N112-144 TITLE: Low-Drag Infrared Dome

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: Produce a precisely figured, polished, ogive-shaped, infrared-transmitting dome from a durable optical material.

DESCRIPTION: Future high-speed missiles require aerodynamic infrared domes that reduce drag and have greater ability to withstand aerothermal heating. By exchanging a conventional hemispheric dome for a pointed dome, drag is reduced and aero heating is reduced on most of the surface of the dome. Decreased drag enables a combination of increased speed, range, and payload. The aerodynamic shape also increases the ability of the dome to fly through rain and particles in the atmosphere without damage.

In the past, infrared domes have had a hemispheric shape because this shape introduces minimal optical distortion and is easy to fabricate. The DARPA Conformal Optics program completed in 2000 demonstrated methods to correct distortions introduced by aerodynamic shapes. Several NAVAIR SBIR topics advanced the state of the art in fabrication and metrology of ogive domes made of infrared-transparent, polycrystalline alumina. To this point, aerodynamic domes meeting optical tolerances have not been produced.

This new SBIR topic builds on previous efforts and will produce optically precise, ogive-shaped domes from polycrystalline alumina or other durable materials. The dome will have an approximate tangent ogive shape with a base diameter near 125 mm, a height near 175 mm, and a wall thickness near 3 mm. Drawings will be provided by the Government during the contract. The desired root-mean-square transmitted wavefront error is less than one third of an optical wavelength measured at 0.633 mm. It is expected that contractors will consider using magnetorheological finishing techniques for final finishing. The tip of the ceramic dome will eventually be replaced by a more durable material and need not be optically finished. The ceramic dome material might be polycrystalline alumina or another hard ceramic selected in consultation with the Government.

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: Use the best available metrology and best available finishing methods to produce a precisely figured ogive dome made of BK7 glass or other material selected in consultation with the Government. A dome drawing will be provided by the Government at the beginning of the contract. The purpose of Phase I is to demonstrate the contractor�s capability for precise fabrication and to identify areas that need the most work in Phase II.

PHASE II: In year 1, produce a BK7 glass or ceramic ogive dome with a root-mean-square transmitted wavefront error less than one half of an optical wavelength measured at 0.633 mm. Refine the methods in year 2 to produce a dome with a root-mean-square transmitted wavefront error less than one third of an optical wavelength measured at 0.633 mm.

PHASE III: Demonstrate commercial production capability for casting and polishing full scale domes

PRIVATE SECTOR COMMERCIAL POTENTIAL/DUAL-USE APPLICATIONS: Methods for grinding, polishing, and measuring non-hemispheric shapes can be applied to aspheric lenses that simplify the design of a wide variety of optical products.

REFERENCES:
1. M. V. Parish and M. R. Pascucci, "Polycrystalline Alumina for Aerodynamic IR Domes and Windows," Proc. SPIE 2009, Volume 7302, p 730205.

2. W. P. Kuhn, M. B. Dubin, R. S. LeCompte, and H. P. Durazo "Measurement Results for Time-Delayed Source Interferometers for Windows, Hemispheric Domes, and Tangent Ogives," Proc. SPIE 2009, Volume 7302, p 73020R.

3. S. DeFisher, M. Bechtold, D. Mohring, ands. Bambrick "An InnovativeNon-ContactMeasurement Solution for Asphere, Deep Parabolic, and Ogive Radome Geometries," Proc. SPIE 2009, Volume 7302, 73020S.

4. D. W. Diehl, C. J. Dichman, and C. T. Cotton, "Low-Coherence Surface Metrology Using a Multiple-Beam Optical Probe," Proc. SPIE 2009, Volume 7302, p 73020T.

5. S. Bambrick, M. Bechtold, S. DeFisher, D. Mohring, and J. Meisenzahl, "Recent Developments in Finishing of Deep Concave, Aspheric, and Plano Surfaces Utilizing the UltraForm 5-Axes Computer Controlled System" Proc. SPIE 2009, Volume 7302, p 73020U.

6. B. Hallock and A. B. Shorey, "Technologies for Precision Manufacture of Current and Future Windows and Domes," Proc. SPIE 2009, Volume 7302, p 7302V.

KEYWORDS: infrared dome; ogive dome; missile dome; optical finishing; optical metrology; metrology

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between April 26 and May 25, 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 May 26, 2011, when DoD begins accepting proposals for this solicitation.

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