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Proceedings Paper

Imaging in scattering media using the phase of modulated light sources
Author(s): Peter Kraemmer; Hartmut Bartelt; Helmut Fischer; Bernard Schmauss
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Paper Abstract

Intensity transmission measurements of biological tissue with light in the wavelength range from 600 nm to 1000 nm yields limited resolution due to strong scattering. The resolution can be improved using time gated methods. These measurements are technically complicated and require a long detection time. A different approach is the measurement of the phase shift of transmitted light using a radio frequency modulated light source. We have investigated the influence of the modulation frequency on the intensity distribution and on the phase shift both theoretically and experimentally. Further the dependence on the scattering and absorption coefficients of the illuminated medium has been examined. The theoretical calculations have been carried out using analytical and numerical solutions of the diffusion equation. Results are given for the modulation frequency range from 60 MHz to 500 MHz. They show that the modulation frequency has an effect mainly on the phase shift and only to a small degree on the intensity distribution.

Paper Details

Date Published: 31 January 1995
PDF: 10 pages
Proc. SPIE 2326, Photon Transport in Highly Scattering Tissue, (31 January 1995); doi: 10.1117/12.200861
Show Author Affiliations
Peter Kraemmer, Siemens AG (Germany)
Hartmut Bartelt, Siemens AG (Germany)
Helmut Fischer, Univ. Erlangen-Nuernberg (Germany)
Bernard Schmauss, Univ. Erlangen-Nuernberg (Germany)


Published in SPIE Proceedings Vol. 2326:
Photon Transport in Highly Scattering Tissue

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