Need help with question regarding polarization filters

In summary, when un-polarized light is incident upon two polarization filters with misaligned transmission axes and 18% of the light passes through, the angle between the transmission axes is 53 degrees. This can be calculated using the formula I = Imax(cosΦ)^2, where the intensity of the transmitted light is exactly half of the incident un-polarized light.
  • #1
ZHIHUI
3
0
Moved from a technical forum, so homework template missing
Un-polarized light is incident upon two polarization filters and do not have their transmission axes aligned. If 18% of the light passes through this combination of filters, what is the angle between the transmission axes of the filters.

I got 64 degrees using I = Imax(cosΦ)^2 but the correct answer is 53 degrees.

Thank you very much!
 
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  • #2
What happens when the light hits the first filter?
 
  • #3
DrClaude said:
What happens when the light hits the first filter?
The light will be linearly polarized. If the first filter is ideal, intensity of the transmitted light will be exactly half that of the incident un-polarized light.
 
  • #4
ZHIHUI said:
The light will be linearly polarized. If the first filter is ideal, intensity of the transmitted light will be exactly half that of the incident un-polarized light.
Correct. So how does that affect the terms in your equation?
 
  • #5
DrClaude said:
Correct. So how does that affect the terms in your equation?
I got it!
Thank you very much!
Sorry for the trouble!
 
  • #6
ZHIHUI said:
I got it!
Thank you very much!
Sorry for the trouble!
No trouble, that what PF is for!
 

1. What is a polarization filter?

A polarization filter is a type of optical filter used to reduce glare and reflections from surfaces. It works by only allowing light waves with a specific orientation to pass through, blocking all other orientations. This results in a clearer, less distorted image.

2. How does a polarization filter work?

A polarization filter is made up of a material that has microscopic parallel lines, known as polarizers, embedded in it. These polarizers only allow light waves with a certain orientation to pass through, while blocking all other orientations. When light passes through a polarization filter, the filtered light becomes polarized in the same direction as the polarizers, resulting in reduced glare and reflections.

3. What are the applications of polarization filters?

Polarization filters are commonly used in photography, especially for outdoor shots where there is a lot of glare, such as in landscapes or water scenes. They are also used in sunglasses to reduce glare and improve visibility. Other applications include LCD screens, 3D glasses, and scientific instruments.

4. Can polarization filters be used with all types of cameras?

Yes, polarization filters can be used with both digital and film cameras. However, they are most effective when used with cameras that have manual exposure and focus control, as this allows for more precise adjustments to the filter.

5. How do I choose the right polarization filter for my camera?

The first step in choosing the right polarization filter is to determine the size of your camera's lens. This can usually be found on the front of the lens or in the camera's manual. Then, consider the type of photography you will be doing and the level of polarization you need. Circular polarizers are recommended for autofocus and digital cameras, while linear polarizers are better suited for manual focus and film cameras. Finally, consider your budget and the brand of the filter, as higher quality filters tend to produce better results.

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