The tube of a gas laser is often sealed at each end by a flat glass plate
PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Wave propagation and light in media · Polarisation and anisotropic media
Optics and Photonics, Ch Reflection and transmission at interfaces
Problem
The tube of a gas laser is often sealed at each end by a flat glass plate, a Brewster window, set so that the beam meets it at Brewster's angle. Take a plate of crown glass (n=1.50) in air with parallel faces, and a beam that meets its first face from the air side at exactly θB for air to glass. Treat the two faces as independent, the only case this chapter computes.
((a)) Find θB and the angle θt at which the beam travels inside the plate, and show that the beam meets the second face at exactly Brewster's angle for glass to air, so that p-polarised light passes both faces with no reflection loss at all.
((b)) Find rs and Rs at the first face and at the second face, with the sign of each under CV5, and hence the fraction of the s-polarised power that passes through the whole plate.
((c)) If the light arriving at the plate is half s and half p in power, find the fraction of the total power that passes through the plate, and the fraction of the transmitted power that is p.