Time-gated imaging through dense scatterers with a Raman amplifier

A time-gated Raman amplifier has been used to detect a bar chart hidden by a strongly scattering material. The time gating was provided by a frequency-doubled Nd:YAG pump laser having a pulse duration of 30 ps. We have amplified and detected images with resolved structures smaller than 125 µm through suspensions of polystyrene spheres and nondairy creamer for light extinction factors of up to e(33). The Raman amplifier system has been shown to produce images under conditions in which the scattering medium was sufficiently dense that an image could not be detected on either a streak camera or by integration on a sensitive, low-noise camera.