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