Optical suppression of tilt-to-length coupling in the LISA long-arm interferometer

Chwalla, M. et al. (2020) Optical suppression of tilt-to-length coupling in the LISA long-arm interferometer. Physical Review Applied, 14(1), 014030. (doi: 10.1103/PhysRevApplied.14.014030)

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The arm length and the isolation in space enable the Laser Interferometer Space Antenna (LISA) to probe for signals unattainable on the ground, opening a window to the subhertz gravitational-wave universe. The coupling of unavoidable angular spacecraft jitter into the longitudinal displacement measurement, an effect known as tilt-to-length (TTL) coupling, is critical for realizing the required sensitivity of picometer / √ Hz . An ultrastable interferometer test bed has been developed in order to investigate this issue and validate mitigation strategies in a setup representative of LISA and in this paper it is operated in the long-arm interferometer configuration. The test bed is fitted with a flat-top beam generator to simulate the beam received by a LISA spacecraft. We demonstrate a reduction of TTL coupling between this flat-top beam and a Gaussian reference beam via the introduction of two- and four-lens imaging systems. TTL coupling factors below ± 25 μ m / rad for beam tilts within ± 300 μ rad are obtained by careful optimization of the system. Moreover, we show that the additional TTL coupling due to lateral-alignment errors of elements of the imaging system can be compensated by introducing lateral shifts of the detector and vice versa. These findings help validate the suitability of this noise-reduction technique for the LISA long-arm interferometer.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Robertson, Dr David and Ward, Professor Henry and Perreur-Lloyd, Mr Michael and Killow, Dr Christian
Authors: Chwalla, M., Danzmann, K., Dovale Álvarez, M., Esteban Delgado, J.J., Fernández Barranco, G., Fitzsimons, E., Gerberding, O., Heinzel, G., Killow, C.J., Lieser, M., Perreur-Lloyd, M., Robertson, D.I., Rohr, J.M., Schuster, S., Schwarze, T.S., Tröbs, M., Wanner, G., and Ward, H.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review Applied
Publisher:American Physical Society
ISSN (Online):2331-7019
Published Online:10 July 2020
Copyright Holders:Copyright © 2020 American Physical Society
First Published:First published in Physical Review Applied 14(1): 014030
Publisher Policy:Reproduced under a Creative Commons License
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