Question

  Suppose you need an anti-reflection coating for glass, under yellow
    light (589.3nm).  You can coat it with a thin layer of flourite
    (CaF_2) -- indices for this wavelength are:

                air         flourite        glass

        yellow: 1.000       1.434           1.500


    a.  Make a diagram showing the two brightest reflected rays from
        a single incident ray at normal incidence.

    b.  By considering the phase changes, find the three minimum
        thickness of the coating that will suppress reflections.

    c.  Would your conclusions change if you considered additional
        reflections between the top and bottom of the film?  Explain,
        briefly.

    d.  Without doing any calculation, explain what would happen
        if the film were on ice instead of glass.

Answer 1