TY - CHAP A1 - Sauvage, Marc A1 - Amiaux, Jérome A1 - Austin, James A1 - Bello, Mara A1 - Bianucci, Giovanni A1 - Chesné, Simon A1 - Citterio, Oberto A1 - Collette, Christophe A1 - Correia, Sébastien A1 - Durand, Gilles A. A1 - Molinari, Sergio A1 - Pareschi, Giovanni A1 - Penfornis, Yann A1 - Sironi, Giorgia A1 - Valsecchi, Guiseppe A1 - Verpoort, Sven A1 - Wittrock, Ulrich T1 - A development roadmap for critical technologies needed for TALC: a deployable 20m annular space telescope T2 - Space Telescopes and Instrumentation 2016: Optical, Infrared, and Millimeter Wave, Proc. SPIE N2 - Astronomy is driven by the quest for higher sensitivity and improved angular resolution in order to detect fainter or smaller objects. The far-infrared to submillimeter domain is a unique probe of the cold and obscured Universe, harboring for instance the precious signatures of key elements such as water. Space observations are mandatory given the blocking effect of our atmosphere. However the methods we have relied on so far to develop increasingly larger telescopes are now reaching a hard limit, with the JWST illustrating this in more than one way (e.g. it will be launched by one of the most powerful rocket, it requires the largest existing facility on Earth to be qualified). With the Thinned Aperture Light Collector (TALC) project, a concept of a deployable 20 m annular telescope, we propose to break out of this deadlock by developing novel technologies for space telescopes, which are disruptive in three aspects: • An innovative deployable mirror whose topology, based on stacking rather than folding, leads to an optimum ratio of collecting area over volume, and creates a telescope with an eight times larger collecting area and three times higher angular resolution compared to JWST from the same pre-deployed volume; • An ultra-light weight segmented primary mirror, based on electrodeposited Nickel, Composite and Honeycomb stacks, built with a replica process to control costs and mitigate the industrial risks; • An active optics control layer based on piezo-electric layers incorporated into the mirror rear shell allowing control of the shape by internal stress rather than by reaction on a structure. We present in this paper the roadmap we have built to bring these three disruptive technologies to technology readiness level 3. We will achieve this goal through design and realization of representative elements: segments of mirrors for optical quality verification, active optics implemented on representative mirror stacks to characterize the shape correction capabilities, and mechanical models for validation of the deployment concept. Accompanying these developments, a strong system activity will ensure that the ultimate goal of having an integrated system can be met, especially in terms of (a) scalability toward a larger structure, and (b) verification philosophy. Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-9248 VL - 9904 SP - 99041L ER - TY - CHAP A1 - Verpoort, Sven A1 - Rausch, Peter A1 - Wittrock, Ulrich T1 - Novel unimorph deformable mirror for space applications T2 - International Conference on Space Optics (ICSO), Proc. SPIE N2 - We have developed a new type of unimorph deformable mirror, designed to correct for low-order Zernike modes. The mirror has a clear optical aperture of 50 mm combined with large peak-to-valley Zernike amplitudes of up to 35 μm. Newly developed fabrication processes allow the use of prefabricated super-polished and coated glass substrates. The mirror's unique features suggest the use in several stronomical applications like the precompensation of atmospheric aberrations seen by laser beacons and the use in woofer-tweeter systems. Additionally, the design enables an efficient correction of the inevitable wavefront error imposed by the floppy structure of primary mirrors in future large space-based telescopes. We have modeled the mirror by using analytical as well as finite element models. We will present design, key features and manufacturing steps of the deformable mirror. Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-6516 UR - https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10564/1056414/Novel-unimorph-deformable-mirror-for-space-applications/10.1117/12.2309089.full VL - 10564 SP - 1056414-1 PB - SPIE ER - TY - CHAP A1 - Verpoort, Sven A1 - Welp, Petra A1 - Wittrock, Ulrich T1 - Novel unimorph deformable mirror for solid state laser resonators T2 - MEMS Adaptive Optics III, Proc. SPIE N2 - We present a novel unimorph deformable mirror with a diameter of only 10 mm that will be used in adaptive resonators of high power solid state lasers. The relationship between applied voltage and deformation of a unimorph mirror depends on the piezoelectric material properties, layer thicknesses, boundary conditions, and the electrode pattern. An analytical equation for the deflection of the piezoelectric unimorph structure is derived, based on the electro-elastic and thin plate theory. The validity of the proposed analytical model has been proven by numerical finite-element modelling and experimental results. Our mirror design has been optimized to obtain the highest possible stroke and a high resonance frequency. Y1 - 2009 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-6504 VL - 72090N PB - SPIE ER - TY - CHAP A1 - Verpoort, Sven A1 - Wittrock, Ulrich T1 - Deformable mirrors for high power lasers T2 - Proceedings of the 8th International Workshop on Adaptive Optics for Industry and Medicine (AOIM) N2 - It has been shown that the beam quality and the efficiency of high-power solid-state lasers could be enhanced by the use of deformable mirrors in order to compensate for optical aberrations. An intracavity compensation requires a deformable mirror which is capable of handling very high laser intensities. The active diameter of the deformable mirror should be a few millimeters in order to match typical fundamental mode laser beam diameters. There is a wide variety of commercially available deformable mirrors, but neither meets all requirements. KW - Deformable mirror, adaptive mirror, unimorph mirror, high-power laser Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-106953 UR - http://congresos.um.es/aoim/aoim2011/schedConf/presentations ER - TY - CHAP A1 - Verpoort, Sven A1 - Wittrock, Ulrich T1 - Novel unimorph deformable mirror with monolithic tip-tilt functionality for solid state lasers T2 - MEMS Adaptive Optics V, Proc. SPIE N2 - We present a new type of unimorph deformable mirror with monolithic tip-tilt functionality. The tip-tilt actuation is based on a spiral arm design. The mirror will be used in high-power laser resonators for real-time intracavity phase control. The additional tip-tilt correction with a stroke up to 6 μm simplifies the resonator alignment significantly. The mirror is optimized for a laser beam footprint of about 10 mm. We have modeled and optimized this mirror by finite element calculations and we will present design criteria and tradeoffs for this mirrors. The mirror is manufactured from a super-polished glass substrate with very low surface scattering and excellent dielectric coating. Y1 - 2011 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-6471 VL - 7931 SP - 793107 PB - SPIE ER - TY - CHAP A1 - Verpoort, Sven A1 - Wittrock, Ulrich T1 - Unimorph deformable mirror for telescopes and laser applications in space T2 - International Conference on Space Optics (ICSO), Rhodes Island, Greece N2 - Over the past 5 years we have developed a new type of unimorph deformable mirror. The main advantages of this mirror technology are · very low surface scattering due to the use of superpolished glass · excellent coatings, even suitable for high power lasers, can be applied · active diameter of the mirrors can be between 10 mm and 100 mm · large strokes can be achieved even for small mirror diameters · integrated monolithic tip/tilt functionality based on a spiral arm design We have modeled these mirrors by analytical models as well as by the finite element method. This allows us to quickly design new mirrors tailored to specific applications. One example is a mirror for laser applications that has a diameter of 10 mm and can achieve a stroke in defocus mode of 5 μm. The stroke for these mirrors scales as the square of the mirror diameter, meaning that we can achieve, for example, a stroke of 125 μm for a mirror of 50 mm diameter. We will present design criteria and tradeoffs for these mirrors. We characterize our mirrors by the maximum stroke they can deliver for various Zernike modes, under the boundary condition that the Zernike mode has to be created with a certain fidelity, usually defined by the Maréchal criterion. Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-6484 UR - www.icsoproceedings.org PB - SPIE ER - TY - CHAP A1 - Vorholt, Christian A1 - Wittrock, Ulrich T1 - Wavelength control by angle-tuning of the laser radiation in an intra-cavity pumped Yb:YAG thin-disk laser T2 - Advanced Solid State Lasers (ASSL), paper AM5A.39 N2 - In an intra-cavity pumped thin-disk laser the pump radiation forms a standing wave pattern inside the intra-cavity pumped disk.We demonstrate experimentally that the grating period of the standing wave pattern of the pump radiation can control the laser wavelength. Y1 - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-8298 UR - https://www.osapublishing.org/abstract.cfm?uri=ASSL-2015-AM5A.39 ER - TY - CHAP A1 - Wittrock, Ulrich A1 - Welp, Petra T1 - Adaptive laser resonator control with deformable MOEMS mirrors T2 - MEMS/MOEMS Components and Their Applications III, Proc. SPIE N2 - Adaptive laser resonators with deformable MOEMS mirrors under closed-loop control are discussed and experimental results are presented. The requirements for deformable mirrors and for closed-loop control systems of these mirrors are analyzed. Several deformable mirrors have been characterized and the results are presented. Currently available membrane mirrors deform under laser load and need further development before they can be used for aberration correction of solid state lasers above some tens of Watts. Nevertheless, the results are encouraging and the requirements are within reach of currently available technology. Finally, we demonstrate an Nd.YVO4-laser with a closed-loop adaptive resonator and more than 6 W of output power. The closed-loop system was able to compensate artificially introduced aberrations from a phase plate. Y1 - 2006 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:hbz:836-opus-6537 VL - 6113 SP - 61130C PB - SPIE ER -