When viewing a piece of art that%u2019s behind glass, the glare may be a problem

ID: 2112330 • Letter: W

Question

When viewing a piece of art that%u2019s behind glass, the glare may

be a problem - outside light reflected off the

front of the glass. As a solution, the glass (index of

refraction 1.5) may be coated with material such as rutile

TiO2,

with refraction index n = 2.62. What is the smallest thickness

that will cancel the light of the wavelength 505 nm?

(Hint: this is the wavelength in air, not in rutile. Also

remember the 1/2 cycle phase changes on reflection - where

do they occur in this example?). What are other thicknesses that

will do the job (and may be easier to accurately

control the thickness of) - give two or three.

so one low to high (on air to rutile)

so destructive given by m lambda/n = 2 d

d = m lambda/(2n)

smallest m=1, d = 505/(2*2.62)=96.37 nm

next, m=2, d=192.7 nm

next m=3, d=289.1 nm

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