This filter separates S and P waves and there are two types: prism and plate.

It is frequently used for LD pick up such as DVD, etc.

There is also a non-polarization beam splitter where the polarization component has the same reflection ratio.

There is also a half mirror (semi transparent mirror) that separates light to transparent and reflected light.

The inflection ratio must be stable to increase the accuracy of reproduction.

Design optical characteristics that you desire using some types of inflection ratio and thin film.