TY  - JOUR
A1  - Wittrock, Ulrich
T1  - Grenzen? Welche Grenzen? Prof. Ulrich Wittrock, Leiter des Labors für Photonik an der Fachhochschule Münster, fragt nach den ultimativen Grenzen der Lasertechnik
JF  - Laser Community - das Lasermagazin von Trumpf
Y1  - 2014
VL  - 02:14
ER  - 
TY  - JOUR
A1  - Wittrock, Ulrich
T1  - Limitations? What Limitations? Prof. Ulrich Wittrock, head of the Photonics Laboratory at the Münster University of Applied Sciences, seeks out the ultimate boundaries of laser technology
JF  - Laser Community - the laser magazine from Trumpf
Y1  - 2014
VL  - 02:14
ER  - 
TY  - CHAP
A1  - Rausch, Peter
A1  - Verpoort, Sven
A1  - Wittrock, Ulrich
T1  - Performance verification and environmental testing of a unimorph deformable mirror for space applications.
T2  - Proceedings of the 10th International Conference on Space Optics - ICSO, Tenerife, Spain
N2  - Concepts for future large space telescopes require an active optics system to mitigate aberrations caused by thermal deformation and gravitational release. Such a system would allow on-site correction of wave-front errors and ease the requirements for thermal and gravitational stability of the optical train. In the course of the ESA project "Development of Adaptive Deformable Mirrors for Space Instruments" we have developed a unimorph deformable mirror designed to correct for low-order aberrations and dedicated to be used in space environment. We briefly report on design and manufacturing of the deformable mirror and present results from performance verifications and environmental testing.
KW  - space optics
KW  - adaptive optics
KW  - deformable mirror
KW  - unimorph
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-7716
UR  - http://www.icsoproceedings.org
PB  - FH Münster
ER  - 
TY  - JOUR
A1  - Kazasidis, Orestis
A1  - Wittrock, Ulrich
T1  - Interferometric measurement of the temperature coefficient of the refractive index dn/dT and the coefficient of thermal expansion of Pr:YLF laser crystals
JF  - Opt. Expr.
N2  - We report interferometric measurements of the temperature coefficient of the refractive index (dn=dT) and the coefficient of thermal expansion (a) of a praseodymium-doped yttrium lithium fluoride (Pr:YLF) crystal and of a fused silica reference sample. Our phase-resolved interferometric method yields a large number of data points and thus allows a precise measurement and a good error estimation. Furthermore, both dn=dT and a are obtained simultaneously from a single measurement which reduces errors that can occur in separate measurements. Over the temperature range from 20 °C to 80 °C, the value of dn=dT of Pr:YLF decreases from -5.2 x 10-6 /K to -6.2 x 10-6 /K for the ordinary refractive index and from -7.6 x 10-6 /K to -8.6 x 10-6 /K for the extraordinary refractive index. The coefficient of thermal expansion for the a-axis of Pr:YLF increases from 16.4 x 10-6 /K to 17.8 x 10-6 /K over the same temperature range.
KW  - refractive index change
KW  - thermal expansion coefficient
KW  - laser crystal
KW  - praseodymium
KW  - yttrium lithium fluoride
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-7720
VL  - 22
SP  - 30683
EP  - 30696
PB  - Optical Society of America
ER  -