{HEAD ~ The difference} between {TAIL ~ the focal distances} of the beams can be determined only by controlling a distance between the optical member and the reflecting member, and does not require the positioning precision 
between
{ HEAD ~ The difference } between { TAIL ~ the focal distances } of the beams can be determined only by controlling a distance between the optical member and the reflecting member , and does not require the positioning precision
HEAD HEAD HEAD HEAD HEAD HEAD 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 OTH OTH