Non-Dispersive Infrared Spectroscopy (NDIR Spectroscopy)

Infrared Spectroscopy - Picture credits: mindelio @

NDIR spectroscopy as a physical sensor principle is an established procedure in the sensor field to highly selectively and stably determine concentrations and compositions of materials. InfraTec produces various single channel sensors for analytical instruments and spectrometers.

Infrared Detectors for Narrowband Sources

High-quality lithium (LiTaO3) is an extremely powerful pyroelectric that is also less expensive than other thermal sensors. Through a special metal black layer, the infrared sensor absorbs radiation extremely uniformly over a very wide wavelength range from 2 µm to over 20 µm. The sensor does not require cooling and ensures short reaction times for modulation frequencies up to a few kilohertz.

Detectors for Infrared Spectroscopy with an Integrated Fabry-Pérot Filter

Gases such as hydrocarbons have very closely spaced absorption bands. Therefore, a measurement requires precisely defined narrow bandpass filters. However, unknown gases can not be measured with these filters. This is instead achieved by a tunable filter. With its help, more gases can be measured by a detector. For this purpose, a Fabry-Pérot interferometer (FPI) is integrated into a pyroelectric detector (FPI-Detector). This combination of the FPI detector is particularly advantageous since it can be used for almost all wavelength ranges and does not need to be cooled. The entire assembly is so small that it fits along with a signal preamplifier in a TO8 housing.

Further Applications of FPI Detectors 

  • Environmental and climate research: measurement of emissions, identification of plastics in waste sorting, leak detection on supply lines, composition of the atmosphere
  • Measurement on surfaces: detect contaminants, ensure complete coating with lubricants, determine the type and thickness of coatings
  • Identification of solids
  • Identification of impurities or counterfeits

Picture credits: © mindelio/


Branch office:

InfraTec infrared Ltd
Chesterfield, UK
workPhone:+44 1246 267562


InfraTec GmbH
Infrarotsensorik und Messtechnik
Dresden, GERMANY
workPhone:+49 351 871-8625
Fax:+49 351 871-8727