Stabilized Laser Gravimeter
Final rept. 1 Jul 1974-31 Oct 1976
WASHINGTON UNIV SEATTLE APPLIED PHYSICS LAB
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The development and testing of a stabilized laser gravimeter is discussed. A parametric excitation system that is adaptable to the gravimeter is also described. The design and initial development of the stabilized laser gravimeter system have been previously described in AFCRL-TR-74-0355. In the design a mirror forming one end of a Fabry-Perot optical cavity is mounted on a mechanical suspension system. The suspension consists of a beam, end loaded to obtain the required sensitivity to changes in gravitation. A He-Ne illuminating laser is locked to a fringe of the Fabry-Perot cavity. A He-Ne laser stabilized by locking to a vibration-rotation absorption line of a methane cell is used as a reference. The output of the system is a beat frequency between the two lasers proportional to the gravity change. The proposed parametric excitation system applies a periodic end load in addition to the static load on the beam suspension system. It has been shown theoretically and experimentally that significant order of magnitude gains in sensitivity can be realized by parametric excitation.
- Lasers and Masers