The beamsplitter (BS) plate is a thin optical glass plate. The first face is coated with an all-dielectric thin film having partial reflection properties. The second surface is AR coated for 45° or some other specified incident angle. As an alternative, the second surface may be angled with respect to the front surface (wedge) in order to avoid interference effects. In this case, the direction of the transmitted beam is not parallel to the input direction and the beam shape is slightly distorted.
This beamsplitter may also be designed for low absorption and high damage threshold, suitable for high energy laser applications where cemented cubes may fail.
We provide three kinds of plates, distinguished by the polarization of the incoming and outgoing beams. Unpolarized BS plates (narrow band and broad band), generate partially polarized outgoing beams for randomly polarized incoming light. Polarized plates (narrow band only) generate both s-polarized and p-polarized beams from randomly polarized incoming light. For non-polarizing BS plates (narrow band only), the polarization of the outgoing beams remains the same when the incoming beam is 45° linearly polarized or circularly polarized. The functional features of these designs are similar to the respective cube polarizers.
Plate beamsplitters can be manufactured in almost any shape: round, rectangular, elliptical, or any other shape including cut-outs and drill holes. Holes may also be drilled at an angle to the surface normal.