Spatial Resolution in Time-Gated Transillumination of Turbid Media

The performance of two different time-resolved transillumination approaches applied to turbid media is compared on the basis of the resulting spatial resolution; a photon counting set-up with a time resolution of 35 ps, and a streak camera arrangement with a 6 ps time resolution. In the case of a substantial relative amount of unscattered light, it is found that small detection angles improve spatial resolution irrespective of temporal resolution. For large concentration of scatterers and large sample thicknesses, i.e. when the amount of unscattered light is negligible, it is observed that the spatial resolution is improved by increasing the time resolution. Moreover, the time gate position corresponding to best spatial resolution is found to be at later times than the minimum transit time.