Can Light Be Made Invisible Using Metamaterials and Graded Refractive Index?

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In summary, a recent article described a device that is invisible to static magnetic fields. It consists of a cylinder with two layers - an inner layer of superconducting material that repels magnetic fields and an outer layer of ferromagnetic material that attracts them. When placed in a magnetic field, the device has no effect on the field lines, making it undetectable to objects inside. However, it is unlikely that this phenomenon can be replicated for light due to the complexity of engineering a pattern that would create a negative refractive index for all wavelengths of visible light simultaneously. While similar devices using metamaterials have been developed for microwaves, it would be difficult to achieve the same result with visible light.
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jmmy
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Recently a device invisible to a static magnetic field was described. The device features a cylinder with two concentric layers. While the inner layer consists of a superconducting material that repels magnetic fields, the outer layer is a ferromagnetic material that attracts them. Placed in a magnetic field, the device has no effect on the field lines, showing neither a shadow nor a reflection. So an object inside the device cannot be detected.
www.abc.net.au/science/articles/2012/03/23/3461975.htm

My question is: how can one make it work for light (EM field)? What are the physics /equations involved?
 
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jmmy said:
My question is: how can one make it work for light (EM field)? What are the physics /equations involved?

Well I can't foresee the future, but I would bet that you cannot make this particular phenomenon work for light. Light is an EM wave, not a static field and isn't subject to quite the same rules.
 
  • #3
Some materials called "Metamaterials" have been engineered in the last few years that are invisible to microwaves. Use a specific gradient /material/structure pattern to create a negative refractive index. The materials are designed with very precise gradient pattern that is "invisible" to a small portion of microwaves. The problem with doing this with visible light is that we would need to engineer some kind of pattern that could have a negative refractive index for all wavelengths of visible light at the same time, which would prove quite a challenge!
 
  • #4
Sure, thanks, but I was referring to a similar device like the ones in the article based on superconductivity,not meta-materials, thanks.
 
  • #5
Conductivity is related to refractive index (its complex form), but refractive index is the magnitude preferred in optics. In order to make an object invisible you do need to grade its refractive index, and that's how metamaterials are made.
 

1. How does invisibility to EM fields work?

Invisibility to EM fields is achieved by using materials that can manipulate or redirect the electromagnetic waves around an object, essentially creating a "cloaking" effect. This can be achieved through the use of metamaterials or by creating an electromagnetic field that counteracts the waves coming towards the object.

2. Is invisibility to EM fields possible?

Yes, invisibility to EM fields is possible in theory and has been demonstrated in some experimental settings. However, it is currently limited to specific frequencies and may not be practical for everyday use.

3. Can an object be made completely invisible to all EM fields?

No, it is not currently possible to make an object completely invisible to all EM fields. Different materials and frequencies may require different techniques for achieving invisibility. Additionally, some EM fields may be necessary for certain technologies to function properly.

4. What are the potential applications of invisibility to EM fields?

Invisibility to EM fields has potential applications in military and defense, such as creating stealth technology for aircrafts or ships. It could also have applications in telecommunication and medical imaging, where interference from surrounding EM fields can be problematic.

5. Are there any ethical concerns with invisibility to EM fields?

As with any technology, there may be ethical concerns surrounding the use of invisibility to EM fields. It could potentially be used for surveillance or to hide illegal activities. There may also be safety concerns if the technology is not used responsibly.

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