The Large Lenslet Array Magellan Spectrograph
A 2400-element fiber-optic hyperspectral imager constructed at the MIT Kavli Institute for Astrophysics and Space Research
Instrument Overview
LLAMAS is a facility-class optical Integral Field Unit (IFU) spectrometer designed for the Magellan Baade telescope. It features a lithographic lenslet array that slices the telescope focal plane into 2400 spatial elements with ~91% fill factor, and feeds starlight into a matrix of corresponding optical fibers. These honeycomb-packed elements cover a 35″ x 35″ square field of view with 0.75″ spacing pitch. The fibers are routed to a spectrograph bank approximately 10 meters from the focal plane, where their light is dispersed into spectra covering 3400 angstroms to 1 micron at spectral resolution R=1500-2500 (wavelength dependent). LLAMAS is slated for first-light in November 2024, and will be available for limited shared-risk observations in 2025A.
LLAMAS is made possible by generous support from the US National Science Foundation, via the Mid-Scale Instrumentation Program (MSIP) award number AST-1836002. The LLAMAS team is also grateful for support from the MIT Kavli Institute, Department of Physics, and School of Science, and the North Carolina State University Department of Physics and Astronomy.
Status
LLAMAS is in the final stage of laboratory integration at MIT, with a tentative ship date of October 2, 2024. The team will travel to Magellan to receive the shipment in mid-October, and install on the folded port in mid-November. The first night of commissioning observations is tentatively scheduled for November 25. Investigators interested in using LLAMAS should refer to the Proposers page for more information about use in 2025A and beyond.
Instrument Subsystems
The Integral Field Unit
How LLAMAS slices the Magellan Telescope’s focus into spectral core samples
The LLAMAS Spectrographs
How each fiber image is dispersed into a spectrum covering the full optical bandpass
Software and Controls
How to control a 2-ton precision optical assembly suspended from a moving telescope structure
Latest News
LLAMAS passes pre-ship review
On August 30, the team presented results from laboratory integration and test activities to the required Magellan external pre-ship review committee. We were given a punch list of tasks to complete before LLAMAS leaves MIT, and our team has worked through these toward an approved ship date of October 2, and installing LLAMAS on Magellan in mid-November. Here we see the LLAMAS project architect installing a fiber slit onto one of the eight spectrographs. The fibers are contained in black protective tubes resembling cables, that are routed off to the left of the image.
Micro-lens array is bonded to the fiber array
The final step in assembling the IFU is bonding the micro-lens array in precision alignment to the array of fiber ends. This is achieved using a combination of metrology markings etched into the glass plates, along with holes that were “match drilled” between the plates and mechanically aligned using a fused silica fiber. The alignment achieved a tilt/defocus of < 4 microns across the field of view, and alignment of fiber-to-lens of 1-2 microns, about 1% of the fiber diameter. This image shows the final IFU optical assembly (upward facing circle at left) with the coupled fiber bundle. Once this assembly is boxed and shipped, the fibers will be protected and (hopefully) never serviced again. Ready to pack up and ship!