Three telescope nuller based on multibeam injection into single-mode waveguide

Anders L. Karlsson; Oswald Wallner; Josep M. Perdigues Armengol; Olivier Absil

doi:10.1117/12.550307

20 October 2004 Three telescope nuller based on multibeam injection into single-mode waveguide

Anders L. Karlsson, Oswald Wallner, Josep M. Perdigues Armengol, Olivier Absil

Proceedings Volume 5491, New Frontiers in Stellar Interferometry; (2004) https://doi.org/10.1117/12.550307
Event: SPIE Astronomical Telescopes + Instrumentation, 2004, Glasgow, United Kingdom

Abstract

Nulling interferometry of exo-solar planets requires as a minimum two telescopes, of which one is phase shifted by 180 degrees, such that the on-axis stellar object is cancelled, while the light from the off-axis planet interferes constructively. Improvement of the nulling performance and the introduction of chopping leads to space interferometers of four or more telescopes and a separate spacecraft dedicated to beam recombination, as currently baselined for Darwin and TPF. It has recently been demonstrated that the stellar leaks mainly affects the integration times for near-by target stars [o,c]. Considering that there are only a few near-by targets and that the integrations times for each of these is short compared to that of distant stars, it appears advantageous to simplify the interferometer, by accepting higher levels of stellar leaks for near-by targets. A simple, chopping nulling interferometer can be obtained by adding one equal size telescope to the basic two telescope nulling interferometer. Modulation is obtained by applying time-varying phase-shifts to the beams before recombination, i.e. inherent modulation [d]. The recombination of 3 multi-axial beams is achieved by coupling into a single mode waveguide, leading to high modulation and coupling efficiencies, and a single focal plane [i]. Linear and circular telescope configurations are proposed and investigated, including a discussion on the need of a separate spacecraft for beam recombination. The associated transmission and modulation maps and efficiencies are calculated and discussed.

Citation Download Citation

Anders L. Karlsson, Oswald Wallner, Josep M. Perdigues Armengol, and Olivier Absil "Three telescope nuller based on multibeam injection into single-mode waveguide", Proc. SPIE 5491, New Frontiers in Stellar Interferometry, (20 October 2004); https://doi.org/10.1117/12.550307

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