Reflective-type photoelectric switch, fresnel lens and method of manufacturing said lens.

摘要

A reflective-type photoelectric switch projects emitted light from a light-emitting element toward a detection zone by a light-projecting optical system, and guides reflected light from an object to be detected in the detection zone to a light-receiving element by a light-receiving optical system. A special optical element is used in part of at least one of the two optical systems. The optical element functions to diverge light in a direction parallel to a plane containing the optic axes of the light-emitting and light-receiving elements, and condense light in a direction perpendicular to the same plane. As a result, it is possible to detect, with excellent sensitivity, both an object which is far from the switch and an object very near the switch.