Accept it? Some of us may love to roam around without being seen. However, this idea of being invisible has long fascinated human imagination. Meanwhile, the advancement of optical technology led the path for us to witness real-life invisibility cloaks. The cloaks are quite easy to use as used in Star Trek and Harry Potter redefining the meaning of the word stealth.
How does an invisibility cloak work?
About the working of the invisibility cloak H.G. Well said; “Visibility depends on the action of the visible bodies on light. Either a body absorbs light, reflects or refracts it, or does all these things. If it neither reflects nor refracts nor absorbs light, it cannot be visible.”
Basically, the invisibility technology depends on manipulating light waves on which our visual perception also depends. Thus, researchers used this concept innovatively by bending and redirecting the light that conceals the objects from the view.
It is certainly true that developing a full-blown invisibility cloak in the complete visual spectrum is a huge challenge. We all know that scientists have made distinctive amazing technologies such as fighter jets that are invisible to radar and also made thermal invisibility jackets that hide the soldiers from any enemy’s thermal cameras. But still, concealing something from the naked eye is quite difficult and needs some serious engineering of the scientists.
Generally, when an object interacts with light, it interacts by absorbing or reflecting to make the object visible. For true transparency, the lights pass through an object undisturbed. In this case, the cloaking device will redirect the light from all directions around the object. Thus, the object will appear invisible from an angle.
Examples of invisibility cloak:
Some true invisibility cloaks are still present in the realm of scientific research and development as many notable advancements and demonstrations have been made in this field:
Quantum Stealth:
One of the invisibility cloak prototypes comes from Hyperstealth Biotechnology. The company first introduced this as a paper-thin material that bends according to the sizes from soldiers to tanks and ships. The cloaking not only works for the visible but also for the infrared and shortwave infrared light perfectly.
Rochester cloak:
The Rochester cloak was developed in 2014 which is also a notable advancement. The cloak utilizes a system of lenses to disappear small objects. This cloaking device uses four standard lenses in a unique configuration. It creates a three-dimensional multidirectional cloaking that works in the visible spectrum.
Thus, you can hide an object with this device regardless of the viewer’s position relative to the object. The researchers carefully choose the type of lenses, power, and distance between the lenses by the team.
Copper ring cloaks from Duke:
Engineers at Duke University made the world’s first functional cloaking device that they introduced to the world in 2006. However, the device showed some limitations in its working of reflection and reduced efficiency. However, in 2012, some researchers devised an improved design for this device and led a path for us to witness the entire potential of controlled light transmission.
This device is 2 feet square and forms a diamond shape along with an empty center. The Duke researchers mitigated the reflections efficiently by arranging each strip to meet the mirror image at each interface. But this cloak achieved invisibility in 2-D at a specific angle only.
Invisibility cloak for security cameras:
Some Chinese graduate students invented Meet InvisDefense to outsmart security cameras. This is an unassuming coat that renders its wearer completely invisible to AI-monitored cameras. It makes the wearer completely invisible to the surveillance camera but remains visible to the naked eye. The secret is the perfectly crafted pattern that they cleverly configured to prevent detection by AI algorithms.
A computer science graduate who designed the coat algorithm Wei Hui said; “Security cameras using AI technology are everywhere. They pervade our lives, and our privacy is exposed under machine vision.” He added, “We designed this product to counter malicious detection, to protect people’s privacy and safety in certain circumstances.”
Metalenses:
The metalenses are considered as the first single lens to focus on the complete visible spectrum of light efficiently including white light also in the same spot and high resolution. It works by utilizing titanium dioxide nanofins to focus on wavelengths of light and eliminate chromatic aberration.
In 2018, in metalenses, the researchers used titanium-based nanofins to let them bend the light in the required amount to get invisibility. However, all the previous metamaterials unfortunately, could not cover the visible light wavelengths, but the combination of metalenses and metamaterials promised to provide extended invisibility to the visible light spectrum. Thus, these advancements played a crucial role in generating the visible light cloaking device, where light from distinctive wavelengths instantly renders objects invisible.
Invisibility shield:
It utilizes a precision-engineered lens array that manipulates the light. The shield camouflages the person behind the shield by redirecting the majority of light reflected from the subject away from the observer. This redirected light will move sideways across the shield’s face and create the illusion of the background instead of a person.
Future of invisibility cloak:
The invisibility cloak can be very beneficial in the future in military domains as the cloaking technology may revolutionize stealth operations, and render military assets invisible to radar or surveillance services. Moreover, in the field of optics, invisibility techniques may enhance the working of telescopes, microscopes, and other imaging devices.
Thus, invisibility technology might transform the way of our living soon. According to the current research collaborations among scientists, engineers, and material specialists promise a further breakthrough in the future. This technology may play an integral part in our lives in the future. It may revolutionize various industries and transform the way of living life.
