3. The Michelson interferometer

The Michelson interferometer is a two-wave interferometer whose two separate arms allow a wide variety of set-ups. Albert Michelson built his first model in Berlin to demonstrate the Earth's translational motion in relation to the vacuum. We'll start by describing this interferometer, then look back at the extremely important results obtained with it.

A source illuminates a semi-reflective splitter plate at 45° incidence. The transmitted beam and the beam reflected in the perpendicular direction fall under zero incidence on two plane mirrors M ₁ and M ₂ (figure 8 ) and autocollimate back onto the splitter blade, which then becomes a mixer. One part of the beams returns to the source. The other,...