Time–Resolved Imaging in Dense Scattering Media

J. Chang et al. (1993)


The ability to image at optical frequencies objects embedded in a dense scattering medium has been experimentally evaluated using a previously described Progressive Expansion (PE) algorithm. Optical backscatter measurements were performed in a limited faster- type scan using a colliding pulse modelocked (CPM) femtosecond laser operating at 620 nm and streak camera. Data were collected in the presence and absence of the embedded absorber (3 mm diameter bead) located at a depth not visible from the surface, smoothed and evaluated between 0- 200 ps in steps of 36 ps, using an overlapping approach contained in the PE algorithm, which is based on a linear perturbation model. Results obtained demonstrate the sensitivity of reconstructed images to variations in source and detector locations in relation to the subsurface location of the absorber.