JPS5512463A - Optical liquid level detection - Google Patents

Abstract

PURPOSE:To highly accurately measure the displacement of a liquid level by detecting the existence of a transmission light which has transmitted through an optical waveguide. CONSTITUTION:There are buried in a substrate 11 of low refractive index a plurality of integrated optical waveguide arrangements 31 to 35 under the condition in which their one side is in contact with a gas phase 39 or a liquid phase 40. Integrated light source arrangements 21 to 25 connected with an electric input terminal 36 are attached to one end of the waveguide arrangements 31 to 35, and integrated optical detecting arrangements 26 to 30 connected with an electric output terminal 37 are attached to the other end of the same. Thus, if the optical waveguide arrangements 31 to 33 and 34, 35 are disposed above and below the liquid level 38, the lights from the sources 21 to 23 are allowed to transmit without any attenuation through the waveguide arrangements 31 to 33 until they reach the detectors 26 to 28 so that optical output can be taken out of the output terminal 37. However, the lights from the sources 24 and 25 are abruptly attenuated to fail to reach the detectors 29 and 30. As result, the fine displacement of the liquid level can be highly accurately measured even under bad circumstances by judging the existence of the optical outputs of the detectors 26 to 30.