Title:
GRAVIMETER
Document Type and Number:
Japanese Patent JPS54156686
Kind Code:
A
Abstract:
A gravity gradiometer includes a ring laser cavity 4, 6, 8, 10, two modulator elements 12, 22 in the path of the laser beam produced by laser tube 2, and spaced masses 18, 28 attached to the modulator elements to provide a differential modulation of circular polarization modes proportional to the difference in gravity at the location of the two masses. In one form, a biasing element 42 is added to shift the operating point of the laser system to improve performance by preventing phase locking; the bias may be checked by a second ring laser using the same cavity with a second laser tube 50. Beat frequencies indicative of the polarization modes are measured by photodetectors 40, 52, the initial circular polarization being established by a magnet 20 near the laser tubes. Because of the differential measurement, the apparatus can be used when moving, e.g. in a borehole, without being affected by acceleration.
Inventors:
SEODOAA BARII RAUTSUZENHAIZAA
Application Number:
JP6670979A
Publication Date:
December 10, 1979
Filing Date:
May 29, 1979
Export Citation:
Assignee:
STANDARD OIL CO
International Classes:
G01V7/00; (IPC1-7): G01V7/04
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