CN209541665U - The caliberating device of optics paraboloid of revolution standard array center distance - Google Patents

Abstract

The utility model relates to a calibration device for the center distance of an array of optical rotating paraboloid reference parts, which comprises an array of optical rotating paraboloid reference parts, an angle sensor, and a three-coordinate measuring machine. It includes an array base and multiple optical rotating paraboloid references arranged on the base. The angle sensor is used to measure the angle information of points on the optical rotating paraboloid reference, including lasers, mirrors, pinhole filters, converging lenses, Polarizing Beamsplitter Prism, Quarter Wave Plate, Objective Lens, and Photodetector. The utility model can eliminate the position error caused when the optical rotating paraboloid reference part is installed.

Description

Calibration device for center distance of optical rotating paraboloid reference array

technical field

The utility model relates to a calibration device for an optical reference part, in particular to a calibration device for the center distance of an array of optical rotating paraboloid reference parts.

Background technique

The optical free-form surface has a large degree of processing freedom and high processing accuracy, and can be used as a reference part for measurement. For example, the optical rotating paraboloid has the characteristic that the surface slope change is linearly related to the position change, and can be used to measure the position. In the current mature processing technology, the surface shape and surface roughness of a single optical rotating paraboloid are processed with high precision. When the optical rotating paraboloid is used for measurement, multiple paraboloids are often arranged and combined into an array. In the advanced processing technology, the positioning accuracy of the center distance between each paraboloid is not high or a large processing cost is required. The improvement of the overall accuracy of the measurement system also depends on the processing accuracy of a single optical rotating paraboloid and the positioning accuracy of the distance between multiple paraboloids.

In many applications, such as CNC machine tools, motion detection of multi-axis translation stages need to use position reference and angle reference for measurement. Using optical free-form surface processing technology to design and process an optical reference that can provide position and angle reference for measurement and detection. Due to the deviation between the center of each optical rotating paraboloid and the designed theoretical position during the arrangement and processing of each optical rotating paraboloid, and the slight deformation of the reference part due to the influence of external environmental conditions during long-term use, the distance between each feature point The pitch will also deviate from the design value, so it is not correct to measure the position and angle of the measured system only by using the designed pitch and angle between the optical rotating paraboloids as a reference. The actual processed paraboloid pitch and the theoretically designed pitch There are differences, so it is necessary to calibrate the center distance of each paraboloid on the actually processed reference part, so as to improve the accuracy and precision of using the standard part to measure the position of the system under test.

Utility model content

The purpose of the utility model is to provide a calibration device for the center distance of an array of optical rotating paraboloid reference elements. The technical scheme that the utility model takes for solving the technical problem existing in the known technology is:

A calibration device for the center distance of an array of optical rotating paraboloid reference elements, comprising an array of optical rotating paraboloid reference elements, an angle sensor, and a three-coordinate measuring machine. and a plurality of optical rotating paraboloid reference pieces arranged on the base, the angle sensor is fixed on the movement spindle of the measuring machine, and the array base is placed on the workbench of the three-coordinate measuring machine, characterized in that,

The angle sensor is used to measure the angle information of a point on an optical rotating paraboloid reference piece, including a laser, a mirror, a pinhole filter, a converging lens, a polarizing beam splitter, a quarter wave plate, an objective lens and a photodetector ; The light emitted by the laser reflected by the mirror is filtered by the pinhole filter and then converged by the converging lens, and the direction and energy of the light are changed after the converged light passes through the polarizing beam splitter; After changing the phase of the light, the light is irradiated onto the optical rotating paraboloid reference piece, and the light reflected by the optical rotating parabola reference piece is received by the photodetector after passing through the polarization beam splitter and the objective lens in turn; the photodetector is located on the focal plane of the objective lens;

Preferably, the laser is a spot laser. The pinhole filter is an aperture stop.

The advantages and positive effects of the utility model are: using the calibration method realized by the utility model, the calibration of the horizontal and vertical distances of the center points of each optical rotary paraboloid on the array of optical rotary paraboloid reference parts can be completed through a three-coordinate measuring machine and an angle sensor. Eliminate the position error caused by the installation of the optical rotating paraboloid reference piece.

Description of drawings

Fig. 1 is the schematic diagram of the calibration device applied by the utility model

In the figure: 1. Optical rotating paraboloid reference element array, 2. Angle sensor, 3. Coordinate measuring machine

Fig. 2 is a schematic diagram of an array of optical rotating paraboloid reference elements applied in the utility model

In the figure: 1-1, optical rotating paraboloid reference piece; 1-2, array base

Fig. 3 is the schematic diagram of the optical path structure of the angle sensor applied by the utility model

In the figure: 2-1, laser; 2-2, mirror; 2-3, pinhole filter; 2-4, converging lens; 2-5, polarization beam splitter prism; 2-6, quarter wave plate ; 1-1, optical rotating paraboloid reference piece; 2-7, objective lens; 2-8, photoelectric detector

Detailed ways

In order to further understand the utility model content, characteristics and effects of the present utility model, the following examples are given hereby, and detailed descriptions are as follows in conjunction with the accompanying drawings:

The utility model provides a method and a device for calibrating the center distance of an array of optical rotating paraboloid reference elements in order to solve the technical problems in the known technology. The center distance eliminates the error caused by the installation of the optical rotating paraboloid, and provides benchmark data for related detection.

The technical scheme adopted by the utility model to solve the technical problems existing in the known technology is: a calibration method and device for the center distance of the array center of the optical rotating paraboloid reference element, and the calibration method for the center distance of the array center of the optical rotation paraboloid reference element 1. The device includes an optical rotating paraboloid reference element array 1 , an angle sensor 2 and a three-coordinate measuring machine 3 .

The optical rotating paraboloid reference element array 1 is placed on the workbench of the coordinate measuring machine 3, and is composed of a plurality of optical rotating paraboloid reference elements 1-1 and an array base 1-2. The optical rotating paraboloid reference piece is made of brass, and an optical rotating paraboloid is processed on the surface of the reference piece. There are threaded holes at the bottom of the reference piece, which are connected to the array base through bolts, and the center distance between the reference pieces needs to be further calibrated. A single optical rotating paraboloid on the optical rotating paraboloid reference element array is numbered by row and column, the x direction is the row, the y direction is the column, and the i-th row and the j-th column are numbered as P(i, j).

As shown in Figure 2, an angle sensor suitable for optical free-form surface detection, the angle sensor 2 consists of a laser 2-1, a mirror 2-2, a pinhole filter 2-3, and a converging lens 2-4 , polarization beam splitter prism 2-5, quarter-wave plate 2-6, optical rotating paraboloid reference piece 1-1, objective lens 2-7, photodetector 2-8, etc., can measure the optical rotating paraboloid reference piece Point angle information.

The laser is a dot spot laser, and the light emitted by the laser is a vertical light; the reflector is located directly below the laser, at an angle of 45° with the horizontal direction, and the mirror surface is inclined to the upper left; the pinhole filter is Aperture diaphragm, the aperture size is 200um, and the center of the hole is facing the laser beam; the converging lens is located on the right side of the pinhole filter to converge the light, and its focal length should not be selected larger; the polarizing beam splitting prism is a half-transparent mirror, The direction and energy of the light can be changed; the quarter-wave plate is located directly under the polarization beam splitter prism, which can change the phase of the light; the optical rotating paraboloid reference piece to be tested is connected to the workbench of the three-dimensional coordinate measuring machine through a connecting piece Above; the objective lens is a convex lens, which converges the imaging light beam to improve the imaging quality; the photodetector is located on the focal plane of the objective lens, and is generally an industrial CMOS camera.

Further, the laser light emitted by the laser is reflected by the mirror so that the vertical coarse beam becomes a horizontal coarse beam, and the horizontal coarse beam is restricted by a pinhole filter and becomes a thin beam with a diameter of 200um, and then converged by a converging lens After passing through the polarization beam splitter, the p light in the beam passes through completely at this time, the s light is reflected through the quarter wave plate and reaches the optical rotating paraboloid reference piece to be detected, and the reflected light passes through the quarter wave plate and the polarization beam splitter in turn , The objective lens is imaged on the photodetector. According to the position information of the light spot on the photodetector, the surface information of the free-form surface to be measured can be obtained.

It is assumed that the optical free-form surface to be detected is a small-caliber optical paraboloid of revolution, and it is known that the slope of a point on the optical paraboloid of revolution is proportional to its horizontal distance from the apex of the paraboloid of revolution. For the processed optical rotating paraboloid, it is fixed on the three-coordinate measuring machine table; by adjusting the three-coordinate measuring machine to make a linear movement in the X direction of the horizontal plane with a certain step distance, n points are measured; and then by adjusting the three The coordinate measuring machine moves a certain step distance in the Y direction of the horizontal plane, and repeats the above steps to measure m points; it reciprocates in this way until the measurement points basically cover the optical rotating paraboloid to be measured. Theoretically, the spot position distribution of the measurement points on the photodetector conforms to a certain rule, such as an n×m array with equidistant distribution. If the actual detection results are not in line with expectations, it means that the processed optical paraboloid of rotation does not meet the requirements, and there is a surface error. , and can be corrected according to the detection information, otherwise it is a qualified processed product.

The three-coordinate measuring machine 3 has three mutually orthogonal motion axes and a horizontal workbench, and the angle sensor 2 is mounted on the main axis of the vertical movement of the three-coordinate measuring machine, and the optical rotating paraboloid reference element array 1 is placed on the three on the table of the coordinate measuring machine.

This calibration method uses the following steps:

1) Calibration adopts the way of row by row to collect points, first measure the coordinates of the first row and first column of the optical rotating paraboloid reference part P(1,1) in the x direction, and the spindle of the three-coordinate measuring machine drives the angle sensor along the X direction P(1,1) measures the angle information α ₁₁ , α ₁₂ ···α _1n of n points, and simultaneously records the feedback values X ₁₁ , X ₁₂ ···X _1n of the coordinate measuring machine in the X direction.

2) Then measure the coordinates in the y direction of the optical rotating paraboloid reference part P(1,1) in the first row and the first column, and the three-coordinate measuring machine spindle drives the angle sensor to measure the angles of n points at P(1,1) along the Y direction information β ₁₁ , β ₁₂ ···β _1n , and simultaneously record the feedback values Y ₁₁ , Y ₁₂ ···Y _1n of the three-coordinate measuring machine in the Y direction.

3) Perform least squares linear fitting on the feedback values X ₁₁ , X ₁₂ ···X _1n and angle information α ₁₁ , α ₁₂ ···α _1n obtained from the measuring machine, and obtain the intercept b of the fitted line equation ₁₁ is the coordinate of P(1,1) in the x direction; similarly, the least squares is performed on the feedback values Y ₁₁ , Y ₁₂ ···Y _1n and angle information β ₁₁ , β ₁₂ ···β _1n obtained from the measuring machine. Multiplying the linear fitting, the intercept B ₁₁ of the fitting straight line equation obtained is the coordinate of the y direction of P(1,1); then the coordinate of P(1,1) in the three-coordinate measuring machine coordinate system is (b ₁₁ , B ₁₁ ).

4) The x-direction coordinates and y-direction coordinates of the optical rotating paraboloid reference member numbered P(i,j) in row i, column j, can be obtained by repeating steps 1)-3), as (b _ij , B _ij ); the coordinates of the x-direction and the y-direction of the optical rotating paraboloid reference member whose number is P(m, n) in the nth row of the mth row and the coordinates in the y direction can also be obtained by repeating steps 1)-3), as ( b _mn ,B _mn ); then the center distance between P(i,j) and P(m,n) is (b _ij -b _mn ,B _ij -B _mn ).

5) By repeating the above steps, the relative distance between the centers of the individual optical rotating paraboloids in the array of optical rotating paraboloid reference elements can be calibrated.

Principle of the utility model:

The utility model utilizes the sensitivity of the optical free-form surface to the collimated light beam with a small area and the known change law of the surface shape, and designs a set of simple optical path structure. , the optical free-form surface shape can be detected through the optical path structure, and the products with large processing errors can be identified.

When using the optical rotating paraboloid reference element array as the position reference for position measurement, since the optical rotating paraboloid reference element usually has a certain position error during installation, it is necessary to calibrate the center distance of each optical rotating paraboloid reference element to obtain the distance between them. precise location. The utility model utilizes the surface characteristics of the optical rotating paraboloid itself, uses a three-coordinate measuring machine to record the position information of the measuring point, obtains the angle information of the measuring point by means of an angle sensor, and accurately obtains the reference piece of the optical rotating paraboloid through the linear fitting of the least square method Center coordinates, and then accurately calibrate the center distance between each optical rotating paraboloid, eliminate the error caused by the installation of optical rotating paraboloids, and provide reference data for related detection.

Although the preferred embodiment of the utility model has been described above in conjunction with the accompanying drawings, the utility model is not limited to the above-mentioned specific implementation, and the above-mentioned specific implementation is only illustrative and not restrictive. Under the enlightenment of the utility model, those skilled in the art can also make many forms without departing from the purpose of the utility model and the protection scope of the claims, and these all belong to the protection scope of the utility model.

Claims (3)

1. A calibration device for the center distance of an optical rotating paraboloid reference element array, comprising an optical rotating paraboloid reference element array, an angle sensor, and a coordinate measuring machine. The optical rotating paraboloid reference element array is placed on the three coordinate measuring machine workbench, including the array The base and a plurality of optical rotating paraboloid reference parts arranged on the base, the angle sensor is fixed on the main axis of motion of the measuring machine, and the array base is placed on the workbench of the three-coordinate measuring machine, characterized in that, The angle sensor is used to measure the angle information of a point on an optical rotating paraboloid reference piece, including a laser, a mirror, a pinhole filter, a converging lens, a polarizing beam splitter, a quarter wave plate, an objective lens and a photodetector ; The light emitted by the laser reflected by the mirror is filtered by the pinhole filter and then converged by the converging lens, and the direction and energy of the light are changed after the converged light passes through the polarizing beam splitter; After changing the phase of the light beam, it irradiates the optical rotating paraboloid reference piece, and the light reflected by the optical rotating parabola reference piece passes through the polarization beam splitter prism and the objective lens in turn and is received by the photodetector; the photodetector is located on the focal plane of the objective lens. 2. The device according to claim 1, wherein the laser is a spot laser. 3. The device according to claim 1, wherein the pinhole filter is an aperture stop.