For as long as people have been writing about fantasy, myth and science fiction, the desire to remain invisible has been a favourite topic. You may have seen an invisibility cloak in the 2010 film Harry Potter and the Deathly Hallows. The invisibility cloak was a piece of magical clothing that made anyone or whatever it covered invisible. But is it even possible to disappear? How would you feel if we say an invisibility cloak exists in real life too? Yes, it has been made possible by a Canadian company.&nbsp;&nbsp;



Explained: The concept of visibility  Let us first understand what happens when an object is exposed to light. When any object is exposed to light under normal conditions, the typical response is either absorption or reflection of light. If the light is absorbed, any background light and signals will be blocked, alerting you to the presence of the object. This indicates that the object will be visible! If the light is reflected, whatever signal you send out will be returned to you, highlighting the object and allowing you to see it. So, the bottom line is, light must interact with the object for it to be visible. 



Becoming invisible: Is it possible?&nbsp;



During the last two decades, a unique, multi-layered covering of an object known as a metamaterial has been developed, allowing light to travel freely around an object. The metamaterial structure diverts light around an object, sending it off uninterrupted in the same direction that it came from. This would give the impression that there is no object present in between! However, a perfect cloaking device needs one more thing. Let us see what it is. As you may have learned in your physics class that a lens is a transparent piece of glass that can converge or diffuse light rays by bending them at a desired angle! Similarly, a metalens is a flat lens that can concentrate light onto a single point, even on the smallest surfaces. It simply enhances the light-focussing capability of a lens. A metalens has several other appealing qualities such as being incredibly thin and easy to make! A merger of metalens and metamaterials could be the perfect technical fusion needed for a practical cloaking device for invisibility. &nbsp;



Invisibility cloaks: How do they work?  When you hear the term ‘invisibility cloak,’ you often think of thrilling adventures, magical spies and strange deceptions. But, how does an invisibility cloak work, actually? This cloak functions as a light bender. It bends light around it and sends it back to where it came from, making an object invisible. This light can be of any wavelength (the distance between identical points in a wave.)  



An invisibility cloak for the battlefield  HyperStealth Biotechnology Corporation, founded in 1999, is a Canadian manufacturer of military camouflage uniforms for troops all over the world. In 2019, it developed a material called ‘Quantum Stealth’ that makes the target entirely invisible by bending light waves around it! HyperStealth Biotechnology Corporation demonstrated how it can hide a scaled-down model of a tank by laying a sheet of ‘Quantum Stealth’ above it! The amazing thing about this invention is that it does not require a power source and is both paper-thin and affordable — all of which might make it suitable for use on the battlefield. They have now obtained a patent for the ‘Quantum Stealth’ material which can be used to hide military members, or even tanks, planes and ships, by making whatever is behind it to become invisible!

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