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A newly developed mirror-mounting clip for Matisse.

Submitter: Martijn Zijlstra
Description: The MATISSE instrument will combine the four VLT UT beams to create a single pattern of interferometric fringes on the detector. The cold section, which operates at 38K, is being developed by NOVA-ASTRON and contains dozens of 40x40 mm Fused Silica folding mirrors. These fold about 24 meters of light-path into a volume no bigger than 0.2 m3.

Such mirrors are usually mounted using many parts (bolts, washers, springs, threaded inserts, special housings). This increases the risk of damage or malfunction, it requires tools, it can be expensive to produce, and in general it takes up a considerable amount of precious space.

NOVA-ASTRON has started a program to develop an alternative mounting that would accurately position these mirrors with minimum deformation, while being simple in use and design, being applicable in a cryogenic environment, lowering the risks and cost of manufacturing, assembly and integration (MAIT), and taking up a minimum amount of space. The result is a compact sheet-metal assembly of only three separate parts that snaps the mirror into its final position.

The image shows the final design which is based on the experience gained with the testing and use of the two previously designed prototypes. Yellow and red: leaf springs, black: optics, grey: clip, gold: main structure. At first glance it looks like a deceptively simple piece of kit. But "the Devil is in the Details", and much thought has gone into many small details at a scale of 0.1 mm to achieve proper functionality. Production of the clip assembly will start in the near future.

Copyright: NOVA-ASTRON
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