A thin film of polystyrene is used as an antireflective coating for fabulite (known as the substrate). The index of refraction of the polystyrene is 1.49, and the index of refraction of the fabulite is 2.409.
What is the minimum thickness of film required? Assume that the wavelength of the light in air is 480 nanometers.
3 Answers
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minimum thickness of film t = λ / 4n
where λ = wave length = 480nm =520 * 10 -9 m
n = The index of refraction of the polystyrene = 1.49substitue values
and make sure to multiply by 10^9 as the question ask for the answer in nanometers.
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Anti Reflective Coating Mastering Physics
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Need t= λ / 4n_poly
t= 480 / 4(1.49)
t= 85.6 nm
