The MICADO first light imager for the ELT: eliminating vibrations and excessive earthquake-loads on specific subsystems
Ensuring earthquake resilience is paramount for the upcoming Extremely Large Telescope (ELT). Instruments positioned on the ELT's Nasmyth platform are anticipated to endure substantial seismic accelerations, peaking at 3.6g in specific scenarios. These instruments have to be designed not only to survive such events but also to only require minimal repairs for sustained optimal functionality. This paper presents our approach to mitigate the dynamic forces impacting the rotary platform. This platform hosts various critical components, including cryogenic control units and mosaic detector control systems, essential for the operation of MICADO in its mechanical de-rotating motion. Furthermore, this paper tackles the challenge of minimizing instrument-induced vibrations affecting the telescope's structure. Given that the ELT's optical system, composed of 798 segments, operates very similar to an interferometer, maintaining an extremely stable wavefront is crucial - a key insight learned from the Very Large Telescope Interferometer (VLTI). Our focus is on identifying potential sources of vibration within specific frequency ranges where the telescope demonstrates increased sensitivity. We will explore strategies for mitigating these vibrations to maintain a wavefront error below 50nm.