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Application of fibre-optic rotational seismometer in investigation of seismic rotational waves

100%

Jaroszewicz L. R. , Krajewski Z.

tom Vol. 16, No. 3

314-320

Application of a fibre-optic Sagnac interferometer as a rotational seismometer is presented in this paper. It is a new device which parameters (sensitivity equal to 4.3x10⁻⁸ rad/s for 2ð) are comparable with the parameters of typical mechanical rotational seismometers. However, a direct measurement of rotation without influence of linear motions for fibre-optic rotational seismometer designed it for a direct measurement of a ground rotation component. Experimental data obtained during simultaneous application of the above two types of sensors are also presented. Research of near-field seismic events, the amplitude of which has been identified in the range of 1.5x10⁻⁶ rad/s to 2x10⁻⁷ rad/s, shows directly that, so-called, seismic rotational waves exist independently of typical seismic waves generated during earthquakes.

Optical fibre interferometric system for Doppler effect measurement

100%

Jaroszewicz L. R. , Krajewski Z.

2002

tom Vol. 10, No. 3

185-191

A novel idea of optical fibre laser Doppler velocimetry especially useful for non-contact testing of rotation elements is presented. The main idea of the system is based on an application of interferometric measurement of Doppler effect by a specially constructed optical fibre interferometer. The standard single-mode coupler, connected with laser diode operated at 0.68 µm, has been used as the main optical element. A suitable selection of a target distance from the specially constructed optical head makes the system work as a single-reflection Fabry-Perot fibre interferometer. Such device provided polarisation stability as well as good environmental shielding. The special numerical processing of interferometric output signals by a technique based on FFT gives a possibility of rotation element testing. The theoretical investigation was compared with experimental data obtained for the commercially available magnetic hard disc and the dynamically tuned electromechanical gyro.

Application of Fiber-Optic Sagnac Interferometer for Detection of Rotational Seismic Events

80%

Jaroszewicz L. , Krajewski Z. , Świłło R.

2001

tom Vol. 22

133-144

A new area of fiber-optic Sagnac interferometer application is presented and discussed. The fiber-optic sensor described in the paperm in well-known classic FOG configuration, has been designed for a detection of the rotational seismic events. The basic system optimisation for a detection rotation only without cenversion for rotation ac give an advantage for this system in compare to other rotational seismometers, which calculate rotational events in indirect ways. The comparison of data from th described fiber-optic rotation seismometer and two antiparallel pendulum seismometers are also presented.