Improvement of spatial resolution in reflectance near-infrared imaging by laser-beam interference

Alexander R. Knuettel; Joseph M. Schmitt; Jay R. Knutson

doi:10.1117/12.58232

1 April 1992 Improvement of spatial resolution in reflectance near-infrared imaging by laser-beam interference

Alexander R. Knuettel, Joseph M. Schmitt, Jay R. Knutson

Proceedings Volume 1640, Time-Resolved Laser Spectroscopy in Biochemistry III; (1992) https://doi.org/10.1117/12.58232
Event: OE/LASE '92, 1992, Los Angeles, CA, United States

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.

Citation Download Citation

Alexander R. Knuettel, Joseph M. Schmitt, and Jay R. Knutson "Improvement of spatial resolution in reflectance near-infrared imaging by laser-beam interference", Proc. SPIE 1640, Time-Resolved Laser Spectroscopy in Biochemistry III, (1 April 1992); https://doi.org/10.1117/12.58232

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