Polarisation of reflected light

[sperryrand]

Hi,

I have a question regarding the projection of polarised light onto a screen, such as commonly used in 3D or VR cinemas. I'm only concerned with linearly polarised light for the moment.

I understand that when light undergoes reflection the polarity is altered.
I've attached a diagram. Light from projector is typically polarised at 45 degrees to the horizontal.
My question is, is the polarity of the reflected light a function of:

a) angle of incidence θ_i,
b) the angle of reflectance to the eye θ_v,
c) or the difference between v and r: θ_vr, or
d) none of the above?
​

Is there a simple expression, or does it depend greatly on the optical properties of the screen material? Does the Brewster angle have anything to do with this?

Thanks in advance,
M

 

[UltrafastPED]

You can use the Fresnel equations for s and p polarized light; this is discussed in detail here:
http://www.semrock.com/understanding-polarization.aspx

See section 4.

 

[sperryrand]

Hi,

Thanks. A few things are unclear to me..
a) How do I use these equations for an opaque material, where there is no transmittance or refraction? (What is the refractive index of an opaque material?)
b) These equations seem to tell me the amount of light reflected or transmitted along r - the reflection of i. But I need the ratio of the "p" component to the "s" component for light scattered in all directions.
Sorry if I am missing something obvious.
M

 

[UltrafastPED]

You mean like a metallic surface? There is a discussion here:
http://books.google.com/books?id=OB...&q=polarization reflected light metal&f=false
Here is an older discussion: https://www.physicsforums.com/showthread.php?t=175337

 

[nasu]

Hi,

I've attached a diagram. Light from projector is typically polarised at 45 degrees to the horizontal.

It's not clear if you are really interested in 3D projection or just in the phenomenon itself.
But I thought that in 3D projection they use circular polarization.

 

[sperryrand]

Hi,

I'm interested in the degradation of stereo contrast (i.e. increase in cross-talk) caused by high angles of incidence and reflection.
Yes, in some theatres it is circular, but in others linear. Here, I have a linear system.
M