Detectors with a spectrometer function as a basis

The core of the innovation is a miniaturised infrared spectrometer with a tunable, micromechanical Fabry-Pérot-Filter and fast photodiode as a detector. The spectroscopic measurement technique with a spectral resolution of 30 – 40 nm in the spectral range 3.0 – 3.7 µm makes it possible to detect and quantify a wide variety of gases with just one detector element. The previous customary NDIR detectors with fixed narrowband filters are normally only calibrated to one substance and do not allow for any differentiation. Due to the compact design in a TO-8 housing, insensitivity to vibrations as well as low energy consumption the spectrometer provides good preconditions for integration into an explosion-proof, portable gas detector. The MIREX project is laying the foundation to ensure that even gases with heavily overlapping spectrums such as ethane and propane can be detected later in practice by a complex analogue and digital signal evaluation.

As part of the personal protective equipment, the gas detector will be able to increase safety for rescue workers during operations in the future. For this purpose it will measure explosive and combustible gases within the range of the lower explosion limit. This limit marks the lowest concentration, in which a gas can ignite and a flame can spread automatically. The measurement results reach the operations centre by radio. In this way, several rescue forces can be better coordinated and monitored.

Suitable for other applications

With the Gesellschaft für Gerätebau mbH, the Fraunhofer Institute for Physical Measurement Technology Freiburg as well as the Institute for Fire Brigade and Rescue Technology of the Fire Brigade of the city of Dortmund, three additional partners are involved alongside InfraTec, which bring their expertise to bear in this special application. In terms of perspective, the device has a far greater range of application, however. The basic operating principle can also be adapted for other purposes. The concept of similar detectors for mining, refineries and chemical industry is conceivable, for example.