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The challenges met in the design of cryogenic instruments for infrared astronomy involve a certain level of uncertainty in the dynamic responses of mechanical components when going from warm to cold. These types of responses include differential contraction of unlike materials, slipping between contact surfaces, and the potential for warping of mechanical components depending on stresses inherently present in the material. This paper will go over the design and manufacturing principles practiced to mitigate these types of variables that would result in detriment to performance. The optics, mounts, and alignment features detailed in this paper are to be used for the Slicer Combined with an Array of Lenslets for Exoplanet Spectroscopy (SCALES) instrument, a 2-5 micron coronagraphic integral field spectrograph under construction for Keck Observatory.
Design principles, such as monolithic mount structures, a bolt-and-go approach to mounts, flexure designs for the optical substrates, cryogenic compatible alignment features, and the approach taken to athermalize a titanium tip/tilt stage present in the forward optics section will be explained in detail in this paper. Manufacturing principles and techniques are discussed in this paper concerning the types of tolerances and features called out along with machining conditions to meet the technical requirements of the SCALES instrument.
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