A method that combines scanning white-light interferometry with phase-shifting interferometry is proposed. The best-focus scanning position of correlograms is located by calculating the maximum modulation contrast, and the twice averaging four-frame algorithm is utilized to determine the phase difference between the best-focus position and the zero optical path difference point. The surface height is obtained according to the best-focus frame position and the unwrapped phase, which is achieved by a process of removing the phase ambiguity. Both simulated and experimental results demonstrate that the advanced method can achieve the advantages of high precision, large dynamic range, and be insensitive to the phase shifting deviation.
Ultraviolet detection technology, as immediate area of research focus, has been adopted in the fields of fingerprint identification, corona detection and exhaust plume detection. Low-light CMOS, which can work in even 10-3lux, is used in visible light channel. The prominent advantage of the dual-channel Ultraviolet/Low-light CMOS camera is the fusion of UV and wide dynamic range visible light information, which can enrich image details and help observers locate the UV targets in the complicated background around the clock rapidly. The paper studied on the component structure of UV ICMOS, imaging driving, the Ultraviolet/Low-light images fusion algorithm and the photon counting algorithm. The one-inch and wide dynamic range CMOS chip with the coupling optical fiber panel are coupled to the UV image intensifier. In consideration of the ultraviolet detection demand, the driving circuit of the CMOS chips is designed and the corresponding program based on Verilog language is written. After analysis and comparison of the characteristics of UV image and Low-light CMOS image, the improved Laplace pyramid fusion algorithm is applied. UV image and Low-light CMOS image are multiscale decompose, and the features in different frequency layer are chosen from either UV image or Low-light CMOS image. The connected components labeling way is utilized for the UV detection and imaging. At last, the detection experiments of the ultraviolet signal are carried out, and the results are given and analyzed.
Ultraviolet detection technology has been widely focused and adopted in the fields of ultraviolet warning and corona detection for its significant value and practical meaning. The component structure of ultraviolet ICMOS, imaging driving and the photon counting algorithm are studied in this paper. Firstly, the one-inch and wide dynamic range CMOS chip with the coupling optical fiber panel is coupled to the ultraviolet image intensifier. The photocathode material in ultraviolet image intensifier is Te-Cs, which contributes to the solar blind characteristic, and the dual micro-channel plates (MCP) structure ensures the sufficient gain to achieve the single photon counting. Then, in consideration of the ultraviolet detection demand, the drive circuit of the CMOS chip is designed and the corresponding program based on Verilog language is written. According to the characteristics of ultraviolet imaging, the histogram equalization method is applied to enhance the ultraviolet image and the connected components labeling way is utilized for the ultraviolet single photon counting. Moreover, one visible light video channel is reserved in the ultraviolet ICOMS camera, which can be used for the fusion of ultraviolet and visible images. Based upon the module, the ultraviolet optical lens and the deep cut-off solar blind filter are adopted to construct the ultraviolet detector. At last, the detection experiment of the single photon signal is carried out, and the test results are given and analyzed.