You must have seen what an "invisible cloak" is in harry potter.To give you a fair idea check this out,
But something that is really interesting about it is the fact that it is quite a feasible technology.
I felt bending of light around the object is a potential principle to make this fantasy come true.
So i checked on the web about the existing technologies for the invisible cloak.Here I am giving you the site where you can check out the existing technology to achieve it
let me brief you about this existing principle :
- In this process, the object you want to make invisible, is covered with a silver coloured jacket made of retro-reflective material,whose properties can be compared to that of a picture screen.
- At the back of the object a camera is placed which takes a picture of the background and sends it to the computer.
- Then signals are sent to the projector, from which the image falls on a beam splitter
- The beam splitter's function is to split the light to allow the light to fall on the cloak as well as toreach the observer's eyes.
The whole principle is shown in the picture above.In short the principle is, take the picture of the background ,display it on the object so that would act as a camouflage
Disadvantages:
- The whole system is stationary.I mean it cannot be moved if the object is in motion.
- The observer gets to see the image only within some subscribed angle
So I have thought of an alternate way of overcoming the drawback and achieve this mystical"Invisible cloak"
Alternate technology:
- The cloak can insted of a retro reflective material,be made of optical fibres.
- So the light,when falls on the object insted of getting reflected transmits along the fibres making the object transparent instead of opaque.
- Now using the principle of total internal reflection, we get the light out of the fibres from the back.
- This light when reflected from the background travels in the same path in exactly opposite direction,by the principle of symmetry.
- Thus what the observer sees is, the light from the background and hence the object in between is invisible.
Disadvantages:
Reflected light from the background may not be more intense than untransmitted light from the cloak.in such case the observer sees both the object as well as the background ,as overlapping images.
Corrections:
To decrease the intensity of reflected light,the critical angle of the optical fibre should be minimum.This would allow maximum amount of light to pass through and reflects small amount of light.
