N121-087 TITLE: Infrared Transmitting Aspheric Window Optics

TECHNOLOGY AREAS: Materials/Processes

ACQUISITION PROGRAM: Free Electron laser INP and Airborne Fiber laser FNC

RESTRICTION ON PERFORMANCE BY FOREIGN CITIZENS (i.e., those holding non-U.S. Passports): This topic is "ITAR Restricted". The information and materials provided pursuant to or resulting from this topic are restricted under the International Traffic in Arms Regulations (ITAR), 22 CFR Parts 120 - 130, which control the export of defense-related material and services, including the export of sensitive technical data. Foreign Citizens may perform work under an award resulting from this topic only if they hold the "Permanent Resident Card", or are designated as "Protected Individuals" as defined by 8 U.S.C. 1324b(a)(3). If a proposal for this topic contains participation by a foreign citizen who is not in one of the above two categories, the proposal will be rejected.

OBJECTIVE: To develop infrared (IR) transmitting glass or ceramics, with good environmental durability, that can be molded or cast into domes and aspheric shapes using spin casting, sintering or other techniques. Perform complete characterization of the material, optimize the fabrication process, and fabricate a full-size hyper-hemispherical dome using this glass/ceramic for IR sensing applications.

DESCRIPTION: IR optics such as lenses, domes, and hyper-hemispherical domes (domes greater than 180o) are needed for military and commercial applications of IR sensing, thermal imaging and threat warning systems and high energy laser propagation. Traditional IR transmitting optics are manufactured by cutting and polishing glasses into the desired shape. This is a costly and lengthy process. Additionally, typical IR dome materials, such as ZnS and CaF2, are difficult to polish due to crystalline grain boundaries, are soft and prone to environmental degradation, and are difficult and expensive to form into hyper-hemispherical dome shapes.

The goal of this project is to develop improved IR glass or ceramics that can be molded at low cost by spin casting or sintering and which has good environmental durability. The advantage of spin casting is that the inner surface of the part remains pristine and highly smooth and should not require any additional polishing. Glass hardness should be greater than ZnS and CaF2 and have good transmission to 5 microns. Transmission into the visible is also desirable. In order to be used by optical designers, the glass properties including optical, mechanical, and thermal should be measured.

The ability to produce various shaped optical elements at low cost opens up new design possibilities such as wider field of view sensing for threat warning and conformal shapes for reduced aero drag. The Navy is interested in the free-electron-laser (FEL) as a ship self-defense weapon and airborne lasers for small boat and other target engagement. Based on these desires, there is a need for robust materials and low cost fabrication processes for IR for optical window components.

PHASE I: Develop a robust fabrication process for IR transmitting glass or ceramics having improved hardness and durability, and measure its optical, thermal and mechanical properties. Determine technical feasibility of spin casting or other technique by fabricating a small 3" reagent grade hyper-hemispherical dome.

PHASE II: Based upon the results from Phase 1, optimize the fabrication method including studying wall thickness as a function of spin casting parameters such as melt volume, spin time, temperature and speed. Fabricate a prototype mid-scale (6") IR asphere using this approach. Then, fabricate, polish and characterize a full scale (12" diameter) hyper-hemispherical dome.

PHASE III: Designs of IR optics and domes will be implemented for specific military requirements. Full-scale IR optics will be fabricated using the developed processes. The SBIR effort will be transitioned into a product that will enable the development and acquisition of low cost IR optics.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Commercial applications include aircraft threat warning systems, homeland security IR systems, and thermal imaging systems.

REFERENCES:
1. Harris, D.C., "Materials for Infrared Windows and Domes - Properties and Performance," SPIE Press, Bellingham, WA, 1999

2. "Progress toward an athermal HEL optical window", Billman, Kenneth W.; Tran, Danh C.; Levin, Ken H.; Daigneault, Steven M.; Edwards, Nathan J. Proceedings of the SPIE, Volume 5647, pp. 207-223 (2005)

KEYWORDS: IR domes; moldable IR glass; IR window materials; ceramic windows; free-electron-laser (FEL); IR asphere

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between November 9 and December 11, 2011, you may talk directly with the Topic Authors to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting December 12, 2011, when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (12.1 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 12.1 topic under which they are proposing.

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