Osteoporosis:Unmasking a Silent Thief: Your Step-By-Step Guide to Understanding, Diagnosing, Preventing, and Treating One of the Worst Dangers of Aging
John C. Murphy - Columbia MD Raymond C. Cole - Baltimore MD
Assignee:
The Johns Hopkins University Applied Physics Laboratory - Laurel MD
International Classification:
G01M 304
US Classification:
73 405A
Abstract:
The present invention relates generally to the utilization of laser interferometry for performing detection of buried structures such as underground natural gas pipeline. More specifically, the invention relates to the use of a laser interferometer system for detecting leaks and similar defects, such as corrosion, in buried pipelines, pressurized containers or other metallic structures, based upon the sensing of subnanometer earth surface displacements produced by elastic waves which are emanated from the leak or defect and propagate in the surrounding earth medium.