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