Check out the discussion here.
http://www.diyaudio.com
search the forum for 337 (author = 7n7is).
There is a detector from a Perkin Elmer model 710B IR in it.
see
http://chemapparati.topcities.com/PE337/PE337-5.htm
I ran a spectrum of polystyrene film on it a number of times and the resolution isn't too bad.