Patent ID: 6172377
Filing Date: 2001-01-09
Classification: G01F,Y10S

Abstract:
A fluid level sensor comprising:means to provide light of a first wavelength;means to collect light of a second wavelength; and a single, continuous optical waveguide having a first refractive index that is immersed in a volume designed to contain an interface between an upper fluid and a lower fluid with different refractive indices, wherein the means to provide light and the means to collect light are in optical communication with one end of the waveguide and the waveguide contains a fluorescent material that absorbs light at the first wavelength and re-emits light at the second wavelength, such that the means to provide light introduces the light of the first wavelength into the waveguide at an angle for total internal reflection within the waveguide where the waveguide is contacted by the upper fluid and such that the refractive index of the lower fluid is such that the light of the first wavelength will no longer be reflected within the waveguide adjacent to the interface where the lower fluid contacts the waveguide and the light is transmitted into the lower fluid,wherein the light of the second wavelength is only emitted from the fluorescent material in the region of the waveguide that is contacted by the upper fluid, thereby providing an indication of the position of the interface between the upper and lower fluids along the length of the waveguide.