Optical foam sensor for detection of e.g. foam condition of medium in washing area of domestic washing machine, has light emitter, where portion of light striking from emitter on flat boundary surface passes through surface

摘要

The sensor has a light emitter (24) and a light collector (28). An optical boundary surface arrangement has a flat boundary surface (40) and a convex boundary surface (42). The flat surface is oriented relative to the emitter such that light striking on the flat surface is partly reflected at the flat surface, and is made to pass through the convex surface and arrive at the collector in case of transition of the flat surface to air. A portion of the light striking from the emitter on the flat surface passes through the flat surface in case of transition of the flat surface to liquid.