Camera Lens works as a Polarizer or not?

[Mustafa Umut]

I read maxwell says electric field polarizes the dielectrics.

Does it mean above effect used at photographic camera lens design to make that lens sometimes works like polarizer filter ?

Mustafa Umut Sarac
Istanbul

 

[berkeman]

No, they are different effects that share the same name.

I believe the effect that you are referring to Maxwell about is the polarization of a dielectric due to an external electric field. This just means that the charges in the dielectric are displaced from their equilibrium distribution by the external E-field.

Polarization of light (and other frequencies of EM radiation) refers to the majority of the EM E-field's orientation in space. Passing unpolarized light through a polarizing filter attenuates the light that is not oriented with the axis of the polarizing filter, and only let's the light through that has an AC EM E-field oriented with the axis of the filter.

I'll see if I can find a few references for further reading for you to help clear this up. Will post them in a few minutes...

 

[berkeman]

Here are a couple of wikipedia articles that should help. Please read through them and let us know if you have follow-up questions, or if the difference makes sense now.

https://en.wikipedia.org/wiki/Dielectric#Dielectric_polarization

https://en.wikipedia.org/wiki/Polarizer

 

[Mustafa Umut]

thank you , I will.

 

[berkeman]

By the way, there is an application that uses both of those effects at the same time, and you are probably reading this reply on one of those devices right now -- a Liquid Crystal Display.

https://en.wikipedia.org/wiki/Liquid-crystal_display

Electric fields are used to polarize and physically move mobile liquid crystal structures to create different kinds of polarizers (generally switching between random polarization and circular polarization) rotations of the plane of the polarized light (RPPL) in the liquid crystal. This varying polarization rotation in the liquid crystal interacts with fixed polarizers on the glass display to gate light through the pixels in the display. It's an interesting technology that has matured a lot over the last 30 years or so, and has brought us the most common high-resolution video displays that we use today in so many applications.

EDIT -- Fixed up my brief explanation about how polarization is used in LCDs (RPPL is the key).

EDIT / ADD -- here is a nice diagram showing the layers of a typical LCD screen:

http://www.mmt.io/wp-content/uploads/2015/08/LCD-Panel-FunctionalityInfographic-English_580px.jpg