Documents / Report
This Defense Intelligence Reference Document, dated 2 March 2010 and produced by the Defense Intelligence Agency under its Advanced Aerospace Weapon System Applications (AAWSA) Program, is a technical survey of invisibility. It covers camouflage, including stealth aircraft and optical camouflage, then transparency, cloaking by coordinate transformation, metamaterials and non-Euclidean broadband cloaking. It concludes that perfect cloaking is impossible but imperfect microwave cloaks are within reach of present technology. Whether cloaking will work at visible wavelengths remains unclear.
UNCLASSIFIED/ }Cg A grrI&ItliL '1181!! 8HLY Camouflage Invisibility may be achieved through three principal methods: camouflage, transparency, and cloaking. Many animals and some plants use camouflage to disguise themselves from predators-for example, by assuming the shapes and colors of objects in their surroundings. 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 their reflection by an object-an airplane, for example-is detected. From the direction and the time 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 the 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 stealth plane has become completely black in the 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. 1 UNCLASSIFIED//fgA 8FFI1il.«1k WliEii SU.k'J.'
Not linked to a story yet.
Report, from the dia 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.