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Proceedings Paper

DIPSI: the diffraction image phase sensing instrument for APE
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Paper Abstract

Large segmented mirrors require efficient co-phasing techniques in order to avoid the image degradation due to segments misalignment. For this purpose in the last few years new co-phasing techniques have been developed in collaboration with several European institutes. The Active Phasing Experiment (APE) will be a technical instrument aimed at testing different phasing techniques for an Extremely Large Telescope (ELT). A mirror composed of 61 hexagonal segments will be conjugated to the primary mirror of the VLT (Very Large Telescope). Each segment can be moved in piston, tip and tilt. Three new types of co-phasing sensors dedicated to the measurement of segmentation errors will be tested, evaluated and compared: ZEUS (Zernike Unit for Segment phasing) developed by LAM and IAC, PYPS (PYramid Phase Sensor) developed by INAF/ARCETRI, and DIPSI (Diffraction Image Phase Sensing Instrument) developed by IAC, GRANTECAN and LAM. This experiment will first run in the laboratory with point-like polychromatic sources and a turbulence generator. In a second step, it will be mounted at the Nasmyth platform focus of a VLT unit telescope. This paper describes the scientific concept of DIPSI, its optomechanical design, the signal analysis to retrieve segment piston and tip-tilt, the multiwavelength algorithm to increase the capture range, and the multiple segmentation case, including both simulation and laboratory tests results.

Paper Details

Date Published: 26 June 2006
PDF: 11 pages
Proc. SPIE 6267, Ground-based and Airborne Telescopes, 626732 (26 June 2006); doi: 10.1117/12.671070
Show Author Affiliations
Luzma Montoya-Martínez, Instituto de Astrofísica de Canarias (Spain)
Marcos Reyes, Instituto de Astrofísica de Canarias (Spain)
Achim Schumacher, Gran Telescopio Canarias (Spain)
Elvio Hernández, Instituto de Astrofísica de Canarias (Spain)

Published in SPIE Proceedings Vol. 6267:
Ground-based and Airborne Telescopes
Larry M. Stepp, Editor(s)

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