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Free keywords:
Astrophysics, Instrumentation and Methods for Astrophysics, astro-ph.IM, Physics, Instrumentation and Detectors, physics.ins-det, Physics, Optics, physics.optics
Abstract:
The Laser Interferometer Space Antenna (LISA) is a future space-based
interferometric gravitational-wave detector consisting of three spacecraft in a
triangular configuration. The interferometric measurements of path length
changes between satellites will be performed on optical benches in the
satellites. Angular misalignments of the interfering beams couple into the
length measurement and represent a significant noise source. Imaging systems
will be used to reduce this tilt-to-length coupling.
We designed and constructed an optical test bed to experimentally investigate
tilt-to-length coupling. It consists of two separate structures, a minimal
optical bench and a telescope simulator. The minimal optical bench comprises
the science interferometer where the local laser is interfered with light from
a remote spacecraft. In our experiment, a simulated version of this received
beam is generated on the telescope simulator. The telescope simulator provides
a tilting beam, a reference interferometer and an additional static beam as a
phase reference. The tilting beam can either be a flat-top beam or a Gaussian
beam. We avoid tilt-to-length coupling in the reference interferometer by using
a small photo diode placed at an image of the beam rotation point. We show that
the test bed is operational with an initial measurement of tilt-to-length
coupling without imaging systems.
Furthermore, we show the design of two different imaging systems whose
performance will be investigated in future experiments.
