Ultrasound detection through turbid media.
Optical coherence-domain reflectometry and laser-based ultrasound detection have been combined with the use of adaptive optics to detect ultrasound through turbid media. The dynamic hologram in a photorefractive quantum-well device performs as a coherence gate that eliminates multiply scattered background. Quadrature homodyne detection conditions are selected by the choice of center wavelength of the pulse spectrum, requiring no active stabilization or feedback. A depth resolution of 30 microm was achieved, with a pulse duration of nominally 120 fs for ultrasound detection through turbid media up to optical thicknesses of 11 mean free scattering lengths.
Yu
P
P
Department of Physics, Purdue University, West Lafayette, Indiana 47907-1398, USA. pingyu@physics.purdue.edu
Peng
L
L
Nolte
D D
DD
Melloch
M R
MR
D006696:Holography; D007834:Lasers; D008962:Models, Theoretical; D055095:Optics and Photonics; D014463:Ultrasonography