Low-Stress Silicon Cladding for Surface Finishing Large UVOIR Mirrors

Award Information
Agency:
National Aeronautics and Space Administration
Amount:
$123,161.00
Program:
SBIR
Contract:
NNX13CP28P
Solitcitation Year:
2012
Solicitation Number:
N/A
Branch:
N/A
Award Year:
2013
Phase:
Phase I
Agency Tracking Number:
125536
Solicitation Topic Code:
S2.03
Small Business Information
ZeCoat Corporation
CA, Encinitas, CA, 92024-4607
Hubzone Owned:
N
Woman Owned:
N
Socially and Economically Disadvantaged:
N
Duns:
969332829
Principal Investigator
 David Sheikh
 Principal Investigator
 (858) 342-7515
 dsheikh@zecoat.com
Business Contact
 David Sheikh
Title: Business Official
Phone: (858) 342-7515
Email: dsheikh@zecoat.com
Research Institution
 Stub
Abstract
In this Phase I research, ZeCoat Corporation will develop an affordable, low-stress silicon cladding process which is super-polishable for large UVOIR mirrors. The proposed ion-assisted evaporation process is directly scaleable to SiC mirrors several meters in diameter. The process is based on a novel, low temperature, ion-assisted, evaporation technique (IAD), whereby the coating stress of a silicon film may be manipulated from compressive to tensile, in order to produce a near-zero net stress for the complete layer. A cladding with little intrinsic stress is essential to minimize bending that would otherwise distort the figure of very lightweight mirrors.Current methods to produce a polishable silicon cladding utilize CVD processes that produce highly stressed Si coatings. The current processes require high-temperatures (hundreds of degrees Celsius) and are not readily scaleable to large mirrors. CVD Si cladding is currently limited to mirror substrates less than 1-meter in diameter. The proposed IAD process produces little heat, and the mirror size is limited only by the size of the vacuum chamber.Large silicon carbide (SiC) mirrors (3-4 meters in diameter) are being considered for future space-based UVOIR astronomy missions. These lightweight mirrors will likely require a highly-polishable layer of silicon (10 to 50 microns) applied on top of the SiC. A relatively thick layer of Si is desirable for the purpose of reducing figuring time and for achieving a super-polished surface, suitable for UV astronomy.Normal incidence 4-meter class UVOIR telescopes have been cited as a high priority by multiple government review panels including; the National Research Council's (NRC) study of NASA's Space Technology Roadmap and Priorities, The Office of the Chief Technologist, The Cosmic Origins Program and NWNH Decadal.

* information listed above is at the time of submission.

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