US Patent 9541445 Optical level sensor for reflective liquids

An optical sensor enables a level of reflective fluid to be detected. The optical sensor includes a prism mounted at one end of a housing. The prism has an exterior surface that is parallel to the end of the housing and a width that corresponds to a width of the end of the housing. A photoemitter and a photodetector are mounted at another end of the housing to enable light emitted by the photoemitter to be reflected by the prism when the prism contacts reflective fluid and to enable light emitted by the photoemitter to pass out of the sensor when the prism is in contact with air.