The laboratory investigation of the innovative sensor for torsional effects in engineering structures’ monitoring

Abstract

The main objective of this work is to characterize the performance of an interferometric

The Fiber-Optic Rotational Seismograph – Laboratory Tests and Field Application

“…This was made on the base of the Earth rotation measurement regards procedure in detail described in our previous paper [18]. Several experimental tests were carried out to confirm FOSREMs' parameters and reliability including experimental uncertainties calculation based on the registration of the rotational component of the Earth at different frequency bandpass [19], recording strong rotation motion with a new set-up using earthquake simulation [10] and other. As an example, in Figure 4 Because determined parameters fulfill all requirements described for rotational seismology [10], that can be concluded, so FOSREM seems to be appropriate for registration of rotational events associated with rotational seismology.…”

“…Example of a laboratory test of FOSREM-2: (a) temperature stability for the cooling and heating cycle[19], (b) recording rotational speed with increasing angular velocity up to 0.9 rad/s. Finally, regarding the investigation of the sensitivity of the system, as well as their drift, the Allan variance analysis (AV), have been performed[20,21].Figure 5 presents the result of these analyses for FOSREM-1 and -2.…”

Review of the Usefulness of Various Rotational Seismometers with Laboratory Results of Fibre-Optic Ones Tested for Engineering Applications

“…Figure 10 shows FOSREM, which was previously described in detail [101]. This device consists of two parts: optical and electronic.…”

“…The electronic unit calculates and records rotational data through the use of open-loop synchronous detection in a digital form using a 32-bit DSP. This involves specific electronic solutions using signal processing to directly determine the component of rotation according to a previously developed approach [102] using the following formula [101]: $\mathrm{normal\Omega }=S_o\cdot \arctan false[S_e\cdot ufalse(tfalse)false]=S_o\cdot \arctan false[S_e\cdot \left(A_{1\omega }/A_{2\omega }\right)false]$ where S e , S o are the electronic and optical constants of the system, and A 1ω and A 2ω are the first and second amplitudes of the harmonic output signal [ u (t)].…”

“…The obtained accuracies are in the range 3 × 10 −8 rad/s to 1.6 × 10 −6 for the abovementioned frequency bandpass [101]. Moreover, FOSREMs are stable during cooling and heating processes within a temperature range of 0 °C to 50 °C with temperature sensitivity of the scale factor <0.03%/°C [101]. …”