Laser Polarimetry of Biological Tissues: Principles and Applications

3.1 Introduction

Light based techniques are becoming an increasingly popular method of probing strongly scattering media such as body tissues [1-23]. For superficial tissue layers or thin tissue samples it is possible to use the coherence or polarization properties of the light [3,4,6-18,20-23].

Early works in the field of tissue optics assumed a homogeneous scattering medium and measured the bulk scattering and absorption properties. More recently, attempts have been made to characterize the effect of different tissue layers. The problem using light to probe layered scattering media is that the scattered light propagates through many random paths through the different layers. It would be extremely useful to be able to characterize the optical properties and thickness of the different layers from measurements of the properties of the emerging light. For example, in studies of thick tissues models of the brain have