Light barrier

摘要

A light barrier detects an object which interrupts a beam of light of the light barrier. A light transmitter transmits a light beam in the direction of a reflector and a light receiver receives a reflected portion of the light beam. The improved light barrier has a reflector which is made as a cylindrical reflector column having a plurality of retroreflecting elements aligned toward the outer surface. The diameter of the reflector column is considerably smaller than the extent of the light beam perpendicular to the cylinder axis so that an optically effective detection beam of light is formed between the sensor and the reflector column whose cross-section at the sensor is determined by the light transmitter and, in direct proximity to the reflector column. The cross-section is determined by the areal overlap of the light beam with the reflector column.