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