The first infrared measurement systems have been developed in the second decade of the 19th century. At that time L. Nobili had the idea of connecting several bismuth-copper thermocouples in series, generating a higher output voltage that allows the remote measurement of small surface temperatures. During the last 30 years infrared sensors have been developing from niche products to mass market applications. While in the nineteen-eighties most progress in infrared sensing has been achieved in high-end products such as military night vision systems or infrared space telescopes, current developments are equally driven by consumer products. However, in numerous applications NDIR sensors can still not compete with other sensors due to the elevated system costs. Since the single components are already cost-optimized, different ways, such as a standardization of the sensor hardware, have to be found to increase the overall attractiveness. The present work investigates a novel and completely different approach: instead of narrow bandwidth transmission filters with specifically adapted center wavelengths broadband filters, which have not to be adapted to specific substances, are employed. The wavelength range of the filters can overlap. The non-linearity of Planck’s law of radiation is taken advantage of to detect gas mixtures through different emitter temperatures and several broadband filters or to solve complex detection tasks. Such a concept can be flexibly applied to many different detection and measurement tasks because no specific transmission filters need to be used.
