ABSTRACT
This chapter reviews the underlying principles of acousto-optic (AO) interactions and describes the materials considerations and the relevant acoustic technology. The most useful photoelastic effect is the ability of acoustic waves to diffract a light beam. The interaction length is sometimes expressed in terms of a ratio known as the Raman-Nath parameter. A number of important AO devices make use of the properties of birefringent materials. The chapter explores the important characteristics of anisotropic diffraction. There are two factors limiting the bandwidth of an AO device: the bandwidth of the transducer structure and the acoustic absorption in the delay medium. The number of resolution elements will be determined by the frequency bandwidth of the transducer and delay line, but a number of other bandwidth considerations are also of importance for the operation of a scanning system. Most AO applications are based on diffraction effects, requiring interaction over at least a few periods sinusoidal index change in the acoustic media.
