AM ultrasound-modulated optical tomography with real-time FFT

We report on a novel ultrasound-modulated optical tomographic technique app lied in dense tissue-simulating turbid media. A 1 MHz ultrasound beam is fo cused into the media to modulate and tag the scattering laser light passing through the ultrasonic focused zone. A 10 kHz sinusoidal wave, as a detect ion wave, is carried by the ultrasound beam through amplitude-modulation (A M). The scattering photons that come from the focused zone carry the modula ted information, received by detector and demodulated by real-time fast Fou rier transform (FFT). The optical tomographic images of the tissue simulati ng media and buried object are reconstructed with AM spectral intensity. Th is method can be applied to imaging three-dimensional tissue structures wit h different optical parameters. For the first time, we obtained the tomogra phy of buried objects in biological tissue phantoms with a detecting depth of 30 mm.