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This Defense Intelligence Reference Document, dated 2 March 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office under the Advanced Aerospace Weapon System Applications program. It reviews invisibility through camouflage, transparency, and cloaking, covering metamaterials, transformation optics, and non-Euclidean broadband cloaking designs. It concludes that perfect cloaking is impossible, but imperfect devices could be made. Microwave cloaking is within reach of present technology, while visible-light invisibility remains uncertain and depends mainly on new theoretical research.
From the source: Release of 2026-09-18 Incident: 3/2/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD surveys the theory and early experiments behind invisibility cloaking, describing several ways an object might be hidden from visual or sensor detection, including camouflage, transparency effects, and optical cloaking that bends light around an object. It focuses mainly on metamaterials, negative refraction, and transformation optics, and reviews experiments that had already demonstrated limited cloaking at microwave frequencies. The report argues that “imperfect” cloaking is physically achievable in some parts of the electromagnetic spectrum, especially for microwaves, but that “perfect” cloaking is not practical because it would require material properties that conflict with the underlying physics. Its overall conclusion is that cloaking is a scientific field with plausible narrow applications, but that useful visible-light cloaking depends more on future theoretical breakthroughs than on conventional advances in materials science.
UNCLASSIFIED/ /FOA OFFI&Il.tl l::181: 8HL'f Camouflage Invisibility may be achieved through three principal methods: camouflage, transparency, and cloaking. Many an imals and some plants use camouflage to disguise themselves from predators-for example, by assuming the shapes and colors of objects in their surround ings. The military has long used forms of camouflage; a recent military application of camouflage is stealth technology. Stealth planes have aerodynamically unusual, edgy shapes and are coated with a special material. Both features serve the same purpose: to make the plane " invisible" to radar. How does it work? In radar, electromagnetic microwaves are emitted by a source, and thei r reflection by an object-an airplane, for example-is detected. From the direction and the t ime delay of the reflected waves, the direction and distance of the object are inferred. If the object does not reflect the electromagnetic microwaves back to the source, it will not appear on the radar. This is precisely what stealth technology achieves. Owing to t he edgy shape of Figure 1. B2 Stealth Bomber the stealth plane, most of the incident electromagnetic waves are reflected in different directions; the coating of the plane absorbs the rest. In this way, the stea lth plane has become completely black in t he spectral range of radar. As for radar waves, the sky is black, not blue, and the plane has assumed the color of the background: the stealth plane is camouflaged. UNCLASSIFIED/ /&iOA: OFFICl.t.k W&li 8,.lY 1
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Official release, from the pursue collection. The PDF is mirrored here; the original link is above. 29 pages are in the text index: search them above, or from the library's search.