Research On The Plenoptic Wavefront Sensing Technique

Adaptive optics is a technique that combines several disciplines.By detecting and compensating for the wavefront distortion in real time,it can improve the image quality of the system.After more than half a century of development,adaptive optics technology has been successfully used in many fields.Traditional wavefront sensors(such as the Shack-Hartmann wavefront sensor)can achieve good wavefront sensing results under weak turbulence conditions,but when faced with strong turbulence environments,the sensing result is significantly underminded,even that wavefront reconstruction becomes impossible.Therefore,the study of wavefront sensing methods under strong turbulence conditions is of great significance for extending the application of adaptive optics systems.In this paper,the wavefront reconstruction and correction methods of the plenoptic wavefront sensor are studied,and an adaptive optics system experimental platform is built to verify its wavefront reconstruction and correction ability under strong turbulence conditions.The main work of this paper are as follows:1.The sensing principle of the plenoptic wavefront sensor is analyzed in detail from the perspective of Fourier optics,and the factors that influence its sensing performance are studied.The imaging process is simulated,and the simulated plenoptic images of an ideal plane wave and incident wave with Zernike aberrations are obtained.2.Aiming at the problem of low reconstruction accuracy of the wavefront reconstruction algorithm based on “checkerboard segmentation”,a calculation method of weighted summation of the top-2 values of the light intensity of each“checkerboard” unit is proposed,which improves the accuracy of the wavefront gradient.Then we use the improved method to reconstruct the simulated plenoptic images,the simulation results show that the method can obtain higher wavefront reconstruction accuracy.3.Aiming at the adaptive optical system based on the plenoptic wavefront sensor,the direct gradient method is proposed to correct the wavefront of the system.Then two methods of measuring the system response matrix,push-pull method and mode method are analyzed.Experimental verification shows that using mode method can obtain a more accurate response matrix.4.An adaptive optics system experimental platform based on the plenoptic wavefront sensor is designed and built,then the proposed wavefront reconstruction and correction methods are experimentally verified.The experimental results of wavefront reconstruction show that the improved reconstruction algorithm significantly improves the reconstruction accuracy.The experimental results of wavefront correction show that the proposed wavefront correction method can effectively correct the distorted incident wavefront,and in the face of severely distorted incident wavefront,the plenoptic wavefront sensor can still effectively perform the wavefront reconstruction,and then control the deformable mirror to complete the closed-loop correction,which verifies its wavefront sensing ability under strong turbulence.