High-precision focusing mechanism of optical system

Abstract

The high-precision focusing mechanism of an optical system belongs to the technical field of focusing mechanism of optical system, and aims to solve the problems of positioning precision affected by movement empty return, unable to effectively lock and poor anti-vibration impact capability. The high-precision focusing mechanism of an optical system comprises a base, a focusing base arranged on one side of the inner side of the base, a focusing driving mechanism for driving a focusing guide mechanism to guide an optical component mounting base to slide along the optical component mounting base axis direction relative to the base and the focusing base, a positioning assembly comprising a position sensor sensing piece arranged on the focusing guide mechanism, and a first position sensor and a second position sensor arranged on both sides of the position sensor sensing piece and fixed on the base, the two opposite sides of the position sensor sensing piece being parallel to the first position sensor and the second position sensor, and the position sensor sensing piece being arranged in a tilt manner relative to the movement direction of the optical component mounting base, and an anti-empty return assembly for providing a movement restoring force between the optical component mounting base and the focusing base.

Description

Technical Field

[0001] This invention belongs to the technical field of optical system focusing mechanisms, and specifically relates to a high-precision focusing mechanism for optical systems. Background Technology

[0002] Airborne optical lenses experience changes in focal length due to variations in environmental factors such as temperature and air pressure during use, both on the ground and in the air. These changes in focal length alter the image plane position, leading to blurry images. Therefore, a precise and rapid focusing mechanism is required to adjust the lens's focal length and ensure clear imaging.

[0003] Currently, there are two main ways to focus an optical lens: one is to move the imaging detector assembly using a drive mechanism; the other is to move the optical lens assembly using a drive mechanism.

[0004] The movement of the imaging detector assembly to achieve focusing places high demands on the motion accuracy, positioning accuracy, and servo control of the drive mechanism, making it very difficult to implement.

[0005] Therefore, focusing of optical lenses is usually achieved by driving the movement of optical lens assemblies. Commonly used driving mechanisms include the following: 1) A spur gear drive rotates a cylindrical cam with a cam groove, causing the focusing lens assembly to move back and forth along the optical axis to achieve focusing. An angle sensor measures the rotation angle of the cylindrical cam to control the focusing amount. This method has the advantage of simple structure, but the cam groove of the cylindrical cam requires high machining accuracy, and the presence of backlash in the gear drive affects the positioning accuracy of the focusing lens assembly.

[0006] 2) A worm gear drives a disc cam to move the focusing lens assembly back and forth along the optical axis to achieve focusing. The rotation angle of the disc cam is measured by an angle sensor to control the amount of focusing. This mechanism can achieve focusing motion of relatively large focusing components, but its structure is complex and it suffers from poor resistance to vibration and shock, as well as poor motion stability.

[0007] 3) Focusing is achieved by directly driving the focusing lens assembly along the guide rail using a linear motor. The linear displacement of the focusing lens assembly is measured using a grating ruler. This method can achieve a large focusing range, but it requires high precision in the machining and installation of the guide rail. Furthermore, this mechanism suffers from problems such as ineffective locking and poor resistance to vibration and impact. Summary of the Invention

[0008] The purpose of this invention is to propose a high-precision focusing mechanism for an optical system, which solves the problems of motion backlash affecting positioning accuracy, inability to effectively lock, and poor resistance to vibration and shock in existing technologies.

[0009] To achieve the above objectives, the present invention provides a high-precision focusing mechanism for an optical system, comprising: Base; A focusing base is disposed on one side of the inner side of the base; The focusing guide mechanism guides the optical component mounting base to slide relative to the base and the focusing base along the axial direction of the optical component mounting base. The focusing drive mechanism provides power to drive the optical component mounting base to move relative to the base and the focusing base. The positioning component includes a position sensor element disposed on the focusing guide mechanism and a first position sensor and a second position sensor located on both sides of the position sensor element and fixed on the base; the two sides of the position sensor element opposite to the first position sensor and the second position sensor are parallel, and are inclined relative to the movement direction of the optical component mounting base. And an anti-dry-return assembly, which provides motion restoring force between the optical component mount and the focusing base.

[0010] The focusing guide mechanism includes at least: A focusing motion component, wherein the position sensor is mounted on the focusing motion component, and one side of the optical component mounting base is fixedly connected to the focusing motion component; One end of the lead screw is supported on the focusing base by a bearing assembly; The screw and nut together form a screw and nut pair, and the screw and nut are fixedly connected to the focusing motion component. The focusing motion component and the optical component mounting base slide relative to the focusing base and the base through the screw and nut pair.

[0011] The focusing guide mechanism also includes: A first guide rail and a second guide rail are disposed between the focusing motion component and the focusing base along the direction of motion, and the focusing motion component and the focusing base slide together through the first guide rail and the second guide rail. And a third guide rail is provided on the other side of the optical component mounting base and between the base along the direction of movement, and the optical component mounting base and the base slide together through the third guide rail.

[0012] The focusing drive mechanism includes at least a drive element fixed on the focusing base, and the drive element is connected to the end of the lead screw via a coupling.

[0013] The focusing drive mechanism further includes: Motor mounting bracket, the drive element is fixed on the focusing base by the motor mounting bracket; A speed reducer, disposed between the drive element and the coupling; And an encoder installed at the tail of the drive element.

[0014] The anti-dry-return assembly includes a spring connected between the focusing motion component and the focusing base. One end of the spring is connected to the focusing motion component via a first spring support, and the other end is connected to the focusing base via a second spring support.

[0015] The positioning component also includes: A first position sensor mounting bracket is used to fix the first position sensor on the base; And a second position sensor mounting base, wherein the second position sensor is fixed on the base by the second position sensor mounting base.

[0016] The angle θ between the position sensor sensing element and the optical element mounting base in the direction of movement ranges from 0.1° to 10°.

[0017] More preferably, the angle θ between the position sensor sensing element and the optical element mounting base in the direction of movement is in the range of 2°≤θ≤3°.

[0018] The beneficial effects of this invention are as follows: This invention provides a high-precision focusing mechanism for an optical system. One end of a lead screw is connected to the output shaft of a reducer via a coupling. The input shaft of the reducer is connected to the output shaft of a drive element. An encoder is installed at the tail of the drive element. The rotation of the drive element drives the lead screw to rotate. The lead screw nut is mounted on the focusing moving part. The rotation of the lead screw drives the lead screw nut to move along the first, second, and third guide rails, thereby driving the focusing moving part to perform linear motion. This invention uses a combination of ball screw and reducer drive. The reducer ensures that the optical element is locked in place after power failure. The position sensor uses a high-precision non-contact sensor to achieve high positioning accuracy. The motion mechanism uses a double-sided guide rail support method to improve the rigidity and motion accuracy of the focusing mechanism. Spring preload eliminates the backlash in the focusing mechanism. It has strong resistance to vibration and impact. The focusing mechanism of this invention has high versatility and can be fitted with optical lenses, reflectors, visible light detectors, infrared detectors, etc. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the overall structure of a high-precision focusing mechanism for an optical system according to the present invention; Figure 2 This is a top view of a high-precision focusing mechanism for an optical system according to the present invention; Figure 3 This is a side view of a high-precision focusing mechanism for an optical system according to the present invention; The components are as follows: 1. Base; 2. Focusing base; 3. Optical component mounting base; 4. Focusing guide mechanism; 401. Focusing moving component; 402. Bearing assembly; 403. Lead screw; 404. Lead screw nut; 405. First guide rail; 406. Second guide rail; 407. Third guide rail; 5. Focusing drive mechanism; 501. Drive element; 502. Coupling; 503. Motor mounting base; 504. Reducer; 505. Encoder; 6. Positioning assembly; 601. Position sensor sensing element; 602. First position sensor; 603. First position sensor mounting base; 604. Second position sensor; 605. Second position sensor mounting base; 7. Anti-dry-back assembly; 701. Spring; 702. First spring support; 703. Second spring support. Detailed Implementation

[0020] The embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0021] See Figures 1-3 The high-precision focusing mechanism of an optical system according to the present invention includes: Base 1; A focusing base 2 is disposed on one side of the inner side of the base 1; The focusing guide mechanism 4 guides the optical component mounting base 3 to slide relative to the base 1 and the focusing base 2 along the axial direction of the optical component mounting base 3. The focusing drive mechanism 5 provides power to drive the optical component mounting base 3 to move relative to the base 1 and the focusing base 2. Positioning component 6 includes a position sensor 601 disposed on the focusing guide mechanism 4 and a first position sensor 602 and a second position sensor 604 located on both sides of the position sensor 601 and fixed on the base 1; the two sides of the position sensor 601 opposite to the first position sensor 602 and the second position sensor 604 are parallel and tilted relative to the movement direction of the optical component mounting base 3. And the anti-air return assembly 7, which provides motion restoring force between the optical component mount 3 and the focusing base 2.

[0022] The focusing guide mechanism 4 includes at least: The focusing motion component 401 is equipped with a position sensor 601 mounted on the focusing motion component 401, and one side of the optical component mounting base 3 is fixedly connected to the focusing motion component 401. One end of the lead screw 403 is supported on the focusing base 2 via the bearing assembly 402; And a lead screw nut 404, the lead screw nut 404 and the lead screw 403 form a lead screw nut pair, the lead screw nut 404 and the focusing motion component 401 are fixedly connected; the lead screw nut pair drives the focusing motion component 401 and the optical component mounting base 3 to slide relative to the focusing base 2 and the base 1.

[0023] The focusing guide mechanism 4 also includes: A first guide rail 405 and a second guide rail 406 are disposed between the focusing motion component 401 and the focusing base 2 along the direction of motion, and the focusing motion component 401 and the focusing base 2 slide together through the first guide rail 405 and the second guide rail 406. And a third guide rail 407 is provided on the other side of the optical component mounting base 3 and the base 1 along the direction of movement, and the optical component mounting base 3 and the base 1 are slidably engaged by the third guide rail 407.

[0024] The focusing drive mechanism 5 includes at least a drive element 501 fixed on the focusing base 2, and the drive element 501 is connected to the end of the lead screw 403 via a coupling 502.

[0025] The focusing drive mechanism 5 further includes: Motor mounting base 503, the drive element 501 is fixed on the focusing base 2 by the motor mounting base 503; A speed reducer 504 is disposed between the drive element 501 and the coupling 502; And an encoder 505 installed at the tail of the drive element 501.

[0026] The anti-air return assembly 7 includes a spring 701 connected between the focusing motion component 401 and the focusing base 2. One end of the spring 701 is connected to the focusing motion component 401 through a first spring support 702, and the other end is connected to the focusing base 2 through a second spring support 703.

[0027] The positioning component 6 also includes: First position sensor mounting base 603, the first position sensor 602 is fixed on the base 1 by the first position sensor mounting base 603; And a second position sensor mounting base 605, wherein the second position sensor 604 is fixed on the base 1 by the second position sensor mounting base 605.

[0028] The angle θ between the position sensor sensing element 601 and the optical element mounting base 3 in the direction of movement ranges from 0.1° to 10°.

[0029] More preferably, the angle θ between the position sensor sensing element 601 and the optical element mounting base 3 in the direction of movement is in the range of 2°≤θ≤3°.

[0030] The base 1 of this invention is mounted on the optical lens. The focusing motion component 401 is mounted on the focusing base 2 via a first guide rail 405 and a second guide rail 406. A bearing assembly 402 is mounted on the focusing base 2. A lead screw nut 404 is mounted on a lead screw 403, which is in turn mounted on the bearing assembly 402. The lead screw nut 404 is connected to the focusing motion component 401. A drive element 501 is mounted on the focusing base 2 via a drive element 501 mounting seat. The output shaft of the drive element 501 is connected to the input shaft of a reducer 504. The output shaft of the reducer 504 is connected to the lead screw 403 via a coupling 502. Optical component mounting seats 3 are mounted on the third guide rail 407 and the focusing motion component 401 on both sides, respectively. A spring 701 is installed between the focusing motion component 401 and the focusing base 2, with one end connected to the focusing motion component 401 and the other end mounted on the focusing base 2. The position sensor 601 is mounted on the focusing motion component 401, the first position sensor 602 is mounted on the first position sensor mounting base 603, the second position sensor 604 is mounted on the second position sensor mounting base 605, and the first position sensor mounting base 603 and the second position sensor mounting base 605 are mounted on the base 1.

[0031] The driving element 501 is a motor. The rotation of the motor drives the lead screw 403 to rotate. The lead screw nut 404 is installed on the focusing motion component 401. The rotation of the lead screw 403 drives the lead screw nut 404 to move along the first guide rail 405, the second guide rail 406, and the third guide rail 407. The focusing motion component 401 moves linearly along the guide rails. The focusing mechanism adopts a combination drive method of ball screw 403 and reducer 504. The reducer 504 ensures that the position of the optical element is locked after power failure. The first position sensor 602 and the second position sensor 604 are high-precision non-contact sensors to achieve higher positioning accuracy. The motion mechanism adopts a double-sided guide rail support method to improve the rigidity and motion accuracy of the focusing mechanism. The preload of the spring 701 eliminates the backlash in the focusing mechanism.

[0032] The position sensor 601 is mounted on the focusing motion component 401 and moves linearly with it. The non-contact first position sensor 602 and second position sensor 604 are mounted on either side of the position sensor 601, facing each other and maintaining a certain distance from it. The upper and lower sides of the position sensor 601 are parallel and form an angle θ with the direction of movement. When the optical component mounting base 3 moves to the left, the position sensor 601 moves to the left, increasing the distance between its upper side and the first position sensor 602, and decreasing the distance between its lower side and the second position sensor 604. When the optical component mounting base 3 moves to the right, the position sensor 601 moves to the right, decreasing the distance between its upper side and the first position sensor 602, and increasing the distance between its lower side and the second position sensor 604. The amount of motion and the current position of the focusing mechanism can be calculated by measuring the change in gap between the first position sensor 602 and the position sensor sensing element 601. When the focusing motion element 401 moves a distance L to the left, the distance between the first position sensor 602 and the upper side of the position sensor sensing element 601 increases by Ltanθ, and the distance between the second position sensor 604 and the lower side of the position sensor sensing element 601 decreases by Ltanθ. When the focusing motion element 401 moves a distance L to the right, the distance between the first position sensor 602 and the upper side of the position sensor sensing element 601 decreases by Ltanθ, and the distance between the second position sensor 604 and the lower side of the position sensor sensing element 601 increases by Ltanθ.

[0033] The results of physical testing show that the method is practical and effective. Within a stroke of ±3mm, the tilt of the movement is no more than 12″, the positioning accuracy is ±5μm, the focusing resolution is 0.2μm, and the movement speed is 2mm / s.

Claims

1. A high-precision focusing mechanism for an optical system, characterized in that, include: Base (1); A focusing base (2) is disposed on one side of the inner side of the base (1); The focusing guide mechanism (4) guides the optical component mounting base (3) to slide relative to the base (1) and the focusing base (2) along the axis of the optical component mounting base (3); The focusing drive mechanism (5) provides power to drive the optical component mounting base (3) to move relative to the base (1) and the focusing base (2); The positioning component (6) includes a position sensor (601) disposed on the focusing guide mechanism (4) and a first position sensor (602) and a second position sensor (604) located on both sides of the position sensor (601) and fixed on the base (1); the two sides of the position sensor (601) opposite to the first position sensor (602) and the second position sensor (604) are parallel, and are inclined relative to the movement direction of the optical component mounting base (3); And the anti-air return assembly (7), which provides motion restoring force between the optical component mount (3) and the focusing base (2).

2. The high-precision focusing mechanism for an optical system according to claim 1, characterized in that, The focusing guide mechanism (4) includes at least: The focusing motion component (401) is mounted on the position sensor sensing component (601), and the optical component mounting base (3) is fixedly connected to the focusing motion component (401) on one side. One end of the lead screw (403) is supported on the focusing base (2) by a bearing assembly (402). And a lead screw nut (404), the lead screw nut (404) and the lead screw (403) form a lead screw nut pair, the lead screw nut (404) and the focusing motion component (401) are fixedly connected; the lead screw nut pair drives the focusing motion component (401) and the optical component mounting base (3) to slide relative to the focusing base (2) and the base (1) as a whole.

3. The high-precision focusing mechanism for an optical system according to claim 2, characterized in that, The focusing guide mechanism (4) further includes: A first guide rail (405) and a second guide rail (406) are arranged along the direction of motion between the focusing motion component (401) and the focusing base (2), and the focusing motion component (401) and the focusing base (2) slide together through the first guide rail (405) and the second guide rail (406); And a third guide rail (407) is provided on the other side of the optical component mounting base (3) and the base (1) along the direction of movement, and the optical component mounting base (3) and the base (1) are slidably engaged by the third guide rail (407).

4. The high-precision focusing mechanism for an optical system according to claim 2, characterized in that, The focusing drive mechanism (5) includes at least a drive element (501) fixed on the focusing base (2), and the drive element (501) is connected to the end of the lead screw (403) via a coupling (502).

5. A high-precision focusing mechanism for an optical system according to claim 4, characterized in that, The focusing drive mechanism (5) further includes: Motor mounting base (503), the drive element (501) is fixed on the focusing base (2) by the motor mounting base (503); A speed reducer (504) is disposed between the drive element (501) and the coupling (502). And an encoder (505) installed at the tail of the drive element (501).

6. The high-precision focusing mechanism for an optical system according to claim 2, characterized in that, The anti-air return assembly (7) includes a spring (701) connected between the focusing motion component (401) and the focusing base (2). One end of the spring (701) is connected to the focusing motion component (401) through a first spring support (702), and the other end is connected to the focusing base (2) through a second spring support (703).

7. The high-precision focusing mechanism for an optical system according to claim 1, characterized in that, The positioning component (6) further includes: First position sensor mounting base (603), the first position sensor (602) is fixed on the base (1) by the first position sensor mounting base (603); And a second position sensor mounting base (605), wherein the second position sensor (604) is fixed on the base (1) by the second position sensor mounting base (605).

8. The high-precision focusing mechanism for an optical system according to claim 1, characterized in that, The angle θ between the position sensor sensing element (601) and the optical element mounting base (3) in the direction of movement is in the range of 0.1°≤θ≤10°.

9. A high-precision focusing mechanism for an optical system according to claim 8, characterized in that, The angle θ between the position sensor sensing element (601) and the optical element mounting base (3) in the direction of movement is in the range of 2°≤θ≤3°.

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