Measurement of low oxygen concentrations by phosphorescence lifetime using optical fibers

In this paper, a relatively simple, low-cost industrial prototype for measuring low oxygen concentrations in gaseous medium based on phosphorescence lifetime of Al-Ferron in sol-gel probe is presented. The main advantages over other techniques are an excellent sensitivity, precision, selectivity, response time, and facility of maintenance. Fiber optics is used to guide the light. This fact allows one to reach difficult places and to make the measurements from a distance. The design of the system and best ways to maximize the emission maximizing the excitation light from the light source, the optimal distance from the optical fibers to the chemical sensor, and a simple method to filter the response are discussed and verified with the prototype developed. The system allows the detection of oxygen concentrations of 0.005%.