Does Phase Change on Reflection Violate Stokes Relation?

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Discussion Overview

The discussion centers on the phase changes that occur during light reflection, specifically examining whether the observed differences in phase shifts during external and internal reflections violate Stokes Relation. The scope includes theoretical considerations and interpretations of optical phenomena.

Discussion Character

  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants note that reflected light experiences a phase shift of π during external reflection but no phase shift during internal reflection, questioning if this contradicts Stokes Relation.
  • Others reference their studies in Interference in Dielectric Films, stating that external reflection results in a phase change of π, while internal reflection results in no phase change, suggesting a conflict with Stokes Relation.
  • A participant mentions the importance of considering time reversal in the context of phase changes, implying that the relationship between incident and emerging beams may be relevant to the discussion.
  • Some participants share resources, such as lecture notes, to further explore the topic, although access issues with the materials are noted.

Areas of Agreement / Disagreement

Participants express differing views on whether the phase changes observed in reflection violate Stokes Relation. There is no consensus on the implications of these phase shifts, and the discussion remains unresolved.

Contextual Notes

Participants reference specific conditions under which phase changes occur, highlighting the dependence on the refractive indices of the media involved. The discussion includes unresolved assumptions about the implications of these phase changes in relation to established principles.

tanaygupta2000
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We know that reflected light undergo a phase shift of π in EXTERNAL REFLECTION but there is no phase shift in INTERNAL REFLECTION . Does this violate Stokes Relation, which states that every reflected beam undergo of phase shift of π ?
 
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Hi and welcome to PF.
I found this YouTube video which you may find satisfactory. What do you think?
 
sophiecentaur said:
Hi and welcome to PF.
I found this YouTube video which you may find satisfactory. What do you think?
This video is useful in understanding of Stokes Relations but not where they are used
 
tanaygupta2000 said:
This video is useful in understanding of Stokes Relations but not where they are used
Yes. It's not in depth but I can't see that Stokes actually contradicts the result of continuity of fields across the boundary.
 
sophiecentaur said:
Yes. It's not in depth but I can't see that Stokes actually contradicts the result of continuity of fields across the boundary.
True. But it clashes with what I have studied in Interference in Dielectric Films :

(1.) Phase changes by π in external reflection (i.e. reflection in rarer medium when the reflected ray bounces off the boundary of a denser medium).

(2.) Phase changes by 0 (i.e. NO PHASE CHANGE) in internal reflection (i.e. reflection in denser medium when the reflected ray bounces off the boundary of a rarer medium).

(3.) No phase change in any of refraction.

According to Stokes Relation, point (2.) should be false but according to Interference in Dielectric Films, it should be correct.

[emoji54]
 
The phases involved are the result of the change in refractive index in the two directions.
tanaygupta2000 said:
True. But it clashes with what I have studied in Interference in Dielectric Films :

(1.) Phase changes by π in external reflection (i.e. reflection in rarer medium when the reflected ray bounces off the boundary of a denser medium).

(2.) Phase changes by 0 (i.e. NO PHASE CHANGE) in internal reflection (i.e. reflection in denser medium when the reflected ray bounces off the boundary of a rarer medium).

(3.) No phase change in any of refraction.

According to Stokes Relation, point (2.) should be false but according to Interference in Dielectric Films, it should be correct.

[emoji54]
We can't argue with what you've learned about dielectric films. (I assume you were getting the right story!) so I guess you need to look at what it actually implied by this time reversal notion with rays. Time reversing involves two incident beams, which need to be the same as the emerging beams. Could that be what you are ignoring when you reckon you've found a flaw? My problem is that it all seems OK to me - but that could just be because I haven't thought deeply enough about it. :wink:
 
tanaygupta2000 said:
True. But it clashes with what I have studied in Interference in Dielectric Films :

(1.) Phase changes by π in external reflection (i.e. reflection in rarer medium when the reflected ray bounces off the boundary of a denser medium).

(2.) Phase changes by 0 (i.e. NO PHASE CHANGE) in internal reflection (i.e. reflection in denser medium when the reflected ray bounces off the boundary of a rarer medium).

(3.) No phase change in any of refraction.

According to Stokes Relation, point (2.) should be false but according to Interference in Dielectric Films, it should be correct.

[emoji54]

You might want to look at this lecture notes:

http://web.mit.edu/6.161/www/Basic_Electromagnetics-FT07.pdf

Zz.
 
tanaygupta2000 said:
sorry it is showing error opening in webpage
The first two pdf pages appear blank but I can see stuff further down the document.
 
  • #10
sophiecentaur said:
The first two pdf pages appear blank but I can see stuff further down the document.
sorry no downward or sideward scrolling is there. Upward scrolling causes the page to reload
 
  • #11
tanaygupta2000 said:
sorry no downward or sideward scrolling is there. Upward scrolling causes the page to reload
I can read it all, afaics. Try a different browser, perhaps. I used Safari on the latest OS X.
Edit: You mentioned sideways scrolling so you are using a mobile, I guess.
 
Last edited:

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