Is P-Polarization Essential for Effective Laser Cutting on Target Surfaces?

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Discussion Overview

The discussion revolves around the role of p-polarization in laser cutting processes, particularly in relation to the effects of different polarization states on target surfaces. Participants explore the implications of polarization on laser ablation, the physical principles involved, and the conditions under which these effects are observed.

Discussion Character

  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant asserts that a p-polarized laser beam irradiated normally on a target surface results in an electric field parallel to the surface, suggesting this has a significant effect on the target.
  • Another participant questions whether the electric field is not parallel for other polarizations and asks for clarification on the term "great effect."
  • It is noted that with oblique incidence, the electric field will not be parallel to the surface, particularly in s-polarized beams.
  • Clarifications are requested regarding the definitions of "normally on the target" and "p-polarized," with an emphasis on the degeneracy of polarization states at normal incidence.
  • A participant relates the discussion to an ablation experiment and seeks to understand the rationale behind choosing p-polarization.
  • Some participants suggest that the right polarization could maximize ablation effects, particularly when considering the angle of incidence.
  • One participant explains that using p-polarized light can lead to lower reflection from steep channel walls, resulting in a more regular cut compared to s-polarized light, which may yield deeper cuts.
  • Another participant requests resources to support the explanation of polarization effects in laser cutting.
  • Responses indicate that the effects discussed are basic and can be found in optics textbooks and numerous papers on laser cutting experiments.

Areas of Agreement / Disagreement

Participants express varying views on the implications of polarization in laser cutting, with some agreeing on the significance of p-polarization while others raise questions about the conditions and definitions involved. The discussion remains unresolved regarding the definitive advantages of one polarization over another in specific contexts.

Contextual Notes

Participants highlight the dependence of polarization effects on the angle of incidence and the geometry of the cutting process, indicating that assumptions about the polarization state may vary based on experimental conditions.

Amany Gouda
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if I have laser beam irradiated normally on the target surface and in the same time time it is p- polarized. under these conditions, we will have the electric field which is completely parallel to the target surface and have a great effect on the target surface.
my questions is;
is this statement correct physically. if yes, which law or equation can confirm this statement
 
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Is the electric field not parallel to the target surface for other polarizations?

How do you quantify "great effect"?
 
if you have laser beam with oblique incidence then you will not get electric field parallel to the surface especially in s- polarized beam.
 
Please clarify what you have in mind "normally on the target" and "p-polarized".Polarization state is defined in reference to the laser incident plane, so if your beam falls perpendicularly to the target your polarization state is in degenerate state (p-and s- polarization are the same). Are you performing some ablation/laser cutting experiments?
 
Domullus said:
Please clarify what you have in mind "normally on the target" and "p-polarized".Polarization state is defined in reference to the laser incident plane, so if your beam falls perpendicularly to the target your polarization state is in degenerate state (p-and s- polarization are the same). Are you performing some ablation/laser cutting experiments?
yes, you are true. this is related to ablation experiment. and the choice of the p-polarized is done by my boss and I am try to understand why that happen by adding some physical explanation.
 
Amany Gouda said:
if you have laser beam with oblique incidence then you will not get electric field parallel to the surface especially in s- polarized beam.
The first post was about a normal angle of incidence.

For other angles: yeah, I can imagine that the right polarization maximizes ablation.
 
mfb said:
The first post was about a normal angle of incidence.

For other angles: yeah, I can imagine that the right polarization maximizes ablation.
now I am try to find the required law to ensure the difference between p-polarization and s- polarization for my case
 
I understand your problem. I guess you use polarization perpendicular to laser cutting direction. This is indeed p-polarized beam. Why? Imagine that you move laser beam and ablate a narrow channel. When you translate laser beam second time along this channel, you can distinguish separate polarizations, because your incidence angle is not perpendicular anymore (your reference plane is the walls of the channel). As channel is rather steep, you are close to Brewster angle at this stage, therefore with p-polarized beam you will get lower reflection from the walls. If you use s-polarized light (parallel to cutting direction), greater amount of light will be reflected from the walls. Usually with p-polarized beam you will get more regular cut, but with s- polarized - deeper cut.
 
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Domullus said:
I understand your problem. I guess you use polarization perpendicular to laser cutting direction. This is indeed p-polarized beam. Why? Imagine that you move laser beam and ablate a narrow channel. When you translate laser beam second time along this channel, you can distinguish separate polarizations, because your incidence angle is not perpendicular anymore (your reference plane is the walls of the channel). As channel is rather steep, you are close to Brewster angle at this stage, therefore with p-polarized beam you will get lower reflection from the walls. If you use s-polarized light (parallel to cutting direction), greater amount of light will be reflected from the walls. Usually with p-polarized beam you get more regular cut, but with s- polarized - deeper cut.
wonderful explanation, is there any official resource (books, articles,..etc) to explain this fact.
 
  • #10
I am not sure. It is rather basic effects and you can refer to any optics textbook (Fresnel equation, Brewster angle, polarization). There are myriads of papers on laser cutting experiments where you can read about polarization effects :)
 
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  • #11
Domullus said:
I am not sure. It is rather basic effects and you can refer to any optics textbook (Fresnel equation, Brewster angle, polarization). There are myriads of papers on laser cutting experiments where you can read about polarization effects :)
thank you very much.
 

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