Optical beamsplitters play a vital role in many laser-based measurement and positioning systems. Although the operation of a typical beamsplitter is conceptually simple, its performance characteristics can dramatically affect the accuracy and repeatability of the overall system. Consequently, understanding the variables that distinguish beamsplitter performance is an important step in comparing and specifying components. There are two basic types of beamsplitters:

  • Non-polarizing beamsplitters (NPBS): This type of splitter is used to divide (split) a beam into two beams and each output beam is a fraction of the incoming beam regardless of the polarizations. Non-polarizing beamsplitters are used in a variety of applications in optical instrumentation to distribute fractions of a laser beam to other optical sub-assemblies. The listed split percentage tells you the percentage of power of the beam that is split off (reflected) of the main path. The split path is typically at 90 degrees to the main path.
  • Polarizing beamsplitters (PBS): This type splitter is used to separate the S- and P-polarization components of a beam. Polarizing beamsplitters are used in a variety of applications including optical instrumentation, laser interferometry, and biomedical applications. Polarizing beamsplitters typically come in cube form but custom geometries are available as well.

The performance of the beamsplitter is determined by the quality of the glass, the optical surfaces, and the optical coatings that are used.

To select a suitable beamsplitter, you need to consider the form-factor, glass-homogeneity, coating, transmission range and damage threshold.

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