Magnesium aluminate spinel is a durable electro-optical material with high visible through mid-IR transmission. Technology Assessment and Transfer (TA and T) reports on their efforts to integrate electromagnetic interference protection into spinel domes through the use of metallic grids. TA and T is developing an approach to embed noble metal EMI grids in spinel domes by encapsulating the grid with a germanate glass that has matching refractive index and coefficient of thermal expansion to spinel. Achievements to date and an outlook on this method as a viable manufacturing route are presented.
Magnesium aluminate spinel is a durable, broadband, electro-optical material that can be readily manufactured into
transparent domes for multimode seeker applications. Technology Assessment & Transfer, Inc. reports on the results of
its Army SBIR-funded research and development efforts to resolve manufacturing issues with regard to transparent
spinel domes. The specific areas of study have been cost, quality, and ability to scale up to full production. Alternative
manufacturing approaches were evaluated and compared. A clear path to full scale production has been identified.
Magnesium aluminate spinel is a durable, broadband, electro-optical material that can be readily manufactured into
transparent domes for multimode seeker applications. Technology Assessment & Transfer reports on the results of its
research and development effort to resolve manufacturing issues with regard to transparent spinel domes. The specific
areas of study have been cost, quality, and ability to scale up to full production. Alternative manufacturing approaches
were evaluated and compared.
Magnesium aluminate spinel is a durable, broadband, electro-optical material that can be readily manufactured into
transparent domes for multimode seeker applications. Actual spinel domes have suffered from manufacturing difficulties
and light-scattering inclusions. The program described herein has solved many of the difficulties to achieve better optical
properties and better process yields.
Transparent magnesium aluminate spinel is an attractive material for use in a wide range of optical applications
including windows, domes, armor, and lenses, which require excellent transmission from the visible through to the mid
IR. Theoretical transmission is very uniform and approaches 87% between 0.3 to 5 microns. Transmission
characteristics rival that of ALON and sapphire in the mid-wave IR, making it especially attractive for the everincreasing
performance requirements of current and next-generation IR imaging systems. Future designs in missile
technology will require materials that can meet stringent performance demands in both optical and RF wavelengths. Loss
characteristics for spinel are being investigated to meet those demands. Technology Assessment and Transfer Inc. (TA&T), have established a 9000 ft2 production facility for optical quality
spinel based on the traditional hot-pressing followed by hot isostatic pressing (HIPing) route. Additionally, TA&T is
developing pressureless sintering - a highly scalable, near net shape processing method based on traditional ceramic
processing technology - to fabricate optical components. These two main processing approaches allow the widest
variety of applications to be addressed using a range of optical components and configurations. The polycrystalline
nature of spinel facilitates near net shape processing, which provides the potential to fabricate physically larger optical
parts or larger quantities of parts at significantly lower costs compared to single crystal materials such as sapphire.
Current research is focused at optimizing the processing parameters for both synthesis routes to maximize strength and
transparency while minimizing the cost of fabrication.
There are presently three materials (sapphire, ALON and spinel) which exhibit a desirable combination of material properties such as hardness, strength, and transmission in MWIR that are considered for various window/dome applications. Of the three, sapphire exists in a number of service applications. It is, however, the most expensive of the three and depending on application, can have significant drawbacks owing to its birefringent nature. ALON, by comparison is less expensive, benefits from greater development efforts, is an easily shaped polycrystalline ceramic, optically does not possess the birefringent nature of sapphire, but requires very high formation temperatures for the starting powders and equally long processing times for fabricated parts. The remaining material, transparent spinel, offers improved optical performance over the spectrum from UV to MWIR, comparable mechanical properties, and can be fabricated at much lower temperatures and shorter times than the other materials making it less expensive to produce. Data will be described which compares the transparency and mechanical properties and discusses the relevant processing efforts for spinel products.
Cryocoolers are a key component for many spacecraft. We summarize some spacecraft cryocooler requirements and discuss our observations regarding the current production capabilities of cryocoolers. The MODIL's interaction with industry, especially throught the Producible Technology Working Groups is also summarized. The current Spacecraft Fabrication and Test MODIL's plans to improve producibility include working closely with industry, executing a demonstration project, and holding a workshop to bring key members of the current cryocooler development network together.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.