The ability to detect small quantities of a specific gas is of paramount importance in many applications, from quality control to leak detection of flammable or toxic gases. ESI has developed considerable expertise in evolving a low-cost, real-time system based on differential absorption spectroscopy that may be used on gases that have the ability to attenuate or absorb visible and near-infrared light. One such gas is that of Oxygen and a system using inexpensive infrared laser diodes has been constructed.

In this case a test cell has been constructed with a laser diode at one end and a photo-detector at the other. Various gas samples may be introduced into the cell and their oxygen concentrations measured and compared with that of a gas analyzer.

A computer controls the test cell temperature and pressure as well as undertaking the measurement cycle and analyzing the resulting gas concentrations.

Once the initial O2 calibration points were obtained, measurements of different unknown oxygen concentrations were acquired in real time and determined to provide a high degree of accuracy.

Calibration of the system was performed using different calibration grade Oxygen (O2) gas samples. Results of the calibration show a high degree of linearity is achieved by such a system.

A comparison between the ESI gas detection system and established commercial gas measurement systems was undertaken. O2 measurements in the physiological range demonstrated the superior performance of the ESI Laser Diode system when compared to the Illinois, Delta and Columbus Oxygen Measurement Systems.