| 摘要 |
<p>Light beam detection is taught in method and apparatus where a light source of coherent light (LS) is directed toward a reflecting hologram 44, 52, 62, 72, 82, 106, 108, 110, 112 made to simulate a parabolic mirror to generate light beams detected by photoreceptors (X) along one side of an opto-frame (32), such receptors (X) being scanned in a manner to preclude false detection of an object within the field of light. An an alternative, multiple light sources are used with a single receptor and an appropriate hologram.</p> |
