These filters have a high peak transmission at the chosen wavelength; typically greater than 70% combined with high attenuation levels outside the passband, typically less than 0.1%.
The passband measured at the half peak transmittance levels is less than six percent of the centre wavelength value.
In NDIR gas is passed through a measurement cell where a broadband IR source is used to emit light through the cell to a detector.
The detector uses our IR optical fi lters to filter light at the absorption wavelength of the target gas, say 4.3 microns for CO2.