Classical optics: Lambda-quarter plates

Click For Summary

Discussion Overview

The discussion revolves around the use of lambda-quarter plates in optics, specifically regarding the conversion of linearly polarized light to circular polarization (σ+ or σ-) in the context of a magnetic field. Participants explore the mechanics of polarization transformation and the characteristics of optical components.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions how to determine whether a lambda-quarter plate produces σ+ or σ- polarization and whether calibration is necessary.
  • Another participant points out that the magnetic field does not align with the polarization direction, emphasizing that polarization is defined by the electric field.
  • There is a suggestion that a half-wave plate, rather than a quarter-wave plate, is needed to rotate linearly polarized light, depending on the definitions of π- and σ- polarization.
  • A participant notes that lambda/4 wave plates should indicate the orientation of their fast and slow axes, which affects the resulting polarization state based on the incoming light's polarization.

Areas of Agreement / Disagreement

Participants express differing views on the appropriate use of wave plates for polarization conversion, with some confusion regarding the definitions of polarization types and the role of the magnetic field. No consensus is reached on the correct approach or terminology.

Contextual Notes

There are unresolved aspects regarding the definitions of π- and σ- polarizations, as well as the implications of the magnetic field's orientation relative to the polarization of light.

Niles
Messages
1,834
Reaction score
0
Hi

Say I have a magnetic field point in some well-known direction, and I have linearly polarized light incident in that direction. I want to convert my π-polarization to σ-polarization, so I find my lambda-quarter plate.

However, how do I know whether it produce σ+ or σ-? Do they come with a manual, or do people calibrate them by themselves? I'm not sure how I would do this.


Niles.
 
Science news on Phys.org
I'm confused by your question- first, the magnetic field will not point along the polarization direction, the polarization is defined by the electric field. Second, to rotate linearly polarized light (if π- and σ- refer to p- and s-polarized) you would use a 1/2 wave plate, not a 1/4-wave plate.
 
lambda/4 wave plates should have some indication where the fast and the slow axes are. The orientation relative to the (linear) polarization of incoming light will determine how the polarization afterwards looks like.
 
Andy Resnick said:
I'm confused by your question- first, the magnetic field will not point along the polarization direction, the polarization is defined by the electric field. Second, to rotate linearly polarized light (if π- and σ- refer to p- and s-polarized) you would use a 1/2 wave plate, not a 1/4-wave plate.
Hi

What I meant was tbat B points along some direction I call z. My laser propagates along z too, and it is linearly polarized perpendicular to z. I want to convert this linear polarization to σ+ (wrt. to z).
mfb said:
lambda/4 wave plates should have some indication where the fast and the slow axes are. The orientation relative to the (linear) polarization of incoming light will determine how the polarization afterwards looks like.
Hi

Thanks for that.
 

Similar threads

  • · Replies 5 ·
Replies
5
Views
2K
Replies
12
Views
2K
  • · Replies 5 ·
Replies
5
Views
3K
  • · Replies 5 ·
Replies
5
Views
5K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 4 ·
Replies
4
Views
3K
  • · Replies 4 ·
Replies
4
Views
2K
  • · Replies 8 ·
Replies
8
Views
5K
  • · Replies 1 ·
Replies
1
Views
2K
  • · Replies 1 ·
Replies
1
Views
10K