Beam misalignment causes visibility loss in fringe measurements made by long-baseline optical interferometers. An Automated Alignment System (AAS) has been designed for the Magdalena Ridge Observatory Interferometer (MROI) to keep the visibility loss associated with misalignment under ∼1%. Production versions of collimated reference light sources and precision beam alignment sensors for the AAS have recently been integrated into the first beamline of the MROI. This paper describes the lessons learned during their installation and provides results from their site acceptance tests.
KEYWORDS: Mirrors, Education and training, Beam path, Relays, Beam diameter, Telescopes, Optical components, Design, Beam combiners, Signal to noise ratio
The Magdalena Ridge Observatory Interferometer has been designed to deliver an unprecedented capability for model-independent imaging of faint astronomical targets. As a consequence, its design methodology has focused on optimizing the interferometric sensitivity of all of its opto-mechanical subsystems. We report here on initial testing of one of the MROI beam-trains, outlining the performance metrics utilized to characterize the elements of the optical train from the Unit Telescopes through to the MROI beam combiner tables, the tests performed on each subsystem, and how our results compare to the design error budget for the MROI. The impact of the tests on the initial sensitivity limit of the MROI are discussed.
The Beam Relay System at the Magdalena Ridge Observatory Interferometer, exposed to outdoor environmental conditions, includes 6-inch mirrors mounted on aluminum frames and steel platforms, equipped with piezoelectric motors and a laser/camera alignment system. This subsystem faces challenges with misalignments that disrupt observations, addressed by a proposed correction strategy. The system uses temperature sensor data around mirrors to predict and correct misalignments as a feedforward control system through calibrated motors, and incorporates a periodic closed-loop control system using light source and camera. Advanced predictive models refined over time using temperature, shear, and tilt data, aim to maintain beam stability within interferometric tolerances, ensuring optimal performance.
The Magdalena Ridge Observatory Interferometer is an ambitious project to build a 10 telescope long-baseline optical/near-infrared in the mountains about a one-hour drive outside of Socorro, NM. The project is being led by New Mexico Institute of Mining and Technology and being built in cooperation with our primary collaborators at the University of Cambridge. We are currently funded via a cooperative agreement with the Air Force Research Lab in Albuquerque, NM to demonstrate imaging capabilities on geosynchronous objects. We have recently installed the second full beamline for the interferometer system and are working our way towards first fringes on an ~8m baseline later this year. In this manuscript, we report on the status of each of the subsystems, the installation progress and challenges to date, and on the ramp-up to measurements of first fringes. We also report on plans for early science and offer public shared-risk access with the facility in the near future.
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