Determining the Phase and Amplitude Distortion of a Wavefront using a Plenoptic Sensor

摘要

We have designed a plenoptic sensor to retrieve phase and amplitude changesresulting from a laser beam's propagation through atmospheric turbulence.Compared with the commonly restricted domain of (-pi, pi) in phasereconstruction by interferometers, the reconstructed phase obtained by theplenoptic sensors can be continuous up to a multiple of 2pi. When compared withconventional Shack-Hartmann sensors, ambiguities caused by interference or lowintensity, such as branch points and branch cuts, are less likely to happen andcan be adaptively avoided by our reconstruction algorithm. In the design of ourplenoptic sensor, we modified the fundamental structure of a light field camerainto a mini Keplerian telescope array by accurately cascading the back focalplane of its object lens with a microlens array's front focal plane andmatching the numerical aperture of both components. Unlike light field camerasdesigned for incoherent imaging purposes, our plenoptic sensor operates on thecomplex amplitude of the incident beam and distributes it into a matrix ofimages that are simpler and less subject to interference than a global image ofthe beam. Then, with the proposed reconstruction algorithms, the plenopticsensor is able to reconstruct the wavefront and a phase screen at anappropriate depth in the field that causes the equivalent distortion on thebeam. The reconstructed results can be used to guide adaptive optics systems indirecting beam propagation through atmospheric turbulence. In this paper wewill show the theoretical analysis and experimental results obtained with theplenoptic sensor and its reconstruction algorithms.