Introduction to Wave Optics

Figure 27.1 Katharine Burr Blodgett (1898–1979) was a physicist and chemist who made significant advancements in the study of surfaces and thin films. The trough she developed is still used in thousands of labs around the world, and her invention of non-reflective glass has had massive impact in cinema, medical, and scientific research arenas. (credit: Smithsonian Institution)

Chapter Outline

27.1 The Wave Aspect of Light: Interference

27.2 Huygens’s Principle: Diffraction

27.3 Young’s Double Slit Experiment

27.4 Multiple Slit Diffraction

27.5 Single Slit Diffraction

27.6 Limits of Resolution: The Rayleigh Criterion

27.7 Thin Film Interference

27.8 Polarization

27.9 *Extended Topic* Microscopy Enhanced by the Wave Characteristics of Light

Examine a compact disc under white light, noting the colors observed and locations of the colors. Determine if the spectra are formed by diffraction from circular lines centered at the middle of the disc and, if so, what is their spacing. If not, determine the type of spacing. Also with the CD, explore the spectra of a few light sources, such as a candle flame, incandescent bulb, halogen light, and fluorescent light. Knowing the spacing of the rows of pits in the compact disc, estimate the maximum spacing that will allow the given number of megabytes of information to be stored.

If you have ever looked at the reds, blues, and greens in a sunlit soap bubble and wondered how straw-colored soapy water could produce them, you have hit upon one of the many phenomena that can only be explained by the wave character of light (see Figure 27.2). The same is true for the colors seen in an oil slick or in the light reflected from a compact disc. These and other interesting phenomena, such as the dispersion of white light into a rainbow of colors when passed through a narrow slit, cannot be explained fully by geometric optics. In these cases, light interacts with small objects and exhibits its wave characteristics. The branch of optics that considers the behavior of light when it exhibits wave characteristics (particularly when it interacts with small objects) is called wave optics (sometimes called physical optics). It is the topic of this chapter.

Figure 27.2 These soap bubbles exhibit brilliant colors when exposed to sunlight. How are the colors produced if they are not pigments in the soap? (credit: Scott Robinson, Flickr)