The groove 150 and the slider member 152 together operate in {HEAD ~ conjunction} to provide {TAIL ~ a linear bearing} such that the carriage member 148, the slider member 152, and the reflective surfaces 72 and 74 move in the lineal direction 154 
The groove 150 and the slider member 152 together operate in { HEAD ~ conjunction } to provide { TAIL ~ a linear bearing } such that the carriage member 148 , the slider member 152 , and the reflective surfaces 72 and 74 move in the lineal direction 154
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD 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 OTH