An optical filter including {TAIL ~ a plurality} of {HEAD ~ dielectric layers} is provided between first and second substrates 
An optical filter including { TAIL ~ a plurality } of { HEAD ~ dielectric layers } is provided between first and second substrates
OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH