Gravimeter, Fiber Optic, Absolute
Saturday, September 09, 2006
An Absolute Gravimeter has been designed and developed using Fiber Optics to optically link two or more Gravimeters together. Using an Interferometer, this configuration would provide an Absolute Differential Gravimeter, which could sense both the magnitude and direction of a gravity gradient.
In the Gravimeter dual-sensor configuration, light from a single 35-mW helium neon Laser is coupled into a single-mode Fiber Optic. The Fiber Optic is then split by a 2 x 2 Fiber Optic coupler and sent through separate Fiber Optics. Each Fiber Optic serves as the light source for each separate interferometer gravimeter chamber, where a retroreflector is dropped and tracked.
The return signals from the retroreflectors consist of fringe counts and are recombined in the original Fiber Optic coupler. This creates a differential signal, which is then sent to a photodetector. The two retroreflectors are dropped at slightly different times, producing a return signal at a measured frequency that shifts in the presence of a gravity gradient. The resulting gradient measurement and the distance between the two chambers determine the magnitude of the field gradient. Direction of the gradient requires a configuration containing a 2 x 4 Fiber Optic coupler and four orthogonally placed chambers. Absolute Gravimeters can determine the strength of a gravity field to an absolute accuracy to 1 cm/s2.
Source: None Available
Reference:
1) University of Calgary, Calgary, Alberta, Canada
2) Colorado School of Mines, Golden, CO
3) Micro-g Solutions, Erie, CO
4) EM-g Inc., Denver, CO
5) Jim Faller, Joint Institute for Laboratory Astrophysics, Boulder, CO
Industrial Products
posted by JD52 @ 12:59 PM,
