Optical camouflage uses augmented reality technology to project the scene behind an object onto that object, making it appear invisible. It was first prototyped in 2003 by displaying a video feed onto a cloth using an external projector. Since then, metamaterials have been used to create invisibility cloaks in the microwave range. Optical camouflage systems require retroreflective material, cameras, computers, projectors, and half-silvered mirrors to work.

3.  Process to create the illusion of invisibility by covering
with something that projects the scene directly behind
that object is called OPTICAL CAMOUFLAGE.
 It displays an image of the scene on the side opposite the
viewer on it, so that the viewer can "see through" the
wearer, rendering the wearer invisible.
 Although optical is a term that technically refers to all
forms of light, most proposed forms of optical
camouflage would only provide invisibility in the visible
portion of the spectrum.
WHAT

4.  Prototype examples and proposed designs of
optical camouflage devices range back to the late
eighties at least, and the concept began to appear in
fiction in the late nineties.
 In 2003, three professors at University of Tokyo
Susumu Tachi, Masahiko Inami and Naoki
Kawakami created a prototypical camouflage
system in which a video camera takes a shot of the
background and displays it on a cloth using an
external projector. The same year Time magazine
named it the coolest invention of 2003
 In 2006, Duke University achieved enveloping and
"disappearing" an object in the microwave range
using Metamaterials
WHEN

5. It is done in two ways
HOW

6.  Optical camouflage doesn't work by way of magic. It
works by taking advantage of something called
Augmented-reality technology
 Augmented-reality systems add computer-generated
information to a user's sensory perceptions
 Most augmented-reality systems require that users
look through a special viewing apparatus to see a
real-world scene enhanced with synthesized
graphics. They also require a powerful computer.
Optical camouflage requires these things, as well,
but it also requires several other components

7.  A garment made from retro-reflective material
 A video camera
 A computer
 A projector
 A special, half-silvered mirror called a combiner
Here's everything needed to make a person appear invisible

11.  Rely on product called metamaterial
 Meta in Greek means “beyond”…
 Therefore the term “metamaterial” means to create
something that doesn't exist in nature
 Metamaterials (MTMs) are a class of artificially
engineered composite materials having
extraordinary electromagnetic properties

12.  Depending on the structure , metamaterials may
have refractive index less than 1 and even negative
 Metamaterials having negative refractive index are
called Left Handed Metamaterials

13.  it is possible to design metamaterial "cloak" so that it
guides light around some region, rendering it invisible over
a certain band of wavelengths.
 The Duke team used metamaterials to make their cloaking
device have gradually varying refractive indices - from 1 on
the outside of the device, decreasing to zero in the centre .
The result is that microwave light subtly bends around the
device and is able to reform on the other side, although
with some detectable distortion .

16.  Patient centered design rooms
Improve the psychological well-being
of people in closed environments
 Surgery
Doctors performing surgery could use
‘invisibility’ to see through their hands
and instruments to the underlying
tissue more ‘visible’

17.  Pilots landing a plane could use this
technology to make cockpit floors
transparent
 This would enable them to see the
runway and the landing gear simply
by glancing down

18.  Drivers backing up cars
could benefit one day from
optical camouflage. A quick
glance backward through a
transparent rear hatch or
tailgate would make it easy
to know when to stop

19.  More fanciful applications like
transparent ceiling to provide a
view of the outside
 Transparent door replaces peep
hole

20. Now all of us have had a small tour of the world of optical
camouflage
A lot of interesting thing have been done and already we have
seen that anyone can be almost invisible with this technology
But the future promises us a lot more
Research work is going on and soon we will have even more
astonishing results
CONCLUSION

22. QUERIES
ANY