Carbon dioxide detection at 2 µm using an integrating sphere as an optical absorption cell

Eamonn Hawe; Paul Chambers; Colin Fitzpatrick; Elfed Lewis

doi:10.1117/12.738407

2 July 2007 Carbon dioxide detection at 2 &mgr;m using an integrating sphere as an optical absorption cell

Eamonn Hawe, Paul Chambers, Colin Fitzpatrick, Elfed Lewis

Proceedings Volume 6619, Third European Workshop on Optical Fibre Sensors; 66191H (2007) https://doi.org/10.1117/12.738407
Event: Third European Workshop on Optical Fibre Sensors, 2007, Napoli, Italy

Abstract

This paper describes a multipass absorption sensor based on an integrating sphere. The sphere has an internal coating which is highly reflective (over 95%) in the near infrared region and this allows the detection of carbon dioxide (CO₂) gas at 2 &mgr;m. CO₂ was detected using a light emitting diode as the emitter and a photodiode as the detector. A two inch (50.8 mm) diameter integrating sphere was used as an absorption gas cell. A method of calculating the effective path length of the integrating sphere is also presented. The latter is shown to be dependant on the reflectance of the sphere's internal surface, the sphere's port fraction and the level of attenuation of the optical signal due to the gas present in the sphere. Effective optical path lengths of 40 cm at the 2 &mgr;m region are reported. Experimental results demonstrating the detection of CO₂ using a two inch diameter integrating sphere are presented and these are compared to simulation results based on a CO₂ absorption over a 40 cm path length at 2 &mgr;m.

Citation Download Citation

Eamonn Hawe, Paul Chambers, Colin Fitzpatrick, and Elfed Lewis "Carbon dioxide detection at 2 &mgr;m using an integrating sphere as an optical absorption cell", Proc. SPIE 6619, Third European Workshop on Optical Fibre Sensors, 66191H (2 July 2007); https://doi.org/10.1117/12.738407

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