The second layers are generally one quarter wavelength optical thickness at a particular tuned wavelength, whereas {HEAD ~ the first layers} are generally {TAIL ~ a plurality} of quarter wavelength optical thicknesses 
The second layers are generally one quarter wavelength optical thickness at a particular tuned wavelength , whereas { HEAD ~ the first layers } are generally { TAIL ~ a plurality } of quarter wavelength optical thicknesses
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 OTH OTH OTH OTH OTH