Optical images, Optics


The detectivity and resolution of single aperture and multiple aperture optical imaging systems are compared for single point sources in optically background limited environments. The single aperture system assumes a single large diameter lens with a detector array at the focal plane. The multiple aperture system assumes an independent detector array at the focal plane of each of the apertures of the multiaperture system. The multiaperture lenses are arranged in a rectangularly symmetric pattern within the perimeter that a single large aperture would occupy.

Due to the presence of a constant signal plus an optical noise field whose amplitude is Rayleigh distributed, Rician squared statistics are used to model the detector voltage random variable. The detectivity is analyzed assuming a detector optical amplitude threshold is chosen such that the signal is considered present when the optical amplitude exceeds threshold and considered absent when the optical amplitude falls below threshold. The optimum threshold is found to be given by

Io(AT/n2 ∝ EXP [A2/(2n2)]

where (A2/n2) is the signal to noise power ratio, T is the optical amplitude threshold, and IO is the modified Bessel function of order zero.

Detector size is found to be the predominant factor in resolution, due to the minute size of an Airy disc image from a point source. The resolution angle ( γ resolution) can be approximated by γresolution = (Ae/f) where Ae is the distance between detector centers and f is the imaging system focal length.

Single aperture and multiple aperture systems are found to be equal in detectivity performance when optically background limited. For equal detector sizes and spacings, and equal imaging system focal lengths, multiple aperture systems are found to provide resolution improvement over single aperture systems. This resolution improvement depends on the overlap of the field of view between the detector arrays of the individual apertures in the multiple aperture system.


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Graduation Date



Phillips, Ronald L.


Master of Science (M.S.)


College of Engineering




160 p.




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Masters Thesis (Open Access)



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