The base is preferably formed such that the registration surface 22 is in a precise location with respect to the optical system so that the active surface 16 of {HEAD ~ the substrate} is at {TAIL ~ a focal point} within a few microns 
The base is preferably formed such that the registration surface 22 is in a precise location with respect to the optical system so that the active surface 16 of { HEAD ~ the substrate } is at { TAIL ~ a focal point } within a few microns
OTH OTH OTH OTH OTH OTH OTH OTH OTH 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 REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH