Application of the zooming method in near-infrared imaging

Images of a tissue simulating phantom are obtained by inverting a limited number of continuous-wave relative transmission measurements. The diffusion approximation to the radiative transfer equation is used as a light propagation model. The inversion procedure is based on a quasi-Newton method and the Levenberg-Marquardt method, and the imaging parameter is the absorption coefficient of the phantom. It is shown that the resolution of the images can be improved using the zooming method. The image indicates the presence of an inhomogeneity in approximately the correct location, but the shape and size of the inhomogeneity in the reconstructed image differs from the shape and size of the actual inhomogeneity. Possible methods for further enhancement of the images are discussed.