Patent ID: 7075631

Claim:
A fiber optic filling level determination apparatus for liquid transparent medium disposed in a container, comprising: a light wave conductor disposed within said container and adapted to be immersible at least partially in said medium, wherein said light wave conductor is connected to a light source disposed externally of said container, wherein a difference in intensity between introduced light and exiting light is used to determine the filling level of said medium in said container, wherein said light wave conductor has an input section that is connected to said light source and is guided in said container, in a helical path, to a deepest level of said container that is accessible for said filling level determination, and wherein, proceeding from said input section, said light wave conductor has a linear output section that is guided out of said container along a length of the helical path of the input section; a first intensity measuring device, for measuring the intensity of introduced light, associated with said input section externally of said container; and a second intensity measuring device, for measuring the intensity of exiting light, associated with said output section externally of said container, wherein a ratio of the intensities measured by said first and second intensity measuring devices is to be represented in a filling level value.