At an angle of incidence of zero degrees (normal incidence), the transmission of S and P polarizations is identical. This occurs because:
At normal incidence, the concepts of S and P polarizations do not apply.
The electric field vector of the incident light is always perpendicular to the direction of propagation.
There is no preferential orientation of the electric field relative to the plane of incidence.
Polarization Response
Vertical and horizontal polarizations will exhibit the same transmission response at normal incidence.
The filter's performance is uniform regardless of the polarization state of the incident light.
Implications for Filter Design
Filters designed for use at normal incidence do not need to account for polarization-dependent effects.
This simplifies the design process and allows for more predictable performance in applications where the light is incident perpendicular to the filter surface.
Understanding this behavior is crucial for accurately specifying and using optical filters in various applications, especially those requiring precise control of light transmission and polarization states.
