Refractive Index: Methods for Determining Beyond Newton's Rings

  • Context: Undergrad 
  • Thread starter Thread starter Berdi
  • Start date Start date
Click For Summary

Discussion Overview

The discussion revolves around methods for determining the refractive index of materials, specifically exploring alternatives to the Newton's Rings method. Participants consider various techniques applicable in experimental settings.

Discussion Character

  • Exploratory, Technical explanation, Experimental/applied

Main Points Raised

  • One participant mentions using Newton's Rings to determine the refractive index of water and inquires about other methods.
  • Another participant suggests that total internal reflection (TIR) measurements, particularly critical angle measurement, provide highly sensitive refractive index determinations.
  • A different viewpoint introduces Brewster's Angle as a method that allows for measuring the refractive index of opaque objects.
  • Another participant proposes using an interferometer to compare the path lengths of coherent waves in different media, noting that this method is conceptually similar to Newton's Rings.

Areas of Agreement / Disagreement

Participants present multiple methods for determining refractive index, indicating a lack of consensus on a single best approach. Various techniques are discussed without resolution on their relative effectiveness.

Contextual Notes

Some methods mentioned may depend on specific conditions, such as the homogeneity of particles for Mie scattering or the coherence of light in interferometry. The accuracy of different methods is also noted to vary.

Who May Find This Useful

This discussion may be of interest to students and researchers in experimental physics, optics, and materials science looking for alternative methods to measure refractive index.

Berdi
Messages
12
Reaction score
0
So, I was in my Undergraduate Labs yesterday, using Newton's Rings to determine the Refractive index of water. I was just wondering, other than measuring the angles of incident and refracted beams, if there were many other methods to determine refractive index?
 
Science news on Phys.org
The most sensitive measurements, AFAIK, use total internal reflection (critical angle measurement).

For small homogeneous particles, the refractive index can be measured via scattering (Mie scattering), but the accuracy is not as good as TIR.
 
You might also look up "Brewster's Angle". This even let's you measure the index of refraction of opaque objects.
 
You can use an interferometer to compare the distance a coherent wave goes in air (or ieally vacuum) with one going through an other medium and see how they add up - this is essentially what Newton's rings is doing.
 

Similar threads

Graduate Feasibility of Micro‑Plasma–Induced Refractive‑Index Phase Modulation
  • · Replies 5 ·
Replies
5
Views
685
Graduate When should I analyze optical problems using ray tracing vs. wavefront analysis?
  • · Replies 12 ·
Replies
12
Views
2K
Graduate Free‑Carrier Index Modulation in Thin Transparent Layers at Visible Wavelengths
  • · Replies 2 ·
Replies
2
Views
575
Undergrad Why is Cherenkov radiation blue? And what about refractive index?
  • · Replies 3 ·
Replies
3
Views
2K
Undergrad Prism Spectrometer Objective: Optics Question
  • · Replies 9 ·
Replies
9
Views
3K
Undergrad Photodetector Output & Refractive Index of FO Cladding/Coating
  • · Replies 1 ·
Replies
1
Views
2K
Undergrad Newton's Rings using refractive index of water
  • · Replies 4 ·
Replies
4
Views
3K
Undergrad Colloid complex refractive index from UV-vis spec
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad How does optical density relate to mass density and refractive index?
  • · Replies 7 ·
Replies
7
Views
20K
Graduate Reflection and transmission of waves in a medium of nonuniform density
  • · Replies 10 ·
Replies
10
Views
3K