TY  - BOOK
ED  - Wittrock, Ulrich
T1  - Adaptive optics for industry and medicine. Proceedings of the 4th International Workshop on Adaptive Optics for Industry and Medicine
Y1  - 2005
UR  - https://www.springer.com/de/book/9783540239789
SN  - 3-540-23978-2
PB  - Springer
CY  - Berlin
ER  - 
TY  - CHAP
A1  - Verpoort, Sven
A1  - Wittrock, Ulrich
T1  - Miniaturized adaptive mirror for solid state laser resonators
T2  - Proceedings of the 7th International Workshop on Adaptive Optics for Industry and Medicine, Shatura, Russia
Y1  - 2009
ER  - 
TY  - JOUR
A1  - Wittrock, Ulrich
T1  - Laryngeally echolocating bats (Brief Communication Arising)
JF  - Nature
Y1  - 2010
U6  - http://dx.doi.org/10.1038/nature09156
VL  - 466
SP  - E6
ER  - 
TY  - JOUR
ED  - Wittrock, Ulrich
ED  - Kynast, Ulrich
ED  - Jüstel, Thomas
ED  - Bredol, Michael
T1  - 6th Laser Ceramics Symposium
T2  - Opt. Mat.
Y1  - 2012
UR  - https://www.sciencedirect.com/journal/optical-materials/vol/34/issue/6
VL  - 34
SP  - 935
EP  - 1002
PB  - Elsevier B.V.
ER  - 
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  - JOUR
A1  - Verpoort, Sven
A1  - Bittner, Matthias
A1  - Wittrock, Ulrich
T1  - Fast focus-shifter based on a unimorph deformable mirror
JF  - Applied Optics
N2  - On-the-fly remote laser processing plays an increasingly important role in modern fabrication techniques. These processes require guiding of the focus of a laser beam along the contours of the workpiece in three dimensions.
State-of-the-art galvanometer scanners already provide highly dynamic and precise transverse x−y beam steering. However, longitudinal focus shifting (“z-shifting”) relying on conventional optics is restricted to a bandwidth of a few hundred Hz. We have developed and manufactured a fast piezo-based z-shifting mirror with diffraction-limited surface fidelity providing a focus shift of 1z> 60 mm with an actuation rate of 2 kHz.
KW  - beam steering
KW  - deformable mirrors
KW  - optical components
KW  - laser machining
KW  - laser materials processing
Y1  - 2020
UR  - https://www.osapublishing.org/ao/abstract.cfm?uri=ao-59-23-6959
U6  - http://dx.doi.org/10.1364/AO.397495
SN  - 1559-128X
VL  - 59
IS  - 23
SP  - 6959
EP  - 6965
ER  - 
TY  - JOUR
A1  - Kazasidis, Orestis
A1  - Verpoort, Sven
A1  - Wittrock, Ulrich
T1  - Sensor for dynamic focus control of a deformable mirror
JF  - Appl. Opt.
N2  - We recently presented a novel unimorph deformable mirror which allows for dynamic focus shift with an actuation rate of 2 kHz. Such mirrors suffer from hysteresis and creep. Therefore, they have to be operated in closed-loop. For this purpose, we developed a defocus sensor based on an astigmatic detection system. In this paper, we present the sensor design and discuss its performance.
KW  - deformable mirrors
KW  - diode lasers
KW  - laser beams
KW  - laser machining
KW  - sensor performance
Y1  - 2020
UR  - https://www.osapublishing.org/ao/abstract.cfm?uri=ao-59-18-5625
U6  - http://dx.doi.org/10.1364/AO.392970
IS  - 59
SP  - 5625
EP  - 5630
ER  - 
TY  - JOUR
A1  - Pues, Patrick
A1  - Laube, Michael
A1  - Fischer, Stefan
A1  - Schröder, Franziska
A1  - Schwung, Sebastian
A1  - Rytz, Daniel
A1  - Fiehler, Torben
A1  - Wittrock, Ulrich
A1  - Jüstel, Thomas
T1  - Luminescence and up-conversion of single crystalline Lu3Al5O12:Pr3+
JF  - Journal of Luminescence
N2  - This work deals with the spectroscopic properties of praseodymium doped single crystalline lutetium aluminum garnet (LuAG:Pr3+). A special focus was set on temperature- and time-dependent spectroscopy. Beyond the well-known down-conversion luminescence of LuAG:Pr3+, also UV-A/B up-conversion luminescence under excitation with a 488 nm laser was thoroughly investigated. Furthermore, the results of the spectroscopic investigations on the single crystalline material were supplemented and compared with measurements on a microscale powder sample.

In addition, to the spectroscopic investigations, mechanistic considerations are presented to obtain a closer look at the up-conversion process in LuAG:Pr3+. We promote the thesis of a temperature-dependent energy transfer up-conversion mechanism.
KW  - Pr3+ luminescence
KW  - Single crystal
KW  - Photoluminescence
KW  - Up-conversion
KW  - Temperature-dependent spectroscopy
Y1  - 2021
U6  - http://dx.doi.org/10.1016/j.jlumin.2021.117987
VL  - 234
SP  - 117987
EP  - 117995
ER  -