High-resolution computed tomography of refractive index distribution by transillumination low-coherence interferometry.

We present a method to image refractive index distribution within a sample across 8 mm dimension with high spatial resolution by a transmission low-coherence interferometer. The relative strong forward-scattering light is collected, from which the parallel projections of refractive indices within the sample are obtained. A convolution backprojection algorithm is used to transform the projection data set recorded at sufficient angular views into the spatial distribution of refractive indices within the sample. We experimentally demonstrate this method by imaging a phantom. We show that this method can achieve a precision of 0.01 in determining the refractive index and a spatial resolution of 40 microm.