Beam splitters

Beam splitters are optical components that split incoming radiation beams into various parts. The splitting can take place within a specific intensity ratio, according to various wavelengths or polarization orientations. To produce such effects various optical designs are used. Semi-permeable mirrors are often used, whereby one proportion of the radiation is reflected and the other is passed through. However, prisms and other configurations can also be utilized. For example, pure reflection beam splitters reflect the incoming radiation in various directions respectively. Such reflection configurations are particularly well suited in the infrared spectral range mainly due to the very high degree of reflection properties of most metals there. Furthermore, they can be designed to allow the exact same reflected intensities of the individual radiation beams with simple constructive solutions.

Reflection beam splitters – a specific kind of beam splitters

Beam splitter detectors by InfraTec

The beam splitters used by InfraTec in multi channel detectors are solely reflection beam splitters and consist of highly reflective gold plated microstructures. The radiation entering through the aperture opening of the detector is split into several radiation beams of equal intensity but in different, predefined directions within the detector based on the architecture of the innovative microstructure inside. Each of the beams impinges on a corresponding pyroelectric sensor element with an upstream optical filter. The microstructures vary according to the detector type. In four channel detectors these resemble four-sided micro-pyramids, whereas in dual channel detectors these are V-shaped grooves.

Accurate and stable measurement results over the long term

Unlike conventional multi channel detectors, beam splitter detectors only have one single aperture opening. Thus, major parts of the incoming radiation impinge vertical to the pyroelectric crystal, which allows for very precise gas analysis particular in gas detection technology. Hence, a gas cell with an effective diameter of just 2.5 mm is sufficient. Apart from an accelerated exchange of gas, this results in very low dead volumes of the measuring system. Measurement devices equipped with the detector can be correspondingly smaller. The permanently stable signal ratio between the individual channels ensures a high degree of measurement accuracy. This is because mechanical expansions in the optical system of the measurement device, ageing effects or any possible contamination in these detectors are already accounted for before the beam is split and thus affect all channels equally.