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Field Lens

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The field lens transfers the telescope beam onto the fold mirrors which in turn pass the beam to the filters wheel and collimator lens. Below will be a photo of the field lens installed in the science instrument (once one has been taken). The field lens is a single component spherical lens made of ZnSe It is 138mm in diameter. The field lens reduces (?) the telescope beam f-ratio to Y.

Focal Plane Mask Wheel

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Beam-splitter Wheel

NIRI Optical Overview - Beam-splitter Wheel

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The NIRI beam-splitter wheel contains three beam-splitters to direct the science beam and OIWFS (On-instrument wavefront sensor) beam to the appropriate on-board instruments. The beam-splitters are flat mirrors of different sizes to allow the OIWFS beam for each camera, f/6, f/14 and f/32, to be picked off without modifying the science

Entrance Window

NIRI Optical Overview - Entrance Window
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Gemini Telescope

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On Gemini, science instruments are mounted at the cassegrain focus below the 8.2 meter primary mirror. The picture below shows a schematic of the telescope and specifically the bottom end where instruments are mounted. The f/16 telescope beam passes through the 1.18 meter diameter central primary hole, through the Acquisition &

OT Library

The Observing Tool libraries contain "pieces" of observations e.g. commonly used configurations, sequences, standard calibrations and ancillary information which may be copy-and-pasted into a new observation. The intent of these libraries is to speed the development of new science programs. As observing procedures and instrumental configurations may change from semester to semester (installation of new GCAL filters, for instance), it is advisable that PIs download the most recent libraries when defining new observations.