Bichannel radiation detection apparatus

Apparatus for detecting the radiation received through a port from an object at elevated temperature, the apparatus comprising:

• detector means disposed to receive radiation through the port from the object for producing an output therefrom indicative of the radiation received thereby;
• filter means interposed between the port and the detector means for producing outputs therefrom that are indicative of the radiation received thereby within a selected waveband, said filter means including a plurality of optical filters of different radiation transmissive characteristics that are oriented to be positioned cyclically between the port and the detector means;
• circuit means connected to receive the outputs from the detector means for selectively storing and processing a portion of each output produced during a cyclic interval of radiation in a selected waveband of radiation received by the detector means, said circuit means including a plurality of sampling circuits each connected to receive the output from the detector means for producing therefrom a plurality of outputs each indicative of the magnitude of the output of the detector means at a selected period within an interval during which radiation is supplied to the detector means within a selected waveband, said selected period being shorter than said interval and being determined in response to the cyclic operation of the filter means and during which the least amplitude gradient is present.