Invisibility : Futuristic Technology That Is Possible
We May Have Mobile Applications That Are Almost Invisible.
Invisibility is the state of an object that cannot be seen. An object in this state is said to be invisible (literally, “not visible”).
The term is often used in fantasy/science fiction, where objects cannot be seen by magical or technological means; however, its effects can also be demonstrated in the real world.
Since objects can be seen by light in the visible spectrum from a source reflecting off their surfaces and hitting the viewer’s eye, the most natural form of invisibility (whether real or fictional) is an object that neither reflects nor absorbs light (that is, it allows light to pass through it). This is known as transparency, and is seen in many naturally occurring materials.
Invisibility is often considered to be the supreme form of camouflage, as it does not reveal to the viewer any kind of vital signs, visual effects, or any frequencies of the electromagnetic spectrum detectable to the human eye, instead making use of radio, infrared or ultraviolet wavelengths.
A cloaking(conceal or hide something) device is a hypothetical 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.
Invisibility concept has come a long way since H.G.Wells’ 1897 book — a classic science fiction novel “The Invisible Man”. Scientists around the world applied different methods including switching electromagnetic waves for making objects invisible. Researchers have devised materials that bend light around an object, effectively causing it to disappear. They’ve used cameras to record and project images of what’s behind an object onto the object’s surface, making it appear like it’s out of sight. Also they have used photonic crystals to develop invisible cloak that make objects disappear. However, all these technologies are far from perfect and not yielded invisibility cloaks that hide something from view.
Metamaterials are a subset of a larger group of heterogeneous structures consisting of a base solid material added with elements of a different material. Metamaterial cloaking is the usage of metamaterials in an invisibility cloak. There is one invisibility method, involves metamaterials, because they possess properties not found in nature. Some metamaterials can bend light, and a metamaterial cloak could effectively curve incoming light around an object behind it, making it appear to drop out of sight. The drawback is that they only work for a single wavelength.
One tech firm has made the technology a reality, with its own invisibility cloak, dubbed the Quantum Sheath. Researchers from Hyperstealth Biotechnology Corporation, Canada have developed the light-bending material, which they claim can ‘hide a person, a vehicle, a ship, spacecraft and buildings’. The material known as Quantum Stealth, works with all wavelengths of visible light, and it works by bending light coming from the background on both sides toward the viewer to create a blind spot in the middle, and make people and objects near invisible to the naked eye. Unlike traditional camouflage materials, which are limited to specific conditions such as forests or deserts, and this “invisibility cloak” works in any environment or season, at any time of day. But there are drawbacks to this invisibility cloak, too. Objects need to be a certain distance behind it to disappear and can reappear if they move too far to one side.
Invisibility is often considered to be the supreme form of camouflage, as it does not reveal to the viewer any kind of vital signs, visual effects, or any frequencies of the electromagnetic spectrum . Military researchers around the world are interested in a topic called “Active Camouflage” in a bid to find more robust form of invisibility. The idea is similar to the tactics that make octopuses and cuttlefish invisible. By matching their skin to the background behind them, these marine animals blend in almost seamlessly. The same could be done for humans with cameras and a suit or cloak that projects images. While some researchers have attempted to design prototype active camouflage suits with a 360-degree camera paired with a body suit, the results fall far short of invisibility and the suits don’t disappear entirely.
On a different scale, scientists looked at a promising new way to manipulate electromagnetic waves to make objects appear invisible. The team developed an approach using photonic crystals. Making objects invisible comes down to switching electromagnetic waves. The cloak medium requires bending the wave’s path around an area. It hides an object and accelerates waves along the bent trajectories. With the help of properly structured crystals composed of dielectric rods(Dielectric resonators make electromagnetic waves bounce back and forth which allows controlling wave propagation in the cloak medium) , scientists developed cloak medium from photonic crystals. Photonic crystals in this cloak provide superluminal phase velocity of propagating waves. Thus, waves move faster as compared to light speed. Such kind of speed creates invisibility illusion.
In 2020, a new physical phenomenon related to the electronic resonance of laser processed materials was discovered and using the new phenomenon, researchers have fabricated invisible photonic circuits. They discovered that the structure of a material can be modified so as to be usable for frequencies operating photonic devices and sensors, while the structural modification becomes invisible for frequencies detectable by the eye. They explained their discovery may lead to a new concept of direct fabrication of invisible structures. The beneficial combination of high refractive index (RI) change for operating frequencies and the invisibility for the rainbow frequencies may help to enable several invisible applications in phone screens, desktop computers, etc
According to scientists, invisibility would become useful for both national security and industry. An Invisible Cloak, known as Quantum Stealth, can bend light around an object or person behind it, leaving only the background visible and can ‘hide a person, a vehicle, a ship, spacecraft and buildings’. Experts envisions the technology being used for police riot shields or to hide tanks on a battlefield, in the future. The Invisibility Cloak primarily for military purposes, to conceal agents and equipment such as tanks and jets in the field and foremost interest being the “active camouflage. In addition, It may be possible someday to create several invisible applications in Mobile Phones using invisible photonic circuits or structures.
The on-going research suggests that invisibility is possible by Cloaking Objects on a single bandwidth. However, emerging prospect of invisibility cloaking of an object by modern science of Metamaterials or Photonic Crystals is not very far from achieving full cloaking in the visible spectrum but that may take a decade or more to achieve full capability.
