| abstract |
Multichannel infrared detector assemblies for use in the detection and monitoring of gas concentrations are provided. The detector assemblies include a detector housing having a port for receiving infrared radiation therethrough; a substrate mounted within the detector housing, the substrate having three apertures therein to transmit radiation entering the detector assembly therethrough; a first, a second and a third thermopile detector fabricated on the bottom side of the substrate, the hot junctions of each thermopile detector positioned over one of the apertures in the substrate so as to receive radiation transmitted through the aperture, and the cold junctions of each thermopile detector positioned over the substrate; a first interference bandpass filter mounted on the top side of the substrate so that the first filter covers the aperture above the first detector and the first filter is interposed between the port and the first detector, the first interference bandpass filter designed to pass incident radiation at a first spectral band; a second interference bandpass filter mounted on the top side of the substrate so that the second filter covers the aperture above the second detector and the second filter is interposed between the port and the second detector, the second interference bandpass filter designed to pass radiation at a second spectral band; and a third interference bandpass filter mounted on the top side of the substrate so that the third filter covers the aperture above the third detector and the third filter is interposed between the port and the third detector, the third interference bandpass filter designed to pass radiation at a third spectral band. The disclosed infrared detector assemblies can be used in traditional NDIR gas sensors having an active source or in passive infrared analysis gas sensors which use a passive infrared temperature source and the space between the detector assembly and the source as the sample chamber. |