Patent ID: 6192261
Filing Date: 2001-02-20
Classification: A61B,G01N

Abstract:
The method of determining parameters of a highly scattering medium, which comprises:passing at least two groups of modulated beams of light, each group being of a single wavelength, through differing distances of said medium, said beams of light being modulated at a first frequency, each group of light beams comprising light of a wavelength which is different from the wavelength of the other group;detecting said beams of light which transverse said medium using at least one light sensor, modulated at a second frequency that is different from said first frequency but phase-coherent with said modulated light;deriving at a third frequency resultant signals from said light beams detected at said second frequency, said third frequency being the difference between said first frequency and said second frequency; determining data comprising at least two of phase shift, DC and AC components of said light; an determining a parameter of said medium from said data, said method being free of a step of comparing said beams of light which traverse said medium with beams of said light as emitted prior to transverse said medium.