Large Area Sagnac Interferometer

I designed this project as a scientific showpiece and an interactive education tool for Saddleback College. LASI consists of two interferometers, one free-space, and one fiber-space. Their combined optical path length is two kilometers making the detector sensitive enough to measure the rotational velocity of Earth. Each interferometer respectively sits on a 2-axis and a 3-axis motorized mount in order to calibrate and align the system with Earth's spin. The system is controlled and read from the user interface screen which outputs both integrated voltage photo-diode measurements and phase shift measurements using a CMOS camera. For calibration, the inner drum can be set to spin at specific rates. The laser sources consist of a 532nm and one telecom 1550nm laser diode. The main parameter in the selecting the laser sources was the narrow bandwidth to give us the necessary coherence length and fringe visibility for the optical path-length. For this reason, gas lasers would have been desired if it weren't for their larger size and high-speed nature of the apparatus. Once completed students will be able to gain experience aligning interferometers, handle optical mounting systems, learn the science behind interferometry, and run their own measurement experiments using the Sagnac effect.

See below for more images and a partial bill of materials.