LumaSense Technologies INNOVA 1316A-2 - Manual (Page 12)

Chapter 1
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BE6021-11 1316A-2 Multi Gas Monitor LumaSense Technologies A/S
Instruction Manual Page 12 of 97
Fig.1.2 Simple NDIR Gas Monitor
1.4.2 The Infrared Transmission Spectra.
The concentration of a subject gas in the sample is computed as a
function of the light intensity measured by the detector. The figure
below characterizes the band pass filters for Freon and CO
2
gases.
Filter
Centre
Wavelength Band
Width Centre
Wavelength Band
Width
μm μm
cm-1 cm-1
Freon 8.73 1.24 1145 163
Carbon
dioxide
4.425 0.07 2260 36
Fig.1.3 Infrared optical filters for Freon and Carbon Dioxide.
1.4.3 The NDIR Module Building blocks
Infrared Source
A current-regulated infrared (IR) source provides a photon stream.
Light is collimated and directed through the sample cell to the optical
block. The source is modulated at 1 Hz, with a duty cycle of 50%.