ALGORITHMS FOR UNEQUAL-ARM MICHELSON INTERFEROMETERS

A method of data acquisition and data analysis is described in which t he performance of Michelson-type interferometers with unequal arms can be made nearly the same as interferometers with equal arms. The metho d requires a separate readout of the relative phase in each arm, made by interfering the returning beam in each arm with a fraction of the o utgoing beam. Instead of throwing away the information from a single a rm by subtracting it from that from the other arm, the data in one arm is first used to estimate the laser phase noise and then correct for its effect in the normal differenced interferometer data.