Hazardous gas detection with an integrating sphere in the near infrared

This paper describes an optical fibre near infrared Carbon Dioxide sensor. Using an integrating sphere as a test cell, increased path length is achieved due to multiple reflections within the sphere. Carbon dioxide is input into the sphere via an unused optical port. Light from a C + L band ASE source is transmitted through the sphere and any absorption is detected using a near infrared spectrometer. A change in optical intensity was observed at a wavelength of 1.59 um when carbon dioxide was present from which the carbon dioxide concentration can be determined