Zonal model of an adaptive mirror.

An approximate model of an adaptive optic element is presented which works well for components having many actuators. This zonal model is used to gain insight into the general behavior of systems that correct for high spatial frequency errors. The model is derived from the method of least squares, and considers the nonshift invariant properties of adaptive mirrors. It may be implemented with Fourier transform techniques and is, therefore, easy to program. The relationship between the zonal model and the simpler bandpass filter model of Harvey and Callahan is discussed.