The Research On Laser Wavefront Detection Based On The Shack-Hartmann Sensor Principle

Shack-Hartmann wavefront sensor is widely applied in the fields of astronomical observation,laser atmospheric communication,measurement of aberrations of the human eye,optical element surface measurement and beam quality diagnosis,which is generally composed of two parts,one part is the micro lens array that is used to divide the measured wavefront of laser beam and the other part is the CCD imaging camera that is used to capture the wavefront information.The sensor makes the incident wavefront divided into a number of sub wavefront.They pass through the micro lens array and become the hartmann light spot array image on the CCD.Finally,the laser wavefront is reconstructed by the wavefront slope calculation.Based on the principle of Shack-Hartmann sensor,this paper makes a deep research on some technical problems of measuring laser wavefront,and verifies the scheme,the main research work is as follows:1.The paper designs the Shack-Hartmann sensor simulation system,using ZEMAX custom surface US_ARRAY and Zernike type surface to simulate the system.The gray image of spot array is obtained by the physical optics propagation analysis.The simulation of the whole detection process of laser wavefront sensor is realized.2.The paper design and improvet the wavefront sensing algorithm.In the light spot array centroid calculation algorithm,the traditional calculation method of centroid is improved by using image processing method,the centroid is obtained by judging the spot centroid connected area and the restriction on the area of connected region is added.It increases the dynamic measurement range and the detection precision of the sensor.At the same time it avoid the interference of the scattered spot.In the matching centroid deviation calculation algorithm,using spot matching extrapolation algorithm,this algorithm can greatly improve the dynamic range of the sensor.3.The paper verify the feasibility of the algorithm.Through the image processing and algorithm realization of the gray scale image.Finally,the laser wavefront is reduced by the spot image and the reduction results are in agreement with the standard results.In this paper,a laser wavefront sensing scheme based on Shack-Hartmann sensor principle is designed.Several Algorithm modules are designed and improved in this paper.It includes image preprocessing,beam centroid calculation,centroid matching deviation calculation and wavefront reconstruction.Finally,he paper achieves the purpose of measuring the laser wavefront.