Fiber-based two-wavelength heterodyne displacement interferometer

Abstract

Precision displacement laser interferometry is crucial in various applications such as microlithography, high-performance profilometry, and gravitational wave detection. We are currently developing a fiber-based heterodyne laser interferometer that features compact size and low noise floor. Laser beams at two different wavelengths are utilized to construct a fiberbased interferometer system. Narrow band spectral filters are used to separate the beams of different wavelengths and to control their optical paths. The highly common optical paths between the two interferometers provide a high commonmode rejection ratio to instrument and environmental noise sources. In this paper we present the interferometer design, benchtop prototype system, and preliminary measurement results obtained in the lab environments. A benchtop prototype shows sub-nm/Hz displacement sensitivities in air at frequencies above 100 mHz in our lab. © COPYRIGHT SPIE. Downloading of the abstract is permitted for personal use only.