Optical axis control mechanism based on decoupling of kinematic pairs

Abstract

The application provides an optical axis control mechanism based on decoupling of kinematic pairs, comprising an axle system component, an actuator and a decoupler, wherein the axle system component is used for controlling the rotation angle of an optical mirror, the actuator is installed on the top of the truss of the axle system component, the actuator is used for generating reciprocating linear displacement to drive the optical mirror, one side of the decoupler is fixed with the axle system component, and the other side of the decoupler is fixed with the actuator, and the decoupler is used for decoupling / releasing the over-rigid freedom degree between the linear motion of the actuator and the circular motion of the axle system component. The application adopts the decoupling mode of kinematic pairs, can release the over-rigid freedom degree between the linear motion of the actuator and the rotation of the axle system, reduce the peak value and fluctuation of resistance, and further realize the control of the optical mirror with large rotation angle, high resolution and high positioning accuracy.

Description

Technical Field

[0001] This invention relates to the field of optical technology, and more specifically to an optical axis control mechanism based on decoupling of kinematic pairs. Background Technology

[0002] In scientific research, industrial production, and communications, there are stringent requirements for the precision of optical axis / beam pointing. For example, in astronomy, telescopes need to be precisely aimed at specific celestial bodies for observation; in laser processing, the laser beam must be accurately focused on a specific location on the workpiece to achieve high-quality cutting, welding, and other operations; in fiber optic communication, the beam needs to be accurately coupled into the fiber to ensure efficient signal transmission. Furthermore, environmental factors such as atmospheric turbulence, mechanical vibration, and temperature changes can alter the optical axis pointing, requiring precise beam pointing control to compensate for these effects. Therefore, beam pointing control is of paramount importance to optical systems.

[0003] In the field of optics, high precision is generally required for optical axis control. For applications requiring resolution or positioning accuracy better than 10 μrad, piezoelectric drive or flexible hinges are commonly used in engineering for optical axis control. While these two control methods meet the requirements in terms of precision and rigidity, the control angle range is very small, affecting the stability of the control. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the first objective of this invention is to propose an optical axis control mechanism based on the decoupling of kinematic pairs.

[0005] The technical solution adopted in this invention is as follows:

[0006] An embodiment of the first aspect of the present invention provides a device comprising: a shaft assembly 1, an actuator 2, and a decoupler 3, wherein the shaft assembly 1 is used to control the rotation angle of an optical mirror 4, the actuator 2 is mounted on the top of the truss of the shaft assembly 1, and the actuator 2 is used to generate a reciprocating linear thrust to drive the optical mirror 4, one side of the decoupler 3 is fixed to the shaft assembly 1, and the other side of the decoupler 3 is fixed to the actuator 2, and the decoupler 3 is used to decouple / release the over-stiffness degree of freedom between the linear motion of the actuator 2 and the circular motion of the shaft assembly 1.

[0007] The optical axis control mechanism based on kinematic pair decoupling proposed in this invention may also have the following additional technical features:

[0008] According to one embodiment of the present invention, the shaft system assembly 1 is a one-dimensional shaft system focusing assembly or a multi-dimensional shaft system focusing assembly.

[0009] According to one embodiment of the present invention, the shaft assembly 1 includes a U-shaped frame 11, a fixed end 12, a movable end 13, a mirror chamber 14, and an encoder 15. The fixed end 12, the movable end 13, and the mirror chamber 14 together form the pitch shaft system of the whole machine and are mounted on the U-shaped frame 11. The encoder 15 is connected to the pitch shaft system and is used to monitor and provide feedback on the angular position of the pitch shaft system. The mirror chamber 14 is used to house the optical mirror 4.

[0010] According to one embodiment of the present invention, the actuator 2 includes: a base 21, a ball screw 22, a main screw nut 23, a secondary ball screw nut 24, an angular contact bearing 25, an ultrasonic motor 26, a coupling 27, a first threaded pressure ring 28, a first threaded spacer 29, and a limiting plate 210. The ultrasonic motor 26 drives the ball screw 22 to push the screw nut 23 via the coupling 27. The angular contact bearing 25 is used to fix the ball screw 22 for transmission. The ball screw 22 is simultaneously fitted with the main nut 23 and the secondary nut 24. A preload is applied between the main nut 23 and the secondary nut 24 to eliminate the backlash difference between forward and reverse rotation. The main screw nut 23 is provided with an interface for installation with the decoupler 3. The limiting plate 210 is used to limit the movement of the screw nut 23.

[0011] According to one embodiment of the present invention, the decoupling device 3 includes a base 31, a drive connecting shaft 32, a load connecting shaft 33, a flexible joint 34, an angular contact bearing 35, a second threaded pressure ring 36, and a second threaded spacer 37. The load connecting shaft 33 and the drive connecting shaft 32 are respectively installed at both ends of the base 31 to form two mutually perpendicular two-dimensional articulated arms. Each articulation includes a pair of angular contact bearings 35. The load connecting shaft 33 is connected to the shaft assembly 1 through the flexible joint 34, and the drive connecting shaft 32 is fixed to the actuator 2.

[0012] The beneficial effects of this invention are:

[0013] This invention employs a kinematic pair decoupling method, which can release the excessively stiff degree of freedom between the linear motion of the actuator and the rotation of the shaft system, reduce the peak resistance and fluctuation, and thus achieve large-angle, high-resolution, and high-positioning-precision control of the optical mirror. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of an optical axis control mechanism based on motion pair decoupling according to an embodiment of the present invention;

[0015] Figure 2 This is a schematic diagram of the structure of a photoactuator according to an embodiment of the present invention;

[0016] Figure 3 This is a schematic diagram of the structure of a decoupler according to an embodiment of the present invention.

[0017] Reference numerals: Shaft assembly 1, Actuator 2, Decoupler 3, Optical mirror 4, U-shaped frame 11, Fixed end 12, Moving end 13, Mirror chamber 14, Encoder 15, Base 21, Ball screw 22, Main screw nut 23, Secondary ball screw nut 24, Angular contact bearing 25, Ultrasonic motor 26, Coupling 27, First threaded pressure ring 28, First threaded spacer 29, Limiting plate 210, Base 31, Drive connecting shaft 32, Load connecting shaft 33, Flexible joint 34, Angular contact bearing 35, Second threaded pressure ring 36 and Second threaded spacer 37. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] Figure 1 This is a schematic diagram of the overall structure of an optical axis control mechanism based on motion pair decoupling according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a photoactuator according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the structure of a decoupler according to an embodiment of the present invention.

[0020] like Figure 1 As shown, the optical axis control mechanism based on kinematic pair decoupling includes: a shaft assembly 1, an actuator 2, and a decoupler 3. The shaft assembly 1 is used to control the rotation angle of the optical mirror 4. The actuator 2 is installed on the top of the truss of the shaft assembly 1 and is used to generate reciprocating linear thrust to drive the optical mirror 4. One side of the decoupler 3 is fixed to the shaft assembly 1, and the other side of the decoupler 3 is fixed to the actuator 2. The decoupler 3 is used to decouple / release the over-rigidity degree of freedom between the linear motion of the actuator 2 and the circular motion of the shaft assembly 1.

[0021] Specifically, the shaft system assembly 1 can be a one-dimensional shaft system or a multi-dimensional shaft system composed of serially connected shaft systems. The shaft system assembly 1 is used to control the rotation angle of the optical mirror 4. The actuator 2, as the whole machine drive assembly, is installed on the top of the truss of the shaft system assembly 1 to generate high-precision reciprocating linear thrust. The decoupler 3 is installed between the actuator and the shaft system assembly 1 as a transmission assembly. It is used to decouple the excessively stiff degree of freedom between the linear drive of the actuator and the circular motion of the shaft system, reduce the peak resistance and fluctuation, thereby increasing the control angle. The rotation angle precision control range is not less than 10°, improving the system stability, and thus realizing the control of large rotation angle, high resolution, and high positioning accuracy of the optical mirror.

[0022] According to the optical calibration requirements, the axis system assembly 1 can be a one-dimensional axis system focusing assembly or a multi-dimensional axis system focusing assembly. Structurally, it is only necessary to install one set of optical axis adjustment mechanism on each axis system to achieve precise control of the optical axis.

[0023] In one embodiment of the present invention, taking the shaft system assembly 1 as a one-dimensional pitch shaft system as an example, as follows: Figure 1 As shown, the shaft system assembly 1 includes a U-shaped frame 11, a fixed end 12, a sliding end 13, a mirror chamber 14, and an encoder 15. The fixed end 12, the sliding end 13, and the mirror chamber 14 together form the pitch shaft system of the whole machine and are mounted on the U-shaped frame 11. The encoder 15 is connected to the pitch shaft system and is used to monitor and provide feedback on the angular position of the pitch shaft system, i.e., the mirror orientation. The mirror chamber 14 is used to house the optical mirror 4.

[0024] In one embodiment of the present invention, such as Figure 2 As shown, the actuator 2 includes: a base 21, a ball screw 22, a main screw nut 23, a secondary ball screw nut 24, an angular contact bearing 25, an ultrasonic motor 26, a coupling 27, a first threaded pressure ring 28, a first threaded spacer 29, and a limiting plate 210. The ultrasonic motor 26 drives the ball screw 22 to push the screw nut 23 through the coupling 27. The angular contact bearing 25 is used to fix the ball screw 22 for transmission. The ball screw 22 is equipped with both the main nut 23 and the secondary nut 24. The backlash difference between forward and reverse rotation is eliminated by applying a preload between the main nut 23 and the secondary nut 24. The main screw nut 23 is provided with an interface for installation with the decoupling device 3. The limiting plate 210 is used to limit the movement of the screw nut 23.

[0025] In this invention, the ultrasonic motor 26 has high positioning accuracy and self-locking force. The specific positioning accuracy value and self-locking force can be selected according to the design requirements.

[0026] In one embodiment of the present invention, such as Figure 3 As shown, the decoupling device 3 includes a base 31, a drive connecting shaft 32, a load connecting shaft 33, a flexible joint 34, angular contact bearings 35, a second threaded pressure ring 36, and a second threaded spacer 37. The load connecting shaft 33 and the drive connecting shaft 32 are respectively mounted at both ends of the base 31, forming two mutually perpendicular two-dimensional articulated arms. Each articulation includes a pair of angular contact bearings 35. The load connecting shaft 33 is connected to the shaft system assembly 1 via the flexible joint 34, and the drive connecting shaft 32 is fixed to the actuator 2. The flexible joint 34 can eliminate backlash and hysteresis inside the transmission system, improving the stability and accuracy of optical axis control.

[0027] The optical axis control mechanism based on kinematic pair decoupling described above in this invention can eliminate backlash and clearance within the transmission chain by setting a flexible joint. Its resolution and positioning accuracy can be better than 2μrad. On this basis, the positioning accuracy of the control mechanism can be further improved by rationally selecting ultrasonic motors and ball screws, and adjusting parameters such as the installation distance of the decoupler relative to the shaft system. The calculation process is illustrated below:

[0028] Let the contact point between the decoupler and the shaft assembly be the actuation point, the distance of the actuation point from the shaft assembly be L = 65 mm, the positioning accuracy of the ultrasonic motor be better than γ = 40 arcseconds, and the ball screw lead be P = 4 mm. Then the resolution of the optical axis adjustment mechanism of this invention is: That is, 1.9 μrad.

[0029] In summary, the optical axis control mechanism based on kinematic pair decoupling according to the embodiments of the present invention, by adopting the kinematic pair decoupling method, can release the excessive degree of freedom between the linear motion of the driver and the rotation of the shaft system, reduce the peak resistance and fluctuation, and thus achieve large rotation angle, high resolution and high positioning accuracy control of the optical mirror, improve the control accuracy of the optical axis pointing, and eliminate backlash and hysteresis inside the transmission system through the flexible joint, further improving the stability and accuracy of the optical axis control.

[0030] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0031] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0032] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An optical axis control mechanism based on kinematic pair decoupling, characterized in that, include: Shaft assembly (1), actuator (2) and decoupler (3), wherein, The shaft assembly (1) is used to control the rotation angle of the optical mirror (4). The actuator (2) is installed on the top of the truss of the shaft assembly (1). The actuator (2) is used to generate reciprocating linear thrust to drive the optical mirror (4). One side of the decoupler (3) shown is fixed to the shaft assembly (1), and the other side of the decoupler (3) shown is fixed to the actuator (2). The decoupler (3) is used to decouple / release the over-rigidity degree of freedom between the linear motion of the actuator (2) and the circular motion of the shaft assembly (1). The decoupling device (3) includes a base (31), a drive connecting shaft (32), a load connecting shaft (33), a flexible joint (34), an angular contact bearing (35), a second threaded pressure ring (36), and a second threaded spacer (37). The load connecting shaft (33) and the drive connecting shaft (32) are respectively installed at both ends of the base (31) to form two mutually perpendicular two-dimensional articulated arms. Each articulated arm includes a pair of angular contact bearings (35). The load connecting shaft (33) is connected to the shaft assembly (1) through the flexible joint (34), and the drive connecting shaft (32) is fixed to the actuator (2).

2. The optical axis control mechanism based on kinematic pair decoupling according to claim 1, characterized in that, The shaft system assembly (1) is a one-dimensional shaft system focusing assembly or a multi-dimensional shaft system focusing assembly.

3. The optical axis control mechanism based on kinematic pair decoupling according to claim 2, characterized in that, The shaft system assembly (1) includes a U-shaped frame (11), a fixed end (12), a sliding end (13), a mirror chamber (14), and an encoder (15). The fixed end (12), the sliding end (13), and the mirror chamber (14) together form the pitch shaft system of the whole machine and are installed on the U-shaped frame (11). The encoder (15) is connected to the pitch shaft system and is used to monitor and provide feedback on the angular position of the pitch shaft system. The mirror chamber (14) is used to place the optical mirror (4).

4. The optical axis control mechanism based on kinematic pair decoupling according to claim 1, characterized in that, The actuator (2) includes: a base (21), a ball screw (22), a main nut (23), a secondary nut (24), an angular contact bearing (25), an ultrasonic motor (26), a coupling (27), a first threaded pressure ring (28), a first threaded spacer (29), and a limiting plate (210). The ultrasonic motor (26) drives the ball screw (22) to push the screw nut (23) through the coupling (27). The angular contact bearing (25) is used to fix the transmission of the ball screw (22). The ball screw (22) is equipped with both the main nut (23) and the secondary nut (24). The backlash difference between forward and reverse rotation is eliminated by applying a preload between the main nut (23) and the secondary nut (24). The main nut (23) of the screw is provided with an installation interface for the decoupler (3). The limiting plate (210) is used to limit the screw nut (23).

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