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Proceedings Paper

Spectral-encoding for parallel source implementation in NIR tomography
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Paper Abstract

While near-infrared tomography has advanced considerably over the past decade, key technological designs still limit what can be achieved, especially in terms of imaging acquisition speed. One of these fundamental limitations is the requirement that the source light be delivered sequentially or through frequency encoding of the time signal. Sequential delivery inherently limits the speed at which images can be acquired. Modulation frequency-dependent encoding of the sources solves the problem by allowing sources near the same location to be turned on simultaneously, thereby improving the speed for acquisition, but suffers from dynamic range problems. In this study, we demonstrate an alternative parallel source implementation approach which uses spectral wavelength encoding of the source. This new technique allows many sources to be input into the tissue at the same time, as long as the spectrally encoded signals can be decoded at the output. To test the implementation of this approach, 8 single-mode laser diodes of wavelengths distributed within a narrow range of 10 nm are used, and the lights are all input into tissue phantom simultaneously. On the detection side, a high-resolution spectrometer is used to spatially spread out the signals to facilitate parallel detection of the signal from each spectrally-encoded source. This robust approach allows rapid parallel sampling of all sources at all detection locations. The implementation of this technique in a NIR tomography application is examined, and the preliminary results of video-rate imaging at 30 Hz is presented.

Paper Details

Date Published: 28 April 2005
PDF: 8 pages
Proc. SPIE 5693, Optical Tomography and Spectroscopy of Tissue VI, (28 April 2005); doi: 10.1117/12.594061
Show Author Affiliations
Daqing Piao, Dartmouth College (United States)
Shudong Jiang, Dartmouth College (United States)
Subhadra Srinivasan, Dartmouth College (United States)
Yalavarthy Phaneendra Kumar, Dartmouth College (United States)
Xiaomei Song, Dartmouth College (United States)
Brian W. Pogue, Dartmouth College (United States)


Published in SPIE Proceedings Vol. 5693:
Optical Tomography and Spectroscopy of Tissue VI
Britton Chance; Robert R. Alfano; Bruce J. Tromberg; Mamoru Tamura; Eva M. Sevick-Muraca, Editor(s)

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