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Optical Engineering

Imaging system performance based upon Fλ/d
Author(s): Gerald C. Holst
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Paper Abstract

Imaging system performance can be described in the spatial domain, where the optical blur diameter is compared to the detector size, or in the frequency domain [modular transfer function (MTF) approach], where the optics cutoff is compared to the detector cutoff. Both comparisons provide a metric that is a function of Fλ/d, where F is the focal ratio, λ is the wavelength, and d is the detector size. Fλ/d is applied to three models: Schade's equivalent resolution (visible systems), Snyder's MTFA (MTF area; visible systems), and target acquisition (NVThermIP—an infrared system model). All models produced curves that exhibit a transition in the region 0.41<Fλ/d<1.0, representing a change from detector-limited to optics-limited performance. NVThermIP's contrast equations are simplified to easily calculate resolution and acquisition range. Trade-off analyses include range versus detector size, versus focal ratio, and versus field of view (FOV). When Fλ/d<2, no aliasing occurs. This may be important for medical imaging, where sampling artifacts may be interpreted as a medical abnormality, or for space probes, where it is impossible to obtain ground truth.

Paper Details

Date Published: 1 October 2007
PDF: 10 pages
Opt. Eng. 46(10) 103204 doi: 10.1117/1.2790066
Published in: Optical Engineering Volume 46, Issue 10
Show Author Affiliations
Gerald C. Holst, JCD Publishing (United States)

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