Diffraction Theory

Abstract

To understand imaging performance, such as resolution of various optical imaging systems, it is necessary to study the diffraction property of light waves. In this chapter, various diffraction theories are discussed. Readers who are interested in the history of developing diffraction formulas may read the listed reference books [2.1, 2.2]. Section 2.1 gives a qualitative description of the diffraction problem in terms of the Huygens-Fresnel principle. Quantitative descriptions of diffraction problems, based on Kirchhoff and Rayleigh-Sommerfeld diffraction theories, are presented in Sections 2.2 and 2.3, respectively. The paraxial approximation to these diffraction formulas, which is usually valid in optical imaging systems, is discussed in Section 2.4. Finally, Fresnel diffraction patterns by various apertures (including circular, annular, serrated and doughnut apertures), which are relevant to optical imaging by a lens, are depicted and discussed in Section 2.5.