Two-dimensional imaging through turbid media using a continuous wave light source

Abstract

We introduce here a scheme for two-dimensional imaging of an object hidden in a turbid medium using a low power continuous wave source and report its practical implementation. As already known, periodic polarisation modulation of an input continuous wave and subsequent polarisation discrimination enables the separation of the ballistic signal from the diffuse light. In the present work, this is achieved by modulating the input polarisation, recording a sequence of spatially filtered images using a CCD camera, and Fourier transforming the time sequence to extract the periodic ballistic signal. With this technique we have achieved sub-millimeter resolution imaging in scattering media that are more than 30 transport mean free paths thick.