Abstract
A highly sensitive detection system with time-resolved photon counting was developed for modulation optical tomography (diode laser with a power of 15–30 mW, modulation frequency 100 MHz) of extended scattering objects. Experiments with model objects (linear dimensions up to 140 mm, absorption coefficients of 0.005–0.015, scattering coefficients of 1.4 mm-1) showed that the propagation of optical radiation in such media is described by a relative path-lengthening coefficient which varied in the range 1.2–4.2, depending on the absorption coefficient and on the size of the object. A rapid projection algorithm for the solution of the inverse problem was used in the reconstruction of images of strongly absorbing inclusions known as 'phantoms' (cylinders 10–23 mm in diameter). An algorithm was developed for the solution of the direct problem, which made it possible to reduce the solution time to 5–10 min.