Stabilized Laser Gravimeter
Final rept. 1 May-31 Jun 1974
WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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The design, development and testing of a stabilized laser gravimeter are described. In this design a mirror forming one end of a Fabry-Perot optical cavity is mounted on a unique mechanical suspension system using endloaded beams. The low frequency suspension required for high sensitivity is obtained by making use of the decrease in frequency of a vibrating beam system with increasing end load. The wavelength of an external HeNe illuminating laser is tuned to maximize the output of the Fabry-Perot cavity by following a fringe. The reference length for the system is provided by a second laser whose wavelength is stabilized by a vibration-rotation absorption line in methane. The output of the system is the beat frequency between the two lasers. The sensitivities of the optical and mechanical systems have been demonstrated separately in laboratory tests. Further testing will involve the measurement of earth tides in the field.
- Test Facilities, Equipment and Methods