The Research Of High Precision Large Relative Aperture Aspheric Surface Detection

Aspheric optical surface is the surface with spherical deviation. Because in aspheric optical system, the designing parameters of aspheric surface include more comparing the spherical and plane, the aspheric surface has the system structure simplification, correction the aberration, image quality improvement and other advantages. So it’s widely used in modern optical technology. In view of the large relative aperture optical aspheric surface measurement, coordinate measuring technology is a common test method. Because in the early stage of optical aspheric polishing, the surface shape error has not reached the light wavelength scale, and the surface brightness is not enough, the usual interference detection is more difficult, so the coordinate measuring technology is the main detection methods of grinding and polishing period.In view of the large relative aperture optical surface detection, it involves a large number of sampling data processing and improving the measuring speed. A large number of sampling data requires a simple algorithm to fit out the actual surface with high speed and high precision. To improve the measurement speed, a new way of measuring needs to be designed. The measurement speed is increased by using lever device. According to the two main problems, this paper carries out the following works:Firstly, this paper introduces the methods of aspheric coordinate detection and on basis of it, the existing coordinate ideas and methods of detection are summarized. Besides, the two-dimensional case in the process of measuring aspheric surface caused by the probe radius error has been analyzed in this paper, and the three-point-fitting method is used to eliminate the error of the measuring head radius.Secondly, this paper expounds the large relative aperture optical aspheric coordinate measuring methods of contour detection, on basis of the point type measuring device the lever device is added to realize continuous sampling and continuous measurement. In view of the large relative aperture optical aspherical detection problem, the analysis of the basic measuring principle of double-ball-head lever measurement device is conducted, and the lever mechanism deformation model is also established to analyze the size of flexible deformation. For aspheric lens eccentric error influence, the corresponding workpiece coordinate system and the measuring coordinate system are also established to analyze.Lastly, the theoretical simulation is carried out and the accuracy of circle fitting method and leverage measurement error analysis are also verified by using the MATLAB program. Besides, the validation of the leverage measurement is verified by writing the MATLAB program.