The progress in the miniature drive technology and high-precision mechanics makes it possible to use the classic filter wheel spectrometer in a much more competitive and compact form for multi component gas analysis. In contrast to the multi-color detectors, the measuring signal is available in a series through the very same optical and electrical channel. However, for a constant metering time period the modulation frequency of the IR detector rises with a higher channel number. InfraTec GmbH (www.InfraTec.de) builds 11 types of fast pyroelectric detectors in Dresden, which work at modulation frequencies up to several kHz at a high detectivity.
The pyroelectric detector LIE-200 in the TO-18-body (ø4.7mm) contains a JFET as impedance converter, along with feedback components that in combination with an external operational amplifier (OpAmp) comprise the electrical circuit of the pyroelectric elements. 25µm thin pyroelectric chips of Lithium Tantalate (LiTaO3), coated with a spectral broadband blackening, allows for modulation frequencies up to several kHz. The detector LME-353 (TO-39-body) has an integrated transimpedance amplifier and generates a flat signal at 10Hz to 500Hz at a high voltage sensitivity of more than 8,000 V/W without an additional external component. Broadband detector windows like CaF2, BaF2 or Si ARC are recommended.
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