Research On Key Technologies Of Shack Hartmann Wavefront Sensor

The Shack Hartmann wavefront sensor(SHWS) has been widely applied in laser beam quality diagnosis, laser shaping, optics and optical system diagonals, atmospheric turbulence measurement and real-time control, high power laser system and other fields. Due to the advantages such as easy operation, short response time, and convenience to comprehend the wavefront modes., it received extensive attention of scholars. In1900,Hartmann for the first time proposed the Shack-Hartmann wavefront detection technology. After that, Shack replaced the original Hartmann diaphragm with micro lens array, which greatly improved the detection precision and light energy utilization. However, due to the background level, Gaussian white noise and other factors, the traditional centroid algorithm error is large, which leads to inaccurate results, and finally affect the phase image. In addition, due to the constraints of the production process, the micro lens size has always been a bottleneck of restricting its resolution. Its detection accuracy and resolution, is important for the performance of the whole optical system.We focus on some technology problem that the SHWS optical system has faced, and discuss its application on cell detection. The main contents are as following:Firstly, we constructed a SHWS simulation system, and utilized different centroid detection methods, such as higher moment centroid method, the threshold weighted pixel average algorithm, and compared the detection error and detection accuracy in different situation.Also, we set up a SHWS optical system platform and produces all kinds of vortex light field. After that, we analyzed the problems existing in the traditional detection algorithm, and proposed the correlation matching method and hybrid centroiding method. We can increase the resolution from the level of lenslet size to that of pixel size in a short time.Thirdly, the SHWS was applied in cell detection. We set up a quantitative phase microscope optical platform using SHWS. Through our improvement, the optical system will be greatly simplified, and the detection accuracy was improved. In order to test its imaging ability, we applied it in multi-layer sample detection of the refractive index distribution, including monolayer polystyrene beads, double polystyrene beads, etc. We also set up a VTK platform to process the produced three-dimensional refractive index images. We used MarchingCube algorithm and Raycasting algorithm, respectively, to realize the visualization of the three dimensional phase image and human-computer interaction.