Development of a monolithic flexure based tip/tilt cryo-mechanism to stabilize the pupil of METIS (Conference Presentation)

The Mid-infrared ELT Imager and Spectrograph (METIS) is one of the scientific instruments for the ELT. The Common Fore Optics (CFO) is the first set of optics and mechanisms within the cryogenic instrument. A key element of the CFO is the Pupil Stabilization Mechanism (PSM), a tip/tilt mirror used for periodic adjustments of the pupil alignment during observations. The design challenges for the PSM involved achieving the required stability, resolution, and a sufficient stroke range/hold power while operating within the stringent requirements of the CFO. The design development lead to a monolithic design and integrated flexures driven by actuators with an integrated closed loop optical encoder.