Three identical glass lenses are coated with the same transparent dielectric film of…
PHYSICS · Multi-part · AP · Physics 2: Algebra-based · Waves Sound and Physical Optics · Waves Sound and Physical Optics
Problem
Three identical glass lenses are coated with the same transparent dielectric film of refractive index nf=1.38. The incident light of wavelength λ0=550nm in air strikes each lens at normal incidence. The coating thicknesses are
Lens A: tA=8nfλ0
Lens B: tB=4nfλ0
Lens C: tC=8nf3λ0
(a) For each lens, calculate the phase difference between the two reflected rays that interfere, expressing your answers in integer multiples of π.
(b) Rank the three lenses in order of decreasing reflected intensity at wavelength λ0. Clearly justify your ranking using your results from part (a).
(c) When illuminated by white light, describe qualitatively what color tint each lens is expected to exhibit. Explain how your answer is consistent with the ranking from part (b).