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15. mmh A transparent film (n = 1.43) is deposited on a
glass plate (n = 1.52) to form a nonreflecting
coating. The film has a thickness that is 1.07 x 10-7 m. What is the longest
possible wavelength (in vacuum) of light for which this film has been
designed? |
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This is for destructive interference which is what a non-reflecting coating would
need. |
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Since both rays are phase
shifted due to going from lower n reflecting from higher n, the two phase shifts cancel.
So the only phase difference is the optical
path difference. |
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Solve for the wavelength |
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To get the longest wavelength,
we need the smallest denominator. To
get the smallest denominator, we make m the
smallest it can be which would be zero. |
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