Demonstration of high-performance cryogenic probe arms for deployable IFUs

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.