Optimum wavelength for oxygen detection using optical absorption

Oxygen gas detection systems are used in many areas such as environment, clinical, food and automotive industries. Most of the detection systems are based on chemical absorption sensing method. This type of sensing method has their own drawbacks. Therefore, a development of a new oxygen sensor using an optical method is necessary as an alternative to the current sensors. A preliminary study on the molecular absorption cross section for oxygen gas is vital to determine the optimum wavelength is reported. The experimental setup consists of four major components which are light source, gas cell, detector and optical fibre cable. For the light source, a deuterium-halogen bulb will be used as it can provide a broadband wavelength light source from 215 nm - 2500 nm. A miniature spectrometer will be used as the detector and the gas cell is connected to the light source and detector using the optical fibre cables. A software package to display absorption of oxygen molecules is installed in a computer to study on the optimum wavelength. The experiment results show that the light is most absorbed at 230 nm and absorption is increased by cell length. The highest absorption was observed to be in a 100 cm gas cell length with pressurized 5 bar of 99% pure oxygen gas. Based on this result, a wavelength of 230 nm is selected as optimum wavelength to detect oxygen