Analytical comparison of predetection postdetection and hybrid image compensation techniques in the presence of atmospheric turbulence

摘要

Abstract: Images obtained from ground-based telescopes are distorted due to the effects of atmospheric turbulence. This disturbance can be compensated for by employing adaptive optics (predetection compensation), image reconstruction techniques (postdetection compensation), or a combination of both (hybrid compensation). This study derives analytic expressions for the residual mean squared error of each technique. These mean squared error expressions are then used to parametrically evaluate the performance of the compensated imaging techniques under varying conditions. Parameters of interest include actuator spacing, coherence length, and wavefront sensor noise variance. It is shown that hybrid imaging allows for the design of lower cost systems (fewer actuators) that still provide good correction. The adaptive optics system modeled includes a continuous faceplate deformable mirror and a Hartmann Shack wavefront sensor. The linear image reconstruction technique modeled is deconvolution via inverse filtering. The hybrid system employs the adaptive optics for first order correction and the image reconstruction for higher order correction. This approach is not limited to correction of atmospheric turbulence degraded images. It can be applied to other disturbances, such as space platform jitter, as long as the corresponding structure function can be estimated. !6