Jc. Hebden et al., EVALUATION OF THE TEMPORALLY EXTRAPOLATED ABSORBENCY METHOD FOR DUAL-WAVELENGTH IMAGING THROUGH TISSUELIKE SCATTERING MEDIA, Applied optics, 36(16), 1997, pp. 3802-3810
An independent assessment is described of a dual-wavelength imaging te
chnique, known as the temporally extrapolated absorbance method (TEAM)
, proposed by Yamada et al. [Opt. Eng. 52, 634-641 (1993)]. The techni
que involves recording the temporal distribution of light transmitted
across a scattering medium at two carefully chosen wavelengths at whic
h the scattering properties of the medium are assumed to be identical.
The objective is to image internal structure that absorbs more strong
ly at one wavelength than it does at the other. A simple theoretical t
reatment of TEAM is presented that employs a perturbation model of pho
ton transport. This indicates that despite the lack of a secure theore
tical basis, the technique may provide a potentially effective ad hoc
method of generating images of highly scattering media. The method was
also evaluated experimentally by using, for the first time to our kno
wledge, a single object and two wavelengths. A single-projection, two-
dimensional image was obtained of a solid phantom with optical propert
ies representative of breast tissue. The results exhibited good agreem
ent with the theoretical model, and a small embedded feature that abso
rbs 3.5 times as strongly as the surrounding medium at one wavelength
was revealed successfully. (C) 1997 Optical Society of America.