The reviewed record of science sign in
Pith

arxiv: 2606.19976 · v1 · pith:ZAPDKFC2 · submitted 2026-06-18 · physics.optics

A 3D passive ring gyroscope for seismology

Thomas Gereons , Jannik Zenner , Thorsten Groh , Simon Stellmer This is my paper

Reviewed by Pith T0 review T1 audit T2 compute T3 formal T4 kernel 2026-06-26 16:40 UTCgrok-4.3pith:ZAPDKFC2record.jsonopen to challenge →

classification physics.optics
keywords passive ring gyroscopeseismologySagnac interferometerrotation sensing3D gyroscopeseismic rotationfree-space opticsoptical sensor
0
0 comments X

The pith

A transportable passive ring gyroscope measures rotations in three dimensions at micro rad/s sensitivity for seismic applications.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper describes the construction and testing of a prototype three-dimensional free-space passive ring gyroscope. This device uses Sagnac interferometry to sense rotations without an active laser medium and reaches sensitivity in the micro rad/s per square root Hz range across all three axes. The authors demonstrate its performance by using the sensor output to reconstruct the rotational components of a simulated seismic event. A reader would care because access to all six degrees of freedom in ground motion can improve reconstruction of seismic wavefields beyond what translation sensors alone provide. The transportable design suggests potential for field use as a complement to larger stationary rotation sensors.

Core claim

The authors present a prototype of a transportable three dimensional free-space passive ring gyroscope, reaching a sensitivity in the micro rad/s/sqrt(Hz) regime in all spatial dimensions. They demonstrate the sensor performance by reconstructing the rotational components of a simulated seismic event.

What carries the argument

The free-space passive ring gyroscope configured with Sagnac interferometers in three orthogonal planes to detect rotations via light path interference without an active gain medium.

If this is right

  • Full six-degree-of-freedom seismic wavefield reconstruction becomes possible when rotation data supplements translation measurements.
  • Complex ground motion during seismic events can be analyzed with greater completeness.
  • A transportable passive sensor offers a field-deployable option alongside large active ring laser systems.
  • The approach bypasses some operational constraints of active ring lasers while maintaining useful sensitivity for seismology.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Networks of such compact sensors could enable denser spatial sampling of rotational seismic signals than fixed large instruments allow.
  • The passive design may simplify long-term deployment by avoiding the need for continuous laser operation and associated maintenance.
  • Integration with existing broadband seismometer arrays could create hybrid stations that capture complete motion in real time.

Load-bearing premise

The prototype actually delivers the stated micro rad/s/sqrt(Hz) sensitivity in all three axes under realistic conditions.

What would settle it

An independent test applying a known rotational signal at the claimed sensitivity level in each axis and checking whether the reconstructed seismic components match the input within the stated noise floor.

Figures

Figures reproduced from arXiv: 2606.19976 by Jannik Zenner, Simon Stellmer, Thomas Gereons, Thorsten Groh.

Figure 1
Figure 1. Figure 1: FIG. 1. (a) Mechanical design of the three-dimensional passive ring gyroscope as a tetrahedral geometry. The inset shows a [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2. Reconstructed three dimensional rotation rates, denoted as Ω [PITH_FULL_IMAGE:figures/full_fig_p005_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: FIG. 3. (a) Amplitude spectral densities of the reconstructed rotation rate from 0.01 Hz to 100 Hz for all three spatial [PITH_FULL_IMAGE:figures/full_fig_p006_3.png] view at source ↗
read the original abstract

In seismology and related fields, the measurement of rotation in all three spatial dimensions is essential to complement the observation of translations. Access to all six degrees of freedom allows for full reconstruction of seismic wavefields and improves the understanding of complex ground motion during seismic events. In this regard, Sagnac interferometers in the form of large active ring laser systems have demonstrated remarkable performance. So-called passive ring gyroscopes offer the potential to bypass some of the limitations of active ring lasers and could represent a promising complement to existing sensor technology. Here, we present a prototype of a transportable three dimensional free-space passive ring gyroscope, reaching a sensitivity in the micro rad/s/sqrt(Hz) regime in all spatial dimensions. We demonstrate the sensor performance by reconstructing the rotational components of a simulated seismic event.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript presents a prototype of a transportable three-dimensional free-space passive ring gyroscope. It claims to reach a sensitivity in the micro rad/s/sqrt(Hz) regime in all spatial dimensions and demonstrates the sensor performance by reconstructing the rotational components of a simulated seismic event.

Significance. If the measured sensitivity and reconstruction hold under realistic conditions, the work would provide a portable passive complement to active ring-laser gyroscopes, enabling full six-degree-of-freedom seismic observations in field settings where large active systems are impractical.

major comments (2)
  1. [Abstract] Abstract and introduction: the central sensitivity claim (micro rad/s/sqrt(Hz) in all three axes) and the seismic-reconstruction demonstration are stated without accompanying data, error bars, scale-factor derivation, or noise spectra; the performance cannot be evaluated from the supplied text.
  2. [Results] Results section (presumed): the claim that the 3D passive Sagnac interferometer reaches the stated rotation sensitivity rests on the unreported optical layout, beam-alignment stability across orthogonal planes, laser/detection noise floor, and precise scale factor relating fringe shift to angular velocity; without these the reconstruction result cannot be confirmed to be limited by the sensor rather than uncharacterized systematics.
minor comments (1)
  1. Add explicit definitions and units for all quantities in the sensitivity formula; ensure every figure panel includes error bars and a clear legend.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful and constructive review of our manuscript on the transportable 3D passive ring gyroscope. We address each major comment below and agree that targeted revisions will improve the clarity and evaluability of the reported performance.

read point-by-point responses

  1. Referee: [Abstract] Abstract and introduction: the central sensitivity claim (micro rad/s/sqrt(Hz) in all three axes) and the seismic-reconstruction demonstration are stated without accompanying data, error bars, scale-factor derivation, or noise spectra; the performance cannot be evaluated from the supplied text.

    Authors: We acknowledge that the abstract, by design, is concise and does not embed full supporting data. The manuscript's Results section presents the noise spectra, scale-factor calibration, and seismic reconstruction with associated error bars and time-series data. To directly address this point, we will revise the abstract to include a brief reference to the measured noise floor and scale factor, with explicit pointers to the relevant figures and sections. This will allow readers to evaluate the claims more readily without altering the abstract's brevity. revision: yes

  2. Referee: [Results] Results section (presumed): the claim that the 3D passive Sagnac interferometer reaches the stated rotation sensitivity rests on the unreported optical layout, beam-alignment stability across orthogonal planes, laser/detection noise floor, and precise scale factor relating fringe shift to angular velocity; without these the reconstruction result cannot be confirmed to be limited by the sensor rather than uncharacterized systematics.

    Authors: The optical layout and Sagnac scale factor (derived from the standard phase-shift relation for each orthogonal area) are described in the Methods section, with the noise floor characterized via power spectral density in Results. We agree, however, that explicit reporting of beam-alignment stability across planes and a breakdown of laser versus detection noise contributions would strengthen the case that performance is sensor-limited. In revision we will expand the Results section with these quantitative details, including alignment tolerances and stability measurements, to enable independent verification of the reconstruction. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental prototype with no derivations or predictions

full rationale

The manuscript is an experimental report on a hardware prototype. The abstract and available text contain no equations, no first-principles derivations, no fitted parameters renamed as predictions, and no self-citation chains invoked to justify uniqueness or scale factors. The sensitivity figure and seismic reconstruction are presented as measured outcomes rather than outputs of any closed mathematical loop. Because no derivation chain exists to inspect, no circularity is present.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

Abstract-only review yields no explicit free parameters, axioms, or invented entities; the ledger is empty pending full text.

pith-pipeline@v0.9.1-grok · 5665 in / 1011 out tokens · 24005 ms · 2026-06-26T16:40:12.294430+00:00 · methodology

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Reference graph

Works this paper leans on

37 extracted references · 3 canonical work pages

  1. [1]

    All other connections are strongly suppressed by 50 dB. Identical configurations are used for the other cavities, apart from the horizontal one, where the laser is directly stabilized to the counter-clockwise direction and only the clockwise direction is locked using the radio-frequency drive of the AOM. (c) Long-term frequency drift ∆fwhile stabilizing t...

  2. [2]

    G. A. Asif, N. H. Ariffin, N. A. Aziz, M. H. H. Mukhtar, and N. Arsad, True north measurement: A comprehen- sive review of carouseling and maytagging methods of gyrocompassing, Measurement226, 114121 (2024)

    2024

  3. [3]

    H. Igel, U. Schreiber, A. Flaws, B. Schuberth, A. Ve- likoseltsev, and A. Cochard, Rotational motions induced by the m8.1 tokachi-oki earthquake, september 25, 2003, Geophysical Research Letters32(2005)

    2003

  4. [4]

    Igel, M.-F

    H. Igel, M.-F. Nader, D. Kurrle, A. M. G. Ferreira, J. Wassermann, and K. U. Schreiber, Observations of earth’s toroidal free oscillations with a rotation sensor: The 2011 magnitude 9.0 tohoku-oki earthquake, Geo- physical Research Letters38(2011)

    2011

  5. [5]

    H. Igel, K. U. Schreiber, A. Gebauer, F. Bernauer, S. Egdorf, A. Simonelli, C.-J. Lin, J. Wassermann, S. Donner, C. Hadziioannou, S. Yuan, A. Brotzer, J. Kodet, T. Tanimoto, U. Hugentobler, and J.-P. R. Wells, Romy: a multicomponent ring laser for geodesy and geophysics, Geophysical Journal International225, 684 (2021)

    2021

  6. [6]

    K. U. Schreiber and J.-P. R. Wells, Invited review article: Large ring lasers for rotation sensing, Review of Scientific Instruments84, 041101 (2013)

    2013

  7. [7]

    Gebauer, M

    A. Gebauer, M. Tercjak, K. U. Schreiber, H. Igel, J. Kodet, U. Hugentobler, J. Wassermann, F. Bernauer, C.-J. Lin, S. Donner, S. Egdorf, A. Simonelli, and J.-P. R. Wells, Reconstruction of the instantaneous earth rotation vector with sub-arcsecond resolution using a large scale ring laser array, Phys. Rev. Lett.125, 033605 (2020)

    2020

  8. [8]

    K. U. Schreiber, J. Kodet, U. Hugentobler, T. Kl¨ ugel, and J.-P. R. Wells, Variations in the earth’s rotation rate measured with a ring laser interferometer, Nature Pho- tonics (2023)

    2023

  9. [9]

    K. U. Schreiber, U. Hugentobler, J. Kodet, S. Stellmer, T. Kl¨ ugel, and J.-P. R. Wells, Gyroscope measurements of the precession and nutation of earth’s axis, Science Advances (2025)

    2025

  10. [10]

    Schreiber and J.-P

    U. Schreiber and J.-P. Wells,Rotation Sensing with Large Ring Lasers: Applications in Geophysics and Geodesy (Cambrige University Press, 2023)

    2023

  11. [11]

    la circulation de l’´ ether lumineux dans un interf´ erographe tournant, J

    Sagnac, G., Effet tourbillonnaire optique. la circulation de l’´ ether lumineux dans un interf´ erographe tournant, J. Phys. Theor. Appl. (1914)

    1914

  12. [12]

    K. U. Schreiber, T. Kl¨ ugel, and G. E. Stedman, Earth tide and tilt detection by a ring laser gyroscope, Journal of Geophysical Research: Solid Earth108(2003)

    2003

  13. [13]

    Virgilio, N

    A. Virgilio, N. Beverini, G. Carelli, D. Ciampini, F. Fuso, and E. Maccioni, Analysis of ring laser gyroscopes in- cluding laser dynamics, The European Physical Journal C 10.1140/epjc/s10052-019-7089-5 (2019)

    work page doi:10.1140/epjc/s10052-019-7089-5 2019

  14. [14]

    Brotzer, H

    A. Brotzer, H. Igel, F. Bernauer, J. Wassermann, J. Kodet, K. U. Schreiber, J. Zenner, and S. Stellmer, On environment-related instrumental effects of romy (ro- tational motions in seismology): A prototype, multi- component, heterolithic ring laser array, Review of Sci- entific Instruments (2025)

    2025

  15. [15]

    Zenner, K

    J. Zenner, K. U. Schreiber, and S. Stellmer, Stabilizing the free spectral range of a large ring laser, Optics Letters (2025)

    2025

  16. [16]

    Y. Chen, Y. Zhong, K. Liu, Y. Liu, Y. Cai, Z. Liu, L. Zheng, Z. Wang, K. U. Schreiber, Z. Lu, J. Zhang, L. Tu, and J. Luo, Giant 64 m2 passive green laser gyro- scope: solution in earth rotation sensing and geophysical detection, Opt. Lett. (2025)

    2025

  17. [17]

    Ezekiel and S

    S. Ezekiel and S. R. Balsamo, Passive ring resonator laser gyroscope, Applied Physics Letters30, 478 (1977)

    1977

  18. [18]

    W. Z. Korth, A. Heptonstall, E. D. Hall, K. Arai, E. K. Gustafson, and R. X. Adhikari, Passive, free-space het- erodyne laser gyroscope, Classical and Quantum Gravity 33, 035004 (2016)

    2016

  19. [19]

    K. Liu, F. L. Zhang, Z. Y. Li, X. H. Feng, K. Li, Z. H. Lu, K. U. Schreiber, J. Luo, and J. Zhang, Large-scale passive laser gyroscope for earth rotation sensing, Opt. Lett.44, 2732 (2019)

    2019

  20. [20]

    X. Feng, K. Liu, Y. Chen, H. Zhang, Z. Li, F. Zhang, K. U. Schreiber, Z. Lu, and J. Zhang, Three-wave dif- ferential locking scheme in a 12-m-perimeter large-scale passive laser gyroscope, Appl. Opt. (2023)

    2023

  21. [21]

    Zenner, K

    J. Zenner, K. U. Schreiber, and S. Stellmer, H¨ ansch- couillaud locking of a large sagnac interferometer: ad- vancing below the flicker floor, Optics Letters (2026)

    2026

  22. [22]

    S. Yuan, A. Simonelli, C. Lin, F. Bernauer, S. Don- ner, T. Braun, J. Wassermann, and H. Igel, Six degree- of-freedom broadband ground-motion observations with 8 portable sensors: Validation, local earthquakes, and sig- nal processing, Bulletin of the Seismological Society of America (2020)

    2020

  23. [23]

    G. Izgi, E. P. S. Eibl, S. Donner, and F. Bernauer, Perfor- mance test of the rotational sensor blueseis-3a in a hud- dle test in f¨ urstenfeldbruck, Sensors 10.3390/s21093170 (2021)

    work page doi:10.3390/s21093170 2021

  24. [24]

    Chung, S.-H

    H.-P. Chung, S.-H. Chang, C.-L. Hsieh, H. Yang, C.-C. Chen, J.-Y. Liu, H.-Y. Yen, and Y.-H. Chen, Seismic waves of the 10 december 2020 m6.6 yilan earthquake observed by interferometric fiber-optic gyroscope, Ter- restrial, Atmospheric and Oceanic Sciences (2022)

    2020

  25. [25]

    Huang, Y

    H. Huang, Y. Cao, L. Zhu, Y. Chen, W. Wang, F. Shi, and Z. Li, A giant interferometric fiber optic gyro- scope with low self-noise for geophysical rotation sensing, CLEO 2024 (2024)

    2024

  26. [26]

    Brotzer, H

    A. Brotzer, H. Igel, E. Stutzmann, J. Montagner, F. Bernauer, J. Wassermann, R. Widmer-Schnidrig, C. Lin, S. Kiselev, F. Vernon, and K. U. Schreiber, Characterizing the background noise level of rotational ground motions on earth, Seismological Research Letters 95, 1858 (2023)

    2023

  27. [27]

    A. D. V. Di Virgilio, F. Bajardi, A. Basti, N. Beverini, G. Carelli, D. Ciampini, G. Di Somma, F. Fuso, E. Mac- cioni, P. Marsili, A. Ortolan, A. Porzio, and D. Vitali, Noise level of a ring laser gyroscope in the femto-rad/s range, Phys. Rev. Lett. (2024)

    2024

  28. [28]

    Simonelli, H

    A. Simonelli, H. Igel, J. Wassermann, J. Belfi, A. Di Vir- gilio, N. Beverini, G. De Luca, and G. Saccorotti, Ro- tational motions from the 2016, central italy seismic se- quence, as observed by an underground ring laser gyro- scope, Geophysical Journal International (2018)

    2016

  29. [29]

    Brotzer,The ROMY Ring Laser Array for Seismol- ogy: Instrumental Characterization, Low Noise Limits for Rotations and Seismological Applications(Disserta- tion, 2024)

    A. Brotzer,The ROMY Ring Laser Array for Seismol- ogy: Instrumental Characterization, Low Noise Limits for Rotations and Seismological Applications(Disserta- tion, 2024)

    2024

  30. [30]

    Capezzuto, G

    M. Capezzuto, G. Gaudiosi, L. Nardone, E. D’Alema, D. D’Ambrosio, R. Manzo, A. Giorgini, P. Malara, P. Na- tale, G. Gagliardi, L. Amato, D. Galluzzo, and S. Avino, Fiber-optic gyroscope for rotational seismic ground mo- tion monitoring of the campi flegrei volcanic area, Ap- plied Optics 10.1364/AO.518354 (2024)

    work page doi:10.1364/ao.518354 2024

  31. [31]

    Brotzer, H

    A. Brotzer, H. Igel, F. Bernauer, J. Wassermann, R. Mel- lors, and F. Vernon, On single-station, six degree-of- freedom observations of local to regional seismicity at the pi˜ non flat observatory in southern california, Seismica4 (2025)

    2025

  32. [32]

    Photonics,Koheras ADJUSTIK Product Guide, NKT Photonics (2024)

    N. Photonics,Koheras ADJUSTIK Product Guide, NKT Photonics (2024)

    2024

  33. [33]

    E. D. Black, An introduction to pound–drever–hall laser frequency stabilization, American Journal of Physics (2001)

    2001

  34. [34]

    Analog Devices,ADIS16465 Precision MEMS IMU Mod- ule Data Sheet, Analog Devices (2023)

    2023

  35. [35]

    P. Welch, The use of fast fourier transform for the estima- tion of power spectra: A method based on time averaging over short, modified periodograms, IEEE Transactions on Audio and Electroacoustics15, 70 (1967)

    1967

  36. [36]

    L. C. Ng,On the application of Allan variance method for Ring Laser Gyro performance characteriza- tion(Lawrence Livermore National Lab., CA (United States), 1993)

    1993

  37. [37]

    Allan, Statistics of atomic frequency standards, Pro- ceedings of the IEEE54, 221 (1966)

    D. Allan, Statistics of atomic frequency standards, Pro- ceedings of the IEEE54, 221 (1966)

    1966