title: Optical cavity for auto-referenced gas detection.
abstract: An enhanced optical system design for NDIR gas detection is presented. Multiple paths lengths within the same cavity are used to auto reference the system. The system has good thermo-mechanical stability: it requires no special thermal stabilization, shows no sensitivity to thermal emitter drift and has no moving parts involved. Long term stability, virtually no zero-drift and sub-ppm level gas detection were achieved using commercial thermopile sensors and a thermal emitter modulated at low frequency (~0.5 Hz). Experimental tests were performed using carbon monoxide (CO) and a 30.5 cm cavity length. The design can be extended to allow multiple gas detection within the same optical cavity.
authors.affiliation: Departamento de Óptica, Escuela Universitaria de Óptica, Universidad Complutense de Madrid, Madrid, Spain. jcmartin@fis.ucm.es
authors.forename: Juan Carlos Martinez
authors.initials: JC
authors.lastname: Antón
authors.forename: Manuel
authors.initials: M
authors.lastname: Silva-López
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000032:analysis*; D055096:Optical Devices; D010783:Photometry / Q000295:instrumentation*; D012031:Refractometry / Q000295:instrumentation*
chemical_list: D005740:Gases