Control system design issues for retinal imaging adaptive optics systems

This paper presents a review of as well as solutions to control system design issues for adaptive optics systems used in retinal imaging. The development of retinal imaging systems allows for early diagnosis of eye diseases. Such systems can increase the quality of life of patients as well as curtail increasing health care costs through early eye disease detection and treatment. A discussion on control methods that have been, or can be used, in vision based adaptive optics systems is presented. In this paper, the control problem for adaptive optics systems is generalized to that of shape control for a flexible membrane representing a deformable mirror. Due to the unknown dynamic nature of the aberrations in the eye, the control problem addressed is the tracking of an unknown and time-varying shape for a distributed membrane. The design of a controller to achieve the shape control objective is based on a model of a distributed parameter system representing the mirror membrane. Controllers are discussed with respect to two types of membrane models, namely infinite dimensional models, and finite dimensional models. Control system design problems that must be overcome in order to make adaptive optics based retinal imaging systems a viable technology are presented. A solution to these problems, in the form of adaptive shape control algorithms for a flexible membrane, is proposed