Optical Instruments 

Abstract: Surface roughness is an important parameter to reflect the micro-geometry in machine process, and also an important part of modern precise measurement technique. Contact measurement and noncontact measurement was summarized in this paper, and the advantages and disadvantages are disucssed. Some ideas about it's trend are given in the end.

Abstract: The basic principle and method of computer-aided alignment is introduced.The misalignment state of Cassegrain system is simulated in Zemax,the corresponding relationship between the misalignments and Zernike polynomial coefficients is analyzed and the misalignment characteristic of Cassegrain system is summarized by means of Matlab.Finally,the alignment scheme is determined by the above analysis.In order to verify the alignment scheme,the Cassegrain system is aligned according to the value which is calculated in accordance with the alignment scheme.The result demonstrates that the alignment scheme is feasible and guidable to the alignment of Cassegrain system.

Abstract: Panoramic imaging technique plays important roles in the applications of robots,computer vision and virtual realityThe stitching,fish-lens and catadioptric panoramic lens are the main ways of the implement of panoramic imaging techniqueThe stitching and fish-lens panoramic systems follow the way of the central convergence perspective with which human watches the worldThe catadioptric panoramic systems follow the way of the flat cylinder perspective which is the cylinder mapping projectionThe advantage and fault of all kinds of panoramic imaging systems are analyzed and the mathematic model of catadioptric panoramic systems is establishedThe result indicates that catadioptric panoramic systems will be applied more widely due to the features of integration and miniature

Abstract: Optical Low Pass Filter (OLPF) is composed of several birefringent crystals (e.g. three quartz-crystals). A light spot can be separated into several divergent light spots after passing OLPF. This characteristic can be widely used in digital camera and other image-forming system. The imaging beam in practical use is wide spectral and convergent, which causes dispersion and deformation. This paper hereby analyzes and simulates the characteristics of frequency response, dispersion and broad-angle-incident of the OLPF in theory and in experiment. Firstly, several birefringent crystals with proper alignment are introduced into OLPF to get a better frequency response. Compared with the OLPF with one crystal, its side-lobe is suppressed to a great extent without obvious deterioration in the main-lobe. Secondly, although the original dispersion is already acceptable according to optical aberration allowance, the maximum dispersion can be reduced from 8.49% to 5.66% of the pixel-pitch of CCD by changing one of the crystals from positive crystal (quartz) to negative crystal (e.g. calcite) with the same frequency response. Thirdly, broad-angle-incident is analyzed and simulated as a further research. Suppose a conical beam which converging at the CCD passes a birefringent crystal, a circle and ellipse-like faculae instead of two circles will be got. The error is less than 25% of the ideal offset when the incident angle is as large as 14o. The OLPF with two or three crystals can be analyzed in the same way. The characteristics analyzed above are coincident perfectly with simulation in Tracepro and experiment results. Consequently, regular OLPF can meet the requirements of wide spectral range and broad-angle-incident optical system.