Regarding Polarizer and viewing sun

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Discussion Overview

The discussion revolves around the behavior of light when passing through polarizers, particularly in the context of viewing the sun and other strong light sources. Participants explore the implications of using two polarizers oriented at 90 degrees to each other and the unexpected visibility of bright light sources through them.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant notes that when looking at the sun through two perpendicular polarizers, they were still able to see the sun, questioning why this occurs if the polarizers should block all light.
  • Another participant suggests that the polarizers are not perfect and may allow some light to pass through, leading to the observed visibility of the sun.
  • A later reply emphasizes the imperfection of polarizers, mentioning varying qualities and extinction ratios that could explain the leakage of light.
  • Concerns are raised about the safety of looking at the sun through polarizers, as they do not adequately reduce infrared (IR) or ultraviolet (UV) light to safe levels.
  • Discussion includes the nature of the small leakage of light, with considerations of whether it is linearly or circularly polarized, affecting the ability to eliminate it by rotation.

Areas of Agreement / Disagreement

Participants generally agree that polarizers are not perfect and that this imperfection could explain the unexpected visibility of bright light sources. However, there is no consensus on the exact nature of the light leakage or the implications of viewing the sun through polarizers.

Contextual Notes

Participants mention limitations regarding the quality of polarizers and the potential dangers of viewing bright light sources without adequate protection. The discussion does not resolve the technical details of light polarization or the safety concerns raised.

Who May Find This Useful

This discussion may be of interest to those studying optics, light behavior, or safety considerations in experimental setups involving polarizers.

Sab95
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If two polarizers are placed 90 degree rotated to each other, we won't be able to see anything. But when I tried looking directly at sun, which I did only for a second, with that perpendicular pair of polarizers, I was still able to see the sun.
Shouldn't the sun disappear too ? Or why is it am able to see the sun ? Similarly it's applicable when I look at a strong source of light, like tube light or CFL bulbs.
 
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I expect that the polarizers are not perfect and let some small amount of light through.
 
Sab95 said:
If two polarizers are placed 90 degree rotated to each other, we won't be able to see anything. But when I tried looking directly at sun, which I did only for a second, with that perpendicular pair of polarizers, I was still able to see the sun.
Shouldn't the sun disappear too ? Or why is it am able to see the sun ? Similarly it's applicable when I look at a strong source of light, like tube light or CFL bulbs.
I think it is just imperfection in the polarisers. They seem to vary in quality, because those I have here will block ordinary light bulbs. To obtain the very high re
Drakkith said:
I expect that the polarizers are not perfect and let some small amount of light through.
First of all, may I mention that it is unsafe to look at the Sun through the polarisers because they do not reduce IR to a safe level.
Regarding being able to see the Sun through them, polarisers are not perfect. I have found examples on the Net with "extinction ratio" from 0.5% to 0.005%. It is interesting to consider the nature of the small leakage. If it is linearly polarised, it will be possible to remove it by rotating the polariser very slightly. But if it is circularly polarised, then it will not be possible to remove it by rotation. This situation will happen if the film causes different phase shifts for the two linear polarisations.
 
tech99 said:
<snip>First of all, may I mention that it is unsafe to look at the Sun through the polarisers because they do not reduce IR to a safe level. <snip>

Excellent point- and UV light, as well.
 

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