Specifying tissue optical properties using axial dependence of confocal reflectance images: confocal scanning laser microscopy and optical coherence tomography

The optical properties of a tissue can be specified by the depth dependence of a reflectance-mode confocal measurement.. as the focus is scanned down into a tissue. Reflectance-mode confocal scanning laser microscopy (rCSLM) and optical coherence tomography in focus tracking mode (OCT) are two examples of such confocal measurements. The measurement of reflected signal as a function of the depth of focus, R(z), is expressed as rho e(-mu z), where rho [dimensionless] is the local reflectivity from the focus within a tissue and mu [cm(-1)] is the attenuation of signal as a function of z. The reflectivity of a mirror defines rho = 1. This paper describes how the experimental rho and mu map into the optical properties of scattering coefficient, mu(s) [cm(-1)], and anisotropy of scattering, g [dimensionless]. Preliminary results on tissue for the rCSLM and OCT systems' are reported.