Optimization of the geometrical stability in square ring laser gyroscopes

Santagata, Rosa; Beghi, Alessandro; Belfi, Jacopo; Beverini, N.; Cuccato, Davide; Virgilio, A. Di; Ortolan, A.; Porzio, Alberto; Solimeno, S.

doi:10.1088/0264-9381/32/5/055013

Cited by 29 publications

(27 citation statements)

References 21 publications

(33 reference statements)

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“…We have demonstrated that, when the lengths of the two diagonals are locked to the same value, the perturbations to the mirror positions affect only quadratically the ring laser perimeter and scale factor 9 . In this case, the regular square geometry corresponds to a saddle-point of the perimeter, and so the scale factor fluctuations are minimized.…”

Section: The Gp2 Rl Gyroscopementioning

confidence: 96%

GINGER: An array of ring lasers for testing fundamental physics

Ortolan¹,

Belfi²,

Bosi³

et al. 2017

The Fourteenth Marcel Grossmann Meeting

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Ring laser (RL) gyroscopes are, at present, the most precise sensors of absolute angular velocity. In the near future, their application is foreseen to provide ground based tests of General Relativity. We have recently proposed a tri-axial array of RLs that can reach the sensitivity, accuracy, and long term stability required to measure the inertial frame dragging induced by the rotating Earth, as predicted by General Relativity. The effect, also known Lense-Thirring effect, amounts for the Earth to 1 part in 10 9 of its rotation rate, thus requiring an unprecedented sensitivity and accuracy of experimental apparatus. An array of at least 3 RLs would allow us to measure not only the rotation rate, i.e. the angular velocity modulus, but also the angular velocity vector. In this way, having at disposal the time series of the daily estimate of Earth rotation vector from the International Earth Rotation and Reference System Service, it would be possible to isolate the Geodetic and Lense-Thirring contributions. Our proposal GINGER (Gyroscopes IN GEneral Relativity) is intended to push the present knowledge of RL physics and technology to achieve an accuracy in the estimation of the Earth rotation rate of 1 part in 10 9 . In the experimental apparatus we have to account for systematic errors resulting from non linear dynamics of the active laser medium, and changes of the optical cavity geometry. The redundancy of the array, e.g. the addition of a ring almost parallel to the Earth rotation axis, should allow for the reduction of such errors at the level of the geometry control. In this contribution we describe the intermediate prototypes GP2 and GEMS (GINGER External Metrology System) devoted to control the geometrical fluctuations of a RL cavity and the 3D geometry of the RL array (dihedral angles among RLs), respectively.

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Section: The Gp2 Rl Gyroscopementioning

confidence: 96%

GINGER: An array of ring lasers for testing fundamental physics

Ortolan¹,

Belfi²,

Bosi³

et al. 2017

The Fourteenth Marcel Grossmann Meeting

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“…S depends basically on the geometry, the quality of the mirrors, the pressure and composition of the gas mixture, and the plasma. Suitable control strategy for the geometry of the square ring laser has been studied and it is at present under study [30,31], two colocated devices will have equal gas mixture and pressure, each mirror can be characterised and they can be interchanged, accordingly the realisation of two RLs with equal scale factors is feasible. In order to estimate the requirements for the Lense-Thirring test at ρ = 1%, we have studied the specifications for η ∼ 10 −10 and η ⊥ ∼ 3.510 −10 (LT test).…”

Section: Error Budget and Specifications Of The Experimental Apparatusmentioning

confidence: 99%

GINGER: A feasibility study

Virgilio

Belfi

et al. 2017

Eur. Phys. J. Plus

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Abstract. GINGER (Gyroscopes IN General Relativity) is a proposal for an Earth-based experiment to measure the Lense-Thirring (LT) and de Sitter effects. GINGER is based on ring lasers, which are the most sensitive inertial sensors to measure the rotation rate of the Earth. We show that two ring lasers, one at maximum signal and the other horizontal, would be the simplest configuration able to retrieve the GR effects. Here, we discuss this configuration in detail showing that it would have the capability to test LT effect at 1%, provided the accuracy of the scale factor of the instrument at the level of 1 part in 10 12 is reached. In principle, one single ring laser could do the test, but the combination of the two ring lasers gives the necessary redundancy and the possibility to verify that the systematics of the lasers are sufficiently small. The discussion can be generalised to seismology and geodesy and it is possible to say that signals 10-12 orders of magnitude below the Earth rotation rate can be studied; the proposed array can be seen as the basic element of multi-axial systems, and the generalisation to three dimensions is feasible adding one or two devices and monitoring the relative angles between different ring lasers. This simple array can be used to measure with very high precision the amplitude of angular rotation rate (the length of the day, LOD), its short term variations, and the angle between the angular rotation vector and the horizontal ring laser. Finally this experiment could be useful to probe gravity at fundamental level giving indications on violations of Einstein Equivalence Principle and Lorenz Invariance and possible chiral effects in the gravitational field.

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“…While monolithic cavities made of ultra-low expansion materials, like the Gross ring G in Wettzell, have an excellent passive stability, they are not suited to form 3D arrays of very large size. On the other side, heterolithic systems require active stabilization, which is achieved by active control schemes of the cavity geometry, exploiting very accurate optical wavelength references 14,15 . The present structure of GINGERino does not allow the full implementation of these techniques, and this sets a limit to its present long term stability.…”

Section: Gingerino Working Principle and Experimental Setupmentioning

confidence: 99%

Deep underground rotation measurements: GINGERino ring laser gyroscope in Gran Sasso

Belfi

Beverini

Bosi

et al. 2017

Review of Scientific Instruments

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GINGERino is a large frame laser gyroscope investigating the ground motion in the most inner part of the underground international laboratory of the Gran Sasso, in central Italy. It consists of a square ring laser with a 3.6 m side. Several days of continuous measurements have been collected, with the apparatus running unattended. The power spectral density in the seismic bandwidth is at the level of 10 −10 (rad/s)/ √ Hz. A maximum resolution of 30 prad/s is obtained with an integration time of few hundred seconds. The ring laser routinely detects seismic rotations induced by both regional earthquakes and teleseisms. A broadband seismic station is installed on the same structure of the gyroscope. First analysis of the correlation between the rotational and the translational signal are presented.

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Optimization of the geometrical stability in square ring laser gyroscopes

Cited by 29 publications

References 21 publications

GINGER: An array of ring lasers for testing fundamental physics

GINGER: An array of ring lasers for testing fundamental physics

GINGER: A feasibility study

Deep underground rotation measurements: GINGERino ring laser gyroscope in Gran Sasso

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