Optical gauge for determining the level of a medium in a container

An optical gauge for measuring a level of transparent or translucent liquid, the optical gauge comprising:

• an elongate, tubular member having opposite ends with a bore extending between the opposite ends, the bore having a central axis and being adapted to receive liquid;
• a light source positioned for projecting radiant energy into the bore along the central axis from one of the ends of the tubular member;
• an elongate continuous light collector spaced from the light source and extending along a length of the tubular member for receiving, at least indirectly, radiant energy from the light source, the light collector having opposite end and being formed such that radiant energy incident on the light collector is transmitted to the light collector ends;
• a float positioned in the bore for movement with an upper surface of the liquid, the float being opaque to the radiant energy for blocking the radiant energy from a) the liquid, and b) the light collector between the float and the other end of the tubular member, wherein movement of the float with respect to the light collector varies the position of the radiant energy incident on the light collector to thereby vary the amount of radiant energy transmitted to the light collector ends;
• and
• at least one photosensor positioned for detecting the amount of radiant energy transmitted to at least one of the light collector ends;
• wherein the amount of radiant energy transmitted to the at least one light collector end and detected by the at least one photosensor is indicative of the liquid level independent of the degree of transparency of the liquid.