Laser frequency stabilization to molecular resonances for TPF-C, LISA, and MAXIM

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.