Looking all over the world, the story of invisibility emerges endlessly with the whimsy of the creators, and all kinds of strange stealth methods are also colorful.
Invisibility cloak has always existed in myths and legends, novels or video games, and has never become a reality. However, it may not be long before you have an invisibility cloak!
Existing research results
Stealth technology was first used in the military, and stealth aircraft first appeared. Stealth is achieved by reducing the radar cross section and reducing its own infrared radiation.
German scientists have made an optical invisibility cloak. With the development of optical stealth materials, there may be such a situation in the future:
A Canadian high-tech company has developed an advanced material called "quantum invisibility", and its effect is comparable to the invisibility cloak in Harry Potter and The Lord of the Rings's elf cloak!
It can not only "cheat" the naked eye, but also be successfully invisible under the detection of military night vision goggles, infrared rays and thermal imaging technology.
At the same time, the US military is also actively developing invisibility cloaks, which is expected to hide soldiers in the future battlefield environment.
Last June, 1 1 foreign media reported that researchers from Nanyang Technological University led by scientist Zhang Peier were about to develop a peculiar "invisible hat".
Invisibility cloak principle
Is the invisibility cloak really magical? Absolutely not!
It turns out that the invisibility cloak can guide the irradiated light in other directions, so that electromagnetic waves (including light waves) "turn around" and walk around objects.
In this way, people can't see the invisibility cloak and the things hidden inside!
key technology
At this point, we will find that the key to the development of stealth technology is stealth materials.
The research and development of stealth materials is a hot spot in the world today. Let's take a look at the development of several new mainstream stealth materials in the world.
1) nano stealth material
In recent years, the research on nano-materials has been deepened, which proves that nano-materials have excellent wave-absorbing characteristics, which has aroused great interest of researchers.
The chrysanthemum-shaped nano titanium dioxide (CNA) prepared in the following figure is used to prepare composite stealth materials, and the pattern is beautiful from a microscopic point of view.
2) Intelligent stealth materials
A kind of high-tech developed gradually in 1980s is a kind of material and structure with the functions of perception, information processing, self-command, optimal response to signals, etc., which makes it possible to realize the stealth function by using intelligent materials.
The mechanical chameleon in the invention patent with the publication number CNA is such a material.
The outer surface of the mechanical chameleon is covered with a plasma element. When the mechanical chameleon reaches the corresponding background color through a control circuit and a sensor, the mechanical chameleon automatically turns into the corresponding color and always keeps the same color as the colored background.
Can you find me?
3) Metamaterials
The most promising new development of stealth technology is a strange material called metamaterial, which may make objects really invisible one day.
Metamaterials can modulate electromagnetic waves and change their propagation modes, so they have many applications in radar, antenna, electronic warfare, electromagnetic stealth and other fields.
Ironically, metamaterials were once considered impossible because they violated the laws of optics.
However, in 2006, researchers from Duke University in North Carolina and Imperial College London in London successfully challenged the traditional concept and used metamaterials to make objects invisible on the 2D plane under microwave radiation.
In 20 10, researchers from Karlsruhe Institute of Technology and Imperial College London, London, successfully made the gold film invisible in the 3D space of 1.4 to 2.7 microns, which is a step forward from the invisibility of visible light (wavelength of visible light is 0.4 to 0.7 microns).
Metamaterial technology belongs to the frontier research field of international science. At present, the level gap between major countries is not obvious, and the problem facing * * * is how to prepare metamaterials.
It is gratifying that China is currently in the international leading position in metamaterial research.
On April 8, 20 16, a seminar on metamaterials was held in Chengdu. As a frontier country of metamaterial research, China is realizing many applications including "stealth" function.
Pencils and invisibility cloaks are put into invisibility materials.
By analyzing the global patent data before 20 15, the research of metamaterial technology entered a rapid stage at 20 1 1 and 20 12.
As for important applicants, Shenzhen Guangqi, which relies on the State Key Laboratory, is the leader in this field, with more than 80% of the total patents in the world and complete patent layout.
abstract
What will the world look like if the perfect invisibility cloak finally becomes a reality one day and becomes a randomly selected commodity in the supermarket?
Just like changing the status on MSN or QQ, it can be undisturbed. We hope to have a clean world, as Jiang Yang said, "We just want to get rid of the fetters and travel around".
Invisibility cloak may become a tool of evil, may become the key to future wars, may have no privacy or trust between people, and may not be able to guarantee the most basic sense of security. Is such an invention suspected of being anti-human?
Maybe we shouldn't worry so much. When the invisibility cloak develops rapidly, the anti-stealth technology will also advance by leaps and bounds. Maybe it doesn't need to be so complicated. A handful of flour can make the invisible man appear.
Let's hope that with the help of reasonable imagination, with innovation as the driving force, we can realize the future as soon as possible through scientific research, and we also hope to enter the magical world as soon as possible!