26 Interference and Diffraction Lectures by James L. Pazun Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley

Goals for Chapter 26 To study interference and coherent sources. To expand our understanding of interference to two sources of light. To examine interference in thin films. To study diffraction from single and multiple slits. To explore how x-ray diffraction may be used to examine atomic crystals. To see how the size of a circular aperture changes resolving power. To see how objects may be imaged by holography.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley A simple demonstration – Figure 26.2 I did this for my son at the pool with two pennies. I tossed them in side by side and watched the ripples head outward from each impact until they met and formed the fringes!

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Why should interference patterns be seen? – Figure 26.1 A physical introduction to the concept of two monochromatic waves interfering.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Young’s two slit experiment – Figure 26.3 Young’s classic experiment can be duplicated with a laser and two slits made with two parallel scratches on a blackened microscope slide.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley The analysis can be shown – Figure 26.4 The yellow box on page 866, the surrounding text on page and the previous slide. See figure at right. Quantitative Analysis 26.1 and Example 26.1 also pertain. See figure below.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley An example from broadcast media – Figure 26.7 Example 26.2 is an example from AM radio broadcast.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Surfaces of thin films can create interference. Refer to Figures 26.8 and 26.9 This explains why thin films of oil on roads generate “rainbow” scattering

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Thin film examples Refer to Quantitative Analysis 26.2, Example 26.3 and 26.4 and Figure Figure 26.11

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Newton’s Rings – Figures and Figure at left, diagrams the phenomenon. Figure at right, shows application for optics QC.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Structural pigments Some of the purest and vibrant colors are made mechanically from gratings rather than from pigments. The example shows a brilliant blue and electromicrograph of the grating that created it.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Non-reflective coatings – Figure 26.14

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley A sharp edge can create fringes by diffraction. This is illustrated in Figure with a common razor blade.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Fresnel diffraction – Figure A near field phenomenon. The opposite (not illustrated), is a far-field effect known as Fraunhofer diffraction.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Fringes from single slit diffraction – Figure An interesting case that shows actual results that differ from the ray model prediction.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Results from a single slit – Figures and 26.20

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Analysis of fringes from a single slit – Figures 26.21,22 Refer to worked Example 26.6 on page 878. Figure Figure 26.22

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Experimental effects on diffraction – Figure The color of the light and the width of the slit will modify the diffraction pattern observed.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Multiple slit diffraction – Figures 26.24, 25

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley A music CD can act as a grating – Figures 26.26, 26.27

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Gratings replacing prisms – Figure Analysis of light, first done with optical glass or quartz prisms may also be done with gratings.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Spectra from gratings – Figure Refer to Example 26.7 on page 881 and Example 26.7 on page 882. The figure refers to the latter.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Study of crystal structure - Figures 26.30, 26.31

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Size of an aperture and resolving power – Figure The diameter of a circular opening determines it’s resolving power. See the yellow box on page 885 and the text on pages

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley The resolving power of the human eye – Example Refer to Example in your text.

Copyright © 2012 Pearson Education, Inc. publishing as Addison-Wesley Holography – Figure Objects can be imaged in remarkable clarity by lasers and interference.