Chapter 35 Diffraction and Polarization http://deepspace.jpl.nasa.gov/dsn/images/album/ds n67.jpg http://sciencenow.sciencemag.org/content/vol2008/ issue320/images/200832011.jpg
Introduction Our approach –Take a more quantitative look at diffraction of light passing through single and double slits –Look at the limits of resolution due to diffraction –Look at diffraction gratings and their use –Look at polarization causes and effects
Light through a single slit Look at light through your fingers. What diagram of the single slit shows the situation in which light at a particular angle undergoes the first intensity minimum away from the central axis? Mathematically, describe the situation where the first intensity minimum (above) occurs. Sketch the intensity pattern for the single slit, giving the angular distance scale.
Resolution through circular apertures Mathematically, describe the angle where the first minimum occurs for light coming through a circular aperture. For two points close together, describe (sketch) the intensity pattern after the light goes through a circular opening. What is the Rayleigh criterion?
Diffraction gratings … What is a transmission diffraction grating? How does the intensity pattern of a diffraction grating differ from the intensity pattern of light through a double-slit in which the distance between slits is the same in both? Mathematically, describe the angles at which intensity maxima occur. Lab activity (Wavelength of laser light)
Polarization … What plane is referred to when it is said that particular light is “plane polarized”? What is light like if it is unpolarized? How does polarization occur through absorption? Explain the three Polaroid demo. How does the intensity vary as light passes through two offset polarizers?
… Polarization (cont’d) … Describe the polarization occurring through reflection? What is the polarization axis of Polaroid lenses used while fishing? (more examples) At what angle does the maximum polarization through reflection occur (expressed in a diagram and mathematically) ? How does polarization occur through scattering?
… (Circular) polarization What is circularly polarized light? How is circular polarized light related to plane polarized light? What is an effect (demonstrated in class) of the uneven index of refraction between right- and left-handed circularly polarized light? Elliptically polarized light (comment)