User:Brhaspati/ActiveStealth

ActiveStealth is a program by the United States Department of Defense to develop the next generation of camouflage uniforms for use in the United States Army and United States Marine Corps. The program uses active camouflage to achieve much higher levels of invisibility than with conventional camouflage patterns.

Principle
ActiveStealth is based on optical camouflage. The basic idea is to project the background image onto the camouflage outfit so that the person wearing the uniform appears invisible. The first publicly available prototype of this technology was developed by Susumu Tachi at the University of Tokyo, who made a raincoat that achieved partial invisibility. ActiveStealth combines this concept with other features to make it suitable for military applications.

Technology
The basic ActiveStealth uniform has approximately 3600 tiny fisheye lenses, each the size of a pinhead. Interleaved between these lenses are hexagonal screens of retro-reflective material with back-lit LED lighting. The entire array of lenses and screens covers the outer surface of the uniform in an unbroken layer. Each of the lenses and screens is connected to a glass filament a few microns in diameter. These filaments serve as a reduced-scale optical fiber network to allow communication with a powerful microprocessor that reads the inputs from the lenses and sends an appropriately mixed output to each of the screens so that the worst-case distortion from any angle is minimized.

In addition to reading the visible spectrum, the lenses also read the thermal radiation levels in their vicinity. This information is sent along the same channels, and the screens are used to emit infrared waves of matching frequency and intensity. This renders the wearer invisible to night vision too, since the heat emitted by his uniform is indistinguishable from the background thermal radiation.

Limitations
The weakest link in ActiveStealth is currently the life of the battery used to power the camouflage suit. Current prototypes have been reported to last only for six hours, after which they lose much of their invisibility. Another inherent limitation is that the processor works best when presented with a relatively static image. If the soldier is running fast or rolling on the ground, the image undergoes a slight delay in projection. This leads to a "ripple effect" in the background as seen by an observer, compromising the effectiveness of the camouflage. Due to both these limitations, ActiveStealth is currently suited only for snipers on short watches who don't move about much.

Prototypes
A fully functional prototype was tested by the Department of Defense in 2004. The effect of the uniform is very apparent.

Project timeline

 * Concept - April 1, 2002
 * Preliminary design - April 1, 2003
 * Prototype and field trials - April 1, 2004
 * Production and deployment - April 1, 2006