L. Cui and W. Knox, "Enhancement of Penetration Depth for Backscattering-Mode Nonlinear-Absorption Imaging in Turbid Media,"
in Frontiers in Optics 2010/Laser Science XXVI,
OSA Technical Digest (CD)
(Optical Society of America, 2010), paper FWY3.
Using only ~5 mw laser power, we imaged in backscattering mode a nonlinear absorbing object at 2.5 mm depth, which is five times the mean-free-path-length in a turbid medium, by optimizing the detection.