrain motion in each dimension. All six dimensions of motion do not interfere with each other.

[0027] The present invention realizes the tilt adjustment of the upper frame and the lower frame in two dimensions through two pairs of arc-shaped rails. The two rotation axes intersect at one point through the square frame and intersect with the vertical rotation axis, ensuring the decoupling of the rotation adjustment and translation adjustment of the optical element.

[0028] All hinge shafts in the present invention are specially selected axle pins called Flexure Pivot. Its characteristics are that the pin cylinder surface and the connecting piece are rigidly fixedly connected without sliding and gap. The rotation occurs due to the elastic deformation of the pin itself. In this way, the connection gap can be eliminated and the movement accuracy can be improved.

[0029] In the present invention, all dimensions of motion are controlled by preloaded linear guides, linear drivers, and linear grating scales to form a closed loop, thereby achieving high precision and high repeatability.

[0030] The present invention also has greater flexibility. Changing the position of the moving parts in each dimension can obtain a special-purpose optical element driving effect. For example, placing the vertical drive unit on the swing unit can be used to replace different optical elements to the working position in the vertical direction, or to replace different working areas of the same optical element. Figures 8(a) and 8(b) show the situation of two optical working surfaces of a mirror. Figure 8(a) is the situation of optical surface B working. The rotation center O of the three rotation dimensions of the motion platform coincides with the pole of optical surface B, and all adjustments are centered on the pole of optical surface B. When optical surface A needs to work, the rotation center O remains unchanged, and the vertical drive unit lifts the mirror to coincide with the pole of optical surface A and the rotation center O. At this point, all adjustments become centered on the pole of the working optical surface A, see Figure 8(b). Similarly, placing the horizontal unit on the swing unit and the vertical unit at the bottom can replace different optical elements in the horizontal direction to the working position. And the rotation center is still kept coincident with the pole of the working optical element.

[0031] Figure 1 Schematic diagram of the overall structure of a six-degree-of-freedom optical element precision control platform in an embodiment of the present invention;

[0032] Figure 2 It is a schematic diagram of the exploded structure of the vertical linear unit in the six-degree-of-freedom optical element precision control platform in an embodiment of the present invention;

[0033] Figure 3 It is a schematic diagram of the exploded structure of the vertical linear unit in the six-degree-of-freedom optical element precision control platform in another perspective in an embodiment of the present invention;

[0034] Figure 4 It is a schematic diagram of the exploded structure of the rotating unit in the six-degree-of-freedom optical element precision control platform in an embodiment of the present invention;

[0035] Figure 5 This is a simplified model diagram of the principle of the intersection of the three-dimensional rotation axes of the rotation units in the six-degree-of-freedom optical element precision control platform in an embodiment of the present invention;

[0036] Figure 6 The actual angle A0 and the estimated angle A0 in the experimental process of the embodiment of the present invention are p The difference curve graph.

[0037] Figure 7 It is a curve diagram of linear and angular resolution tested during the experiment in the embodiment of the present invention.

[0038] FIG8(a) and FIG8(b) are schematic diagrams showing the vertical linear unit 2 installed above the rotating unit 3 and changing different optical elements or working surfaces to the working position in the vertical direction. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] This embodiment provides a six-degree-of-freedom optical element precision control platform that can be arbitrarily combined and whose rotation center always intersects the set center, including a horizontal linear unit 1, a vertical linear unit 2, and a rotation unit 3 that can be vertically coupled in any order; a horizontal swing unit 4 is fixed at the top. Figure 1 As shown, this embodiment is fixed in the order of horizontal linear unit 1, vertical linear unit 2, rotation unit 3, and horizontal swing unit 4 from bottom to top. Horizontal linear unit 1 completes horizontal movement in the x-axis and y-axis directions. The characteristic is that the top of the x-axis movement is combined with the bottom of the y-axis movement; the vertical linear unit 2 completes the vertical movement in the z-axis direction; the rotation unit 3 completes the rotation around the z-axis; the horizontal swing unit completes the rotation around the x-axis and y-axis in two directions; the rotation unit 3 drives the optical element horizontal swing unit 4 to complete circumferential rotation and two angle adjustments; when the rotation unit 3 moves, it intersects with the two rotation axes of the swing unit 4 at one point. No matter how the six movements change, this rotation center remains constant relative to the top plane of the platform (optical element mounting surface). The optical element can be properly installed on the top platform so that the pole of the optical element is consistent with the rotation center point. In this way, the six-dimensional movement of the optical element is decoupled from each other. In this embodiment, the degree of freedom can be selected based on the control requirements through a detachable assembly method. When the mirror needs three degrees of freedom (such as two translations and one rotation), it can be equipped with only three degrees of freedom to reduce cost and improve stability. When it needs six degrees of freedom, it can operate with six degrees of freedom like a Hexapod.

[0041] like Figure 1 As shown, the horizontal linear unit 1 includes a first slider 11, a second slider 12, and a third slider 13; the three sliders are stacked in sequence, wherein the first slider 11 and the second slider 12 are slidably matched through a cross roller slide rail in the x direction, and the second slider 12 and the third slider 13 are slidably matched through a cross roller slide rail in the y direction. The output end and the base of the first driving linear motor 14 are respectively fixed to the first slider 11 and the second slider 12 to realize the driving in the x-axis direction. The second driving linear motor ( Figure 1The output end and the base of the motor (not shown) are respectively fixed to the second slider 12 and the third slider 13 to realize the drive in the y-axis direction, and the first drive linear motor 14 and the second drive linear motor are started to adjust the two-dimensional position of the third slider 13 in the horizontal direction as needed. In this embodiment, the relative displacement of the slider is also measured by two grating rulers 15. The ruler body of one grating ruler 15 is fixed to the first slider 11, and the paddle wave measurement head fixed on the second slider 12 is used. The ruler body of the other grating ruler 15 is fixed to the second slider 12, and the paddle wave measurement head fixed on the third slider 13 is used. By using two grating rulers 15, the horizontal movement can be more accurately monitored and closed-loop control drive can be realized.

[0042] like Figure 2 , Figure 3 As shown, the vertical linear unit 2 includes an upper wedge 21, a lower wedge 22, and a wedge base 23; the inclined surfaces of the upper wedge 21 and the lower wedge 22 are connected by a precision linear guide rail; the bottom of the lower wedge 22 is connected to the wedge base 23 by a precision linear guide rail; the lower wedge 22 is provided with a waist-shaped groove 24 that runs through from top to bottom, and the length direction is consistent with the sliding direction of the lower wedge 22; the upper wedge 21 is fixed with a vertical guide column 26'; a vertical guide sleeve 25 is fixed on the wedge base 23, and the guide column 26' and the guide sleeve 25 are precisely slidably matched in the vertical direction. When the lower wedge drive motor 27 drives the lower wedge 22 to move forward and backward horizontally, the upper wedge 21 can only move up and down under the action of the guide column 26' and the guide sleeve 25. In order to prevent the upper wedge 21 from being blocked by the guide sleeve 25 when it descends, a limit hole 26 is opened in the center of the upper wedge 21 to meet the requirements of a large adjustment in height.

[0043] In this embodiment, the vertical linear unit is not limited to the above structure, and other suitable structures may be selected according to needs.

[0044] like Figure 4 As shown, the rotating unit 3 includes a base 31 rotating around the z-axis and an angle adjustment mechanism; the rotating base 31 is detachably connected to the top of the lower unit; the upper surface of the rotating base 31 is rotatably connected to the bottom of the angle adjustment mechanism, and the rotating shaft coincides with the light beam line of the fast reflection mirror.

[0045] The angle adjustment mechanism includes a lower frame 32, an upper frame 33, and a central U-shaped frame 34; the upper frame 33 and the lower frame 32 are both U-shaped structures, and after being buckled up and down, a hollow non-enclosed rectangular parallelepiped structure is formed (the upper frame 33 and the lower frame 32 have no contact points), and the U-shaped frame 34 is located at the center of the rectangular parallelepiped, and the opening is in the vertical direction; the two side walls of the upper frame 33 and the two side walls opposite to the U-shaped frame 34 are slidably connected by a first pair of arc-shaped tracks 35, and the two side walls of the lower frame 32 and the other two opposite side walls of the U-shaped frame 34 are slidably connected by a second pair of arc-shaped tracks 36; the U-shaped frame 34 has no contact with the upper frame 33 and the lower frame 32, and is suspended and fixed by the arc-shaped tracks around it. In this embodiment, the bottom of the U-shaped frame 34 is in a semi-enclosed state, and the center position of its bottom is open, and the enclosed area provides a fixed foundation for the driving member.

[0046] In this embodiment, the base of the rotary drive member 30 is fixed to the rotating frame 37, and the rotating frame 37 is rotatably connected to the side of the rotating base 31; a rotating shaft is fixed to the bottom of the lower frame 32, the rotating shaft is vertically downward, and the output end of the rotary drive member 30 is rotatably connected to the rotating shaft. The rotating shaft of the output end of the rotary drive member 30 and the rotating shaft of the base are parallel to the rotating shaft of the rotating base. When the rotary drive member 30 is started, the lower frame 32 and the rotating base rotate relative to each other, thereby driving all components above the rotating base to rotate circumferentially.

[0047] like Figure 4As shown, the output end of the upper frame driving member 38 is hinged to the first rotating ear 41 fixed on the upper frame 33, and the machine base is hinged to the second rotating ear (not shown in the figure) fixed on the U-shaped frame 34; the output end of the lower frame driving member 39 is hinged to the third rotating ear 42 fixed on the U-shaped frame 34, and the machine base passes through the U-shaped frame 34 and is hinged to the fourth rotating ear (not shown in the figure) fixed on the lower frame 32; the axis of the upper frame driving member 38 is perpendicular to the line connecting the hinge center of the first rotating ear 41 to the rotation center of the arc guide rail 35; the axis of the lower frame driving member 39 and the line connecting the axis center of the third rotating ear 42 to the axis of the arc guide rail 36 are perpendicular to each other. In this embodiment, the arc openings of the two pairs of arc tracks face upward. When the upper frame driving member 38 is started, the upper frame 33 is driven to slide along the arc track. When the lower frame driving member 39 is driven, the square frame 34 is driven to slide along the arc. At this time, the upper frame 33 is driven to move together. With the cooperation of the two driving members, the angle adjustment of the upper frame 33 is completed, thereby driving the angle adjustment of the optical element fixed on the top of the upper frame 33. In this embodiment, the upper frame driving member 38 and the lower frame driving member 39 have the same structure, which is composed of a movable end hinge, a linear motor, a fixed end hinge and a screw nut. According to different precision requirements, this linear drive can be replaced with other forms, such as piezoelectric linear drive. In mass production, this drive can be designed as a rod with holes at both ends, and the length can be changed by control. Position switches and linear grating rulers can also be installed on the rod. In this embodiment, the three rotations are all linear drives. The connection between the drive arm and the fixed part or the rotating part is hinged through a flexible shaft (Flexural Pivot) to improve the repeatability. The rotating drive arm is perpendicular to the line connecting the rotation center to the movable end hinge axis. This ensures the linearity of the rotary motion driven by the linear motion within a certain rotation range.

[0048] In this embodiment, the vertical linear unit 2 is detachably fixed to the top of the third slider 13 through the connecting plate 5. Screw holes are provided on the bottom walls of the third slider 13 and the vertical linear unit 2. The connecting plate 5 is provided with screw holes corresponding to the screw holes at the bottom of the third slider 13 and the vertical linear unit 2, so that the vertical linear unit 2 and the third slider 13 can be fixed. The rotating unit 3 is also fixed to the top of the upper wedge 21 through the connecting plate 5, and the horizontal swing unit 4 is fixed to the top of the upper frame 33 through the connecting plate 5.

[0049] In the beam line, there is often a requirement to replace optical elements (such as optical mirrors) in the vertical direction or horizontal direction. In this embodiment, the connection order of the horizontal linear unit 1, the vertical linear unit 2, and the rotating unit 3 can be detachably changed through the connecting plate 5, so as to realize the function of replacing different optical elements in the vertical direction or horizontal direction (or replacing different optical surfaces of the same optical element) while always keeping the rotation center coincident with the center of the working optical surface. This greatly facilitates the adjustment of the beam line. For example, the vertical linear unit 2 is installed above the rotating unit 3, and different optical elements or working surfaces can be changed to the working position in the vertical direction (see Figure 8 (a), Figure 8 (b)); the horizontal linear unit 1 is above the rotating unit 3, and different optical elements can be changed to the working position in the horizontal direction (two optical mirrors are placed opposite to each other, and the two mirrors are moved horizontally to the working position respectively, so that the light beam can be reflected in different directions). The driving parts used in this embodiment are all HYDON stepping linear motors, and can also be any linear driving unit driven by stepping or servo. When the motion step length is required to be ultra-fine, piezoelectric ceramic linear drive can be used. In mass production, the rotating shaft hinge holes can be directly processed at both ends of the driving unit, thereby eliminating the movable end hinge joint and the fixed end hinge joint.

[0050] In this embodiment, Figure 1 As shown, the three rotation axes of circumferential rotation and angle adjustment in two directions intersect at one point. This center point can be adjusted horizontally or vertically by horizontal linear units and vertical linear units, and the optical center of the optical element is placed at this rotation center. Then, the rotation adjustment of the optical element will not affect the linear position of the optical center. This feature is particularly beneficial when adjusting optical elements.

[0051] The three rotations of the control platform are driven by linear motors. The schematic diagram of the mechanism is shown in Figure 5 As shown. The two points P and P0 (P1, P2) at the bottom of the triangle in the figure are the flexible bearing points at both ends of the linear motor 30. The vertex O is the rotation center of the rotating base 31. The bottom side L0 (L1, L2) is the arm length of the linear motor. The length D on the right is the fixed frame. The length R on the left is the rotating base 31 (rotating arm). At the center angle A0, when the shaft length of the motor 30 changes by ΔL, the platform rotation angle changes by A. r .

[0052]

[0053] Theoretically, A r The angle change and length change ΔL are not linearly related. However, if the platform rotation angle Ar is within the range of ±1.0° (±17.5 mrad), this relationship can be approximately regarded as a linear relationship.

[0054] A p=ΔL / R (3)

[0055] A p The actual value A r The estimated value of .

[0056] When R is 400mm and L0 is 144mm, the actual angle value A r and the angle estimate A p The difference is as Figure 5 The horizontal coordinate is the number of linear drive motor steps (in half-step units), and the angular resolution R a Calculate according to formula (4). p is the pitch of the linear actuator screw. The coefficient 2.5 is calculated based on the resolution and pitch of the stepper actuator.

[0057]

[0058] This embodiment uses the following hardware assembly for experimental simulation. The guide rail uses THK's R400 arc track. The linear motor uses a Haydon stepper linear motor with a neutral length of 144mm. A 1:1 weight mirror is used to simulate the load. A Heidenhain absolute grating ruler is installed to read the motor displacement. An autocollimator is used to test the angle change. The motor is driven to move, and the output of the grating ruler and autocollimator is tested and recorded.

[0059] Theoretically, the resolution of the Haydon linear motor is 3.1 microns per step, or 1.55 microns per half step. The controller angular resolution is 1.60 arc seconds per step (7.76 microradians per step), or 3.88 microradians per half step.

[0060] To test the resolution, two tests were performed. In the first test, the motor 30 was driven with a half-step step size. The actual resolution was measured to be 1.58 μ / half-step, and 0.78 arc-seconds / half-step. In the second test, the linear motor was driven in a 1 / 32 microstep mode. The linear average resolution was measured to be 0.05 μ / microstep or 0.024 arc-seconds / microstep.

[0061] This embodiment only illustrates the mechanism of 6-DOF driving. The driver can be selected according to the requirements of motion accuracy, repeatability and step length. For example, under the requirements of high precision and sub-micron step length, piezoelectric linear drive can be selected.

[0062] At the same time, the present invention can be used for precise control of optical elements such as ordinary optical mirrors, fast-reflection mirrors with piezoelectric motors or voice coil motors, etc. The control implementation example of ordinary optical mirrors is as described above. The fast-reflection mirror with a piezoelectric motor or a voice coil motor can be realized by installing an appropriate supporting mechanism on the platform. The six degrees of freedom of movement are independent of each other. When it is necessary to drive a certain dimension of movement, only one corresponding motor needs to be driven, and each dimension of movement can be independently changed arbitrarily within the designed motion control range. Each dimension of movement has a pre-tightened linear guide rail and grating scale feedback, with high motion accuracy and repeatability. The position and angle of the optical element can be monitored intuitively.

[0063] The invention provides a six-degree-of-freedom optical element precision control platform which can be arbitrarily combined and whose rotation center always intersects with the set center, comprising a horizontal linear unit, a vertical linear unit (any commercial vertical linear unit that meets the precision travel requirements), and a rotation unit connected by vertical coupling; the horizontal rotation unit is installed at the top. The horizontal linear unit completes the horizontal movement in the x-axis and y-axis directions; the vertical linear unit completes the vertical movement in the z-axis direction; the rotation unit completes the rotation around the z-axis; the swing unit drives the optical element to complete the horizontal angle adjustment; when the rotation unit moves, the three rotation axes always intersect with the set center. The invention can be arbitrarily combined, and the degrees of freedom can be selected based on the control requirements of the optical element. When three degrees of freedom are needed, it can be equipped with three degrees of freedom, thereby reducing costs and improving stability. The three rotation axes of the rotation unit intersect at one point, and the center of the optical element can be installed at this rotation center point. The six degrees of freedom of movement are independent of each other. When a certain dimensional movement needs to be driven, only one corresponding motor needs to be driven, and each dimensional movement can be independently and arbitrarily changed within the designed movement control range. Each movement has a preloaded linear guide rail and a grating ruler feedback, and the movement accuracy and repeatability are high. Optical component position and angle can be monitored visually.

[0064] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A six-degree-of-freedom optical element precision control platform, characterized in that: The invention comprises a horizontal linear unit (1), a vertical linear unit (2), a rotation unit (3), and a horizontal sway unit (4) which are coupled and connected in sequence in a vertical direction; the horizontal sway unit (4) is fixed at the top, the horizontal linear unit (1) completes horizontal movement in the x-axis and y-axis directions; the vertical linear unit (2) completes vertical movement in the z-axis direction; the rotation unit (3) completes rotation around the z-axis, and the horizontal sway unit (4) completes rotation around the x-axis and the y-axis directions; the three rotation axes of the rotation unit (3) and the horizontal sway unit (4) intersect at one point; The vertical linear unit (2) comprises an upper wedge block (21) and a lower wedge block (22); the inclined surfaces of the upper wedge block (21) and the lower wedge block (22) are arranged relative to each other and slideably matched, and the bottom of the lower wedge block (22) is slidably fixed on the wedge block base (23); the lower wedge block (22) is provided with an elongated sliding hole (24) which passes through from top to bottom, and the length direction is consistent with the sliding direction of the lower wedge block (22); a vertical guide column (26') is fixed on the upper wedge block (21); a vertical guide sleeve (25) is fixed on the wedge block base (23), and the guide sleeve (25) passes through the waist-shaped sliding hole (24) and the limiting hole (26) provided on the upper wedge block in sequence; when the lower wedge block (22) slides, the upper wedge block (21) moves up and down in the vertical direction under the action of the guide column (26') and the guide sleeve (25); The rotating unit (3) comprises a rotating base (31) and an angle adjustment mechanism; the rotating base (31) is detachably connected to the top of the lower unit; the upper surface of the rotating base (31) is rotatably connected to the bottom of the angle adjustment mechanism, and the rotating shaft coincides with the vertical center line of the optical element; The angle adjustment mechanism comprises a lower frame (32), an upper frame (33), and a central U-shaped frame (34); the upper frame (33) and the lower frame (32) are both U-shaped structures, and after being buckled up and down, a hollow, contactless rectangular parallelepiped structure is formed, and the U-shaped frame (34) is located at the center of the rectangular parallelepiped, and the opening is in the vertical direction; the two side walls of the upper frame (33) and the two side walls opposite to the U-shaped frame (34) are slidably connected via a first pair of arc-shaped rails (35), and the two side walls of the lower frame (32) and the other two opposite side walls of the U-shaped frame (34) are slidably connected via a second pair of arc-shaped rails (36); the U-shaped frame (34) has no contact with the upper frame (33) and the lower frame (32); the lower frame (32) is rotatably connected to the rotating base (31); The angle adjustment mechanism further comprises an upper frame driving member (38) and a lower frame driving member (39); the movable end of the upper frame driving member (38) is hinged to a first rotating ear (41) fixed to the upper frame (33), and the machine base is hinged to a second rotating ear fixed to the square frame (34); the movable end of the lower frame driving member (39) is hinged to a third rotating ear (42) of the square frame (34), and the machine base passes through the square frame (34) and is hinged to a fourth rotating ear fixed to the lower frame (32); the axis of the upper frame driving member (38) is perpendicular to a line connecting a hinge center of the first rotating ear (41) to a rotation center of the first pair of arc tracks (35); the axis of the lower frame driving member (39) and a line connecting a center of the axis of the third rotating ear (42) to an axis of the second pair of arc tracks (36) are mutually perpendicular.

2. A six-degree-of-freedom optical element precision control platform according to claim 1, characterized in that: The rotating unit (3) further comprises a rotating drive member (30), the output end of the rotating drive member (30) being rotationally connected to the lower frame (32), the base of the rotating drive member (30) being rotationally connected to the rotating base (31), and the output end of the rotating drive member (30) and the rotating shaft of the base being parallel to the rotating shaft of the rotating base.

3. The six-degree-of-freedom optical element precision control platform according to claim 2, characterized in that: The base of the rotary drive member (30) is fixed to a rotating frame (37), and the rotating frame (37) is rotatably connected to the side of the rotating base (31); a rotating shaft is fixed to the bottom of the lower frame (32), the rotating shaft is vertically downward, and the output end of the rotating frame (37) is rotatably connected to the rotating shaft.

4. The six-degree-of-freedom optical element precision control platform according to claim 1, characterized in that: The horizontal linear unit (1), the vertical linear unit (2) and the rotating unit (3) are all detachably fixed via a connecting plate (5).

5. The six-degree-of-freedom optical element precision control platform according to claim 1, characterized in that: A vertical guide sleeve (25) is fixed on the base (23); a guide column (26') is fixed on the upper wedge block (21); the guide sleeve (25) and the guide column (26') form a precise sliding fit in the vertical direction; the lower wedge block (22) and the upper wedge block (21) and the base (23) are respectively connected through a precise linear track pair; a waist-shaped hole is opened in the center of the lower wedge block (22), and the limiting hole (26) opened in the center of the upper wedge block is circular to avoid conflict with the guide column (26').

6. The six-degree-of-freedom optical element precision control platform according to claim 4, characterized in that: By changing the up and down positions of the horizontal linear unit (1) and the rotation unit (3), it is possible to achieve driving of multiple optical elements while always keeping the rotation center coincident with the center of the working optical surface.

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