Research Of Galvanometer Scanning Strategy Based On Optical Confocal Microscopy

Confocal microscopy is one of the most influential measuring apparatus widely used in surface topography measurement of micro-structures and observations of biological sample due to specialty on noise suppression and high axial resolution. So far, the scanning strategy the optical confocal microscopy based on galvanometer scanners uses, is raster scanning strategy, which has advantages of fine repeatability during scanning movements and easy reconstruction of measurement data of the three-dimensional surface topography. However, because the scanning control waveform of raster scanning strategy is sawtooth wave, which makes it difficult to increase scanning speed. And during the movements of galvanometer scanning, it will impact the galvanometer, damage it and reduce the service life of the galvanometer, leading to lower system reliability. Scanning field of raster scanning strategy is square, and optical system scanning field is round, grating type scanning strategy is used for the use of optical field of inadequate.Raster scanning strategy of scanning field is square, and optical system scan field of view is round, raster scanning strategy can’t take good use of optical field.On the above problems, this topic research established the galvanometer control model and analyzed control waveform characteristics of raster scanning, with the purpose to put forward a scanning strategy to improve scanning speed and system reliability,and solve the problem existed in raster scanning strategy, and provide new ideas for galvanometer scanning strategy of optical confocal microscopy.The main content this topic has completed is shown as follows:(1)The 3-D scanning imaging distortion analysis of optical confocal microscope was completed. Based on Optical confocal microscopy imaging principle, the article analyzed the main reason of causing the lateral scanning distortion of optical confocal microscope on galvanometer, which is the nonlinear mapping relationship of the galvanometer deflection angle and scanning field.(2)The next content was to establish galvanometer system control model. First the article established the control model by analyzing the working principle and completed the analysis of galvanometer system dynamic characteristics with MATLAB simulation experiment.The simulation results show that sine signal tracking characteristic is better than that of sawtooth signal for streaming galvanometer system. Aiming at the existing problem of raster scaning method, the article put forward the circular scanning strategy. Experiments show that the field of circular scanning strategy is expanded by 57%, and the effective utilization rate of the data is increased to 100%, and the scanning speed is raised by 9%.but also improves the system reliability. In galvanometer scanning movement, there is no impact,which will not cause damage to the galvanometer. Thus circle scanning strategy increases the galvanometer system reliability.(3)Galvanometer scanning unit of optical confocal microscope was designed and set up. First the article completed the optical confocal microscope galvanometer scanning unit hardware design, which includes light path design, mechanical design and control system design, and finished installation and debugging; Then the article completed the task of using the Lab VIEW software to write measurement software of optical confocal microscope.The software includes 3-d scanning module, tilt correction module, data storage and processing module, and grating height calculation module as well as man-machine interaction design.(4)The galvanometer scanning unit of optical confocal microscope was test. Then applying circular scanning strategy to measure typical samples,the result is that deviation of measured value and nominal value is 0.6 nm.