Time-gated techniques for biological imaging

Discusses various studies performed at the Naval Research Laboratory related to optical imaging in turbid media. Those studies have concentrated on time-gated imaging using light in both the ballistic and diffuse scattering regimes. In the ballistic regime the authors utilized a high-gain Raman amplifier to achieve diffraction limited imaging through 33 scattering lengths of a highly turbid material. Coherence-gated imaging experiments were also performed in this regime using Raman techniques, and the authors discuss current work that uses low-coherence interferometry to image structural defects in a variety of highly scattering materials. In the diffuse scattering regime, the authors present theoretical and experimental results that were obtained for time-gated light propagating in the full diffusion limit, and also in a regime they have termed quasidiffuse. Spatial-resolution limitations are discussed for both cases.