having a wavelength of from 0 7 microns to 2 0 microns and a second detector 22 is capable of sensing radiation in the 5 to 30 micron spectral region since the output amplitudes of the optical detectors 12 and 22 are usually too small to be fed directly to a microprocessor the detector outputs are amplified by analog amplifiers 14 and 24 respectively and fed to a microprocessor 30 the detector 12 is a commercially available silicon photodiode and the detector 22 is a radiation thermopile the amplifiers 14 and 24 are commercially available operational amplifiers the microprocessor 30 in the preferred embodiment is a model 2920 signal processor made by intel inc of santa clara calif of course depending upon the particular application other microprocessors may be substituted for the intel 2920 the intel 2920 signal processor is described in detail in the 1980 intel component catalog published by intel inc pages 4 43 to 4 50 a simplified block diagram of the intel 2920 is shown within the dotted lines in fig1 the amplified inputs from the detectors 12 and 22 are fed to an input multiplexer 31 the input multiplexer 31 chooses one of the input signals and transmits it to an analog to digital a d converter 33 where the analog signal is converted to a digital signal that digital signal is fed to a central processing unit cpu 35 while the input multiplexer 31 feeds the other input signal to the a d converter 33 the other input signal is convert to digital form and fed to the cpu 35 in the same manner the input multiplexer 31 samples each of the.