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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/ /FOR OFFl@IAL YSE OHL¥ direction from the pro pagation . The clearest and most advanced form of this concept is t he complementary media invisibility cloak. 3 Here, an optical antiobject is placed beside the object one wishes to make disappear. The antiobject should be made of a negatively refract ive materia l that exact ly compensates the optica l appearance of t he object. An image is contain ed in the deformations of light-wave fro nts cau sed by the imaged object. If these deformations are reversed, the image disappears, and t he object becomes tra nsparent- that is, in visible. The optica l antiobject must be tailored to the object and placed precisely at t he correct dista nce-that is, the distance where it is made to ca ncel the image of t he object. The more complex t he object is, the more com plex t he antiobject must be for reversing all the scatt erin gs of light. Such cloaking at the distance ca nnot be instantaneous, as the lig ht scattered by both object and antiobject must settle t o a st ationary state where it becomes synchronized. A stationary light field has only one color. So, in practice , these forms of tra nsparency will work only for small objects and for small parts of the spectrum and not for large objects in ma ny colors. a) b) μ 1mob' -L 0 L -L 0 L c) d) ..,, . ,, • I , ,I ,, ,I I I I I I I ' I I ,I I ,I ,I'I I ,, ., 'μob, - ____ ,,,. -·· --· Figure 5 . Complementary Media Invisibility Cloak: (a) The slab of empty space x with O < x < Lis optically canceled by a slab of negative-index material in -L < x < 0. (b) The same cancellation effect works with an object in O < x < L if the negative-index slab contains an antiobject. (c) A spherical shell b < r < c is optically canceled by a negative-index shell a < r < b. If the corer< a is optically equ ivalent to a sphere of rad ius c, then this device ls invisible. (d ) The same as (c), but with an object in the canceled shell b < r < c. The object is cloaked : both it and the cloa king sphere are invisible . UNCLASSIFIED/ /POlt orrlCIJ!!tt 05E: 014[ I 4
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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.