Adjusting device and method for front group focusing of zoom lens

Abstract

The application belongs to the technical field of assembly and adjustment, and particularly relates to an assembly and adjustment device and method for a front group focusing large objective group of a zoom lens. The method comprises the following steps: S1: building the assembly and adjustment device for the front group focusing large objective group of the zoom lens; S2: controlling the motors to make the optical axis of the first lens coaxial with the optical axis of the zoom lens; S3: controlling the motors according to the acquisition result of the aberration Zernike coefficient acquisition unit, and adjusting the position of the first lens seat by the motors until the aberration Zernike coefficient is the minimum value; S4: controlling the motors according to the acquisition result of the aberration Zernike coefficient acquisition unit, and adjusting the angle of the first lens seat by the motors until the aberration Zernike coefficient is the minimum value. The application can quickly and accurately complete the assembly and adjustment of the front group focusing large objective group.

Description

Technical Field

[0001] This invention belongs to the field of lens assembly and adjustment technology, and particularly relates to an assembly and adjustment device and method for the front focusing objective lens group of a zoom lens. Background Technology

[0002] With the vigorous development of my country's scientific endeavors, zoom lenses are increasingly widely used in aerospace, defense, and other fields. However, zoom lenses suffer from insufficient parfocality, leading to a decline in image quality when imaging close-range targets. To achieve close-range parfocality in zoom lenses, a front-group focusing mechanism is employed to address this issue. Traditional front-group focusing zoom structures require high precision in assembly and adjustment, and their assembly methods are complex and challenging. Summary of the Invention

[0003] In view of this, the present invention aims to provide an assembly and adjustment device and method for the front focusing objective group of a zoom lens, to solve the problems of high difficulty in traditional manual assembly and adjustment, potential for unsuitable parts during the assembly and adjustment process, excessive assembly and adjustment time, and the inability to complete such high-precision assembly and adjustment work without certain experience. The assembly and adjustment method of the present invention is not only highly efficient, but also greatly reduces the requirements for the assembly and adjustment personnel's experience and ability. Assembly and adjustment can be completed quickly by simply following the established process.

[0004] To achieve the above objectives, the technical solution created by this invention is implemented as follows: An assembly and adjustment device for the front focusing objective lens group of a zoom lens includes a control unit and two tooling units. Each tooling unit includes a grating ruler, a motor, a mounting base, and a fixing component. The grating ruler and the motor are both fixedly mounted on the mounting base. The output shaft of the motor passes through the fixing component, which is also fixed to a first lens mount by bolts. Based on feedback information from the grating ruler and the Zernike aberration coefficient of the front focusing objective lens group, the control unit adjusts the control parameters of the motor, causing the motor to drive the fixing component to move. The fixing mechanism then drives the first lens mount to move, thereby realizing the assembly and adjustment of the front focusing objective lens group.

[0005] Furthermore, the front focusing objective lens group also includes a lens barrel and a second lens mount. The first lens mount and the second lens mount are sequentially assembled inside the lens barrel. The lens barrel has a mounting groove at a position relative to the first lens mount. The first lens mount is equipped with a first lens element, and the second lens mount is sequentially equipped with a second lens element and a third lens element. The second lens element is located between the first lens element and the third lens element, and the first lens element is close to the object plane of the zoom lens.

[0006] Furthermore, the number of mounting slots is the same as the number of tooling units, and the mounting slots are symmetrically arranged on the lens barrel. The fasteners pass through the mounting slots and contact the first lens mount.

[0007] Furthermore, the control unit includes a motor control unit, a grating ruler acquisition unit, and an aberration Zernike coefficient acquisition unit. The grating ruler acquisition unit acquires the position and angle of the first lens fed back by the grating ruler, the aberration Zernike coefficient acquisition unit acquires the aberration Zernike coefficient of the front focusing objective lens group, and the motor control unit adjusts the control parameters of the motor.

[0008] A method for mounting and adjusting the front focusing objective lens group of a zoom lens, implemented using a mounting and adjusting device for the front focusing objective lens group of the zoom lens, specifically includes the following steps: S1: Construct the mounting and adjusting device for the front focusing objective lens group of the zoom lens. S2: Based on the position and angle of the first lens acquired by the grating ruler acquisition unit, control each motor to make the optical axis of the first lens coaxial with the optical axis of the zoom lens. S3: Use an interferometer to measure the Zernike coefficient of the front focusing objective lens group, and control each motor according to the acquisition results of the Zernike coefficient acquisition unit, and use each motor to adjust the position of the first lens mount until the Zernike coefficient is at its minimum value. S4: Control each motor according to the acquisition results of the Zernike coefficient acquisition unit, and use each motor to adjust the angle of the first mirror mount until the Zernike coefficient is at its minimum value.

[0009] Furthermore, in step S3, each motor drives each fixing component to move synchronously in the same direction to adjust the position of the first mirror mount.

[0010] Furthermore, in step S4, each motor drives each fixing component to move synchronously in the opposite direction to adjust the angle of the first mirror mount.

[0011] Furthermore, in steps S3 and S4, when the Zernike coefficient is at its minimum value, the Zernike coefficient is less than 0.5λ.

[0012] Furthermore, λ is the wavelength of the laser emitted by the interferometer.

[0013] Compared with the prior art, the present invention can achieve the following beneficial effects: (1) The mounting and adjusting method of the front focusing objective lens group of the zoom lens created by the present invention can not only solve the problem of insufficient close-range parfocality of zoom lenses, but also greatly improve the mounting and adjusting accuracy of the optical engine and the working efficiency.

[0014] (2) The method for assembling and adjusting the front focusing objective lens group of the zoom lens described in this invention is a high-precision and high-efficiency optical lens adjustment device and control method. Based on the real-time feedback mechanism of the grating ruler and interferometer, this invention achieves fine-tuning of the position and angle of the first lens, meeting the ever-increasing requirements for the precision of optical systems. The device of this invention is simple and easy to use, suitable for the focusing and aberration correction needs of various optical devices, and improves the performance and stability of optical devices. Attached Figure Description

[0015] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the structure of the mounting and adjusting device for the front focusing objective lens group of the zoom lens described in an embodiment of the present invention. Figure 2 This is a schematic flowchart illustrating the assembly and adjustment method of the front focusing objective lens group of the zoom lens described in an embodiment of the present invention.

[0016] Explanation of reference numerals in the attached figures: 1. Grating ruler; 2. Motor; 3. Mounting base; 4. Fixture; 5. First lens mount; 6. First lens. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0018] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0019] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0020] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] like Figure 1 As shown, the present invention provides an assembly and adjustment device for the front focusing objective lens group of a zoom lens, including a control unit and two tooling units. Each tooling unit includes a grating ruler 1, a motor 2, a mounting base 3, and a fixing member 4. The grating ruler 1 and the motor 2 are both fixedly mounted on the mounting base 3. The output shaft of the motor 2 passes through the fixing member 4, and the fixing member 4 is also fixed to the first lens mount 5 by bolts. Based on the feedback information of the grating ruler 1 and the Zernike aberration coefficient of the front focusing objective lens group, the control unit adjusts the control parameters of the motor 2, so that the motor 2 drives the fixing member 4 to move, and the fixing mechanism drives the first lens mount 5 to move, thereby realizing the assembly and adjustment of the front focusing objective lens group.

[0023] The front focusing objective lens group also includes a lens barrel and a second lens mount. The first lens mount 5 and the second lens mount are sequentially assembled inside the lens barrel. The lens barrel is provided with a mounting groove (the mounting groove can be a rectangular mounting groove to prevent the fixing member 4 from wobbling in any direction other than the output shaft direction of the motor 2) at a position relative to the first lens mount 5. The width of the fixing member 4 is smaller than the width of the mounting groove to ensure that the fixing member 4 drives the first lens mount 5 to move along the output shaft direction of the motor 2 (inward or outward) within the mounting groove. The first lens mount 5 is equipped with a first lens 6, and the second lens mount is sequentially equipped with a second lens 6 and a third lens 6. The second lens 6 is located between the first lens 6 and the third lens 6, and the first lens 6 is close to the object plane of the zoom lens.

[0024] The number of mounting slots is the same as the number of tooling units. The mounting slots are symmetrically arranged on the lens barrel. The fastener 4 passes through the mounting slot and contacts the first lens mount 5.

[0025] The control unit includes a motor 2 control unit, a grating ruler 1 acquisition unit, and an aberration Zernike coefficient acquisition unit. The grating ruler 1 acquisition unit acquires the position and angle of the first lens 6 fed back by the grating ruler 1. The aberration Zernike coefficient acquisition unit acquires the aberration Zernike coefficient of the front focusing objective lens group. The motor 2 control unit adjusts the control parameters of the motor 2.

[0026] like Figure 2 As shown, this invention provides a method for assembling and adjusting the front focusing objective lens group of a zoom lens, which is implemented using an assembly and adjustment device for the front focusing objective lens group of the zoom lens, specifically including the following steps: S1: Construct the mounting and adjusting device for the front focusing objective lens group of the zoom lens.

[0027] S2: Based on the position and angle of the first lens 6 acquired by the acquisition unit of the grating ruler 1, control each motor 2 to make the optical axis of the first lens 6 coaxial with the optical axis of the zoom lens.

[0028] S3: Use an interferometer (placed at one end near the first lens 6) to measure the Zernike coefficient of the front focusing objective lens group, and control each motor 2 according to the acquisition results of the Zernike coefficient acquisition unit, and use each motor 2 to adjust the position of the first lens mount 5 until the Zernike coefficient is at its minimum value. In step S3, each motor 2 drives each fixing part 4 to move synchronously in the same direction (along the output shaft direction of the motor 2) to adjust the position of the first mirror mount 5.

[0029] S4: Control each motor 2 according to the acquisition results of the Zernike coefficient acquisition unit, and use each motor 2 to adjust the angle of the first mirror mount 5 until the Zernike coefficient is at its minimum value.

[0030] In step S4, each motor 2 drives each fixing part 4 to move synchronously in the opposite direction (along the output shaft direction of the motor 2) to adjust the angle of the first mirror mount 5.

[0031] In steps S3 and S4, when the Zernike aberration coefficient is at its minimum value, the Zernike aberration coefficient is less than 0.5λ. λ is the wavelength of the laser emitted by the interferometer.

[0032] The assembly and adjustment method of this invention divides automatic assembly and adjustment into two parts. One part is to adjust and fix the first lens 6 using a tooling unit, which includes a motor 2 for providing driving force and a position feedback element—a grating ruler 1. The other part is an embedded control system—a control unit, including a motor 2 control unit, a grating ruler 1 acquisition unit, and an aberration Zernike coefficient acquisition unit. The control unit includes a host computer and an FGGA, etc.

[0033] Automatic adjustment principle: The control unit determines the position and angle of the first lens 6 through the grating ruler 1. First, the first lens 6 is adjusted to 0 degrees, making it perpendicular to the optical path. Then, the two motors 2 are controlled to adjust synchronously, thereby adjusting the entire optical path of the front focusing objective lens group. The Zernike aberration coefficient is measured by an interferometer, and the relationship between the position of the first lens 6 (feedback information from the grating ruler 1) and the Zernike aberration coefficient value is recorded throughout the entire stroke. The control unit then adjusts the first lens 6 to the position with the minimum Zernike aberration coefficient value, thus completing the automatic adjustment. Similarly, depending on the type of lens, the two motors 2 are controlled to adjust synchronously in the opposite direction. At the position with the minimum Zernike aberration coefficient value, the lens is angled. The control unit records the relationship between the lens angle (the difference between the grating ruler 1 and the optimal position) and the Zernike aberration coefficient value. At this time, the control unit adjusts the first lens 6 to the angle with the minimum Zernike aberration coefficient value. Thus, both the position and angle adjustments are completed, and the Zernike aberration coefficient value has reached its minimum, achieving the optimal adjustment position and automatically completing the fine adjustment of the front focusing objective lens group.

[0034] After the fine-tuning is completed, the motor 2 and the grating ruler 1 are separated from the fixing part 4, including the embedded control system. When automatic adjustment is required again, the motor 2 and the grating ruler 1 can simply be installed onto the new fixing part 4.

[0035] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0036] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for mounting and adjusting the front focusing objective lens group of a zoom lens, implemented using a mounting and adjusting device for the front focusing objective lens group of the zoom lens, characterized in that: The mounting and adjusting device for the front focusing objective lens group of a zoom lens includes a control unit and two tooling units. Each tooling unit includes a grating ruler, a motor, a mounting base, and a fixing component. The grating ruler and the motor are both fixedly mounted on the mounting base. The output shaft of the motor passes through the fixing component, which is also fixed to a first lens mount by bolts. Based on the feedback information from the grating ruler and the Zernike aberration coefficient of the front focusing objective lens group, the control unit adjusts the control parameters of the motor, causing the motor to move the fixing component. The fixing mechanism then moves the first lens mount, thereby realizing the mounting and adjusting of the front focusing objective lens group. The front focusing objective lens group also includes a lens barrel and a second lens mount. The first lens mount and the second lens mount are sequentially assembled inside the lens barrel. The lens barrel is provided with a mounting groove at a position relative to the first lens mount. The first lens mount is equipped with a first lens element. The second lens mount is sequentially equipped with a second lens element and a third lens element. The second lens element is located between the first lens element and the third lens element. The first lens element is close to the object plane of the zoom lens. The assembly and adjustment method specifically includes the following steps: S1: Construct the mounting and adjusting device for the front focusing objective lens group of the zoom lens. S2: Based on the position and angle of the first lens acquired by the grating ruler acquisition unit, control each motor to make the optical axis of the first lens coaxial with the optical axis of the zoom lens. S3: Use an interferometer to measure the Zernike coefficient of the front focusing objective lens group, and control each motor according to the acquisition result of the Zernike coefficient acquisition unit, and use each motor to adjust the position of the first lens mount until the Zernike coefficient is at its minimum value. In step S3, each motor drives each fixing component to move synchronously in the same direction to adjust the position of the first mirror mount; S4: Control each motor according to the acquisition result of the Zernike coefficient acquisition unit, and use each motor to adjust the angle of the first mirror mount until the Zernike coefficient is at its minimum value; In step S4, each motor drives each fixing component to move synchronously in the opposite direction to adjust the angle of the first mirror mount.

2. The method for assembling and adjusting the front focusing objective lens group of a zoom lens according to claim 1, characterized in that: The number of mounting slots is the same as the number of tooling units. The mounting slots are symmetrically arranged on the lens barrel, and the fixing member passes through the mounting slot and contacts the first lens mount.

3. The method for assembling and adjusting the front focusing objective lens group of a zoom lens according to claim 1, characterized in that: The control unit includes a motor control unit, a grating ruler acquisition unit, and an aberration Zernike coefficient acquisition unit. The grating ruler acquisition unit acquires the position and angle of the first lens fed back by the grating ruler. The aberration Zernike coefficient acquisition unit acquires the aberration Zernike coefficient of the front focusing objective lens group. The motor control unit adjusts the control parameters of the motor.

4. The method for assembling and adjusting the front focusing objective lens group of a zoom lens according to claim 1, characterized in that: In steps S3 and S4, when the Zernike aberration coefficient is at its minimum value, the Zernike aberration coefficient is less than 0.5λ.

5. The method for assembling and adjusting the front focusing objective lens group of a zoom lens according to claim 4, characterized in that: λ is the wavelength of the laser emitted by the interferometer.

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