Abstract

Phase sensitive spectroscopy is achieved by producing a difference in path length between the two counter-propagating beams of a ring laser, which can be measured by beating the two beams together. The beat frequency is linearly proportional to the difference in path length. The intrinsic measurement is a difference in phase (<10⁻⁷) between the two senses of propagation, which can be induced by rotation or a change of index (electro-optic, current induced electro-striction, a change in shift upon reflection, etc.).

© 1994 IEEE