arXiv subjects

Artem Basalaev

Publications and source records attributed to Artem Basalaev.

3 recordsLinked to original sources

arXiv2025

Mitigating effects of nonlinearities in homodyne quadrature interferometers

Homodyne Quadrature interferometers (HoQI) are an interferometric displacement sensing scheme proven to have excellent noise performance, making them a strong candidate for sensing and control schemes in gravitational wave detector seismic isolation. Like many interferometric schemes, HoQIs are prone to nonlinear effects when measuring displacements. These nonlinearities, if left unsuppressed, would substantially limit the use cases of HoQIs. This paper first shows a means of measuring and quantifying nonlinearities using a working HoQI and a mechanical resonator. We then demonstrate a method for real-time correction of these nonlinearities and several approaches for accurately calibrating the correction technique. By correcting in real time, we remove one of the biggest obstacles to including HoQIs in upgrades to future gravitational wave detectors. Finally, we discuss how to post correct data from HoQIs, suppressing even further the nonlinearity-induced errors, broadening the appeal of such sensors to other applications where measurement data can be reconstructed after the fact. We demonstrate all of this on a working HoQI system and show the measured suppression of nonlinear effects from each of these methods. Our work makes HoQIs a more broadly applicable tool for displacement sensing.

physics.ins-det↗

arXiv2025

Reducing suspension control noise with interferometric sensors -- an experimental concept

One of the limiting noise sources of ground-based gravitational wave detectors at frequencies below 30 Hz is control-induced displacement noise. Compact laser interferometric sensors are a prime candidate for improved local displacement sensing. In this paper we present the design of an experiment that aims to demonstrate the advantages of interferometric sensors over shadow sensors. We focus on the compact balanced readout interferometer (COBRI) - a sensor currently in development that is based on deep frequency modulation. We mount COBRIs on two HAM Relay Triple Suspension (HRTS) systems that suspend two mirrors forming an optical cavity. By measuring the length stability of this cavity relative to a stable reference we aim to probe the direct motion reduction when using COBRIs for active damping and we aim to investigate their behavior and auxiliary functions, such as absolute ranging, in the context of the 6 degree-of-freedom controls of the suspensions. Here we describe the design of the experiment and simulations of the achievable noise levels that were obtained using mechanical models of the HRTS suspensions. We discuss all relevant noise sources, the modeled influence of the interferometric sensor damping and the current limitations and necessary improvements of our testing facility in terms of seismic pre-isolation to achieve a shadow sensor limited noise at around 5 Hz, where, according to our simulations, we can demonstrate superior performance for COBRIs in the longitudinal degree of freedom.

physics.ins-det↗

arXiv2024

Characterizing seismic isolation using convolutional neural networks and Wiener filters

We investigate seismic motion propagation through a passively isolated mechanical system, using Wiener filters and convolutional neural networks with time-dilation layers. The goal of this study was to explore the capabilities of neural networks and Wiener filters in characterizing a mechanical system from the measurements. The mechanical system used is a testbed facility for technology development for current and future gravitational wave detectors, "VATIGrav", currently being commissioned at University of Hamburg. It consists of a large vacuum chamber mounted on four active vibration isolators with an optical table inside, mounted on four passive vibration isolators. In this paper we have used seismic data recorded on the ground and on the optical table inside the chamber. The data were divided in 6 hours for training and another 6 hours for validation, focusing on inferring 150-second stretches of time series of table motion from the ground motion in the frequency range from $0.1~\mathrm{Hz}$ to about $50~\mathrm{Hz}$. We compare the performance of a neural network with FTT-based loss function and with Huber loss function to single-input, single-output (SISO) and multiple-input, single-output (MISO) Wiener filters. To be able to compute very large MISO Wiener filters (with 15,000 taps) we have optimized the calculations exploiting block-Toeplitz structure of the matrix in Wiener-Hopf equations. We find that for the given task SISO Wiener filters outperform MISO Wiener filters, mostly due to low coherence between different motion axes. Neural network trained with Huber loss performs slightly worse than Wiener filters. Neural network with FFT-based loss outperforms Wiener filters in some frequency regions, particularly with low amplitudes and reduced coherence, while it tends to slightly underestimate the peaks, where Wiener filters perform better.

physics.ins-det↗