Laser interferometer with a 500-m base for detecting deformations of the earth's surface
Abstract
A Michelson interferometer having arms that are equal and perpendicular to each other and based on an underground optical waveguide line has been tested. A reversible fringe counter provides a continuous analog recording of deformations with amplitudes up to 80 microns over a 0-3 kHz frequency band with a readout discreteness of 1/4 of a pattern period. The use of a high-precision recording system increases the sensitivity of the deformation detection 4 times 10 to the -11th rel. unit when a laser without frequency stabilization is used. The noise due to fluctuations of the air in the optical waveguide varies from 1 times 10 to the -10th to 2 times 10 to the -9th, depending on the season. Examples of traces of deformations due to the effect of distant earthquakes and industrial processes are given.
- Publication:
-
Optiko Mekhanicheskaia Promyshlennost
- Pub Date:
- September 1979
- Bibcode:
- 1979OpMeP..46...16A
- Keywords:
-
- Earth Surface;
- Laser Applications;
- Michelson Interferometers;
- Optical Measurement;
- Surface Distortion;
- Deformation;
- Earthquakes;
- Industrial Areas;
- Optical Measuring Instruments;
- Lasers and Masers