Adaptive Wavefront-Correction Algorithms Using Focal-Plane Array Intensity Measurements

Earth’s atmospheric turbulence induces aberrations in the wavefront of the optical signal from a distant spacecraft. These aberrations cause diffusion and spreading of the signal energy in the receiver’s focal plane, potentially resulting in an increase in bit-error rate (BER) by several orders of magnitude when significant background radiation is present, such as during daytime operation. The adaptive optics (AO) algorithms in this article use the focal-plane intensity distribution to estimate aberrations induced by the atmosphere and to correct these aberrations. Successful wavefront correction concentrates the signal energy into a much smaller area in the focal plane, greatly reducing collected background radiation and improving BER performance.