阅读说明：本技术 一种高精度表面形貌测量机的传感器灵敏度测量方法 (Sensor sensitivity measuring method of high-precision surface morphology measuring machine ) 是由 陈梅云 陈锦标 黄建平 余浩燃 林常青 辜晓波 谢胜利 于 2019-09-27 设计创作，主要内容包括：本发明公开了一种高精度表面形貌测量机的传感器灵敏度测量方法,该测量方法利用准直光束经过非球面反射到透镜光路的原理,推导出利用曲率半径计算灵敏度的公式并实现测量传感器的灵敏度。本方案鉴于现有复光束角度传感器灵敏度测量方法出现的步骤繁琐,精确度低,抗干扰能力差等问题,提供一种操作简单,耗时短,抗干扰能力强的传感器灵敏度测量方法对MBAS进行精确测量,使其精度可以达到理论精度,提高形貌光学测量系统的可靠性和精确性。(The invention discloses a sensor sensitivity measuring method of a high-precision surface morphology measuring machine, which utilizes the principle that collimated light beams are reflected to a lens light path through an aspheric surface to deduce a formula for calculating sensitivity by using curvature radius and realize the sensitivity measurement of a sensor. In view of the problems of complicated steps, low accuracy, poor anti-interference capability and the like of the conventional complex beam angle sensor sensitivity measurement method, the method for accurately measuring the MBAS is simple to operate, short in time consumption and high in anti-interference capability, so that the accuracy of the MBAS can reach the theoretical accuracy, and the reliability and the accuracy of the morphology optical measurement system are improved.)

1. A sensor sensitivity measuring method of a high-precision surface morphology measuring machine is characterized by comprising the following steps:

step S1: the laser beam is reflected by an aspheric surface with the curvature radius of R, wherein the included angle between incident light and reflected light is 2 alpha, and then the laser beam is focused by a lens with the focal length of f; setting the lattice interval of the lens as d, the distance between the lens and the aspheric surface as k, and the distance from the tangent plane of the contact point of the two lenses to the intersection point position of the incident light and the aspheric surface as c;

step S2: the angle of incidence α can be expressed in terms of lens pitch d and radius of curvature R as:

step S3: from the optical invariants, the lens pitch d from the geometric relationship is:

step S4: the distance c from the tangent plane of the two lens contact points to the position of the intersection of the incident light and the aspheric surface can be obtained from equations (1) and (2) as:

step S5: the distance d between the spot middle point A and the spot middle point B can be obtained by the geometrical relation_RABComprises the following steps:

step S6: the lens pitch d and the spot pitch d can be obtained from equations (3) and (4)_RABDifference Δ d of_ABComprises the following steps:

step S7: from equation (5) we can derive:

step S8: in the formula, W_ABSensitivity between point a and point B for MBAS; two independent calculation methods can be used to calculate the sensitivity, and the specific formula is described as follows:

W_AB＝(f_A+f_B)d (7)

W_AB＝(R+2k)Δd_AB (8)。

2. the sensor sensitivity measurement method of a high-precision surface topography measuring machine according to claim 1, characterized in that the first method in step S8 is to use a plane mirror and a tilt table in combination to measure the sensitivity of MBAS: in order to determine the sensitivity of the MBAS, a measuring point is selected and an appointed angle is accurately adjusted; using equation (7), the sensitivity W can be calculated by measuring only the focal length f of two points and the lens separation d between the two points:

step S811: l is the distance between the fulcrum and the observation point, h is the displacement in the tilting phase, and t is the tilting angle, then the tilting angle t can be expressed as:

step S812: the sensitivity of MBAS can be expressed as:

wherein p represents the inclination angle t and the sensitivity W of MBAS_ABThe ratio of (A) to (B);

step S813: sensitivity W of MBAS was obtained from (9) and (10)_ABIs represented as follows:

step S814: the focal length f of the lens can be expressed as:

step S815: the focal length f of the lens, which can be derived from (11) and (12), is expressed as follows:

in the formula d_sThe length of the sensitive area range of the CMOS; the ratio p can be calculated by repeatedly measuring and averaging for many times according to the calibration experiment of the plane mirror, so that the focal length f can be calculated;

step S816: calculating the distance d of the lens according to the formula (14);

d＝(d_A-d_B)d_s (14)

step S817: the sensitivity W of MBAS between point A and point B is calculated by equation (7) using the focal length f and the lens pitch d_AB。

3. The sensor sensitivity measurement method of a high-precision surface topography measuring machine according to claim 1, characterized in that said second method in step S8 is to use a cylindrical plano-convex lens in cooperation to measure the sensitivity of MBAS: using equation (8), only the differential spacing Δ d needs to be measured_ABAnd (R +2k) then sensitivity W can be calculated_AB：

Step S821: calculating the differential spacing Δ d_AB: the relationship between the differential pitch and the two-point angular difference is expressed as:

two-point angular difference Deltac in the formula_abCan be measured directly by MBAS;

step S822: repeatedly measuring (R +2k) for multiple times to obtain an average value;

step S823: using radius of curvature R and differential spacing Δ d_ABSensitivity W was calculated by equation (8)_AB。

Technical Field

The invention relates to the technical field of optical detection, in particular to a sensor sensitivity measuring method of a high-precision surface morphology measuring machine.

Background

With the development of miniaturization and modularization of microsystem manufacturing, the demand for improving the manufacturing efficiency of high-precision small-size products is also sharply increased. People have higher and higher requirements on surface profile, surface quality, size, roughness and the like of mechanical products or various industrial products, and have higher and higher requirements on precision of measuring instruments.

The appearance of a high-precision surface appearance optical measurement system, namely a Mult-beam angle sensor (hereinafter abbreviated as MBAS), overcomes the problems of low precision, low efficiency and the like of the traditional measurement technology, the theoretical precision of the system can reach very high, but the theoretical precision cannot be reached in practical application, the detection precision of the sensitivity of the system cannot reach the theoretical requirement, the traditional measurement mode cannot be suitable for the MBAS, the existing detection scheme also has various problems, such as four-point measurement of a measurement plate, the method has complicated steps, the angle problem of the measurement plate can cause errors, and points outside the range of four mark points also have larger errors; compared with the commonly used integral method for measuring the individual difference of the micro-lens array error to the lens, the method can not measure the image distortion and the local degradation easily caused.

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 provide a sensor sensitivity measuring method of a high-precision surface morphology measuring machine.

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

a method for measuring the sensitivity of a sensor of a high-precision surface morphology measuring machine mainly comprises the following specific steps:

step S1: the laser beam is reflected by an aspheric surface with the curvature radius of R, wherein the included angle between the incident light and the reflected light is 2 alpha, and then the laser beam is focused by a lens with the focal length of f. And d is the lattice spacing of the lenses, k is the distance between the lenses and the aspheric surface, and c is the distance from the tangent plane of the contact points of the two lenses to the intersection point of the incident light and the aspheric surface.

Step S2: the angle of incidence α can be expressed in terms of lens pitch d and radius of curvature R as:

step S3: from the optical invariants, the lens pitch d from the geometric relationship is:

step S4: the distance c from the tangent plane of the two lens contact points to the position of the intersection of the incident light and the aspheric surface can be obtained from equations (1) and (2) as:

step S5: the distance d between the spot middle point A and the spot middle point B can be obtained by the geometrical relation_RABComprises the following steps:

step S6: the lens pitch d and the spot pitch d can be obtained from equations (3) and (4)_RABDifference Δ d of_ABComprises the following steps:

step S7: from equation (5) we can derive:

step S8: in the formula, W_ABSensitivity between point a and point B for MBAS; two independent calculation methods can be used to calculate the sensitivity, and the specific formula is described as follows:

W_AB＝(f_A+f_B)d (7)

W_AB＝(R+2k)Δd_AB (8)。

as a preferred embodiment of the present invention, the first method in step S8 is to use a plane mirror and a tilted stage to measure the sensitivity of MBAS: to determine the sensitivity of the MBAS, a measurement point is selected and the specified angle is fine-tuned. Using equation (7), the sensitivity W can be calculated by measuring only the focal length f of two points and the lens separation d between the two points:

step S811: l is the distance between the fulcrum and the observation point, h is the displacement in the tilting phase, and t is the tilting angle, then the tilting angle t can be expressed as:

step S812: the sensitivity of MBAS can be expressed as:

wherein p represents the inclination angle t and the sensitivity W of MBAS_ABThe ratio of (A) to (B);

step S813: sensitivity W of MBAS was obtained from (9) and (10)_ABIs represented as follows:

step S814: the focal length f of the lens can be expressed as:

step S815: the focal length f of the lens, which can be derived from (11) and (12), is expressed as follows:

in the formula d_sThe length of the sensitive area range of the CMOS; the ratio p can be calculated by repeatedly measuring and averaging for many times according to the calibration experiment of the plane mirror, so that the focal length f can be calculated;

step S816: calculating the distance d of the lens according to the formula (14);

d＝(d_A-d_B)d_s (14)

step S817: the sensitivity W of MBAS between point A and point B is calculated by equation (7) using the focal length f and the lens pitch d_AB。

As a preferable aspect of the present invention, the second method in step S8 is to measure the sensitivity of MBAS using a cylindrical plano-convex lens in cooperation: using equation (8), only the differential spacing Δ d needs to be measured_ABAnd (R +2k) then sensitivity W can be calculated_AB：

Step S821: calculating the differential spacing Δ d_AB: the relationship between the differential pitch and the two-point angular difference can be expressed as:

two-point angular difference Deltac in the formula_abCan be measured directly by MBAS;

step S822: repeatedly measuring (R +2k) for multiple times to obtain an average value;

step S823: using radius of curvature R and differential spacing Δ d_ABSensitivity W was calculated by equation (8)_AB。

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

(1) the device used by the sensor sensitivity measuring method of the high-precision surface morphology measuring machine provided by the invention has the advantages of simple structure, convenience in operation and strong anti-interference capability.

(2) According to the method for measuring the sensitivity of the sensor of the high-precision surface morphology measuring machine, the sensitivity error of the measured sensor is less than 0.5 percent according to the measured experimental data, so that the absolute precision of MBAS (moving bed absolute system) can reach tens of nanometers.

(3) The sensor sensitivity measuring method of the high-precision surface morphology measuring machine provided by the invention also has the advantages of small required calculation amount, short period and low cost.

Drawings

FIG. 1 is a schematic diagram of the relationship between the distance k between the lens and the aspheric surface provided by the present invention.

Fig. 2 is a schematic diagram of the sensor sensitivity measurement provided by the present invention.

FIG. 3 is a flow chart of a method for measuring the sensitivity of a sensor of a high-precision surface topography measuring machine according to the present invention.

Fig. 4 is a schematic diagram of the structure and principle of the complex beam angle sensor provided by the present invention.

The reference numerals in the above figures illustrate:

the optical filter comprises a semiconductor laser 1, a first optical filter 2, a collimating lens 3, a second optical filter 4, a beam splitter 5, a cylindrical lens 6, a small aspheric body 7, a micro-lens array 8, a CMOS camera 9 and a convex lens 10.

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.