Cloaking Device

Background

A cloaking device is a theoretical or fictional stealth technology that can cause objects, such as spaceships or individuals, to be partially or wholly invisible to parts of the electromagnetic (EM) spectrum. However, over the entire spectrum, a cloaked object scatters more than an uncloaked object. We can bend light around an object and see it after the blocking.

fig1

Figure 1. A multidirectional “perfect paraxial” cloak using four lenses. From a continuous range of viewing angles, the hand remains cloaked, and the grids seen through the device match the background on the wall (about 2 m away), in color, spacing, shifts, and magnification.

Question: Will you able to see the hand if it blocks center of the lens?

The device above used four lenses to build up the system. You can “see” the background behind the hand because the background was “zoom in” to a small image and pass from center of light path. Look at the laser path below to see how light is deflected between lenses.

device setup

Figure 2. Setup of the multidirectional `perfect paraxial’ cloak as seen from the side. Laser shows the paths that light rays travel through the system, showing regions that can be used for cloaking an object.

This is the video of cloaking device constructed in University of Rochester.

The Rochester Cloak

They also built up a cloaking system using mirrors

Mirror Optical Cloaking

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