Thursday, December 6, 2018

Scaling Atomic Layer Deposition to Astronomical Optic Sizes

Here is a recent paper shared by Henrik Pedersen on twitter using a cool rather huge ALD machine for coating  covered here earlier (LINK) during its start up at University of California, Santa Cruz. The reactor with a 1 m wide ALD process chamber that has been designed and built by Structured Material Industries Inc. (LINK). It is large enough to accommodate telescope mirrors that has been refurbished with a silver coating that needs a perfect protective ALD coating. The initial test shows that lateral thickness uniformity across a 0.9 m substrate is within 2.5% of the average film thickness, and simple steps to realize 1% uniformity have been identified for next growths.

Scaling Atomic Layer Deposition to Astronomical Optic Sizes: Low-Temperature Aluminum Oxide in a Meter-Sized Chamber
David M. Fryauf, Andrew C. Phillips, Michael J. Bolte, Aaron Feldman, Gary S. Tompa, and Nobuhiko P. Kobayashi
ACS Appl. Mater. Interfaces, 2018, 10 (48), pp 41678–41689
DOI: 10.1021/acsami.8b10457
Publication Date (Web): November 12, 2018

 
Left: The summit of Mauna Kea is considered one of the world's most important astronomical viewing sites. The twin Keck telescopes are among the largest optical/near-infrared instruments currently in use around the world. Middle: The night sky and Keck Observatory laser for adaptive optics. Right: W. M. Keck Observatory at sunset (Wikipedia)