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Stroboscopic illumination for ultrasound-modulated optical measurements. The location of the pulse is given as , where is the velocity of a propagating ultrasound pulse. A laser beam irradiates the optical sample for a short time to capture an instantaneous speckle pattern. A variety of speckle patterns are obtained as a function of the ultrasound pulse location . (a) A speckle pattern at the position of the ultrasound pulse . (b) A speckle pattern at the position of the pulse .
Experimental setup. PL: Pulsed-laser diode; M: Mirror with a hole; PUT: Pulsed-ultrasound generator; CCD: Charge-coupled device camera; FG: Flame grabber; COM: Computer; DG: Delay generator; PG: Pulse generator; AMP: Amplifier; and SMP: A sample.
Observation of an absorptive object at depth embedded in a scattering medium of thickness. The size of the absorber is and in thickness. (a) A one-dimensional axial distribution of along the axis. (b) A one-dimensional cross-sectional distribution of along the axis.
Dependence of as a function of . A series of for of the absorber embedded in a scatterer with .
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