Cancellation of Laser Noise in an Unequal-Arm Interferometer

A method of processing phase measurements in an unequal-arm laser Michelson interferometer makes it possible to detect phase effects much smaller than the laser phase noise. In the original application for which the method has been proposed, the interferometer, used to detect gravitational waves, would be based on three spacecraft flying in an approximately equilateral triangular formation with arm lengths of the order of 5 × 106 km. In principle, the method could also be utilized in other applications in which one seeks to measure relative lengths interferometrically with high precision and the interferometer arm lengths cannot be made equal.