Ultrasound-modulated optical tomography of absorbing objects buried in dense tissue-simulating turbid media

By detecting ultrasonically tagged diffuse light, ultrasound-modulated optical tomography images optical contrast with ultrasonic resolution deep in turbid media, such as biological tissue. However, small detection etendues and weak tagged light submerged in strong untagged background light limit the signal detection sensitivity. In this Letter, we report the use of a large-area (∼5 cm × 5 cm) photorefractive polymer film that yields more than 10 times detec-tion etendue over previous detection schemes. Our polymer-based system enabled us to resolve absorbing objects embedded inside diffusedmedia thicker than 80 transport mean free paths, by using moderate light power and short ultrasound pulses. © 2013 Optical Society of America OCIS codes: 170.3880, 170.6960, 080.2175, 190.7070. Light diffusion limits high-resolution optical imaging in turbid media, such as biological tissue, to depths up to ∼one transport mean free path (l0t). To break this limita-tion, ultrasound-modulated optical tomography (UOT) was proposed to generate and detect ultrasonically modulated (or tagged) light and visualize optical proper-ties at depths>l0t with ultrasonic spatial resolution [1]