RESUMO
We report on the development of a new type of mode cleaner that reduces any geometric noise of the laser beam in an interferometric gravitational-wave detector. The mode cleaner is a Fabry-Perot cavity that comprises independently suspended mirrors and works as a frequency-stabilization reference as well as a mode selector; the length of the cavity is 1 m. Stand-alone tests have shown at least a 30-dB reduction in the geometric fluctuation of the beam and a 60-dB reduction of the frequency noise of the laser. We have also succeeded in operating a 20-m Fabry-Perot prototype detector (at the National Astronomical Observatory, Tokyo, Japan) by using this mode cleaner.
RESUMO
We report here on the development of an optical transducer for mechanical vibration, making use of an ultrashort Fabry-Perot cavity. The noise level measured by a cavity 150 µm long is ~1.3 × 10(-16) m/âHz at ~1 kHz, which was obtained without a frequency-stabilization system. It was, however, large compared with the shot noise.
RESUMO
In interferometric gravitational-wave detectors, most of the optical components are suspended by wires so that they are isolated from all kinds of forces except gravity. The requirement for the alignment of optical components to the laser beam is crucial. We have demonstrated a servo system developed for a Fabry-Perot cavity whose mirrors are suspended independently. We use mechanical modulation and a lock-in detection method to detect any misalignment. This system directly detects the relation between the axis of the laser beam and the axis of the cavity and automatically aligns the cavity to the laser beam. We confirmed that the intensity of the reflected light from the suspended Fabry-Perot cavity can be minimized with this system. Automated control of the alignment of the large-scale detectors is also discussed.
RESUMO
Details concerning the design of the stabilization system for a He-Ne laser based on a two-mode method that uses a thin-film heater are discussed. The stability is evaluated by measuring the beat signal between two stabilized lasers; it is 1.1 × 10(-12), expressed in terms of the root Allan variance (τ = 35 s).
