We have conducted experiments using a prototype time resolved optical tomography system. This setup uses 150 femtosecond excitation pulses from Argon ion pumped mode locked Ti:sapphire laser system, and streak camera (Hamamatsu, C151A7) detection system. The temporal resolution of the system is 10 picoseconds. The excitation wavelength is 750 nm and the rep rate is 76 Mhz. The average power used in the experiments was 1.5W. The phantom which consisted of a glass container filled with water solution of polystyrene microsheres was used to simulate turbidity of breast tissue. We delivered light at multiple points across the surface of the container by means of optical fibers, and collected light with the aid of the multichannel detection methodology of streak camera. Both fluorescent and absorption contrast agents were used in these experiments. We were able to localize 3-5 mm cells with an accuracy of 3-4 mm in the presence of background absorption and fluorescence (10:1 contrast ratio) and work is under way in localizing multiple objects and finding a distributions of absorption in the phantom.
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