Question

I’m looking at a pair of vintage Oakleys on eBay right now. They’re 1st gen Juliet X-metals with the ruby Iridium lenses, and I cannot afford them. But they are a great example of thin-film interference! The lenses are polycarbonate, which has an index of refraction ?" = 1.60, with a thin film of iridium oxide (?! = 2.50) coating the lens.

A) Calculate the wavelength ?! of red light (?0 = 650nm) through the iridium film.

B) The lenses appear strongly red. Explain briefly why (as opposed to the lenses appearing transparent, or maybe gray like ordinary sunglasses)

C) What thickness ? of iridium oxide film should coat the lenses? Assume that the reflected red color has a wavelength ?0 = 650nm.

Answer 1