In the past several decades there have been many designs investigated for the use of infrared spectroscopic instruments for the analysis of gases. The majority of these instruments have utilized one or more filters in order to select an analytical frequency for the detection of a specific gas or gases. The source is selected from various heated elements from 800 to 1000.degree. C. which give a broad band of IR energy continuous from 2-15 microns. The energy emitted by the heated element, termed the source, is customarily "chopped", i.e. intermittently interrupted by a mechanical means, which constitutes a moving part.
The gas mixture or single component is contained in a cell, a metal or glass tube fitted with IR transmitting windows, as sodium chloride, etc., with inlet and outlet pipe to give entry and egress to the gas or gases to be analyzed; this act of filling and emptying the gas cell requires a pump with moving parts.
In addition to the components comprising a modern filter IR spectrometer intended for the analysis of single or multiple gases, it is, of course, essential to have a filter or an array of filters with a suitable optical system to focus light from the source onto said filter or filter array, and thence to a detector or array of detectors in order to generate an electrical signal proportional to the concentration of the species to be analyzed. Said electrical signal is processed via a micro-processor which is calibrated by means of conducting analysis on gas mixtures of known composition and the result suitably displayed by means of a graph CRT screen, LED display or the like.
By a critical examination of each of the above elements of today's classic gas analyzer, we have discovered a simple, accurate device for the analysis of a gas sample without moving parts, without complex optical systems, capable of economic manufacture and eminently portable.