Cryogenic mechanical design of the Gemini South Adaptive Optics Imager (GSAOI)

摘要

The Research School of Astronomy and Astrophysics (RSAA) of the Australian National University (ANU) has designed and constructed The Gemini South Adaptive Optics Imager (GSAOI) that will be used with the Multi-Conjugate Adaptive Optics system on the Gemini South telescope in Chile. GSAOI contains three cryogenic mechanisms; two filter wheels and a utility wheel. An approach to the athermalization of cryogenic mechanisms is presented. The 280 mm diameter filter wheels are athermalized using bi-material conical bearing seats where the bearing preload is constant, irrespective of temperature. The lens mounting method is also described. Lenses up to 170 mm in diameter are mounted within precision cells such that radial clearances reduce to zero at operating temperature. The method used to derive the room-temperature lens and cell dimensions is described. Lenses are preloaded axially against conical seats using wave washers. This technique has been used successfully to mount lenses of ～100 mm diameter in the Gemini Near-infrared Integral Field Spectrograph (NIFS), also designed and constructed by RSAA.