We describe the design, development, and laboratory test results of cryogenic probe arms
feeding deployable integral field units (IFUs) for the Mid-resolution InfRAreD Astronomical
Spectrograph (MIRADAS) - a near-infrared multi-object echelle spectrograph for the 10.4-meter
Gran Telescopio Canarias. MIRADAS selects targets using 20 positionable pickoff mirror optics
on cryogenic probe arms, each feeding a 3.7x1.2-arcsec field of view to the spectrograph
integral field units, while maintaining excellent diffraction-limited image quality. The probe arms
are based on a concept developed for the ACES instrument for Gemini and IRMOS for TMT.
We report on the detailed design and opto-mechanical testing of MIRADAS prototype probe
arms, including positioning accuracy, repeatability, and reliability under fully cryogenic
operation, and their performance for MIRADAS. We also discuss potential applications of this
technology to future instruments.
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