Beam Splitters
Beam splitters are optical components that provide a specific function within the detector. The incident radiation beam is split into several sub-beams. While one sub-beam can be used as a reference signal, the remaining sub-beams provide the actual measurement signal.
Because all partial beam bundles travel along identical optical path lengths before reaching the detector, interfering effects can be easily compensated. This improves the stability and accuracy of the measurement (for example, through drift correction).
Semi-transparent mirrors, prisms, and other optical assemblies are used as beam splitters.
Beam Splitter Detectors: Precise and Long-Term Stable Measurement Results
The principle of beam splitting offers the advantage that mechanical expansion in the optical system of the measuring device, aging effects, or potential contamination act on these detectors prior to beam splitting, and therefore affect all channels equally. The consistently stable signal ratio between the individual channels produced by the beam splitter thus ensures a high degree of measurement accuracy.
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Reflective Beam Splitters – A Special Type of Beam Splitter
Beam splitter detectors utilize various types of beam splitters—InfraTec uses only pure reflection beam splitters for its multi channel detectors. These are composed of highly reflective gold-coated microstructures with a very high reflectivity in the infrared spectral range. The design of the reflection beam splitters varies depending on the detector type: In quad channel detectors, they resemble four-sided micro-pyramids, whereas in dual channel detectors, they consist of V-shaped grooves.
In contrast to conventional multi channel detectors, beam splitter detectors have only a single aperture. The incoming radiation is split within the detector by microstructures into several sub-beams of equal intensity travelling in different directions. Each of these sub-beams then strikes a pyroelectric sensor element equipped with an upstream optical filter.
The incident radiation strikes the IR filters in the TO8 detector (with four spectral channels) perpendicularly and subsequently reaches the pyroelectric element. This additional advantage simplifies the requirements for the IR filter specification and provides extremely precise results, particularly in gas analysis. Perpendicular incidence of the radiation on the TO39 detector (with two spectral channels) is not feasible due to geometric constraints, which must be taken into account when selecting the IR filters.
For installation in a gas cell, both TO39 and TO8 configurations require an effective aperture of only 2.5 mm. The very low dead volumes of the measurement system result in faster gas exchange. By taking advantage of this effect, measurement devices equipped with beam splitter detectors can be made correspondingly smaller.
Detector Search
InfraTec offers different product groups including approximately 50 standard pyroelectric detectors. Detectors with reduced microphone technology and integrated operational amplifier as well as digital detectors are part of our product range.
Choose your suitable infrared detectors with the help of our detailed detector search.
