REAL-TIME 3-D HOLOGRAPHIC IMAGING USING PHOTOREFRACTIVE MEDIA INCLUDING MULTIPLE-QUANTUM-WELL DEVICES

We discuss a real-time coherence gated three-dimensional (3-D) imaging system, based on photorefractive holography with ultrashort pulses, w hich has been applied to imaging through turbid media with a view to d eveloping biomedical instrumentation. Sub-100-mu m depth-resolved imag es of 3-D objects embedded in a scattering medium have been obtained. Using a long integration time in rhodium-doped barium titanate (Rh:BaT iO3), an image of a test chart has been obtained through 16 mean-free paths of scattering medium. Real-time depth-resolved imaging through 1 3 mean free paths of scattering medium has been demonstrated using a f ast response time (< 0.4 ms) photorefractive multiple quantum well dev ice. This latter system can acquire depth-resolved images direct to vi deo with no requirement for frame grabbing or signal processing. We di scuss the tradeoffs and limitations of these photorefractive media for this application.