The Smartec infrared sensors SMTIR99XX are sophisticated full silicon infrared sensors and comprise of so called thermopiles. Thermopiles are based on the Seebeck effect, which is a long time standard for conventional thermocouples. The application of thin film technology allows the production of miniaturised and low cost sensor elements. For specific applications there is a version with a small openings angle (7°).
The sensors can be used in measuring the radiation temperature without any contact. For different radiation temperature ranges various filters are available. The sensor type SMTIR9902 contains a temperature sensor for measuring the temperature of the sensor itself. The temperature range of the sensor-element is between -40 to 100 °C. The sensor is available in a standard TO-05 encapsulation and is standard wise equipped with a 5.5 micrometer filter. For a small field of view there is an infrared sensor available with a silicon lens.
The output voltage is generated by a thermopile, formed by a series connection of thermojunctions deposited on a silicon substrate. The hot junctions are thermally isolated from the cold junctions on the substrate by etching an extremely thin membrane. A black absorbing layer on the hot junctions transform the incoming radiation into heat. A voltage proportional to the radiation is generated by the thermoelectric effect.
The used thermopiles are processed on silicon substrates using BiSb and NiCr for the thermojunctions. For different radiation spectra various filters are available to get the optimal solution.
Easy and accurate measuring of the sensor temperature can be done with a built-in temperature sensor (only for type SMTIR9902).
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