Determination of spatial correlation functions of refractive index of living tissue

We present what to our knowledge the first method of determination of spatial correlation functions of refractive index fluctuations of living tissues by Fourier domain optical coherence tomography (FDOCT). Based on the second-order statistical description of the random characteristic of living tissue, a formula which clearly relates the spectral electrical power from the detector to the Fourier spectrum of the refractive index correlation function is given. The method is characterized by its capability of noninvasive measurements in vivo. It has the potential of allowing quantitative discrimination between different tissue types or the same tissue at different pathological states by determining their Fourier components of spatial correlation functions of refractive index.