Abstract

Within the next few years, several interferometric gravitational wave detectors with long arm lengths will go into operation. GEO 600 is an advanced interferometer of Michelson-type with 600 m arm length and dual recycling [1]. To achieve the planned strain sensitivity of $\delta l/l=4\cdot {10}^{-23}/\sqrt{\text{Hz}}$ in the frequency range of 100 Hz to 1 kHz the lasers must fulfill extreme stability requirements regarding frequency, amplitude and spatial beam quality.

© 1996 IEEE