Telescope Design for a Space-Based Gravitational-Wave Observatory
Abstract
Space-based Gravitational-wave Observatories will enable the systematic study of the low-frequency band (0.0001 - 1 Hz) of gravitational waves, where a rich array of astrophysical sources is expected but the motion of the ground is too large to permit construction of a sensitive detector below about 10 Hz. Optical telescopes play an important role in the measurement of gravitational waves in space, but for displacement measurement, not for imaging. They deliver laser light efficiently from one sciencecraft to another over million-kilometer scale separations and both transmit and receive light simultaneously. Transmitting and receiving at the same time puts tight constraints on the scattered light performance because the displacement measurement is made with heterodyne interferometry. Furthermore, there are two telescopes directly in the measurement path between each pair of sciencecraft, so each one requires picometer/√Hz dimensional stability in the measurement band. We report on the performance requirements and design trade-offs required to turn a telescope of modest size and conventional design into a key element of a precision optical metrology system, with an emphasis on the two requirements, optical pathlength stability and scattered light performance, that are beyond the usual specifications for high quality image formation. This work funded in part by NASA SAT grant 11-SAT11-0027 as part of solicitation NNH11ZDA001N.
- Publication:
-
American Astronomical Society Meeting Abstracts #223
- Pub Date:
- January 2014
- Bibcode:
- 2014AAS...22334404L