Abstract: A method for imaging objects in turbid media. According to one embodiment of the invention, the method comprises the steps of (a) illuminating the object through the turbid medium with a pulse of light, the light emergent from the turbid medium consisting of a ballistic component, a snake-like component and a diffusive component, the diffusive component including Fermat photons and non-Fermat photons; (b) gating the light emergent from the turbid medium to preferentially select Fermat photons; and (c) forming an image of the object using the gated light. Preferably, a spatial gate is used to preferentially select Fermat photons from the emergent light. This may be done by orienting the source of the illuminating light and a light detector to lie along a most favorable path travelled predominately by Fermat photons. A time gate, such as a streak camera or the like, may be used in addition to the spatial gate to more carefully select Fermat photons from the emergent light.

Abstract: A method and apparatus for examining a two-dimensional region of a tissue sample. This is accomplished, according to one embodiment of the invention, by illuminating, i.e., exciting, the two-dimensional tissue sample with light at a first wavelength. The resultant fluorescence is then measured at an emission wavelength as a function of location within the two-dimensional tissue sample. The two-dimensional tissue sample is then illuminated again with light at a second wavelength, and the resultant fluorescence is measured at the same emission wavelength. The two excitation wavelengths and the emission wavelength are appropriately chosen so that the ratio or difference of fluorescence intensities at the emission wavelength is indicative of the carcinomatous condition of the tissue. A value, such as a ratio or difference, of the respective intensity measurements obtained at each location of the tissue sample is then calculated.

Abstract: Biological material is characterized by illuminating the material with a beam of light, measuring light scattered from the material and then determining the condition of the material using the measurements. In one embodiment the angular line shape of the backscattered light is measured and then used to determine the scattering mean free path (1) and the absorption length (la) of the light scattered in the material to find out the condition of the material. These values so obtained are compared to values for a material whose condition is normal to determine if the condition of the material being examined is abnormal or normal. In another embodiment the temporal profile of the scattered pulse is used to determine (1) and (1a).