Laser Differential Confocal Curvature Measurement System With Grating Length

In the field of modern optical measurement, the radius of curvature is a basicparameter of the optical lens, which will directly affects the accuracy of the len’s focallength and other optical parameters, and these parameters have great influence on overallperformance of the optical system. Therefore the radius of curvature requires precision test.However, the current high precision non-contact measurement of the radius of curvatureincludes the spherical interferometry methods, auto-collimation and single mode fiberauto-collimation. Based on the cateye-confocal fixed focal, spherical interferometry is themost commonly used, high precision non-contact measurement method, this methodmeasures radius of curvature by the zero fringe interpretation to determine the cateyepositon and confocal position. Due to diffraction effects, the light cannot be focused to apoint, limiting the focusing accuracy, and air turbulence makes a huge impact on thestability of the interference fringes, high precision measurement of the radius of curvatureis difficult to guarantee. In order to enhance the ability of high-precision,anti-environmental interference to meet the needs in this field, this paper develops laserdifferential confocal curvature measurement system with grating length.The main research work includes:1) Based on the differential confocal curvature measurement principle, laserdifferential confocal curvature measurement system with grating length isdiscussed.2) According to laser differential confocal curvature measurement principle,completes the optical design of the overall system，and selects the importantcomponent. Based on the overall optical system design，makes the systemstructure. The mechanical structure consists of sub-confocal system, air-bearingslider, five-dimensional adjustor, motorized stage, and grating length measurementsystem.3) Builds laser differential confocal curvature measurement system with gratinglength. Designs grating length measurement systems, writes length measurement calibration progress, and completes the grating length measurement calibration;designs the experimental radius measurement of the ball and the standard lens, theexperimental resistance to environmental interference.4) This paper analyzes the error of measurement results, the same time gives theimproved measures.Experimental results show that the system has an accuracy of better than10×10-6. So itcan meet the demand of high-precision measurement of radius of curvature.