What is the ideal refractive index difference for achieving invisibility?

  • Context: Graduate 
  • Thread starter Thread starter lanik05
  • Start date Start date
  • Tags Tags
    Index Refractive index
Click For Summary

Discussion Overview

The discussion revolves around the ideal refractive index difference required to achieve invisibility through optical matching of materials, specifically focusing on a glass fiber and potential resin systems. The scope includes theoretical considerations and practical applications in material science.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • One participant inquires about the closeness of refractive indices needed for invisibility, mentioning specific values for a glass fiber and two resin systems.
  • Another participant suggests that the sensitivity of measurement plays a crucial role, referencing the use of an Abbe refractometer and differential interference microscopy to observe index mismatches.
  • A third participant introduces the Fresnel equations as a method to calculate the reflection coefficient, implying its relevance to the discussion.
  • A follow-up question asks if there is a general rule of thumb regarding the acceptable refractive index differences across various materials, while acknowledging that other factors may influence the effectiveness of achieving invisibility.

Areas of Agreement / Disagreement

Participants express varying perspectives on the factors influencing invisibility, with no consensus on a specific ideal refractive index difference or a general rule applicable to all materials.

Contextual Notes

Limitations include the dependence on measurement sensitivity, potential variations in material properties, and the influence of additional factors not fully explored in the discussion.

Who May Find This Useful

Researchers and practitioners in material science, optics, and engineering interested in optical properties and applications related to refractive indices.

lanik05
Messages
2
Reaction score
0
I was wondering how close 2 refractive Indexes have to be in order to be not visible? I currently have a glass fiber at 1.521 and am researching resin systems to match and so far have 2 - one at 1.506 and the other at 1.4736. I know which one is better (1.506), but is it close enough to "disapear"?
 
Science news on Phys.org
It depends on how sensitive your measurement is. I've used an Abbe refractometer that measured the refractive index down to 0.1% error, and using index-matching fluids I've used differential interference microscopy to observe particles with an index mismatch slightly above that.

Have you talked with Cargille? Another company worth talking to is Norland. Either can help you with your specific application needs better than I.
 
You can calculate reflection coefficient using Fresnel equations: http://en.wikipedia.org/wiki/Fresnel_equations"

see also: http://reflectioncoefficient.info/"
 
Last edited by a moderator:
Thanks for the inquiries. Is there just a general rule of thumb for how far apart the RI's can be for the majority of materials or is there always other factors that can play a significant role in how well a material will "disapear" into another?
 

Similar threads

  • · Replies 6 ·
Replies
6
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 8 ·
Replies
8
Views
3K
  • · Replies 2 ·
Replies
2
Views
6K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 1 ·
Replies
1
Views
7K
  • · Replies 14 ·
Replies
14
Views
4K
  • · Replies 10 ·
Replies
10
Views
6K
  • · Replies 1 ·
Replies
1
Views
3K