Distance measuring system using dual focus light beam - has four quadrant detector which monitors reflections from remote object

摘要

The beam output from a semiconductor laser diode (1) is focussed into a parallel beam (3) by two lenses (11,12). The beam passes through a semi-silvered mirror (9), set at 45 degrees to the beam axis. The beam then passes through a bi-convex lens (8) and a cylindrical lens (7) and out of the housing (2). The beam reflected from the object passes back through the cylindrical lens (7) and bi-convex lens (8) to the mirror (9), which reflects it via a converging lens (10) to a four-quadrant detector (4). The output from the detector (4) is used to keep the monitored object between the focal points (5,6) of the lenses (7,8).