Fighting Shadows: Military Holograms

In science fiction, holograms are realistic, moving three-dimensional images. (Remember Arnie being spooked by his mirror self in Total Recall, and the priceless line Watch out, hes got a hologram!). In the movies, if they flicker a bit ("Help me, Obi-Wan Kenobi..."), its just so the audience realises its a hologram and doesnt get confused. Real life holograms are a lot more limited, so I was interested to see this study carried by Dr David Watt on Holograms As Nonlethal Weapons for NTIC, the Nonlethal Technology Innovations Center in New Hampshire.

This is a serious look at the technical possibilities for holograms. Its a far cry from blue sky fantasies like the Air Force 2025 Airborne Holographic Projector which displays a three-dimensional visual image in a desired location, removed from the display generator or the even more wildly optimistic Hologram, Death: Hologram used to scare a target individual to death.
Real holograms will not fool people at short range and they do not move, nor can they be projected into a remote location. But they might still have their uses.
One of Watt's suggested applications is 'deception in an urban environment'. Take a shop window and replace it with a hologram of a window display, and you have an apparently innocuous space where troops can be stationed without any hint of their presence. A vehicle (a car or bus) could use similar trompe loeil effect.
There is the possibility of using holograms to create virtual forces or virtual obstacles, but the problems are all too apparent. The situation is much better indoors where the optical environment can be controlled. Dr Watt suggests installations could have virtual doors, walls and windows as ways of confusing or misleading intruders.
A more unusual approach is using a speckle hologram as virtual smoke. This type of hologram produces an image that appears to be in front of its real surface, and this could project a confusing image of three-dimensional spots before their eyes, making it impossible for viewers to judge what is in front of them and how far away it is.
The human eye is difficult to fool, notes Dr Watt, but infra-red sensors are much less sophisticated there is no need for the same level of colour fidelity. An infra-red hologram of a vehicle could make a very convincing decoy. Automated systems (such as missile guidance) with no humans to spot the flaws should be particularly easy to fool. However, as Watt points out the technology does not yet exist to create infra-red holograms.
It is the third dimension that makes holograms uniquely different to other means of camouflage and potentially valuable. During WWII, circles of black cloth were used to give the impression of bomb craters on runways after air raids, but these would not stand up to close inspection. Holograms would allow you to put realistic-looking holes or craters on any surface and confuse any possible damage assessment.
Watts conclusion is Fascinating, but - there are just too many limitations at present. Size limits and material restrictions are a real problem, and

Most NLT [non lethal technology] applications rely on psychological predisposition of belligerents.

In other words it will take a certain amount showmanship to set the illusion up in the first place; this may be feasible in Las Vegas, but not on the battlefield.
But perhaps the biggest stumbling block at present is the cost of holograms large enough for practical applications. Watt quotes $10,000 for a one metre by two hologram, or a hefty $200k for one metre by six metres, which is a lot of money especially if the bad guys decide to test whether one is real by putting a bullet through it.
-- David Hambling
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