Astronomers observe the chromosphere of the sun with a filter that passes the red hydrogen spectral line of wavelength 656.3 nm, called the Hα line. The filter consists of a transparent dielectric of thickness d held between two partially aluminized glass plates. The filter is kept at a constant temperature.
(a) Find the minimum value of d that will produce maximum transmission of perpendicular Hα light if the dielectric has an index of refraction of 1.378.
(b) If the temperature of the filter increases above the normal value increasing its thickness, what happens to the transmitted wavelength?
(c) The dielectric will also pass what near-visible wavelength? One of the glass plates is colored red to absorb this light.