Adaptive wavefront correction: a hybrid VLSI/optical system implementing parallel stochastic gradient descent

We present a hybrid VLSI/Optical system for real-time adaptive phase distortion compensation. On-chip CMOS circuitry performs parallel perturbative stochastic gradient descent/ascent of an externally supplied optimization metric, e.g. a direct measure of image or laser beam quality. Our custom mixed-mode analog-digital VLSI system can directly control several adaptive optics elements such as micro-electromechanical mirrors, liquid crystal spatial light modulators and tilt mirrors. Here we use a tilt mirror and a MEMS mirror with 37 control parameters each of which is adjusted independently and in parallel to manipulate the wavefront phase profile. We present experimental results demonstrating successful operation for an adaptive laser-beam transmitter system. The parallel VLSI architecture is extendable to higher resolutions (N = 10(3) to 10(6) parameters).