Maximum-Likelihood Scheme for Tracking an Optical Source

A fine-pointing scheme that involves correlation of images and maximum-likelihood estimation has been proposed to enable tracking of optical sources. This scheme is intended for implementation in the pointing-control system of an imaging instrument (e.g., a telescope equipped with an image detector) to provide a capability for highly stable and accurate pointing to a specific area within a moving target, even under conditions that ordinarily give rise to pointing jitters. Such conditions include motion of the target relative to the instrument, instability of the platform that supports the instrument-aiming mechanism, and turbulence in the atmosphere or other optical medium. In the original intended application, the scheme would be implemented in a ground station for tracking a laser that would be part of an optical communication aboard a distant spacecraft. Other potential applications include stabilization of images for video cameras and precise pointing of lasers in military, industrial, and surgical settings. This scheme is expected to make it possible to achieve subpixel resolution in a high-disturbance environment.