Time-gated imaging through scattering media using stimulated Raman amplification

We propose the use of stimulated Raman scattering for time-gated image amplification and demonstrate its use for the detection of images through a strongly scattering material. Using 30-ps pulses from a frequency-doubled Nd:YAG laser, we have amplified and detected images through a suspension of nondairy creamer with a spatial resolution of less than 300 microm and at concentrations such that the nonscattered extinction ratio was e(-33). Our time-gated image amplifier can produce images under conditions in which the scattering medium is sufficiently dense that an image cannot be seen by using multiple exposures on a streak camera or time-integrated exposures on a sensitive, low-noise CCD camera.