DOUBLE PHASE MODULATION APPROACH TO AN INTERFEROMETRIC SYSTEM

Abstract

A novel method for measuring the phase difference between interfering beams in an interferometric system is demonstrated by using a double phase modulation technique. There are two modulation signals applied to the interferometric system. The first modulation signal is used to modulate the path length for pseudo-heterodyne processing. The second modulation signal is used to modulate the frequency of the laser diode for equivalent wavelength synthesis. This approach is demonstrated by using a fiberoptic Mach-Zehnder interferometer.