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Advanced Vacuum Coating Solutions               Aerospace, Defense & Astronomy


 

 

 

 

Publications by David Sheikh



1. Sheikh, D., "Battery-powered thin film deposition process for coating telescope mirrors in space", SPIE Proceeding 9904-253, Edinburgh, Scotland, 2016 


Abstract: Aluminum films manufactured in the vacuum of space may increase the broadband reflectance response of a space telescope operating in the EUV (50-nm to 115-nm) by eliminating absorbing metal-fluorides and metal-oxides, which significantly reduce aluminum’s reflectance below 115-nm. Recent developments in battery technology allow small lithium batteries to rapidly discharge large amounts of energy. It is therefore conceivable to power an array of resistive evaporation filaments in a space environment, using a reasonable mass of batteries and other hardware. This paper presents modeling results for coating thickness as a function of position, for aluminum films made with a hexagonal array of battery-powered evaporation sources. The model is based on measured data from a single battery-powered evaporation source.


The full article is available for download on the SPIE Digital Library by clicking here.

2. Sheikh, D., "Improved silver mirror coating for ground and space-based astronomy", SPIE Proceeding 9912-114, Edinburgh, Scotland, 2016


Abstract: A durable, UV-enhanced, silver mirror coating has been developed by ZeCoat Corporation. The coating is highly reflective from 350-nm through the long IR, and durable in warm-humid environments on earth, as well as, high radiation environments in space. This paper presents polarized-angular reflectance data, as well as, average reflectance data before and after simulated space radiation exposure.


3. Sheikh, D.,"Low-stress silicon cladding made by pulsed-ion-assisted evaporation", SPIE Vol.9574, San Diego, CA, 2015

Abstract:A low-stress, polishable, silicon (Si) cladding process for lightweight mirrors is presented. The cladding process is based on the thermal evaporation of silicon in the presence of low-energy argon ions. The process utilizes an ion bombardment technique whereby the coating stress of a silicon film is manipulated periodically from compressive to tensile in order to achieve a low net stress for the complete layer. A Si cladding with little intrinsic stress is desirable to minimize bending that would otherwise distort the figure of very lightweight mirrors. The process has yielded silicon claddings up to 100-microns thick, with less than 85 MPa of compressive stress. This polishable Si cladding was specifically designed for silicon carbide mirror substrates, however, it is also suitable for graphite composite, beryllium, and aluminum mirror substrates, which may be difficult or impossible to polish to sufficient mirror quality without a specialized coating.
The full article is available on the SPIE Digital Library by clicking here.

4. D. Sheikh, S. Connell, R. Dummer, “Durable Silver Coating For Kepler Space Telescope Primary Mirror”, Space Telescopes and Instrumentation, 2008, SPIE Vol. 7010 (MarseilleFrance), doi:10.1117/12.789996.

5. Dan K. Markera, Brian Patrickb,  David A. Sheikhc, James Rotged, “Large Lightweight Optical Quality Windows and Filters”,  Advanced Wavefront Control: Methods, Devices, and Applications II, SPIE Vol. 5553 (SPIE, Bellingham, WA, 2004) 0277-786X/04/$15 · doi: 10.1117/12.562141,

6. Brian G. Patricka,, David Sheikhb, W. Thomas Robertsc “Solar filter for the Mars Laser Communication Demonstration Optical Receiver”, Free-Space Laser Communications IV, Proceedings of SPIE Vol. 5550-45 p. 336 (SPIE, BellinghamWA, 2004).

7. Eldon P. Kasl, Steven J. Connell, David A. Sheikh, “Recent Developments in Composite-Based Optics”, SPIE,Vol. 3356-45 p. 735, 1998.