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Proceedings Paper

Improvement of spatial resolution in reflectance near-infrared imaging by laser-beam interference
Author(s): Alexander R. Knuettel; Joseph M. Schmitt; Jay R. Knutson
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Paper Abstract

The authors studied the use of destructive interference of two diffusive photon-density waves for localization of an absorbing body and a fluorescent probe embedded in a scattering medium. The effect of the position of the embedded objects on the magnitude and phase of the light re-emitted from the medium was evaluated theoretically and experimentally. The objectives, accomplished with an asymmetrical laser-beam arrangement, were to reduce sensitivity to absorbing bodies located in superficial layers, while maintaining sensitivity to those lying deeper; and to establish a confined region of maximum sensitivity in which the distance of an absorbing body could be determined via phase measurement. Intensity and phase data were acquired with a modified frequency-domain spectrometer at modulation frequencies up to 600 MHz. Fluorescent probes were spatially localized with a symmetrical laser-beam arrangement. Magnitude and phase images acquired with a gated intensified CCD camera further defined the probe location. Simulations and experiments show potential applications to imaging.

Paper Details

Date Published: 1 April 1992
PDF: 12 pages
Proc. SPIE 1640, Time-Resolved Laser Spectroscopy in Biochemistry III, (1 April 1992); doi: 10.1117/12.58232
Show Author Affiliations
Alexander R. Knuettel, National Institutes of Health (United States)
Joseph M. Schmitt, National Institutes of Health (United States)
Jay R. Knutson, National Institutes of Health (United States)

Published in SPIE Proceedings Vol. 1640:
Time-Resolved Laser Spectroscopy in Biochemistry III
Joseph R. Lakowicz, Editor(s)

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