Spectrometer test gas chamber

In a broad band automated acousto-optic tunable filter multi-gas infrared analyzer system of the type including:

• (a) means for directing infrared radiation through an environment of interest containing species to be analyzed, which species have predetermined infrared absorption characteristics;
• (b) an acousto-optic tunable filter comprising an optically aligned acousto-optic crystal through which the infrared radiation is passed at a predetermined angle relative to the crystal optic axis, an acoustic transducer means coupled to a variable frequency RF energy source and to the acousto-optic crystal to launch acoustic waves in the crystal to interact with a selected narrow bandwidth portion of the radiation to make it distinguishable from the remaining infrared radiation, which selected narrow bandwidth portion is a function of the frequency of the RF energy and acoustic waves, said selected narrow bandwidth portion being angularly displaced with respect to the non-selected infrared radiation passed through said acoustic-optic tunable filter;
• (c) means for directing the infrared radiation upon said acousto-optic tunable filter;
• (d) infrared radiation detection means which detects the angularly displaced, selected narrow bandwidth portion of the infrared radiation, which detection means generates an output electrical signal as a function of the detected radiation;
• (e) focusing lens means for directing the selected narrow bandwidth portion of the infrared radiation onto said infrared radiation detection means;
• and
• (f) microcomputer means to which the detection means output electrical signal is applied for determining the species present in a sample cell, and including means for the pulsed operation of the RF energy source to determine the timing and frequency of RF energy applied to the acoustic transducer means mated to the acousto-optic crystal to determine the infrared wavelength selectivity or tuning of the acousto-optic tunable filter, wherein the pulsed operation permits discrimination by said detection means between pulsed emission means of the selected narrow bandwidth portion and emissions from the environment of interest;
• the improvement to the analyzer system comprising:
• a test gas means including a housing means defining a chamber with a first end having a first aperture, a second end having a second aperture opposite said first aperture, said chamber having a cone-like inner surface tapering from the first aperture to the second aperture, wherein focusing lens means is mounted in said first aperture and said infrared radiation detection means is mounted in said second aperture so as to render an enclosed cone-like chamber, said housing means having a test gas inlet means in communication with said chamber and disposed proximate said first end, said test gas inlet means being so oriented as to introduce test gas into said enclosed cone-like chamber on a tangent to the first end first aperture wherein a tangential flow path direction is achieved within the cone-like chamber, and a test gas outlet means in communication with said chamber and disposed proximate said second end.