In situ aluminization of the MMT 6.5m primary mirror

Clark, Dusty; Kindred, W.; Williams, J. T.

doi:10.1117/12.672492

Cited by 5 publications

(3 citation statements)

References 54 publications

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“…Much of the design intent and early results of the MMTO coating system are described in the paper "In situ aluminization of the MMT 6.5m primary mirror" [1] . The 2010 coating illustrated some weaknesses in the system, and the coating process followed in 2016 was modified to address these issues.…”

Section: Coating System Descriptionmentioning

confidence: 99%

Re-aluminization of the 6.5m primary mirror at the MMT Observatory

Goble

Gibson

Porter

et al. 2018

Ground-Based and Airborne Telescopes VII

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The MMT Observatory (MMTO) initiated a series of coating process improvement projects after an issue with the coating system in 2010 resulted in blemishes on the 6.5m primary mirror coating. Formally started in 2013, these projects focused on four major tasks: 1) development of a software-based system to control the tungsten filament power sources, 2) characterization of an integrally wound tungsten and aluminum filament, 3) prevent stray molten aluminum droplets from contacting the isolation membrane separating the high and rough vacuum sections of the system, and 4) assemble a coating facility capable of performing full-scale system testing. The completion of these projects was realized with the successful re-aluminization of the MMTO primary mirror in 2016. With a focus on the implementation of the process improvements, the present state of the MMTO coating system is described along with data from the 2016 realuminization.

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Section: Coating System Descriptionmentioning

confidence: 99%

Re-aluminization of the 6.5m primary mirror at the MMT Observatory

Goble

Gibson

Porter

et al. 2018

Ground-Based and Airborne Telescopes VII

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show abstract

“…The coating process that was used through the 2010 re-coating is provided in Ref. 17. A more detailed paper describing the process is also available at https://www.mmto.org/MMTpapers/pdfs/tm/tm03-8.pdf.…”

Section: Primary Mirror Coatingmentioning

confidence: 99%

The 6.5-m MMT Telescope: status and plans for the future

et al. 2016

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The MMT Observatory, a joint venture of the Smithsonian Institution and the University of Arizona, operates the 6.5-m MMT telescope on the summit of Mount Hopkins approximately 45 miles south of Tucson, AZ. The upgraded telescope has been in routine operation for nearly fifteen years and, as such, is a very reliable and productive general purpose astronomical instrument. The telescope can be configured with one of three secondary mirrors that feed more than ten instruments at the Cassegrain focus. In this paper we provide an overview of the telescope, its current capabilities, and its performance. We will review the existing suite of instruments and their different modes of operation. We will describe some of the general operations challenges and strategies for the Observatory. Finally, we will discuss plans for the near-term future including technical upgrades, new instrumentation and routine queue operation of MMIRS and Binospec.

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“…The filaments are arranged in three concentric rings with the filaments electrically connected in ten arrays of twenty filaments each. All 200 filaments are heated simultaneously by applying voltage across to the filaments using voltage controlled direct current sources (commercially available welders) [2] .…”

Section: Introductionmentioning

confidence: 99%

Characterization of an integrally wound tungsten and aluminum filament for physical vapor deposition

Goble

Ortíz

2016

SPIE Proceedings

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As part of the effort to increase the reliability of the MMT Observatory (MMTO) 6.5m Primary Mirror Coating System, the specified filament has changed from a configuration in which the aluminum charge is hand wound around a tungsten filament to a configuration in which the aluminum is integrally wound with the tungsten at the time of filament manufacture. In the MMTO configuration, this filament consists of the three strands of tungsten wire and one strand of aluminum wire. In preparation of a full system test utilizing two hundred filaments fired simultaneously, an extensive testing program was undertaken to characterize these filaments using a four filament configuration in the MMTO small coating chamber (0.5m) and then a forty filament configuration in the University of Arizona Steward Observatory coating chamber (2m). The testing using the smaller coating chambers has shown these filaments provide very predicable coatings from test to test, and with the proper heating profile, these filaments greatly reduce the likelihood of aluminum drips. The initial filament design was modified during the course of testing by shortening the unwound filament length to closer match the aluminum load required in the MMTO coating chamber. This change increased the aluminum deposition rates without increasing the power delivered of the filament power supplies (commercial welders). Filament power levels measured at the vacuum chamber feedthroughs, currents, and deposition rates from multiple coating tests, including a full system test, are presented.

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In situ aluminization of the MMT 6.5m primary mirror

Abstract: On May 20, 2000

Cited by 5 publications

References 54 publications

Re-aluminization of the 6.5m primary mirror at the MMT Observatory

Re-aluminization of the 6.5m primary mirror at the MMT Observatory

The 6.5-m MMT Telescope: status and plans for the future

Characterization of an integrally wound tungsten and aluminum filament for physical vapor deposition

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