Abstract: A gas spectrometer is provided having an enhanced capability for maintaining initial calibration conditions therewithin. The gas spectrometer is particularly apt for respiratory gas analysis applications and includes a housing assembly that defines an internal containment area(s), within which a radiation source, optical assembly, sample gas assembly and radiation detection assembly are positioned. A gas removal assembly is provided for removing one or more undesired gas component types from within the internal containment area during field use. The gas removal assembly is selectively retractable from the housing assembly to permit periodic servicing (e.g., replacement of CO.sub.2 absorbent) without requiring disassembly or recalibration of the spectrometer.

Abstract: The source (12) has a heater element (122) sandwiched between elongate emitter plates (124 and 126). In operation, the source (12) is operated at temperatures in excess of 900.degree. C. and, preferably, at least about 1200.degree. C. to provide radiation in the 7-10 micrometer wavelength range. In one embodiment, the source (12) is used in conjunction with an elongate detector array (14) in a gas analyzer (10) for analyzing respiratory and anesthetic gases. Spherical mirrors (36a, 36b) and flat mirrors (38a, 38b) are employed to image the source (12) on the detector array (14). A linear variable filter (26) allows for analysis of the radiation at multiple wavelengths using detector array (14).