title: Signal-to-noise analysis of task-based imaging systems with defocus.
abstract: We analyze the signal-to-noise ratio (SNR) of arbitrary imaging systems in the presence of defocus. The modulation transfer function (MTF) and the mean SNR are combined to calculate the spatial-frequency spectrum of the SNR (the spectral SNR). Computational imaging methods are used for extending the depth of field (DOF) of the system. The DOF of a task-specific imaging system is defined as the range of defocus that causes the spectral SNR to drop below a minimum value within a band of spatial frequencies of interest. We introduce the polar-SNR plot as a tool for visualizing the spectral SNR of defocused imaging systems with asymmetric pupil functions. As an example, we perform the analysis of an imaging system used for biometric iris recognition.
authors.affiliation: CDM Optics, Boulder, Colorado 80303-7816, USA. paulos@cdm-optics.com
authors.forename: Paulo E X
authors.initials: PE
authors.lastname: Silveira
authors.forename: Ramkumar
authors.initials: R
authors.lastname: Narayanswamy