Light propagation through polarizers

In summary, when an unpolarized beam of light passes through a polarizer in the x-direction, all of the light is polarized in that direction. When another polarizer is added in the y-direction, no light is transmitted. However, when a third polarizer is added in the x+y direction, some light is transmitted due to the quantum behavior of polarizing filters. This behavior is different from normal filters which simply remove one aspect, and can be hard to visualize.
  • #1
Heirot
151
0
A beam of unpolarized light falls upon a polarizer which polarizes the light in e.g. x - direction. After that polarizer, we put another one which polarizes it along the y - direction. Of course, no light is transmited. Now we put a third polarizer between the first two, so that the third one polarizes the light in the x + y direction (the diagonal). Is any light transmited form the y - polarizer and if so, why? If not, why?
 
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  • #2
Why don't you give it a shot.
 
  • #3
I think that there will be some light because x-polarized light has a component in the x+y direction and also the x+y - polarized light has a component in the y-direction. So, putting in a third polarizer would act as a sorce of light. On the other hand, I always considered polarizers as some sort of filters so it confuzes me.
 
  • #4
here is the experiment on youtube
 
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  • #5
You're exactly right. And it is weird!---polarizers are a lot like filters, but this is a good example of quantum(like) behavior contradicting our intuition. Apparently polarizing filters are a little more complicated than normal filters---which simply remove one aspect, leaving everything but that aspect.

When light of one polarization passes through a polarizer, the amount of light that will be transmitted is proportional to the square of the cosine of the angle between the polarization and the polarization filter, i.e. [tex]\textrm{Prob} \propto \cos^2 \theta [/tex]. Thus for any non-90 degree angle, some light will go through, regardless of the previous history of polarization.
 
  • #6
What about classical waves (on a string)? On second thought, this might also apply to them. It's hard for me to visualise things like this.
 
  • #7
Take an X polarized beam. None of it will pass through a Y polarizer. Now run that beam through a 45 degree beam splitter and then recombine the outputs. That resulting beam will go through a Y polarizer at a 50% intensity.
 

What is a polarizer?

A polarizer is an optical filter that only allows light waves of a specific polarization to pass through, while blocking other polarizations. It can be made of various materials, such as polarizing film or polarizing crystals.

How does a polarizer affect the propagation of light?

A polarizer only allows light waves with a specific polarization to pass through, while blocking all other wave orientations. This results in a reduction of the intensity of the light passing through the polarizer, as well as a change in the direction of polarization of the transmitted light.

What is the difference between linear and circular polarization?

Linear polarization refers to light waves that oscillate in a single plane, while circular polarization refers to light waves that rotate in a circular motion. Linearly polarized light can be passed through a polarizer with its orientation aligned, while circularly polarized light cannot be fully transmitted through a polarizer.

How does the angle of incidence affect the transmission of light through a polarizer?

The angle of incidence, or the angle at which light hits the polarizer, affects the intensity of the transmitted light. The maximum transmission of light through a polarizer occurs when the angle of incidence is perpendicular to the polarizer's axis, and the minimum transmission occurs when the angle of incidence is parallel to the axis.

What are some real-life applications of polarizers?

Polarizers have various practical applications, such as in sunglasses to reduce glare and improve visibility, in LCD screens to control the intensity and color of light, in photography to enhance colors and reduce reflections, and in 3D glasses to create the illusion of depth by blocking light from one eye.

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