the third optical beam pointer further includes a optical element for converting {HEAD ~ the third horizontal beam} into {TAIL ~ a fourth vertical beam} spreading vertically by rotating spread directions of the third horizontal beam by 90°, and 
into
the third optical beam pointer further includes a optical element for converting { HEAD ~ the third horizontal beam } into { TAIL ~ a fourth vertical beam } spreading vertically by rotating spread directions of the third horizontal beam by 90 ° , and
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH