Spatial Domain and Spatial Frequency Domain Imaging

摘要

An imaging system's object field to image field transformation operation is usually described in the (spatial) frequency domain using the system's transfer function. The limitation of this description is that the imaging system must be space-invariant. In contrast, an object field to image field transformation can be described in the spatial domain without requiring that the system be space-invariant. For the frequency domain, a summary of free-space and turbulent transfer functions is presented. For the spatial domain, the Normal Mode Approach to imaging is described followed by a summary of spatial eigenvalue distributions and degrees of freedom expressions. The effect of additive background noise on the useable degrees of freedom of an image field is studied. The spatial domain and frequency domain are shown to be related when certain conditions are satisfied, one of which is space-invariance. The operation of two ideal, adaptive imaging receivers (the Channel-Matched Filter and Multiplicative-Phase Receivers) is described and their imaging performance is compared using turbulent coherent transfer functions and minimum average integrated mean square error expressions. (Author)