Imaging in turbid media by photon density waves: Spatial resolution and scaling relations

Spatial resolution of transillumination imaging through highly scattering media normalized to sample thickness d depends an only the normalized wavelength hid of photon density waves and normalized penetration depth delta/d. This was concluded theoretically and verified experimentally by the derivation of edge-spread functions from measured time-resolved transmittance and its Fourier transform by the use of dilute milk at various concentrations as scatterer in cuvettes of d = 2 cm and d = 4 cm. In the frequency domain and the time domain, spatial resolution was found experimentally to be given by approximately 0.3d obtained at Lambda approximate to d or when only the first arriving 1% of all photons detected were taken into account. (C) 1991 Optical Society of America