LIQUID OPTICAL LEVEL Russian patent published in 1998 - IPC

FIELD: measurement technology. SUBSTANCE: liquid optical level has tray filled partially with transparent liquid, light source, two photoreceivers the outputs of which are connected electrically to different circuit inputs. Collimator and polarizer positioned inside tray having flat bottom and two flat mirrors similarly oriented perpendicularly to radiation incidence plane are arranged in direction of radiation. One of mirrors is semitransparent and designed to divide radiation into two beams. Radiation absorber with controllable transmission coefficient is positioned on route of beam passed through semitransparent mirror and reflected from second mirror. Homogeneous planar optical wave-carrying structure provided with liquid coupling layer formed on its upper surface is secured on tray bottom. Coupling layer thickness is less than penetration depth of surface wave field into layer substance, but it differs from its optimal value at which efficiency of surface wave excitation in given wave-carrying structure is maximum. Light source is provided with monochromator. One of side walls of tray has transparent window through which source radiation is supplied. Liquid which fills tray is selected to be more dense optically with smaller specific weight as compared to coupling layer liquid, and it does not mix with the latter. EFFECT: higher measurement results. 2 dwg