ACOUSTICALLY MODULATED SPECKLE IMAGING OF BIOLOGICAL TISSUES

A video laser speckle imaging technique yields images with contrast ba sed on the mechanical properties of a tissue. Fluctuations of laser sp eckle patterns induced by acoustically driving the tissue at various f requencies in the 0-30-Hz range encode the mechanical strain of the ti ssue. At each acoustic frequency and within the camera acquisition tim e, each camera pixel integrates a temporally fluctuating speckle inten sity whose variance encodes the mechanical strain in response to the a coustic modulation. The magnitude and the frequency dependence of this strain provide mechanical information about the tissue and are the co ntrast mechanism for images. (C) 1998 Optical Society of America.