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Unimorph-type deformable mirror for cryogenic telescopes

: Reinlein, C.; Goy, M.; Lange, N.; Kinast, J.


Navarro, Ramón ; Society of Photo-Optical Instrumentation Engineers -SPIE-, Bellingham/Wash.:
Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation : Montréal, Quebec, Canada, 22.-27.6.2014
Bellingham, WA: SPIE, 2014 (Proceedings of SPIE 9151)
ISBN: 978-0-8194-9619-5
Paper 915104, 7 pp.
Conference "Advances in Optical and Mechanical Technologies for Telescopes and Instrumentation" <2014, Montréal>
Conference Paper
Fraunhofer IOF ()

Deformable mirrors can be used in cryogenic instruments to compensate for temperature-induced deformations. A unimorph-type deformable mirror consists of a mirror substrate and a piezoelectric layer bonded on substrates rear surface. A challenge in the design of the deformable mirror is the lack of knowledge about material properties. Therefore, we measured the coefficient of thermal expansion (CTE) of the substrate material TiAl6V4 between 295 K and 86 K. The manufactured mirror is characterized by an adaptive optical measurement setup in front of a test cryostat. The measured mirror deformations are feedback into a finite element model to calculate the CTE of the piezoelectric layer. We compare our obtained results to other published CTE-values for the piezoelectric material PIC151.