Polarization plays a central role in Fresnel’s equations because the amount of light reflected and transmitted at a boundary depends on the orientation of the light’s electric field relative to the plane of incidence.
Light can be polarized in two main ways when it strikes a surface:
1. S-Polarized Light (Perpendicular Polarization):
- The electric field is perpendicular to the plane of incidence.
- Fresnel’s equations show that this type of light always experiences some reflection, and the reflectance increases as the angle of incidence increases.
- There is no angle where reflection becomes zero.
2. P-Polarized Light (Parallel Polarization):
- The electric field is parallel to the plane of incidence.
- The reflectance for p-polarized light decreases with angle and becomes zero at the Brewster angle, where the reflected and refracted rays are at 90° to each other.
- Beyond this angle, reflectance increases again.
Why It Matters:
- Polarization affects how much light is reflected or transmitted.
- This explains why glare from surfaces like water or glass can be reduced using polarizing filters that block specific polarizations.
- It also helps in designing optical coatings, lenses, and fiber optics, where controlling polarization is crucial.