Light - Physical Optics, Refraction

Abstract

The previous chapter on EM waves forms a basis for developing physical optics, which itself traditionally serves as the background to wave mechanics, (Chap. 6). In addition, in this chapter we analyze the propagation of EM waves in dielectrics, with the goal of understanding refraction and reflection at interfaces, the central phenomenon in geometric optics. The chapter begins with a discussion of the generation of light as the outcome of quantum transitions within matter and the role of the Heisenberg uncertainty principle in limiting coherence is pointed out. Analysis of diffraction by a single slit using Fresnel zones, and the consequences for the resolution of illuminated objects follows. Special considerations applying to X-ray diffraction by crystals (three dimensional gratings) completes the discussion of physical optics. Propagation of plane EM waves in insulating dielectrics is treated. Lastly, extension of the Green's function method of solving inhomogeneous wave equations to three dimensions provides a rigorous basis for Fresnel analysis of diffraction. Worked examples include interference of light from two slits, as well as details of reflection and refraction at an interface. There are problems dealing with the Einstein photoelectric effect, the Huygens principle, the square aperture, gratings, Rayleigh's criterion for resolution, Debye-Scherrer X-ray diffraction, and attenuation in metals.