Time-gated transillumination of biological tissues and tissuelike phantoms
The applicability and limits of time-resolved transillumination to determine the internal details of\nbiological tissues are investigated by phantom experiments. By means of line scans across a sharp edge,\nthe spatial resolution (Ax) and its dependence on the time-gate width (At) can be determined.\nAdditionally, measurements of completely absorbing bead pairs embedded in a turbid medium demonstrate\nthe physical resolution in a more realistic case. The benefit of time resolution is especially high for\na turbid medium with a comparatively small reduced scattering coefficient of approximately pL,' = 0.12\nmm-1. Investigations with partially absorbing beads and filled plastic tubes demonstrate the high\nsensitivity of time-resolving techniques with respect to spatial variations in scattering or absorption\ncoefficients that are due to the embedded disturber. In particular, it is shown that time gating is\nsensitive to variations in scattering coefficients.\nKey words: Time-resolved transillumination, turbid media, light scattering, streak camera.