| 摘要 |
A passive unit (15) retransmits to a primary unit (14) a beam of light (19) received from it. A detector (17), by reason of the retransmitted light effect, indicates the position of the primary unit in relation to that of the secondary at right-angles to the transmitted beam. The passive unit comprises a parallel reflective component, which has three divergent reflection surfaces towards the primary unit. The surfaces are connected to each other so that they form a corner in a right-angled parallelepiped. - The position of the primary unit in relation to that of the second in a plane orthogonal to the centre beams of the transmitted light is determined as to size and direction in the parallel displacement of the reflected central light beams in relation to the transmitted central beams. The detector has a sensitivity zone extending in two dimensions on which the reflected light beams fall in a restricted part. It records the position of the point of contact of the light, which position indicates the extent and direction of the parallel displacement. |
