How do we see things around us? When light strikes an object and it gets reflected back and when it reaches our eyes, then we will be able to see things. But what if we can make things invisible using the same light which helps us seeing those things.
Yes, it is possible. Scientists have found a way to achieve this. But this might take a few years more to be developed.
We know that light when incident on an object gets scattered in many directions which makes it visible. But if we can make light pass in a straight line through the object then we can make it invisible. For example, when light incidents on a blue car, blue colour frequency is reflected while all other colours frequencies simply pass through the object.
Spectral Invisibility Cloaking
The researches of INRS (National Institute of Scientific Research) have found a cloaking device. This device has two filters. For example, consider an object that reflects only green light. The first filter is used to temporarily shift the green frequencies in broadband spectrum that is incident on the object to blue. Then another filter is used to convert these frequencies back to green on the other side of the object. The result is there is no light reflected from the object. Hence the object won’t be visible. In this way objects can be made invisible but only in one view. There researches being done to make objects invisible in all directions.
This is just one way of making things invisible. There are many other ways as well like-
- sending a beam of light which has an exact pattern of microscopic arrangement pattern inside the object.
- There is one more way to make this possible. In this method fillers are used, and the object is made invisible from inside and it is not hampered by external cloaking. This is called as plasmonic cloaking.
- Another way is using metamaterials for cloaking. Metamaterials are substances which have better electromagnetic properties, but this is a very old way of cloaking.
Out of all these and many other methods of cloaking, spectral invisibility cloaking is being focussed by researchers and many are trying to develop it. In future we might see many other types of cloaking as well.
Written By- Sri Vardhan