Signal and noise transfer through imaging systems consisting of a cascade of amplifying and scattering processes

The transfer of signal and noise through an imaging system consisting of a cascade of amplifying and scattering processes has been analyzed on the basis of the Burgess variance theorem. Up to second statistical moments, the results are identical to those deduced by Rabbani et al. [ J. Opt. Soc. Am. A4, 895 ( 1987)] with multivariate moment-generating functions. An easy-to-visualize concept of detective quantum efficiency (DQE) that depends on object shape and size has been deduced that can be converted into the commonly used DQE which depends on spatial frequency. A simple expression for the noise power spectrum of a system that consists of an arbitrary number of amplifying and scattering processes has been derived; noise added along the system can be taken into account.