Close-up of the optical bench on the LISA Technology Package
A close-up view of the optical bench on the flight model of the LISA Technology Package (LTP), pictured at the Airbus Defence and Space Friedrichshafen facility, in January 2015.
The LTP, provided by European institutes and industry, is one of two payloads, or test packages, that will be carried by the LISA Pathfinder spacecraft; the other package is the Disturbance Reduction System (DRS), provided by NASA.
LISA Pathfinder is designed to test one of the key ideas behind gravitational wave detectors – that free particles follow geodesics in space-time. The mission can show this more accurately than has been done in the past by tracking two gold-platinum test masses nominally in freefall, using picometre resolution laser interferometry.
The optical bench of the interferometer, measuring 200 mm × 212 mm × 22.5 mm, is constructed from a block of ultra-low expansion Zerodur ceramic glass. Fused silica mirrors and beamsplitters – the transparent tombstones in the picture – are used to split and then recombine a pair of laser beams. These laser beams will measure the slightest movements of the test masses, right down to subatomic scale precision.
An industrial team led by the prime contractor, Airbus DS - Stevenage, is building LISA Pathfinder. Airbus DS – Friedrichshafen is the payload architect for the LISA Technology Package (LTP). The optical bench is provided by the University of Glasgow; the inertial sensors by CGS (Milan); and the mounting hardware and side walls by Airbus DS - Stevenage.