Application Of Image Processing In Self-Adaptive Control Of Interference Pattern

The application of image processing in the self-adaptive control of interference pattern is presented in this paper. Compared with mechanics-electricity feedback control method, laser diode feedback control method and optical bistable equipment control method, the circuit is relatively simple, furthermore, simply adjust the optical system to increase the number of pixel corresponding to the interference pattern width, which will promote the control precision of the system.As for the different implementation of array CCD and linear CCD, different processing methods are provided. To array CCD, computing the interference pattern excursion based on image processing, Fourier transform and interference pattern intensity distribution are discussed. Computing the interference pattern excursion based on image processing is to extract the skeleton of the interference pattern and position the interference pattern according to the skeleton. The binarization, dilation and thinning of interference pattern are stressed. Computing the excursion of interference pattern based on Fourier transform is based on the fact that interference pattern has different phase at different position, the signal extraction of interference pattern and phase unwrapping algorithm are mainly discussed. Computing the excursion of the interference pattern based on the interference pattern intensity distribution is to position the fringe according to the intensity distribution characteristic. To linear CCD, the position of fringe is according to the intensity distribution of interference pattern, too. Local fitting method is applied when position the fringe because of the high noise. The experimental results are showed in each part. Because the image computation is time-consuming, in the end, the experimental result utilizing linear CCD is provided.The experimental result shows that processing the fringe data with above method, sending the control signal afterward can control the interference pattern well and make the fringe keep relatively stable.