Multi-Objective Diffraction-limited High-resolution Infrared Spectrograph (MODHIS)
Location: Mauna Kea, Hawaii
MODHIS
Instrument for TMT, focused on Exoplanet science – Transit and Direct Spectroscopy, Precision Radial Velocity to detect signatures of habitable planets
MODHIS
MODHIS is one of the first light instruments for the future Thirty Meter Telescope (TMT)
MODHIS is a diffraction-limited instrument under development for first-light operation of the Thirty Meter Telescope (TMT). MODHIS consists of a front-end instrument (FEI) fed by and coupled to the Narrow Field Infrared Adaptive Optics System (NFIRAOS), with a fiber delivery subsystem (FIB) linking to the spectrograph subsystem (SPEC) located in the TMT basement.
The light from the telescope is steered into the NFIRAOS adaptive optics system, which delivers the beam vertically into the MODHIS instrument. The on-instrument wavefront sensor (OIWFS) enclosure (part of the SRO sub-system) contains probe arms that pick off light from off-axis stars outside of the MODHIS field of view in laser guide star mode. The front-end instrument (FEI) couples the light into one of the single-mode fibers in the fiber bundle, which is one piece of the FIB subsystem and maintains the alignment throughout the observation. The FIB routes the coupled light to the blue and red spectrographs (BSPEC and RSPEC, respectively). The calibration system (CAL) can optionally inject light from internal sources at several locations via fibers.
MODHIS is in development phase at Caltech (in collaboration with UCSD and UCLA). The instrument will go into Preliminary design phase in 2025.
Design Desciption
CAD rendering of Nasmyth subsystems that mount onto the top port of NFIRAOS, including the Structure, Rotator, and OIWFS (SRO) and Front End Instrument (FEI). SRO and FEI share a common thermal environment, which is also shared with NFIRAOS (held to -30C).
Design features
Fiber Injection Module
Primary Mirror on Internal Barrel
The radial thermal strain on the Aluminum mirror causes a change in the radius of curvature, resulting in defocus. Radial resistive heaters are incorporated to allow for this correction and achieve fine focus.
Focal Plane Assembly consists of field flattener and detector mount and 3 spider vanes all machined from a single piece.
The field flattener consists of a 3” fused silica filter, and two lenses (L1- ZnS and L2 – fused silica). One of the key design considerations is its radially compact footprint, to minimize the beam obstruction. This consideration drives several design decisions such the use of small (M2) fasteners, springs, and no radial flexures. Instead of locating features and pins, the coaxiality between the spider hub and field flattener is achieved using tight tolerances on the outer diameter of the mating section of field flattener (L1/L2 cell). The field flattener cell connects to the spider using 3 fasteners.
Most Recent
Cryoscope is in development and testing phase at Cahill Center of Astronomy and Astrophysics
Cryoscope mission
What is Cryoscope?
Cryoscope is a diffraction-limited, cryogenically cooled telescope for Antarctica. It will have 50 sq. deg. field-of-view and 1.2m aperture. Leveraging the dark Antarctic sky and minimizing telescope thermal emission, Cryoscope achieves unprecedented deep, wide, fast and red observations, matching and exceeding volumetric survey speeds from the Ultraviolet Explorer, Vera Rubin Observatory, and Nancy Grace Roman Space Telescope.
By providing coverage beyond wavelengths of 2microns, we aim to create the most comprehensive dynamic movie of the most obscured reaches of the Universe. Cryoscope will be a dedicated discovery engine for electromagnetic emission from coalescing compact binaries, Earth-like exoplanets orbiting cold stars, and multiple facets of time-domain, stellar and solar system science.
