Cryogenic Robotics Technology
MIRADAS relies on cryogenic robotic arms to select targets and relay their light into the rest of the instrument. This is accomplished using up to 20-independently-controlled/actuated “pick-off” probe arms.
The Consortium makes use of the cryogenic expertise of UF and, in collaboration with UB and AVS, will design and build these novel-technology probes. The first fully cryogenic prototypes were developed in 2012 and show <30-micron RMS position repeatability.
Probe Arm Optics
A view of the MXS probe mechanism. The 20 probe arms each patrol an 18-degree “slice of pie” region just above this focal plane, relaying light to an output focal plane in a pseudo-longslit. A pickoff mirror located near the telescope focal plane relays light down the probe arm, where it encounters a collimating doublet lens. The lens feeds light through a series of folds in the probe mechanism, which maintain a fixed optical path length while the probe arm is moved to variable target locations in the field of regard.
The MIRADAS electrical systems include: mechanism control, detector control electronics, detector and accessories, wiring, and housekeeping electronics (i.e. thermal control, pressure monitors, etc.).
Our baseline detector array control system is the Teledyne SIDECAR controller with SAM interface. This system provides cryogenic clocking and digitization of signals from the HAWAII-2RG HgCdTe detector mosaic in MIRADAS, and interfaces via Linux software to the primary control system of MIRADAS and GTC.
The MIRADAS design uses what are effectively 3 serial focal plane relay systems, The first relay is a MXS probe relay, which relays light from near the GTC focal plane through a collimating doublet and cold pupil stop into a re-imaging doublet. This relay ends with a set of “beam-combiner” fold mirrors that arrange the output probe foci in a pseudo-longslit at a common focal plane.
The second relay is the macro-slicer Integral Field Unit, which takes the 2-dimensional fields of view from the MXS probe arm pseudo-long-slit and optically re-formats it into another pseudo-longslit image. This is accomplished using monolithic diamond-turned aluminum mirror arrays.
The third and final relay is the spectrograph module, which takes the pseudo-longslit, forms a pupil image on an echelle grating followed by selectable cross-dispersion gratings, and then images the resulting spectrum onto the science detector array.