Opto-acoustic gas analyzer

Claim 1

An opto-acoustic gas analyzer comprising a black body light source, a chopper means in the path of the light emitted from said light source for intermittently intercepting the light from said light source, a separate positive interference filter in the path of the light from said chopper and having a plurality of film layers for filtering from the light wavelengths of light other than the wavelengths of light absorbed by the gas for which analysis is being conducted, and an opto-acoustic detector for receiving the filtered light from said positive interference filter and having two compartments therein which are aligned in the direction of the passage therethrough of light from said light source, a filter means between said two compartments for filtering from the light passing therethrough at least some of the light having wavelengths in the range of wavelengths absorbed by the gas for which the analysis is being conducted, means for passing the gas to be analyzed into one of said compartments and from said one compartment to the other compartment and out of the other compartment, and a separate chamber connected to said two compartments and said detector further having pressure change detecting means in said separate chamber and producing an electric signal corresponding to such changes.