276 research outputs found
Fiber-based two-wavelength heterodyne laser interferometer
Displacement measuring interferometry is a crucial component in metrology
applications. In this paper, we propose a fiber-based two-wavelength heterodyne
interferometer as a compact and highly sensitive displacement sensor that can
be used in inertial sensing applications. In the proposed design, two
individual heterodyne interferometers are constructed using two different
wavelengths, 1064 nm and 1055 nm; one of which measures the target displacement
and the other monitors the common-mode noise in the fiber system. A
narrow-bandwidth spectral filter separates the beam paths of the two
interferometers, which are highly common and provide a high rejection ratio to
the environmental noise. The preliminary test shows a sensitivity floor of
7.5pm/rtHz at 1Hz when tested in an enclosed chamber. We also investigated the
effects of periodic errors due to imperfect spectral separation on the
displacement measurement and propose algorithms to mitigate these effects
Laser Interferometry for Gravitational Wave Observation: LISA and LISA Pathfinder
The Laser Interferometer Space Antenna (LISA) is a planned NASA-ESA gravitational wave observatory in the frequency range of 0.1mHz-100mHz. This observation band is inaccessible to ground-based detectors due to the large ground motions of the Earth. Gravitational wave sources for LISA include galactic binaries, mergers of supermasive black-hole binaries, extreme-mass-ratio inspirals, and possibly from as yet unimagined sources. LISA is a constellation of three spacecraft separated by 5 million km in an equilateral triangle, whose center follows the Earth in a heliocentric orbit with an orbital phase offset oF 20 degrees. Challenging technology is required to ensure pure geodetic trajectories of the six onboard test masses, whose distance fluctuations will be measured by interspacecraft laser interferometers with picometer accuracy. LISA Pathfinder is an ESA-launched technology demonstration mission of key LISA subsystems such us spacecraft control with micro-newton thrusters, test mass drag-free control, and precision laser interferometry between free-flying test masses. Ground testing of flight hardware of the Gravitational Reference Sensor and Optical Metrology subsystems of LISA Pathfinder is currently ongoing. An introduction to laser interferometric gravitational wave detection, ground-based observatories, and a detailed description of the two missions together with an overview of current investigations conducted by the community will bc discussed. The current status in development and implementation of LISA Pathfinder pre-flight systems and latest results of the ongoing ground testing efforts will also be presente
- …