Real-time two-dimensional imaging in scattering media by use of a femtosecond Cr4+:forsterite laser

An original femtosecond Cr4+:forsterite laser source associated with a nonlinear optical correlator was used for imaging through scattering media with 1220-nm light. The system, which operates as an ultrafast optical gate by sum-frequency generation in a nonlinear crystal, was able to detect the Light reflected from a resolution chart hidden in a turbid medium, at an attenuation of as much as 15 mean free paths, When the object was illuminated with a collimated beam, real-time two-dimensional images were obtained, with a maximum transverse resolution of similar to 20 mu m. (C) 2000 Optical Society of America. OCIS codes: 320.7110, 320.2250, 290.7050, 290.1990, 290.1350.