Chapter 1 - Optical Pulse Propagation in Biological Media: Theory and Numerical Methods

Abstract

Publisher Summary Different versions of the “Tricorder” device used in Star-Trek science fiction series can noninvasively scan any physical, chemical, or biological entity and cure ailments by hovering over their bodies. Recent advances in ultra-sound and electromagnetics (including optics) could make “Tricorder” a reality. Increasingly, novel innovative ways of using light for clinical applications are developed by researchers all around the world. All these developments rely on having a detailed understanding of light propagation through tissue. Such understanding can only be gained by creating sufficiently accurate models that can capture the essence of light interaction with biological media. This chapter covers the transient characteristics of optical fields propagating through biological media at sufficiently low power levels, which do not induce physical or chemical changes in the material. It specifically looks at short, low-intensity pulses interacting with biological media and discards any light-induced permanent changes (tissue damage and ablation) or secondary emission processes (fluorescence and phosphorescence). A review of the basic features of light scattering from biological media is presented that points out some specific features and provides pointers to literature for specific details. The quantitative aspects of light propagation through tissue are covered by a discussion of the general structure of the transient photon transport equation and related quantities. Various ways of solving the transient photon transport equation is described and the strengths and weakness of each method is highlighted.