Consistent with the present invention, an optical filter is provided comprising a single crystal or crystalline quartz substrate and {HEAD ~ a reflective layer} provided on {TAIL ~ the quartz substrate} 
provided on
Consistent with the present invention , an optical filter is provided comprising a single crystal or crystalline quartz substrate and { HEAD ~ a reflective layer } provided on { TAIL ~ the quartz substrate }
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL