CN112304253A

CN112304253A - Non-contact measurement and adjustment method for parallelism and coaxiality of optical mirror

Info

Publication number: CN112304253A
Application number: CN202010964636.3A
Authority: CN
Inventors: 王皓; 吕嗣鸿; 曹宇
Original assignee: University of Electronic Science and Technology of China
Current assignee: University of Electronic Science and Technology of China
Priority date: 2020-09-15
Filing date: 2020-09-15
Publication date: 2021-02-02

Abstract

The non-contact measuring and regulating method for parallelism and coaxiality of optical mirror surface features that laser distance measuring sensor and reflecting fin are used to make the measured lens to be plane displaced for closed-loop measurement and regulation. The scheme is applied to certain optical equipment, and after pre-adjustment and coaxial adjustment are carried out, the optical equipment can have complete closed-loop measurement and adjustment capacity on the lens through the technology, so that the measured lens and the reference lens keep parallel and a certain axial distance relation.

Description

Non-contact measurement and adjustment method for parallelism and coaxiality of optical mirror

Technical Field

The invention relates to the field of adjustment of certain optical mirror surfaces, and particularly provides a method for non-contact measurement and adjustment of parallelism and coaxiality between two optical mirror surfaces.

Background

In the field of precision optical mechanical industry, in order to make the volume of an optical instrument designed and processed as small as possible and have a complete closed-loop measurement and control system, a complete mirror parallelism and coaxiality measurement system is required; in recent years, a detection method based on rotation is continuously provided in the industry, so that the measurement and control precision is greatly improved; however, due to the limitation of the basic motion, some optical devices that cannot use rotation as the basic motion still face the measurement and control problems.

The traditional mechanical coaxiality measuring method comprises a three-coordinate method of measuring by a grating ruler, a statistical measuring method of measuring by a dial indicator, a measuring method taking a V-shaped groove as a reference and the like, wherein the traditional mechanical methods need contact-type measurement, are low in repetition precision and are strict in measuring conditions; due to the high precision requirement and large distance limitation of the optical device, the traditional mechanical measurement method is often difficult to meet the use requirement.

In recent years, methods for measuring parallelism and coaxiality based on laser measurement, which are proposed at home and abroad, are gradually and widely used, but are limited by requirements on cost and motion control, and the existing schemes for measuring parallelism and coaxiality by laser use rotation as basic motion, so that the design space of an optical device is greatly limited, and the measurement requirements of optical equipment which can only provide plane displacement are difficult to meet.

Disclosure of Invention

In order to solve the difficulty of the current plane displacement motion measurement and require the simultaneous measurement of the parallelism and the coaxiality between the measured plane and the reference plane, the invention provides the method for realizing the detection of the measured plane by utilizing the distance change caused by the plane displacement motion.

The traditional rotation measurement or mechanical measurement method can only coincide two axes, the adjustment mode is usually open loop adjustment, the measurement position is a cylindrical surface where the measured plane is located, and the precision of the measurement is greatly influenced by the processing precision of the cylindrical surface; the measuring and adjusting method has the characteristics and innovation that the axial line position and angle relation of the measured mirror surface can be accurately obtained by using displacement instead of rotation as basic motion through a distance measuring and calculating method; and according to the use requirement, the purpose that the two axes keep a certain distance can be realized; meanwhile, the closed-loop adjustment method adopted by the method can greatly improve the repeatability precision and accelerate the adjustment speed.

In the invention, in order to detect the distance and angle relation between the measured plane and the reference plane in real time, the distance change along the axis direction (Z-axis direction) of the reference plane and the high-precision characteristic of a laser distance measuring instrument are caused when the measured plane translates, the distance change in the Z-axis direction is obtained by continuously moving the measured plane, the measurement of the position and the angle of the measured plane is realized, and the parallelism and the coaxiality of the measured plane and the reference plane are corrected; and the method of closed-loop control can improve the repetition precision and overcome the offset caused by the precision optical equipment in the motion process.

The design method adopted by the invention is that according to the working mode of the laser ranging sensor, in order to enable the laser sensor to have parameters of a plurality of angles, a reflector clamp ring for non-contact optical measurement is designed; the clamping ring comprises two parallel fins and two inclined fins; the clamping ring is assembled at the outer side of the optical lens to be measured, and the assembly requirement of the clamping ring is parallel to the optical lens to be measured; under the condition that the two parallel fins on the clamping ring are not parallel to the reference mirror surface, when the measured mirror surface performs translational motion, the laser sensors corresponding to the two parallel fins can detect different distance changes, so that the deflection angle direction and the deflection angle size of the measured mirror piece can be obtained, and the measured mirror piece can be subjected to closed-loop adjustment through the deflection table to be parallel to the reference plane; when the measured lens and the reference lens are in a parallel state, the distance between the measured lens and the reference lens can be calculated through the included angle between the laser beams of the two lasers and the reference plane and the distance measurement result, and then the coaxiality is measured through the two inclined fins on the clamping ring of the reflector plate; because the installation position of the laser and the size of the measured lens are known, the axial line position of the measured lens can be calculated by using the distance measurement results of the laser sensors corresponding to the two inclined fins and the distance between the measured lens and the reference lens calculated before, so that the axial line can be further adjusted to the designated position by using the micro-motion platform.

In the using conditions of the scheme, the installation of the reference lens and the measured lens is required to be kept stable, the installation of the laser and the installation of the reflector snap ring are required to have certain position precision, and the control precision of the deflection platform and the micro-motion platform meets the requirements.

Drawings

FIG. 1 is a schematic diagram of the overall structure of the application scenario and installation of the present invention;

FIG. 2 is a schematic view of the present invention relating to the installation structure of the plane to be measured;

FIG. 3 is a schematic view of the mounting structure of the reference mirror and the laser ranging sensor according to the present invention;

FIG. 4 is a schematic diagram of the light path and the adjustment process during the process of adjusting the plane to be measured to be parallel;

FIG. 5 is a schematic diagram of an optical path illustrating the two parallel fins of the reflector plate being unable to adjust its axis;

FIG. 6 is a schematic diagram of the light path for adjusting the axis of the plane to be measured by using two inclined fins of the reflector and the adjustment process;

shown in the figure: 101-the whole installation of the measured mirror surface; 102-installation of a reference mirror surface; 201-a reflector panel; 202-optical lens (test lens); 203-a deflection stage (for adjusting the deflection angle of the optical lens); 204-micro-motion stage (for achieving X, Y directional displacement of the lens); 205-mounting a substrate; 301-optical lens (reference lens); 302-laser ranging sensor; 303-mounting a substrate;

the specific implementation scheme is as follows:

in order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to the accompanying drawings and examples, but the scope of the present invention is not limited to the examples described below.

In order to realize a non-contact mode of measuring and adjusting parallelism and coaxiality between lenses of optical equipment through plane displacement instead of rotation, as shown in fig. 1, a structure and a method for measuring a measured lens (202) by using a reflector (201), a micro-motion platform (204) and a laser range finder (302) are designed, and a deflection platform (203) and the micro-motion platform (204) are used for carrying out closed-loop adjustment on the measured lens (202) according to a data result of the laser range finder.

The method mainly comprises the following steps: firstly, as shown in fig. 1, mounting each bracket part, control part, lens and reflector, wherein two parallel fins of the reflector (201) are required to be parallel to the mirror surface of the measured lens (202), and the optical distance meter (302) and the reference mirror surface (301) have certain precision of angle and position relation; at the moment, the relative position and angle relation between the measured lens (202) and the reference lens (301) is unknown; then, the tested lens generates X, Y directional displacement through the micro-motion platform (204), and then the distance measurement is carried out through two reflectors parallel to the mirror surface of the tested lens (202), as shown in fig. 4; when the measured lens (202) is not parallel to the reference lens (301), the optical ranging result changes when the measured lens (202) is moved, as shown in the left and middle diagrams of fig. 4; the deflection angle and direction of the measured lens can be calculated according to the measurement result, so that the measured lens (202) is adjusted to be parallel through the deflection table (203), as shown in the right diagram of fig. 4; repeating the steps until the parallel adjustment is achieved; finally, since the measured lens (202) is parallel to the reference lens (301), the axis position cannot be calculated by the displacement of the two reflector fins parallel to the measured lens (202), as shown in fig. 5; at the moment, the axis can be measured and positioned by utilizing two inclined fins which are arranged on the reflecting plate (201) and form a certain angle relation with the measured lens; as shown in fig. 6, when the measured lens (202) which is parallel to the reference lens (301) moves, the distance data returned by the two inclined fins on the reflector (201) will change, and the position of the axis can be calculated, so that the adjustment of the position of the axis of the measured lens (202) can be completed by the micro-motion platform (204).

Claims

1. A non-contact measurement and adjustment method for parallelism and coaxiality of an optical mirror surface is characterized by comprising the following steps: in the scene of using the parallelism and coaxiality measurement between the lenses of the optical equipment, a non-contact optical measurement method is used, and a method of using plane displacement instead of rotation as basic motion is adopted, so that the parallelism and coaxiality closed-loop adjustment of the measured lens surface is realized according to the reference lens surface.

2. A method of mounting and measuring an optical lens according to claim 1, characterized in that: the reflecting plate is specially designed and provided with a plurality of fins, and in the plurality of fins of the reflecting plate, the plurality of fins are parallel, and other fins and the parallel fins are in a fixed angle relationship.

3. A non-contact measurement method, comprising the steps of: firstly, a section of X, Y-direction displacement is generated through a micro-motion platform; judging the parallelism of the measured mirror surface and the reference mirror surface through a reflector parallel to the measured mirror piece, if not, calculating a deflection angle, and adjusting the parallelism by a deflection table; after parallel adjustment, the coaxiality of the measured mirror surface and the reference mirror surface is judged through a reflecting plate forming a certain angle with the measured mirror surface, if the coaxiality is not the same, deviation is calculated, and adjustment is carried out through a micro-motion platform.