Is this the simplest optical cloak possible?

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Discussion Overview

The discussion centers around the design and effectiveness of a proposed optical invisibility cloak made of water, specifically questioning the choice of refraction methods used in its construction. Participants explore the implications of using different numbers of refractions and the simplicity of the design.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • One participant questions why the authors did not use a system with only three refractions for each light ray, suggesting it might be impossible or could decrease the cloaking angle.
  • Another participant proposes that the choice of four refractions may have been made for simplicity and ease of testing, noting that achieving three refractions could be more complex due to the need for precise angles and equal time spent in different mediums.
  • A third participant critiques the visual presentation in the paper, suggesting that the background selection appears forced to enhance the illusion of continuity and expresses intrigue at the device's inexpensive nature.
  • One participant expresses skepticism about the novelty of the idea, referencing historical uses of reflection for similar effects by stage magicians.

Areas of Agreement / Disagreement

Participants generally agree that simplicity is a likely reason for the design choices made in the cloak, but there is disagreement regarding the novelty of the concept and the effectiveness of the proposed design in all planes.

Contextual Notes

Some participants note potential limitations in the design's effectiveness across different planes and the complexity involved in achieving the desired optical effects with fewer refractions.

Christofer Br
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https://www.researchgate.net/publication/273269952_A_Simple_Unidirectional_Optical_Invisibility_Cloak_Made_of_Water
Why did the authors of this cloak not choose a system with only three refractions for each light ray, so that the cloaked area would be a parallelogram? Is this impossible, or would it decrease the cloaking angle?
 
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You could always write them and ask them, but I suspect the answer was simplicity. It's obvious how to do this with 4, and 4 breaks down to 2+2 so you can test half of it easily. It probably can be done with 3, but not so easily - the middle pice has to be just right: you need to make sure every ray spends an equal time in air and water, and that all the angles work out.
 
Page 3 of the paper could use a fourth picture between pictures (1) background only and (2) 14 cm model that shows (2') background with device sans giraffe. Selection of background with hazy patterns and the large central tree figure directly behind the giraffe appear forced; designed to assist the illusion of continuity. The inexpensive nature of the device is intriguing.

Agree with simplicity as the answer to the OP. Minimal configuration that works ( and costs least).
 
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I see the diagrams are 2 dimensional. Would it work in all planes? Prob some distortion.
I'm amazed that the idea could be 'new',
 
sophiecentaur said:
I'm amazed that the idea could be 'new',

It's been done with reflection for decades (centuries) by stage magicians. As they say "it's all done with mirrors".
 
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