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Proceedings Paper

Spectral characterization of an ophthalmic fundus camera
Author(s): Clayton T. Miller; Carl J. Bassi; Dale Brodsky; Timothy Holmes
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Paper Abstract

A fundus camera is an optical system designed to illuminate and image the retina while minimizing stray light and backreflections. Modifying such a device requires characterization of the optical path in order to meet the new design goals and avoid introducing problems. This work describes the characterization of one system, the Topcon TRC-50F, necessary for converting this camera from film photography to spectral imaging with a CCD. This conversion consists of replacing the camera's original xenon flash tube with a monochromatic light source and the film back with a CCD. A critical preliminary step of this modification is determining the spectral throughput of the system, from source to sensor, and ensuring there are sufficient photons at the sensor for imaging. This was done for our system by first measuring the transmission efficiencies of the camera's illumination and imaging optical paths with a spectrophotometer. Combining these results with existing knowledge of the eye's reflectance, a relative sensitivity profile is developed for the system. Image measurements from a volunteer were then made using a few narrowband sources of known power and a calibrated CCD. With these data, a relationship between photoelectrons/pixel collected at the CCD and narrowband illumination source power is developed.

Paper Details

Date Published: 2 March 2010
PDF: 7 pages
Proc. SPIE 7550, Ophthalmic Technologies XX, 75501U (2 March 2010); doi: 10.1117/12.844855
Show Author Affiliations
Clayton T. Miller, Lickenbrock Technologies, LLC (United States)
Carl J. Bassi, Univ. of Missouri, St. Louis (United States)
Dale Brodsky, Fundus Photo, LLC (United States)
Timothy Holmes, Lickenbrock Technologies, LLC (United States)

Published in SPIE Proceedings Vol. 7550:
Ophthalmic Technologies XX
Fabrice Manns; Per G. Söderberg; Arthur Ho, Editor(s)

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