MOONS recently took delivery of two of the largest optical components in the instrument: the main collimator mirrors for each spectrograph manufactured by KiwiStar Optics in New Zealand. Last week a team from Arcetri Observatory, Florence came to Edinburgh to install these two large optics within the not-insignificantly sized mounting structures that they had designed for them. This went extremely successfully and marks another milestone in the project’s growth.


An unmounted collimator mirror: 60kg of beautifully polished glass.


Each collimator will sit at the base of the optical bench, reshaping the beam emitted from the optical fibres. Since each spectrograph is imaging 500 fibres simultaneously, the beam is very large so these optical elements are over 500 mm in length and each weighs in at an impressive 60 kilograms of finely polished glass. As can be seen in the picture, the collimators sit in large brackets that support the optics at right angles to the optical bench. The mounts have the threefold challenge of providing precise alignment adjustments, holding the lenses safely even in the event of significant seismic activity and also allowing for the contraction of all the different components as they are cooled to 130K.

The Arcetri team with the collimators mirrors sitting in their optical mounts. The two white boards are covering the mirrors to provide protection from any contamination and show well the shape of the mirrors themselves.

Now that the collimator mirrors are mounted, one of the assemblies will be shipped to Cambridge University where it will be used in the alignment of the first camera.



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