阅读说明：本技术 一种基于复光束角度传感器的大型非球面形貌检测方法 (Large-scale aspheric surface morphology detection method based on complex beam angle sensor ) 是由 陈梅云 黄建平 余浩燃 陈锦标 夏益民 周郭许 谢胜利 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种基于复光束角度传感器的大型非球面形貌检测方法,包括如下步骤：步骤S1：将大型非球面工件放置在用于测量的倾斜台上,并从硬件和软件两方面消除测量误差；步骤S2：角度差的测量：使用傅里叶变换算法对大型非球面进行一次圆周扫描；步骤S3：通过角度差Δc计算轮廓P；步骤S4：大型非球面的轮廓测量。该检测方法属于非接触式的形貌测量技术,可以解决接触性检测因物理接触而造成的被测表面损伤；该检测方法有周向扫描功能,可以解决相移干涉测量法适用的测量尺度范围较小的缺点,该装置通过对不同半径的圆形扫描进行重复实验,以获得表面的整体形状,并重建大型非球面的表面形貌,可以解决莫尔测偏法测量精度较低的不足。(The invention discloses a large-scale aspheric surface morphology detection method based on a complex beam angle sensor, which comprises the following steps: step S1: placing a large-scale aspheric workpiece on a tilting table for measurement, and eliminating measurement errors from two aspects of hardware and software; step S2: measurement of the angular difference: performing one-time circular scanning on the large aspheric surface by using a Fourier transform algorithm; step S3: calculating a profile P through the angle difference deltac; step S4: and (4) profile measurement of large aspheric surfaces. The detection method belongs to a non-contact type morphology measurement technology, and can solve the problem of damage to the detected surface caused by physical contact in contact detection; the detection method has a circumferential scanning function, can solve the defect that the measurement scale range applicable to the phase-shift interferometry is small, obtains the overall shape of the surface by performing repeated experiments on circular scanning with different radiuses, reconstructs the surface appearance of a large aspheric surface, and can solve the defect that the Mohr polarization measurement method is low in measurement precision.)

1. A large-scale aspheric surface morphology detection method based on a complex beam angle sensor is characterized by comprising the following steps:

step S1: placing a large-scale aspheric workpiece on a tilting table for measurement, and eliminating measurement errors from two aspects of hardware and software;

step S2: measurement of the angular difference: performing one-time circular scanning on the large aspheric surface by using a Fourier transform algorithm;

step S3: calculating a profile P through the angle difference deltac;

step S4: and (4) profile measurement of large aspheric surfaces.

2. The method for detecting large aspheric surface topography based on complex beam angle sensor as claimed in claim 1, wherein the hardware aspect in step S1 refers to fine tuning and aligning the mechanical and optical system of the complex beam angle sensor by using two XY stage and tilt stage, thereby achieving error elimination.

3. The method for detecting the morphology of the large aspheric surface based on the complex beam angle sensor as claimed in claim 1, wherein the software aspect in the step S1 is to eliminate the error by means of measurement transfer, and the measurement transfer is to be processed by fourier transform formula.

4. The method for detecting large aspheric surface topography based on a complex beam angle sensor as claimed in claim 1, wherein the step S2 specifically comprises: and taking the O point on the surface of the large-scale aspheric surface workpiece as the center and r as the radius to carry out circumferential rotation on the compound beam angle sensor, rotating the large-scale aspheric surface workpiece in an incremental mode, and measuring the angle difference of the large-scale aspheric surface workpiece along the circumference.

5. The method for detecting large aspheric surface topography based on a complex beam angle sensor as claimed in claim 1, wherein the step S3 specifically comprises:

step S31: the profile P of the large aspherical workpiece at angular position t is represented using a fourier series, resulting in:

wherein a is_iAnd b_iIs a Fourier series coefficient, n is the maximum iteration number of the Fourier series, and m is the number of sampling points;

step S32: the angular difference Δ c is measured using a sensor and expressed as the second differential P of the profile data, resulting in:

step S33: the angular difference can be converted into a coefficient d by performing a Fourier transform_iAnd e_iTo obtain:

step S34: and Fourier series (a)_iAnd b_i) And coefficient (d)_iAnd e_i) The relationship between can be expressed as:

thus, the profile P of a large aspherical workpiece can be represented as a fourier series using an inverse fourier transform; when using different radii for reconstructing the overall shape of the curved surface, the profile data P is separated from the measured radius r and the distance x between the points₀And (4) correlating.

6. The method for detecting large aspheric surface topography based on a complex beam angle sensor as claimed in claim 1, wherein the step S4 specifically comprises: let A and B be representative points of rotation angle t on a large aspherical workpiece, c_aAnd c_bIs the corresponding angle, Δ c is the angular difference between points a and B; thus, in the X-axis, the center s is taken into account₀(s₀Not equal to 0), giving the corresponding angle c_ij：

i, j are the positions of the microlens array on the x-axis and y-axis, respectively, where the spacing of the microlens array is 0.5 mm; the large aspherical surface c can be calculated from equation (5)_ijThe angle will be used for the simulation of large aspheric surface measurements.

Technical Field

The invention relates to the technical field of optical detection, in particular to a large-scale aspheric surface morphology detection method based on a complex beam angle sensor.

Background

At present, the topography measuring technology has important development and application in industries such as industrial production, aerospace, semiconductors and the like. In the field of high-precision optical element detection, especially in the coarse grinding and fine grinding forming stages, the topography measurement plays an important role. Large-size high-precision optical components, especially prism elements with different curvatures, are widely and deeply applied in the fields of aerospace, semiconductors and the like. Due to the particularity of the working environment of the large-scale aspheric prism, the requirements on the surface shape precision, the surface roughness and the like of the optical element are extremely high. In the processing and manufacturing process, in order to meet various technical parameter indexes, the surface topography of the prism with different curvatures must be detected for multiple times, and then the topography information obtained by detection is fed back to a processing control system for guiding and correcting the next processing procedure. In order to obtain more accurate measurement information for guiding processing, higher requirements are put forward on the precision and the shape diversity of the shape measuring machine.

Three methods for detecting the shape of the aspheric surface, and advantages and disadvantages thereof will be listed below.

The contact type shape detection method is that a mechanical contact pin is in physical contact with a large-scale aspheric workpiece to be detected, so that surface shape information is converted into a photoelectric signal. But it is inefficient and difficult to record the microscopic topography of the object under test completely. In addition, the probe is in physical contact with the large aspheric workpiece to be measured, which may cause damage to the probe and the measured surface, thereby causing measurement errors and even irreparable damage to the large aspheric workpiece.

Phase-shift interferometry not only can process the entire fringe image at once, but also has many advantages in speed and topography accuracy. But has extremely high sensitivity and is applicable to a small measurement scale range. In order to solve the problem of poor disturbance resistance, a new aspheric three-dimensional shape detection method, namely a Moire polarization measurement method, is developed.

Compared with a phase-shift interference measuring device, the device adopted by the moire polarization measuring method has obvious price advantage and simultaneously improves the anti-interference performance of the whole measuring device. However, due to the limitation of the basic principle, the measurement accuracy of the moire polarization method is low, and the measurement under some extremely precise conditions cannot be well satisfied.

Accordingly, further improvements and improvements are needed in the art.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a large-scale aspheric surface shape detection method based on a complex beam angle sensor.

The purpose of the invention is realized by the following technical scheme:

a large-scale aspheric surface morphology detection method based on a complex beam angle sensor mainly comprises the following specific steps:

step S1: a large aspherical workpiece is placed on a tilting stage for measurement and measurement errors are eliminated both in hardware and software.

Specifically, the hardware aspect in step S1 is to fine tune and align the mechanical and optical systems of the complex beam angle sensor by using two XY stages and a tilt stage, so as to eliminate errors.

Specifically, the software aspect in step S1 is to eliminate the error by using a measurement transfer, where the measurement transfer is processed by using a fourier transform formula.

Step S2: measurement of the angular difference: a circle scan of the large aspheric surface is performed using a fourier transform algorithm.

Specifically, the step S2 specifically includes: and taking the O point on the surface of the large-scale aspheric surface workpiece as the center and r as the radius to carry out circumferential rotation on the compound beam angle sensor, rotating the large-scale aspheric surface workpiece in an incremental mode, and measuring the angle difference of the large-scale aspheric surface workpiece along the circumference.

Step S3: the profile P is calculated from the angular difference ac.

Specifically, the step S3 specifically includes:

step S31: the profile P of the large aspherical workpiece at angular position t is represented using a fourier series, resulting in:

wherein a is_iAnd b_iIs a Fourier series coefficient, n is the maximum iteration number of the Fourier series, and m is the number of sampling points;

step S32: the angular difference Δ c is measured using a sensor and expressed as the second differential P of the profile data, resulting in:

step S33: the angular difference can be converted into a coefficient d by performing a Fourier transform_iAnd e_iTo obtain:

step S34: and Fourier series (a)_iAnd b_i) And coefficient (d)_iAnd e_i) The relationship between can be expressed as:

thus, the profile P of a large aspherical workpiece can be represented as a fourier series using an inverse fourier transform; when using different radii for reconstructing the overall shape of the curved surface, the profile data P is separated from the measured radius r and the distance x between the points₀And (4) correlating.

Step S4: and (4) profile measurement of large aspheric surfaces.

Specifically, the step S4 specifically includes: let A and B be representative points of rotation angle t on a large aspherical workpiece, c_aAnd c_bIs the corresponding angle, Δ c is the angular difference between points a and B; thus, in the X-axis, the center s is taken into account₀(s₀Not equal to 0), giving the corresponding angle c_ij：

i, j are the positions of the microlens array on the x-axis and y-axis, respectively, where the spacing of the microlens array is 0.5 mm; the large aspherical surface c can be calculated from equation (5)_ijThe angle will be used for the simulation of large aspheric surface measurements.

The invention also discloses a large-scale aspheric surface morphology detection device based on the complex beam angle sensor, which mainly comprises a bearing table, a bracket, a first XY platform, a second XY platform, a rotating table, an inclined table and the complex beam angle sensor.

Specifically, the bearing platform is horizontally and fixedly arranged. The two ends of the support are clamped at the two sides of the bearing table and are fixedly connected with the bearing table. The first XY platform is installed on the bearing platform and is fixedly connected with the bearing platform. The rotating table is mounted on the first XY stage, and the position of the rotating table is adjusted by the first XY stage. The second XY stage is mounted on a rotary table and is driven to rotate by the rotary table. The tilting table is arranged on the second XY platform, is fixedly connected with the output end of the second XY platform, and is driven by the second XY platform to adjust the position of the tilting table. The workpiece is arranged on the tilting table. The compound light beam angle sensor is arranged on the support and positioned above the tilting table, and the detection end of the compound light beam angle sensor faces the upper surface of the workpiece.

The compound beam angle sensor comprises a semiconductor laser, a convex lens for focusing laser, a first filter plate, a collimating lens, a second filter plate, a beam splitter, a micro-lens array and a CMOS camera. The first filter plate is provided with a first filter hole for filtering light, and the second filter plate is provided with a second filter hole for filtering light.

Specifically, the semiconductor laser, the convex lens, the first filter plate, the collimating lens, the second filter plate and the beam splitter are sequentially and coaxially arranged from top to bottom. Laser emits from the semiconductor laser and penetrates from the incident end of the beam splitter after sequentially passing through the convex lens, the first light filter plate, the collimating lens and the second light filter plate, and the laser is reflected by the beam splitter and is emitted from the reflecting end and then is projected onto a cylindrical workpiece. The micro lens array and the CMOS camera are sequentially arranged behind the beam splitter, and the micro lens array is opposite to the transmission end of the beam splitter and focuses light reflected from the cylindrical workpiece to irradiate the CMOS camera.

The working process and principle of the complex beam angle sensor are as follows: laser beams generated by the semiconductor laser pass through a pinhole in the first filter plate, are collimated by the collimating lens and are projected onto the surface of the workpiece under the action of the beam splitter; the reflected beam from the surface of the workpiece passes completely through the beam splitter to the microlens array; the incident light is divided into a plurality of small samples by the micro lens array and then focused on the detector array; thus, a number of separate optical focal points are generated on the CMOS camera, the positions of which are directly related to the contour of the workpiece surface; an algorithm is then used to process the image detected from the CMOS camera and determine the position of the focal point, calculate the angular difference for a particular position of the workpiece surface by comparison with the original position, and reconstruct the surface profile from the angular difference.

Compared with the prior art, the invention also has the following advantages:

(1) compared with a contact detection method, the large aspheric surface shape detection method based on the complex beam angle sensor provided by the invention adopts a non-contact detection means, and avoids the damage of the large aspheric surface workpiece to be detected caused by the physical contact with the large aspheric surface workpiece to be detected.

(2) Compared with a phase shift interference method, the large-scale aspheric surface morphology detection method based on the complex beam angle sensor provided by the invention has the advantages that on the basis of ensuring the measurement accuracy, the curvature measurement range is increased and the zero point error is eliminated by using a circular scanning mode.

(3) Compared with the Mohr polarization method, the technical scheme provided by the invention has the advantages that on the basis of ensuring a larger measurement range, the repeated experiment is carried out through circular scanning with different radiuses to obtain the overall shape of the surface, the appearance of the large-scale aspheric surface is reconstructed, and the measurement precision is increased.

(4) The method and the device for detecting the large-scale aspheric surface morphology based on the complex beam angle sensor have the advantages of simple and compact structure, simple optical path of the complex beam angle sensor, strong anti-interference performance, stable use result, high detection precision and large measurement range, and are very suitable for detecting large-scale aspheric surfaces.

(5) The aspheric surface shape detection technology based on the complex beam angle sensor and the detection device thereof can meet the requirements of measurement precision and anti-interference performance, and have a larger measurement range, and have very important significance for improving the precision and adaptability of the aspheric surface lens and reducing the production cost.

Drawings

Fig. 1 is a schematic structural diagram of a large aspheric surface topography detection device based on a complex beam angle sensor provided by the present invention.

Fig. 2 is a schematic structural diagram of a complex beam angle sensor provided by the present invention.

FIG. 3 is a schematic diagram of the present invention for obtaining a point of a circle of a certain radius by stepwise rotating a large aspheric workpiece.

FIG. 4 is a flowchart of a method for detecting a large aspheric surface profile based on a complex beam angle sensor according to the present invention.

FIG. 5 is a schematic diagram of a large aspheric profile measurement provided by the present invention.

FIG. 6 is a schematic diagram of the measurement of the large aspheric angle difference provided by the present invention.

Fig. 7 is a diagram showing simulation results of an output signal from CMOS according to the present invention.

Fig. 8 is a schematic diagram of angle data of 25 different radius points provided by the present invention.

FIG. 9 is a graphical illustration of angular difference data for different radii provided by the present invention.

The reference numerals in the above figures illustrate:

1-support, 2-first XY platform, 3-rotating platform, 4-tilting platform, 5-compound beam angle sensor, 6-workpiece, 7-semiconductor laser, 8-first light filter plate, 9-collimating lens, 10-second light filter plate, 11-beam splitter, 12-micro lens array, 13-CMOS camera, 14-convex lens, 16-bearing platform, and 17-second XY platform.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer and clearer, the present invention is further described below with reference to the accompanying drawings and examples.