Image Sharpness and Beam Focus VLSI Sensors for Adaptive Optics

High-resolution wavefront control for adaptive optics requires accurate sensing of a measure of optical quality. We present two analog very-large-scale-integration (VLSI) image-plane sensors that supply real-time metrics of image and beam quality, for applications in imaging and line-of-sight laser communication. The image metric VLSI sensor quantifies sharpness of the received image in terms of average rectified spatial gradients. The beam metric VLSI sensor returns first and second order spatial moments of the received laser beam to quantify centroid and width. Closed-loop wavefront control of a laser beam through turbulence is demonstrated using a spatial phase modulator and analog VLSI controller that performs stochastic parallel gradient descent of the beam width metric.