Fluorescent optical liquid level sensor

United States Patent

6,172,377
January 9, 2001
View the Complete Patent at the US Patent & Trademark Office
Fluid Level Monitoring Sensor
A liquid level sensor comprising a transparent waveguide containing fluorescent material that is excited by light of a first wavelength and emits at a second, longer wavelength. The upper end of the waveguide is connected to a light source at the first wavelength through a beveled portion of the waveguide such that the input light is totally internally reflected within the waveguide above an air/liquid interface in a tank but is transmitted into the liquid below this interface. Light is emitted from the fluorescent material only in those portions of the waveguide that are above the air/liquid interface, to be collected at the upper end of the waveguide by a detector that is sensitive only to the second wavelength. As the interface moves down in the tank, the signal strength from the detector will increase.
Weiss; Jonathan D. (Albuquerque, NM)
Sandia Corporation (Albuquerque, NM)
09/181,576
October 28, 1998
250/577 ; 250/227.14; 250/227.25; 250/904;
G01F 23/292 (20060101); G01F 23/284 (20060101); G01N 015/06 (); H01J 005/16 ();
250/577,573,227.11,227.14,227.18,227.21,227.23,227.24,227.25,900,901,902,903 385/12,141,142,143,144,145
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT This invention was made with Government support under Contract DE-AC04-94AL85000 awarded by the U.S. Department of Energy. The Government has certain rights in the invention.