{TAIL ~ A filter} of the type depicted in FIG 2 is suitable for infrared radiation in {HEAD ~ the spectral range} of wavelengths from approximately 1.8 microns to 1000 microns 
{ TAIL ~ A filter } of the type depicted in FIG 2 is suitable for infrared radiation in { HEAD ~ the spectral range } of wavelengths from approximately 1.8 microns to 1000 microns
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