Femtosecond transillumination tomography in thick tissues

Abstract
We describe diffuse-light time-gated imaging with transillumination optical coherence tomography. Submillimeter-resolution imaging of objects hidden in thick biological tissue is achieved in cases in which ballistic light is absent by selecting only the early-arriving coherent portion of the diffuse transmitted light. By using a femtosecond laser as a high-power low-coherence light source, we perform high-sensitivity (130-dB dynamic range) optical gating with interferometric heterodyne detection. The dependence of image resolution on coherent photon arrival time is investigated in model scattering media.