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Group alternating integration for distributed acoustic sensing with improved signal-to-noise ratio

Angelsky Oleg, Strynadko Myroslav, Zenkova Claudia, Zheng Jun

Opto-Electronics Review

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2025

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Vol. 33, No. 4

art. no. e155878

EN

Distributed acoustic sensing (DAS) based on Rayleigh backscattering is actively used for perimeter monitoring of critical infrastructure. However, traditional signal processing methods often face challenges in detecting weak or short-term events in noisy conditions. In this paper, we propose an improved signal accumulation method based on group averaging with alternating sign integration. The proposed method provides the efficient noise suppression and improves the detection of local mechanical disturbances along the fibre. Comparative simulation study between the classical and the proposed approach demonstrates a significant improvement in signal visibility in the presence of additive noise. Potential implementations of multi-layered and mesh-integrated DAS configurations are also discussed to further enhance signal-to-noise ratio (SNR). The obtained results can serve as a basis for the development of modern security systems for critical facilities.

2

Automated polarisation-optical method for diagnostics of railway rails surface defects

Angelsky Oleg, Strynadko Myroslav, Zenkova Claudia, Zheng Jun

Opto-Electronics Review

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2025

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Vol. 33, No. 3

art. no. e155876

EN

This paper presents a novel polarisation-optical method for the automated inspection of surface defects in railway rails. The proposed approach is based on the detection of changes in the polarisation state of reflected laser radiation, caused by local anomalies such as cracks, residual stress zones, and surface contamination. A differential signal is generated by separating orthogonal polarisation components using a polarising beam splitter, enabling high sensitivity to surface irregularities while suppressing common-mode noise. To improve the interpretability of the acquired signal, a multi-stage digital processing pipeline is employed. It includes moving average and Gaussian filtering, threshold-based segmentation, and frequency-domain analysis using both discrete Fourier and continuous wavelet transforms. The method was validated through a set of simulated signals, imitating typical rail defects in noisy conditions. The results demonstrate reliable detection and localisation of structural anomalies, with a clear distinction between sharp discontinuities and wide modulations caused by tension. Due to its compatibility with automated processing frameworks, the method is well suited for integration with modern diagnostic platforms, including mobile rail inspection systems. This makes it a promising candidate for predictive maintenance strategies and digital transformation of railway infrastructure monitoring.

3

New possibilities of polarization-sensitive optical coherence tomography using geometric phase approach for diagnostics of thin surface (subsurface) biological layers

Zenkova Claudia, Angelsky Oleg, Ivanskyi Dmytro

Optica Applicata

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2024

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Vol. 54, nr 3

303--316

EN

The paper focuses on presenting the new original results and highlighting of possibilities of geometric phase using in low-coherence polarization-sensitive tomography tasks for noninvasive diagnostics of surface (subsurface) layers of transparent (translucent) biological media (samples and tissues). Determination of the object fields’ geometric phase in the modified Mach–Zehnder interferometer allows one to reproduce the geometric structure (optical axis/collagen orientation) of birefringent biological medium. Polarization-interference noninvasive approach of the collagen orientation structure diagnostics of thin nanosized surface tissue layers is proposed at the first time. It is shown, that taking into account the information about top (surface) layer structure can significantly improve the accuracy of deeper (subsurface) layers parameters estimation. The proposed solution is a unique feature that is not accessible in classical polarization-sensitive techniques of information recovery on tissue structure.