Abstract

We have developed a technique called laser heterodyne imaging (LHI) that extends the imaging capabilities of laser-induced fluorescence to map the depth profile of a fluorophore in tissue. LHI measures the fluorescence originating from the intersection of two laser beams that differ in frequency by a few tens of megahertz. The signal generated within the probe region is modulated by the different frequency, allowing for easy identification and processing. This technique discriminates against the background fluorescence, thus permitting the measurement of the depth profile of a fluorophore in a turbid medium. Experiments on phantoms show that the linearity of the apparatus holds over a wide range of dye concentrations and scatterers. The application of this technique to tissue in vitro will be discussed.

© 1992 Optical Society of America