Large ring lasers for geodesy and beyond
Prof. Dr. Simon Stellmer (Universität Bonn)

Imagine two light fields propagating in opposite directions along a ring-shaped contour. When set into rotation, the constancy of the speed of light will induce a phase shift between the two light fields. This observation, known as the Sagnac effect, is a very powerful yet simple approach to measure rotation.

The first successful measurement of Earth's rotation via the Sagnac effect was performed by Albert A. Michelson and co-workers in late 1924, exactly 100 years ago. I will give a brief review of the historic work, present the current state of the art, and elaborate on potential applications and future developments.