Low-Stress Silicon Cladding for Surface Finishing Large UVOIR Mirrors

Award Information
Agency:
National Aeronautics and Space Administration
Branch
n/a
Amount:
$123,161.00
Award Year:
2013
Program:
SBIR
Phase:
Phase I
Contract:
NNX13CP28P
Award Id:
n/a
Agency Tracking Number:
125536
Solicitation Year:
2012
Solicitation Topic Code:
S2.03
Solicitation Number:
n/a
Small Business Information
CA, Encinitas, CA, 92024-4607
Hubzone Owned:
N
Minority Owned:
N
Woman Owned:
N
Duns:
969332829
Principal Investigator:
DavidSheikh
Principal Investigator
(858) 342-7515
dsheikh@zecoat.com
Business Contact:
DavidSheikh
Business Official
(858) 342-7515
dsheikh@zecoat.com
Research Institute:
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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