GTBL042-19 GTBL042-Callister-v2 September 13, 2007 13:59

Revised Pages

Chapter 19 Optical Properties

Awhite light beam experiences both refraction and dispersion as it passes through the triangular

glass prism. Refraction occurs when the direction of the light beam is bent at both glass-air prism

interfaces (i.e., as it passes into and out of the prism). And dispersion (chromatic) occurs when the

degree of bending depends on wavelength (i.e., the beam is separated into its component colors).

(©cPhotoDisc/Getty Images.)

WHY STUDY theOptical Propertiesof Materials?

When materials are exposed to electromagnetic

radiation, it is sometimes important to be able to

predict and alter their responses. This is possible when

we are familiar with their optical properties and

understand the mechanisms responsible for their optical

behaviors. For example, in Section 19.14 on optical fiber

materials, we note that the performance of optical

fibers is increased by introducing a gradual variation of

the index of refraction (i.e., a graded index) at the

outer surface of the fiber. This is accomplished by the

addition of specific impurities in controlled

concentrations.

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