Remote CO2 optical fibre sensor by molecular absorption at 4.3 mu m.

This paper describes a remote optical fibre sensor for the carbon dioxide detection by molecular absorption in the near infrared (4.3 mu m) corresponding to fundamental mode nu(3). To overcome the problem of the strong attenuation signal of optical fibre in the near infrared, we have used the opto-suppling technique which changes the working wavelength from 4.3 mu m to 860 nm and permits the use of standard optical fibre 50/125. The simulation of absorption has been obtained by original modelisation of the absorption spectrum and the establishment of the calibration curves takes to the sensor to detect a partial pressures greater than 100 mu bar with a minimal error margin of 100 mu bar, which is acceptable considering the future use of the device. The sensor has been designed to monitor the CO2 rate in enriched greenhouses.