SAMOP 2023 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 62: Precision Measurements: Gravity II
Q 62.8: Vortrag
Freitag, 10. März 2023, 12:45–13:00, E214
Laser Welding the 100 g Mirrors for the AEI 10 m Prototype Suspensions with Micrometer Precision — •Juliane von Wrangel1,2, Steffen Böhme3, Matteo Carlassara1,2, Gerd Harnisch3, Firoz Khan1,2, Philip Koch1,2, Tobias Koch3, Johannes Lehmann1,2, Harald Lück1,2, Janis Wöhler1,2, and David S. Wu1,2 — 1Leibniz Universität Hannover — 2Max-Planck-Institut für Gravitationsphysik, Hannover — 3Fraunhofer-Institut für Angewandte Optik und Feinmechanik, Jena
The 10 m Prototype facility of the Albert-Einstein-Institute Hannover will measure and surpass the Standard Quantum Limit (SQL) by constructing the Sub-SQL Interferometer in a gravitational wave detector (GWD) like configuration. Compared to a full scale GWD, the 100 g test mass mirrors are relatively lightweight to enhance the quantum radiation pressure noise. To isolate these mirrors seismically, they are designed as triple suspensions. The last pendulum stage is quasi-monolithic to suppress suspension thermal noise. This final stage consists of four 20 um thin glass fibers laser welded to each of the mirrors. The welding procedure needs to be done with micrometer precision due to the small dimensions of the layout to ensure the suspended mirrors to be straight within a pitch angle of < 10 mrad.
In cooperation with the Fraunhofer Institute for Applied Optics and Precision Engineering in Jena, a semi-automated fiber welding machine was designed. For this setup, a CO2 laser is used to cleave and weld the glass fibers with the desired precision. In the future, this technique will also be applicable to other mirror suspensions of similar dimensions.