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Proceedings Paper • Open Access

Laser modulator for LISA pathfinder
Author(s): C. Voland; G. Lund; W. Coppoolse; P. Crosby; M. Stadler; K. Kudielka; C. Özkan

Paper Abstract

LISA Pathfinder is an ESA experiment to demonstrate the key technologies needed for the LISA mission to detect gravitational waves in space. The LISA Pathfinder spacecraft represents one arm of the LISA interferometer, containing an optical metrology system and two proof masses as inertial references for the drag-free control system.

The LISA Pathfinder payload consists of two drag-free floating test masses located in the inertial sensors with their control electronics and an optical metrology subsystem. The optical metrology subsystem monitors the movement of both test masses relative to each other and to the spacecraft with very high sensitivity and resolution. This is achieved with a heterodyne Mach- Zehnder interferometer. This interferometer requires as input two coherent laser beams with a heterodyne frequency difference of a few kHz.

To generate the two laser beams with a heterodyne frequency difference a Nd:YAG laser is used together with the Laser Modulator. The Nd:YAG laser generates a single coherent laser signal at a wavelength of 1064nm which is fibre coupled to the Laser Modulator. The Laser Modulator then generates the two optical beams with the required heterodyne frequency offset. In addition, the Laser Modulator is required to perform laser amplitude stabilization and optical path difference control for the two optical signals.

The Laser Modulator consists of an optical unit – the LMU – and RF synthesiser, power amplification and control electronics. These electronics are all housed in the Laser Modulator Electronics (LME).

The LMU has four primary functions:

• Splitting of the input laser beam into two paths for later superposition in the interferometer.

• Applying different frequency shifts to each of the beams.

• Providing amplitude modulation control to each of the beams.

• Providing active control of the optical path length difference between the two optical paths.

The present paper describes the design and performance of the LMU together with a summary of the results of the Laser Modulator engineering model test campaign.

Paper Details

Date Published: 21 November 2017
PDF: 8 pages
Proc. SPIE 10566, International Conference on Space Optics — ICSO 2008, 1056613 (21 November 2017); doi: 10.1117/12.2308194
Show Author Affiliations
C. Voland, Oerlikon Space AG (Switzerland)
G. Lund, Oerlikon Space AG (Switzerland)
W. Coppoolse, Oerlikon Space AG (Switzerland)
P. Crosby, Oerlikon Space AG (Switzerland)
M. Stadler, Oerlikon Space AG (Switzerland)
K. Kudielka, Oerlikon Space AG (Switzerland)
C. Özkan, Oerlikon Space AG (Switzerland)


Published in SPIE Proceedings Vol. 10566:
International Conference on Space Optics — ICSO 2008
Josiane Costeraste; Errico Armandillo; Nikos Karafolas, Editor(s)

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