Starting with descriptions of rotational seismology, areas of interest and historical field measurements, the fundamental requirements for rotational seismometers for seismological and engineering application are formulated. On the above basis, a review of all existing rotational seismometers is presented with a description of the principles of their operation as well as possibilities to fulfill formulated requirements. This review includes mechanical, acoustical, electrochemical and optical devices and shows that the last of these types are the most promising. It is shown that optical rotational seismometer based on the ring-laser gyroscope concept is the best for seismological applications, whereas systems based on fiber-optic gyroscopes demonstrate parameters which are also required for engineering applications. Laboratory results of the Fibre-Optic System for Rotational Events & Phenomena Monitoring using a small 1-D shaking table modified to generate rotational excitations are presented. The harmonic and time-history tests demonstrate its usefulness for recording rotational motions with rates up to 0.25 rad/s.

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INTROD~JCTIONThe classic seismic waves describe only the ground particles motion related to displacements [l]. The other kind of ground particles motion can be associated with the rotational effects caused by the earthquakes or by interaction between seismic waves and micromorphic properties of rocks [2-41.Initially these effects have been explained by the inertial properties of objects situated on the Earth surface when hit by the seismic body waves [ 5 ] . Recently such events are treated as the rotation waves which appear in the case of a non-ideal elasticity due to defect content (the non-symmetric dislocations) in a medium [6] or due to internal structure of a medium (micromorphic or micropolar media) [7, 81. The interest in these waves is connected mainly with important seismic information included in them. They give accurate data for arrival times of SH waves, because the rotational component around the vertical axis is sensitive to SH waves, although not to P-SV waves [9]. Moreover, some further advantages can also be expected.Consequently, recording of seismic rotational waves requires new instrumentation techniques, because conventional This work %'ai supponed in part by rhe Polish Sate Cornmirtce for Scientific Research under Grant 6PO4D-066-20 next 4-T10C-013-24 and the MUT Statutory Aciivify PES-636. I . . R. Jaroszewicz is with the lnslitute OfApplied Physics. Milirary University of Technology. .pl). L. Krajewski, and orher are with IAP. MUT Kaliskiego-Str. 2. Warsaw 00-908 POLAND (e-mail: rkrqiewski@uat.edu.pl. lechsolarr@inreria.pI, pmarc@war.edu.pl I. 0-7803-7824-5103A17.00 a2003 IEEE 661 seismographs are inertial sensors of linear velocities 110, I I]. From this reason the new kind of rotational seismometer consisting of two antiparallel seismometers: pendulum [8] or suspension coil one [12], have been proposed recently. Depending on their constructions they may record the distortion (space derivatives of displacements) andor the components of rotations. Unfortunately, the simulation work [I31 showed that the rotational motions are small comparing with the amplitude of the translational motions. Hence, extremelyhigh sensitivity to the translational motions of a conventional seismometer used in the construction of the mentioned above rotational ones can limit its accuracy. Moreover, there exists a serious problem with good their calibration, because in fact it is a set of two independent devices and rotational components obtained by indirect way as a difference oftheir action. From the above reason the other idea of the rotational seismic events recording based on the detection of Sagnac effect [I41 in optical system seems to be attractive proposition. The main advantage of such system is measurement of the absolute rotation rate around any axis perpendicular to the optical path plane, not sensitive to uniform linear motion or distortion [15]. Therefore, in this paper the optical rotation sensor using fiber-optic technique is presented and discussed. The described sensor is based on the configur...

We demonstrate an experimental study of the chromatic dispersion properties for a series of microstructured fibers (MSFs) dedicated for a supercontinuum generation. With white-light interferometry application we analyze experimentally how the small variations of structural parameters, i.e. an air-hole diameter and a lattice constant, influence dispersion characteristics in different groups of MSFs. Our study provides useful information on how to design the fiber which is less sensitive to the fabrication imperfections. Moreover those investigations are the initial step to the development of the customized or tunable supercontinuum light sources based on MSFs with slightly changed structural parameters which can generate light with a different spectrum range, adapted to a proper application.

We present the results of theoretical and experimental characterization of a designed and manufactured dual-mode highly birefringent microstructured fiber. We also demonstrate the measured values of polarimetric temperature and strain sensitivity of both the fundamental and second order modes. As the mode field of the second order mode has a strong interaction with the fiber air holes, we observed a significant (over two orders of magnitude) increase in the polarimetric strain sensitivity of this mode in comparison to the fundamental mode. The enhanced strain sensitivity together with the low temperature sensitivity makes our fiber very attractive for application as extremely sensitive temperature independent strain transducers.