The mirror also independently pivots under the bias of a spring about the mirror pivot axis to an erected operative position wherein {HEAD ~ its upper and lower parallel edges} are disposed perpendicular to {TAIL ~ the optical axis} of the lens 
are disposed perpendicular to
The mirror also independently pivots under the bias of a spring about the mirror pivot axis to an erected operative position wherein { HEAD ~ its upper and lower parallel edges } are disposed perpendicular to { TAIL ~ the optical axis } of the lens
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 HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH