Pulsed ultrasound modulated optical tomography utilizing the harmonic response of lock-in detection

Ultrasound modulated optical tomography (USMOT) can image the optical properties of a scatteringmedium at a spatial resolution approaching that of ultrasound (US). A lock-in parallel speckle detectiontechnique is proposed to detect pulsed US modulated light using a multipixel detector. The frequencycomponents of the pass band match those of the US pulse train and provide efficient detection. The modulationdepth is extracted by taking the difference between a pair of speckle patterns modulated by a pairof phase-inversed US bursts. Modification to pulse inversion mode enables the second harmonic USmodulation due to nonlinear US propagation to be detected. © 2013 Optical Society of AmericaOCIS codes: (110.6150) Speckle imaging; (110.0113) Imaging through turbid media