Ellipsometry

geo_alchemist

Here is my situation:
According to ellipsometry theory the complex reflectance ratio can be expressed as

where tan([tex]\Psi[/tex]) is the amplitude ratio upon reflection and [tex]\Delta[/tex] is a phase shift.
On the other hand, as far as I now, phase shift upon reflection is [tex]\pi[/tex] or 0, depending on materials.
the question: is the [tex]\Psi[/tex] only variable that is being changed in wide range while [tex]\Delta[/tex] is either [tex]\pi[/tex] or 0 in all cases.

Sorry for not following subforum format, I just could not fit my question in it.

chrisk

Phase shifts of pi and 0 occur at normal incidence for s or p polarized light. Ellipsometry uses oblique angles of reflections and compares the phase shifts after reflection of the two states of polarized light. See the below link for a brief tutorial of ellipsometry.

http://www.jawoollam.com/tutorial_1.html

geo_alchemist

So it turnes out that s and p polarized lights are phase shifted differently upon reflection.
but why?