A number of future space observatories will rely on interferometric length measurements to meet mission requirements. A necessary tool for these measurements is a frequency stabilized laser. We present the use of molecular resonances for the frequency stabilization reference for the TPF-C, LISA, and MAXIM missions. For the TPF-C terrestrial planet finder coronagraph mission we have stabilized a 1542nm fiber laser to acetylene and exceeded the required sensitivity for length measurements of less than 25nm over a length scale of 12m and a time scale of 8 hours. For the LISA gravitational wave interferometer mission we have stabilized a frequency doubled 1064nm NPRO laser to molecular iodine. The laser system meets the frequency noise requirements of 30Hz/√(Hz) at mHz frequencies and shows robustness to temperature and alignment fluctuations. It also supplies an absolute reference frequency which is important for lock acquisition of lasers on separate spacecraft. The radiation hardness of the frequency doubling crystal for iodine stabilization was studied. In addition, simplified optical configurations have also been investigated, where the need for auxiliary modulators was eliminated. For MAXIM, we have constructed a stabilized laser system for stabilization of the position of the x-ray optics in the GSFC prototype testbed, and we report some initial results in the testbed operation.
The GEO 600 laser interferometer with 600m armlength is part of a worldwide network of gravitational wave detectors. GEO 600 is unique in having advanced multiple pendulum suspensions with a monolithic last stage and in employing a signal recycled optical design. This paper describes the recent commissioning of the interferometer and its operation in signal recycled mode.
The GEO600 laser interferometric gravitational wave detector is approaching the end of its commissioning phase which started in 1995.
During a test run in January 2002 the detector was operated for 15 days in a power-recycled michelson configuration. The detector and environmental data which were acquired during this test run were used to test the data analysis code. This paper describes the subsystems of GEO600, the status of the detector by August 2002 and the plans towards the first science run.