Super lens

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a) When light passes through a medium with positive refractive index to vacuum. b) When passing through a medium with a negative refractive index. c) _ n _ = - 1 When the light source is placed in front of the medium, the light is refracted inward, and focal points are generated inside and outside the lens, respectively. As a result, super resolution is achieved.

Super lens(: Superlens) orComplete lens(Perfect lens) is the n = -1 of And has a flat plate shape. Ideally infinite is achievable.

This is based on the effect in a medium having a negative refractive index, and can be realized by transmitting information by an evanescent wave having a large wave number.

Since the evanescent wave has no component in the direction of travel, energy is not amplified. Is to the direction of travel []. Also, in the case of a traveling wave in a perfect lens, the pointing vector points in the opposite direction [].

However, the fact that the resolution becomes infinite is theoretical assuming that there is no loss at all, and in reality the following restrictions exist.

Δ = 2 π d | ln  (n "/ 2) | {\ displaystyle \ Delta = {2 \ pi d \ over | \ ln (n '' / 2) |}}! {{\ \ displaystyle \ Delta = {2 \ pi d \ over | \ ln \ (n '' / 2 ) |}}] (https://wikimedia.org/api/rest_v1/media/math/render/svg/b42ee1438ed9e6e3f022089deee83012c807ef8e)

Where d is the distance and n "is the component of the refractive index, ie the loss in the lens.

Notice that the loss in the lens is functional.

It can be seen from this equation that the resolution of the complete lens does not depend on and that in order to obtain high resolution it is necessary to bring the distance closer or to make the lens loss very low.

This restriction is similar to the relationship between the distance and the sensitivity and the resolution limit in the super resolution by the evanescent wave.

After all, as far as using evanescent waves, perfect lenses can not also avoid the problems arising from the properties of evanescent waves.

As a countermeasure, there is a meta-atom optimization and a metamaterial composition.

There is also a curved lens using a negative refractive index, which maximizes this, and its similarity with the super lens in this section is low.

Hyper lens and far-field super lens

In addition to the super lens, a hyper lens made of metamaterial and a far- field Super lens exists, but this succeeded in forming an image expanded to a long distance by converting an evanescent wave into propagating light.

The hyper lens converts the evanescent wave into propagating light without amplifying it.

The far-field super lens is converted to propagating light after exiting the lens after amplifying the evanescent wave.

Both images are enlarged so that high resolution can be maintained without using evanescent waves.

For this reason, it is the interval from the lens to the image, and the object itself to be observed must be close to the lens.

References

• Filippo Capolino edition "Metamaterial Handbook Fundamentals" Kodansha, November 10, 2015. .

footnote

1. *Xiang, Zhang; Liu, Zhaowei (2008). (PDF). Nature Materials *7: 435 - 441. 2. *David R. Smith; David Schurig; Marshall Rosenbluth; Sheldon Schultz; S. Anantha Ramakrishna; John B. Pendry (2003). "Limitations on subdiffraction imaging with a negative refractive index slab". _Applied Physics Letters _ * 82(10): 1506.:. 3. *B. D. F. Casse, W. T. Lu, Y. J. Huang, and S. Sridhar (2008). .Appl.Phys.Lett _*93, 053111. 4. *Xiang Zhang and Zhaowei Liu (June 2008).. Nature materials *7: pp. 435 - 441.

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Post Date : 2018-02-03 08:00