N112-146 TITLE: Fabrication of Corrective Optics for Aerodynamic Domes

TECHNOLOGY AREAS: Materials/Processes, Weapons

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: Demonstrate the grinding, polishing, final finishing, and metrology of corrective infrared-transmitting optics for use with aerodynamic domes such as a tangent ogive.

DESCRIPTION: Infrared-transmitting domes with a shape such as a tangent ogive have the potential to reduce the drag of a missile. Decreased drag enables a combination of increased speed, range, and payload. An aerodynamic dome shape distorts the image of a scene viewed through the dome. It is envisioned that refractive corrector elements will be required between the dome and an infrared imaging seeker.

A corrector element for a tangent ogive dome could be a bilaterally symmetric arch with aspheric terms. Candidate materials include Cleartran® zinc sulfide, spinel, and chalcogenide glasses. For an ogive dome with a base diameter of 125 mm and a height of 175 mm, the arch might have a base dimension of approximately 100 mm and a height of 125 mm. Correctors can be modeled with splines, conics, even and odd ordered polynomial aspheres, superconic, Zernike polynomials, anamorphic aspheres, and toroids. Fabrication challenges include the need to transfer a design representation into a form that a computer numerically controlled machine can accurately create, and the need to grind, polish, and measure the physical form.

Designs for correctors to be fabricated will be provided by the Government at the time of contract awards. Proposals may address all the requirements of this solicitation or may address individual aspects of grinding, polishing, final finishing, and metrology of domes.

PHASE I: Demonstrate techniques of grinding, polishing, final finishing, and measuring a corrector element. Techniques should ultimately apply to a full arch, but, in Phase I, work may be done on a half arch terminated at the vertex of the arch. A material such as glass or fused silica with dimensions on the order of 50 x 125 mm would be suitable for this demonstration. A goal for optical figure is 0.5 wavelength peak-to-valley deviation at 633 nm over the entire clear aperture of the part. Plan a clear path to fabricate a full arch in Phase II.

PHASE II: Demonstrate grinding, polishing, final finishing and metrology of full-size corrector arches with designs provided by the Government. Steps should lead from glass or fused silica to infrared-transparent materials such as Cleartran®, spinel, or chalcogenide glass. The final optical figure should be within 0.5 wavelength peak-to-valley deviation at 633 nm over the entire clear aperture of the part.

PHASE III: Develop a commercial process capable of making corrective optics for aerodynamic domes and conformal windows with arbitrary shapes and optical figure similar to that of Phase II, but with areas on the order of 750 x 750 mm.

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Conformal windows with corrective optics could be used for synthetic vision systems on commercial aircraft. These windows could increase the pilot�s field of regard and might be used in locations that would not be suitable for flat windows.

REFERENCES:
1. P. A. Trotta, "Precision Conformal Optics Technology Program," Proc. SPIE 2001, Volume 4375, p. 96

2. D. J. Knapp, J.P. Mills, R. G. Hegg, P. A. Trotta, and C. B. Smith, "Conformal Optics Risk Reduction Demonstration," Proc. SPIE 2001, Volume 4375, p. 154.

KEYWORDS: corrector optics; optical fabrication; metrology; optical finishing; aerodynamic dome; infrared imager

** TOPIC AUTHOR (TPOC) **

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