Research On High-speed Low-distortion Confocal Scanning Imaging Technology

Confocal microscopy is an important detection method widely used in many research fields,such as industrial inspection,medical examination and biological imaging,due to its high lateral resolution and axial sectioning ability.However,traditional confocal microscopy uses a galvanometer to deflect beam and has a low scanning speed,which cannot meet the increasing demand for high-speed,high-efficiency and dynamic detection and limits its application.On the above problems,this dissertation utilizes a resonant mirror extremely high scanning frequency to perform bidirectional scanning,and uses a galvanometer to achieve row scanning.By completing data acquisition and control programs,and bidirectional scanning circuits,fast lateral scanning imaging is achieved.The image calibration parameter optimization algorithm based on simulated anneal ing and the image misalignment positioning algorithm based on Brief descriptor are used to complete the correction of image distortion.Main research contents are as follows:(1)According to the principle of confocal microscopy and linear imaging,a mapping model of the measured sample to the two-dimensional image is constructed,and the image distortion composition and the factors of the high-speed confocal scanning imaging system are analyzed.(2)Aiming at the synchronization problem of data acquisition and control under bidirectional high-speed scanning,the control logic and timing are designed according to the relevant hardware characteristics and the bidirectional scanning circuit is completed based on FPGA.Based on the Lab VIEW software platform,the confocal lateral scanning imaging program is completed,which realizes the synchronization of data acquisition and control during bidirectional scanning and post-processing of the bidirectional scanning images.(3)Based on the Harris algorithm,the sub-pixel extraction of the coordinates of the calibration point is completed,and the distortion center estimation and simulated annealing algorithm are used to achieve the calibration of the confocal micro scope.Based on Brief descriptor,Hamming distance and RANSAC algorithm,the image misalignment calculation is completed.Finally,the sampling delay and pre-trigger function of the data acquisition card are used to complete the pixel-level misalignment correction,and the displacement property of the two-dimensional discrete Fourier transform is used to perform sub-pixel misalignment.Correction.(4)The bidirectional scanning circuit test and high-speed confocal microscopy imaging experimental system were completed,and high-speed confocal scanning imaging was successfully achieved.Confocal scanning imaging of grid grating samples,and using the distortion correction algorithm to obtain the ideal image-distortion image mapping relationship,according to the ideal image-distortion image mapping relationship to correct,reduce the relative distortion from 16.8% to 0.3%.