Highly sensitive wideband seismometer using a laser interferometer

Abstract

A sensitive double beam laser interferometer for studying highfrequency piezoelectric and electrostrictive strains Rev.

Thermal-noise-limited underground interferometer CLIO

“…LCGT is planned to be constructed in this area. This underground site is suitable for interferometric GW detectors because the seismic noise is less than that in an urban area by about two orders [6,7]. This merit is helpful to achieve the target sensitivity and to obtain stability.…”

“…The mirrors have weights of 1.8 kg (end) and 1.9 kg (front), made of sapphire. They are suspended by bolfur 6 wires at the last stage, whose resonant frequency is 0.79 Hz. The pendulum has a resonant frequency of a primary mode of about 0.5 Hz.…”

Status of Japanese gravitational wave detectors

“…Now this place accommodates scientific activities such as Super-Kamiokande, KamLAND, XMASS and so on. The underground environment of Kamioka is ideal for the interferometer as the seismic activity is 100 times quieter than that of the TAMA site [3,4]. This seismically quiet setting has direct merit of a small displacement of the mirror, as well as indirect advantages such as smaller upconversion noise and better stability of the interferometer operation [5].…”

Vibration isolation support system for a truncated icosahedral gravitational wave antenna

“…In regions of low seismic activity the characteristic spectral behavior of the background scismic is known 6 to follow the empirical expression a(1 Hz/ ͒ 2 m/͑Hz) 1/2 , where is the frequency and a is a parameter that depends on the location at the Earth surface. In a seismically very quiet site (aϭ10 Ϫ8 ), and supposing that the frequency of detection is about 2 KHz the spectral density level of seismic noise will be 10 Ϫ14 m/Hz Ϫ1/2 .…”