Time-domain response of a diffusive medium from speckle pattern frequency correlations

Summary form only given. The optical characterization of scattering media has many important biological and environmental sensing applications. Useful spectroscopic or imaging data from within a scattering domain requires some form of measured data inversion with a model for the scattering domain. Laser speckle data using light of appropriate coherence, coupled with a diffusion equation model, can be used to extract the scattering domain parameters. An external-cavity laser diode whose center frequency could be tuned over a range of approximately 60 GHz was used to illuminate several diffusive media slab samples. Using suitable imaging optics consisting of an aperture and lens, the intensity speckle pattern from the output face of the sample was measured using a CCD camera.