Method and device for optically determining a filling level in liquid-filled containers

Device for determining a filling level in a liquid-filled container, including

• a light guide body which is adapted in operation of the device to project into the internal volume of the container, the light guide body being of rectangular cross-section and having an end face with an entry region for the entry of light into the light guide body and an exit region for the exit of light from the light guide body and first and second side faces each comprising steps providing at least two reflection faces, the reflection faces at the one side face being associated with respective reflection faces at the other side face, wherein the reflection faces of the first side face are at least in part such that light entering the light guide body at said entry region is refracted into the liquid when the reflection face in question is immersed in the liquid but is totally reflected back into the light body in a direction towards the second side face thereof when the reflection face in question is not immersed in the liquid and the light totally reflected by a reflection face at said first side face is reflected by the respectively associated reflection face at the second side face in a direction towards the exit region of said end face, and
• measuring means for separately measuring the intensity of a light beam totally reflected by each said reflection face of said second side face.

Device for determining a filling level in a liquid-filled container, including

• a light guide body which is adapted in operation of the device to project into the internal volume of the container, having an end face with an entry region for the entry of light into the light guide body and an exit region for the exit of light from the light guide body and a side face comprising steps providing at least two at least substantially annular reflection faces, wherein said reflection faces are so designed at least over a portion of their periphery that light entering the light guide body at the entry region is refracted into the liquid at a respective reflection face when the reflection face in question is immersed in the liquid but is totally reflected back into the light guide body in a direction on to the oppositely disposed region of the reflection faces and from there further to said end face when the said reflection face is not immersed in the liquid, and
• measuring means for separately measuring the intensity of the respective light beam totally reflected by each said reflection face to said end face.