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Proceedings Paper

Verification program for a high-precision large cryogenic lens holder
Author(s): A. Boesz; F. Grupp; T. Leberle; A. Mottaghibonab; N. Geis; R. Bender
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Paper Abstract

For the Euclid mission a Pre-Development phase is implemented to prove feasibility of individual components of the system. The Near Infrared Spectrometer and Photometer (NISP) of EUCLID requires high precision and large lens holders (Ø170 mm) at cryogenic temperatures (120K - 150K). The four lenses of the optical system are made of different materials: fused silica, CaF2, and LF5G15 that are mounted in a separate lens barrel design. Each lens has its separate mechanical interface to the lens barrel, the so called adaption ring. The performance of the lens holder design shall be verified by an adapted test facility including an optical metrology system. The characterization of the lens deformation and displacement due to thermally induced loads are driven by the required micrometer precision range and by the operational thermal condition. The surface deformation of the lens and its holder is verified by interferometric measurements, while tilt and position accuracy are measured by fiber based distance sensors. The applied distance measurement sensors have the capability to measure in a few mm range with submicron resolution at ultra high vacuum, in vibration environments and at liquid nitrogen temperatures and below. The calibration of the measurement system is of crucial importance; therefore the sensors shall be mounted on a stiff and well characterized reference structure made of nearly zero-CTE ceramic material. The verification program is currently under development at Kayser-Threde in the context of a contract with Max-Planck-Institute for Extraterrestrial Physics. The paper presents the vacuum chamber design, the metrology system, the used Ground Support Equipment, and the detailed verification program.

Paper Details

Date Published: 27 September 2011
PDF: 12 pages
Proc. SPIE 8126, Optical Manufacturing and Testing IX, 81261C (27 September 2011); doi: 10.1117/12.893621
Show Author Affiliations
A. Boesz, Kayser-Threde GmbH (Germany)
F. Grupp, Max-Planck-Institut für extraterrestrische Physik (Germany)
Univ.-Sternwarte München (Germany)
T. Leberle, Kayser-Threde GmbH (Germany)
A. Mottaghibonab, Kayser-Threde GmbH (Germany)
N. Geis, Max-Planck-Institut für extraterrestrische Phyisk (Germany)
R. Bender, Max-Planck-Institut für extraterrestrische Physik (Germany)
Univ.-Sternwarte München (Germany)

Published in SPIE Proceedings Vol. 8126:
Optical Manufacturing and Testing IX
James H. Burge; Oliver W. Fähnle; Ray Williamson, Editor(s)

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