ApplicationNo. 06/222806 filed on 01/05/1981
US Classes:356/498, Displacement or distance73/293, With illumination73/49.2Receptacle
ExaminersPrimary: Corbin, John K.
Assistant: Koren, Matthew W.
Attorney, Agent or Firm
International ClassesG01M 3/32 (20060101)
G01M 3/00 (20060101)
G01M 3/38 (20060101)
G01F 23/284 (20060101)
G01F 23/292 (20060101)
AbstractA method and apparatus for detecting and measuring leaks in liquid storage vessels, such as underground gasoline storage tanks. A laser source beam is divided into second and third beams which are reflected normally off of a reference surface and the liquid surface, respectively, in the storage vessel. The reflected beams are recombined and the recombined beam is analyzed over time to detect fringes and thereby measure changes in the liquid surface level in the storage vessel.