ABSTRACT
Absorption and scattering are two fundamental interactions of light with biological tissues. The basic optical properties related to absorption and scattering are the absorption coefficient (μa), scattering coefficient (μs), total attenuation coefficient (μt = μa + μs), scattering phase function (p(cosθ)), anisotropy factor (g), and reduced scattering coefficient ( ′ = −µ µs s g( )1 ) (Welch and Van Gemert 1995). In addition, the refractive index, n, is also a basic optical parameter that describes the change of direction when light passes from one medium to another. In this chapter, we will introduce various basic techniques that have been developed to measure optical
6.1 Introduction .................................................................................................. 133 6.2 Beer’s Law for Absorption Measurement ..................................................... 134 6.3 Integrating Sphere Technique ....................................................................... 135
6.3.1 Theory ............................................................................................... 136 6.3.2 Optical Measurements Using Integrating Spheres ........................... 138
6.4 Direct Measurement of Optically Thin (Single Scattering) Tissue .............. 141 6.5 K-M Method................................................................................................. 144
6.5.1 K-M Model ....................................................................................... 144 6.5.2 K-M Measurement Techniques ........................................................ 146 6.5.3 K-M Applications in Food and Agriculture ..................................... 147
6.6 IAD Method .................................................................................................. 149 6.6.1 Theory of IAD .................................................................................. 149 6.6.2 Example Applications of Applying IAD Technique
to Measure the Optical Properties of Food ...................................... 152 6.7 Conclusions ................................................................................................... 156 References .............................................................................................................. 156
scattering and absorption properties of biological tissues, as well as the underlying theory of these techniques.
