Abstract

We describe the implementation of a non-linear grating-based angular filter for the assessment of turbid media with ballistic photons. A monochromatic source incident on a ruled grating, positioned at grazing diffraction, followed by a narrow slit conform the proposed system. We validate the angular amplification experimentally, with values ranging on the order of 10-20X. In addition, similar values of transversal beam size reduction, provide an efficient ~100X filtering scheme. We address the plausible application of the angular filter to perform ballistic transillumination of turbid media, such as biological tissue. Non-linear angular amplification and beam width reduction are employed to separate ballistic photons from forward-scattered ones. Preliminary experimental results of the technique are encouraging, as compared to those of traditional transillumination.

© 2009 OSA/SPIE