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U.S. Department of Energy
Office of Scientific and Technical Information

Optical seismic transducer

Patent ·
OSTI ID:5563293
A spring-suspended mass has top and bottom reflectors. A laser light beam is divided into separate beams that are reflected from the top and bottom reflectors into photo detectors. At the photo detectors, a reference beam from the same laser is recombined with the two reflected beams to produce two interference fringe patterns in response to seismic disturbances of the mass. A count of the number of fringes and fractions thereof that are detected over a unit time interval is proportional to velocity of the mass in terms of the wavelength of the laser beam. The phase difference between the two interference fringe patterns is a measure of polarity of the seismic disturbances.
Assignee:
Western Geophysical Co. of America
Patent Number(s):
US 4500979
OSTI ID:
5563293
Country of Publication:
United States
Language:
English