Research On Optical Elements Surface Defects Measurement Based On Multispectral Technique

Precise and ultra-precise optical systems are applied widely in research and industry field. Optical elements surface defects are the important factor which affect the appearances and performances of optical systems. Optical elements surface defects must be measured precisely.In this dissertation, the existing optical elements surface defects measurement techniques are analyzed. To overcome their disadvantages of less measureable defects and low accuracy, an optical elements surface defects measurement technique based on multispectral technique is proposed.An experimental setup based on the measurement technique is designed and developed. The experimental results show that by combining multispectral technique, optical microscopy scattering imaging technique and image fusion technique, the measurable defect quantity is increased and the measurement accuracy is improved.For extracting the defect edge feature of low-contrast images, the anisotropic diffusion filtering algorithm is proposed to be the filter algorithm of Canny edge detection technique. The experimental results show that the improved edge detection technique can reduce noise and extract the edge features accurately.