Martin–Puplett interferometer

A Martin–Puplett interferometer measures the difference between the powers of two input beams.^[1] It is similar to a Michelson interferometer, except in a Martin Puplett interferometer the beam splitters are wire grid polarizers instead of half-silvered mirrors, and mirrors in the beam path are rooftop mirrors to flip the polarization of the light reflecting off of them by 90 degrees.^[2] Martin–Puplett interferometers are set up with two input ports and two output ports.

The configuration was proposed by Derek Martin and Edward Puplett in 1970.^[3]