Register to reply

Fresnel amplitude coefficients for unpolarized light

Share this thread:
Jan22-13, 12:58 AM
P: 10
I have an issue with the Fresnel amplitude coefficients. I know they are given in two versions, for s-polarization and p-polarization. A version for unpolarized (randomly polarized) light is available for the power coefficients - it's just an average - but I could not find such an expression for the amplitude coefficients. From the power coefficient average expression I get:

$$r_\text{avg} = \sqrt{\frac{|r_s|^2 + |r_p|^2}{2}}$$

Which is obviously wrong, since this value is always real and positive which doesn't make sense for amplitude coefficients (I think).

So is there a simple expression for the average fractional amplitude of the reflected light assuming light is randomly polarized (equal amount of s-polarized and p-polarized waves)? And can the result be extended to an arbitrary proportion of s-polarized and p-polarized waves (say 25%, 30%, etc..)

Or does it simply not make sense to try and find an average of amplitudes? I need this to analyze interference effects, I could go with two versions dependent on the polarization of light, and average the final reflectance at the end, but it seems cleaner and easier to have a single expression. Thanks...

I should mention this is for a computer graphics project and I do not know that much about electromagnetism, please go easy on me :)
Phys.Org News Partner Physics news on
UCI team is first to capture motion of single molecule in real time
And so they beat on, flagella against the cantilever
Tandem microwave destroys hazmat, disinfects

Register to reply

Related Discussions
Unpolarized light Classical Physics 6
What is unpolarized light? General Physics 5
Fresnel power Coefficients Advanced Physics Homework 2
Fresnel Reflection and Transmission Coefficients General Physics 1
Fresnel coefficients General Physics 0