Green Sunglasses Suppose sunglasses are made by applying a thin n = 1.35 coating

Question

Green Sunglasses

Suppose sunglasses are made by applying a thin n = 1.35 coating to plastic lenses. We wish to design the glasses so that they reflect green light strongly. The lenses are made of plastic with an index of refraction n = 1.42, and the coating has n = 1.42 index n = 1.35.

(a) Find the smallest thickness of the coating which will reflect green light strongly. Assume that the green light has a wavelength of 540 nm.

(b) Find the visible or near-visible wavelengths which would not be reflected. How would the wearer of the glasses see the outside world?

Explanation / Answer

smallest thickness = t
2t*1.35 = 540*10^-9
t = 200 nm

Outside world would be White light devoid of green light, so the color green would be missiong from whatever the wearer sees

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