TDOBS: Tilt-dynamics Optical Bench Simulator
This experiment is a platform for studying the critical components involved in the LISA measurement chain under conditions resembling spacecraft angular motion.
Using lasers in space to perform high-precision length, angular, and displacement measurements entails many technological hurdles. The LISA mission will use laser interferometry to probe the gravitational-wave universe by establishing optical links between three satellites over millions of kilometers. One obstacle that must be overcome is the random angular motion of the spacecraft, which, if not addressed, can cause the optical links to be degraded or even lost, spoiling the measurement.
The TDOBS experiment is a platform for studying the critical components involved in the LISA measurement chain under conditions resembling spacecraft angular motion. A simplified model of the LISA Optical Bench was built using fused silica components bonded to an ultra-stable glass ceramic baseplate. A pair of remote-controlled actuators enable us to inject beam tilts into the interferometer, simulating spacecraft pitch and yaw. The testbed was used to investigate and characterize imaging systems, which have been proposed as the main strategy to deal with the unwanted angular motion.
TDOBS is now being upgraded to perform tests of a new and very important hardware development: the LISA Phase Metrology System (PMS). The PMS is the instrument tasked with receiving the interferometric signals from the Optical Bench and extracting the relevant scientific information, i.e., the physical quantities that enable us to derive length, angular, and displacement measurements with high precision and large dynamic range. To probe the performance of the PMS, current efforts focus on reducing the optoelectronic noise of the testbed to conform with the LISA requirement of subpicometer-per-root-hertz.