Interferometer Research Articles

Experimental Analysis of Surface Roughness of Steel by Considering Variable Cutting Parameters for Turning

This paper presents results of experiment conducted in order to analysis of surface roughness of steel by considering variables cutting parameters for turning. Surface roughness measurement is a critical aspect of quality control in manufacturing processes, particularly in the context of lathe and milling machine operations. This abstract provides an overview of the methods, tools, and significance of surface roughness measurement in turning processes. It explores the key techniques, such as stylus profilometry and optical interferometry that are commonly employed for assessing surface roughness. The abstract also highlights the importance of surface roughness measurement in ensuring product quality, functionality, and performance. Furthermore, it emphasizes the relevance of this research in optimizing machining processes, enhancing product aesthetics, and reducing material waste. This investigation contributes to the field of precision manufacturing by presenting an in-depth analysis of surface roughness measurement in lathe machine applications, offering valuable insights for industry professionals and researchers alike.

Laser interferometer measurement and reconstruction of supersonic projectile acoustic pressure fields

Sensing acoustic fields with a laser interferometer offers several advantages over conventional techniques: the probe beam does not disturb the medium in which it operates, the interferometer optics can be placed far from the source, and interferometry typically has a wider bandwidth than microphones. These advantages are particularly useful in situations where precise measurements of high-amplitude shock-generating sources are required. In this work we use a laser interferometer to study the generation and propagation of shock wave signatures of ballistic projectiles. A laboratory experiment was conducted to collect interferometer data from a variety of supersonic projectiles over a range of standoff distances. Simultaneously-captured microphone data is compared to the interferometer measurements, and techniques for inversion and reconstruction of the sound pressure field are discussed.

Large-Range and Highly Sensitive Displacement Measurement With an Optical Carrier-Based Microwave Interferometry

Large-Range and Highly Sensitive Displacement Measurement With an Optical Carrier-Based Microwave Interferometry

TransientX: A high-performance single-pulse search package

Context. Radio interferometers composed of a large array of small antennas possess large fields of view, coupled with high sensitivities. For example, the Karoo Array Telescope (MeerKAT) achieves a gain of up to 2.8 KJy−1 across its >1 deg2 field of view. This capability significantly enhances the survey speed for pulsars and fast transients. It also introduces challenges related to the high data rate, which reaches a few Tb s−1 for MeerKAT, and it requires substantial computing power. Aims. To handle the high data rate of surveys, we have developed a high-performance single-pulse search software called “TransientX”. This software integrates multiple processes into one pipeline, which includes radio-frequency interference mitigation, dedispersion, matched filtering, clustering, and candidate plotting. Methods. In TRANSIENTX, we developed an efficient CPU-based dedispersion implementation using the sub-band dedispersion algorithm. Additionally, TRANSIENTX employs the density-based spatial clustering of applications with noise (DBSCAN) algorithm to eliminate duplicate candidates, using an efficient implementation based on the kd-tree data structure. We also calculate the decrease of signal-to-noise ratio (s/N) resulting from dispersion measure, boxcar width, spectral index, and pulse-shape mismatches. Remarkably, we find that the decrease of S/N resulting from the mismatch between a boxcar-shaped template and a Gaussian-shaped pulse with scattering remains relatively small, at approximately 9%, even when the scattering timescale is ten times that of the pulse width. Additionally, the decrease in the S/N resulting from the spectral index mismatch becomes significant with multi-octave receivers. Results. We have benchmarked the individual processes, including dedispersion, matched filtering, and clustering. Our dedispersion implementation can be executed in real time using a single CPU core on data with 4096 dispersion measure trials, which consist of 4096 channels and have a time resolution of 153 µs. Overall, TRANSIENTX offers the capability for efficient CPU-only real-time single-pulse searching.

Pinpointing gravitational waves via astrometric gravitational wave antennas

The direct detection of gravitational waves by ground-based optical interferometers has opened a new window in astronomy. Besides, the sensitivity of these linear detectors to the direction of arrival of an incoming gravitational wave is limited compared to current prospects of high-precision, space-based, astrometry. Indeed, advanced methods of differential relativistic astrometry offer a unique opportunity to overcome that situation. Here, we present a novel concept for a gravitational wave antenna that uses angles between close pairs of point-like sources as natural (angular) “arms” to characterise the very tiny variations in angular separations induced by a passing gravitational wave. The proposed new astrometric gravitational wave observable proves to be a powerful tool to substantially enhance the effect of gravitational waves of different strengths by exploiting optical resolution to the fullest. Then, by optically multiplexing three (or more) of such astrometric “arms”, it would be also possible to pinpoint source directions to unprecedented levels.

Multi-antenna probing of absorbing regions inside and outside Cassiopeia A

Context. Cassiopeia A occupies an important place among supernova remnants (SNRs) in low-frequency radio astronomy. Located in our Galaxy, this powerful radio source emits synchrotron radiation that propagates through the SNR environment and the ionized interstellar medium. The analysis of its continuum spectrum from low frequency observations reveals the evolution of the SNR absorption properties over time and suggests a method for probing unshocked ejecta and the SNR interaction with the circumstellar medium (CSM). Aims. In this paper, we present low-frequency measurements of the integrated spectrum of Cassiopeia A to find the typical values of free-free absorption parameters towards this SNR in the middle of 2023. We also add new results to track its slowly evolving and decreasing integrated flux density. Methods. We used the New Extension in Nançay Upgrading LOFAR (NenuFAR) and the Ukrainian Radio Interferometer of NASU (URAN–2, Poltava) for measuring the continuum spectrum of Cassiopeia A within the frequency range of 8–66 MHz. The radio flux density of Cassiopeia A relative to the calibration source, the radio galaxy Cygnus A, has been obtained on June–July, 2023 with two sub-arrays for each radio telescope, used as a two-element correlation interferometer. Results. We measured the values of parameters such as the emission measure, electron temperature and average number of ion charges, for both the internal and external absorbing ionized gas towards Cassiopeia A from its integrated spectrum. Generally, their values are comparable to those presented in the literature, but their slight differences demonstrate the evolution of free-free absorption parameters in this SNR. Based on high accuracy of the measurements, we have detected the SNR–CSM interaction. This led to the fact that the maximum of this continuous spectrum, decreasing in intensity, changed in frequency from past higher values to lower ones over time. Probably, such changes occur periodically in which the spectral peak can move in the direction of both higher frequencies and lower ones. This effect is mainly caused by the evolution of emission measure outside Cassiopeia A. Conclusions. The integrated flux-density spectrum of Cassiopeia A obtained with the NenuFAR and URAN–2 interferometric observations opens up new possibilities for continuous monitoring the ionized gas properties in and around Cassiopeia A to observe the evolution of unshocked ejecta and the SNR-CSM interaction in future studies.

Quantum limits of parameter estimation in long-baseline imaging

Telescope systems with distributed apertures are a well-established approach for boosting resolution in astronomical imaging. However, theoretical limits on quantitative imaging precision, and the fundamentally best possible mode-sorting, beam-combining, and detection schemes to use with such arrays, remain largely unexplored. Using mathematical tools of the quantum and classical Crámer-Rao bounds, we perform analyses showing the fundamental origins of the enhancement provided by distributed imaging systems, over and above a single monolithic telescope, and consider the precision with which one can estimate any desired parameter embedded in a scene's incoherent radiation with a multi-aperture imaging system. We show how quantum-optimal measurements can be realized via beam-combination strategies of two classes: (1) , where light from different apertures is directed to a common focal plane, e.g., of a segmented-aperture telescope; and (2) , where light collected at each aperture, e.g., telescope sites of a long-baseline array, is routed to an optical interferometer. As an example, we show an explicit calculation of the quantum Fisher information (QFI) for estimating the angular separation between two-point emitters using two identical apertures separated by a baseline distance. We show that this QFI splits instructively into additive contributions from the single apertures and from the baseline. We quantify the relative benefits of intratelescope (e.g., spatial-mode) optical processing and intertelescope beam combination. We show how both receiver designs can be used to capture both sources of information and discuss how similar methods could be extended to more general imaging tasks. We discuss translating QFI-attaining measurements to explicit receiver designs, and the use of preshared entanglement to achieve the QFI when it is impractical to colocate and combine light collected by the apertures. Published by the American Physical Society 2024

Towards a more practical analysis of Newton's rings using deep learning.

As a typical form of optical fringes with a quadratic phase, Newton's ring patterns play an important role in spherical measurements and optical interferometry. A variety of methods have been used to analyze Newton's ring patterns. However, it is still rather challenging to fulfill the analysis. We present a deep-learning-based method to estimate the parameters of Newton's ring patterns and fulfill the analysis accordingly. The experimental results indicate the excellent accuracy, noise robustness, and demodulation efficiency of our method. It provides another applicable approach to analyzing Newton's ring patterns and brings insights into fringe analysis and interferometry-based measurements.

Concurrent M-QAM transmission performance assessment in a combined four SOA-MZIs arrangement

In this paper, the utilization of four semiconductor optical amplifier Mach-Zehnder interferometers (SOA-MZIs) is explored to achieve concurrent M-QAM (M-ary Quadrature Amplitude Modulation) transmission. Utilizing an actively mode-locked laser, we generate pulses with a duration of 0.5 ps at a repetition rate of 20 GHz, serving as our sampling source. The incoming M-QAM signals, spanning various frequencies, undergo down-mixing at the SOA-MZIs combined exit, resulting in diverse output frequencies by respecting the bandpass sampling procedures. The unparalleled simultaneous M-QAM transmission is assessed through critical metrics such as error vector magnitude (EVM) and bit error rate (BER). The SOA-MZI conversion efficiency (CE) exhibits a notable transition, ranging from 90 % at 76 GHz to 68 % at 84 GHz based on 1024-QAM data. The concurrent down-mixed signals showcase EVM values of 3, 2, 1, and 0.25 % for 16-, 64-, 256-, and 1024-QAM, respectively, at the first range of output frequencies. Besides, an exceptional BER value of 93×10−6 is attained at a symbol rate of 0.25 GSymb/s at 84 GHz for the 1024-QAM replica. A comparative analysis reveals that under identical parameter settings, the proposed Gaussian filter expounds lower EVM values compared to the root raised cosine (RRC) filter. These results highlight the success of the novel experimental approach employing SOA-MZIs for simultaneous down-mixing of four M-QAM carriers with varying levels, showcasing outstanding performance outcomes.

Frequency response of the non-polarization-maintaining depolarized sagnac interferometer based on maximum fringe contrast

The Sagnac Interferometer offers a promising solution to the speckle problem in interferometric detection due to its insensitivity to environmental low-frequency interference, making it well-suited for applications such as laser ultrasonic detection. Control of the polarization state of light is imperative for achieving high sensitivity in optical fiber interferometer and ensuring optimal quiescent operating conditions. This study employed the coherence matrix method to analyze the theory of optimal polarization control in a non-polarization-maintaining depolarized Sagnac Interferometer, encompassing the deduction of the stable π/2 initial phase bias and the maximum fringe contrast of 50% in theory. In experimental observations during PZT simulated large amplitude ultrasound experiments, the fringe contrast reached 48.4%. Furthermore, the system's amplitude-frequency response was evaluated using an electro-optics phase modulator, demonstrating its capability to detect high-frequency signals within 100 MHz These findings provide essential insights into optimizing the Sagnac Interferometer's performance for laser ultrasonic detection and its potential applications in high-frequency signal detection and ultrasonic amplitude measurement.

ANALYSIS OF NULL RESULTS OF HAMMAR EXPERIMENT BY CLASSICAL MECHANICS WITHOUT SPECIAL THEORY OF RELATIVITY

In optics interferometers are used for precision measurements. In interferometry two waves of light are superimposed to generate interference fringes. The interference pattern is observed and analyzed to measure physical process. Gustaf Wilhelm Hammar conducted an experiment in the year 1935 to test aether drag hypothesis. The null results of this experiment were interpreted in consistent with special theory of relativity. Hammar used common path interferometer and observed the changes in interference fringes due to motion of earth. The present work describes that when there is no aether and no medium drags the light in its direction of motion than what will be the behaviour of light.The analysis has been made according to classical mechanics keeping in view Huygen’s principle by tracking the pathways of both the rays of light.It is established that speed of light is independent of velocity of any object,apparatus or any observer and there is no effect of motion of earth.The null results of Hoek’s experiment and Hammar experiment are in consistent with classical mechanics.

Real-time and quantitative investigation of zwitterionic surfactant interaction at oil-water interface: Interferometry experimental and MD simulation insights

In this work, the interaction performances at octadecane oil–water interface were investigated for zwitterionic surfactants of dodecyl dimethyl hydroxypropyl sulfobetaine (HSB-12) and hexadecyl dimethyl hydroxypropyl sulfobetaine (HSB-16) from both experimental and simulation insights. For macroscopic experiment, optical interferometry methodology was developed to real-time measure the interfacial interaction process and obtain the quantitative interfacial thickness and mass results. The four-step dynamic process (diffusion, adsorption, arrangement and aggregation) was characterized by kinetic analysis, indicating arrangement process as slow-limiting step. The rate of the four step process (diffusion rate k1(dif), adsorption rate k2(ads), arrangement rate k3(arr), and aggregation rate k4(agg)) is represented as k3(arr)<k1(dif),k2(ads),k4(agg). The Langmuir model was characterized by thermodynamic analysis, deducing the aggregation spontaneity of HSB-16 > HSB-12. The free energy of the aggregation stages of HSB-16 and HSB-12 was expressed as ΔGagg(HSB16)=-3.95 kJ/mol < ΔGagg(HSB12)=-3.13kJ/mol. For microscopic simulation, the interaction configurations and interaction energies were obtained through molecular dynamics simulation (MDS) calculation. The interaction stability and interaction strength were indicated to be HSB-16 > HSB-12. The interaction mechanism was explained by proposing molecular-orientation model below critical micelle concentration (CMC) and layer-interaction model above CMC. The different mechanisms were attributed to electronic attraction between surfactant molecules and hydrophobic interaction between surfactant and oil molecules. This work successfully constructs the interfacial platform for oil–water interface analysis, which not only elucidate the surfactant-oil intermolecular interactions but also provide mechanism understanding from macroscopic and microscopic scales.

A new method for short-duration transient detection in radio images: searching for transient sources in MeerKAT data of NGC 5068

ABSTRACT Transient surveys are a vital tool in exploring the dynamic Universe, with radio transients acting as beacons for explosive and highly energetic astrophysical phenomena. However, performing commensal transient surveys using radio imaging can require a significant amount of computing power, data storage, and time. With the instrumentation available to us, and with new and exciting radio interferometers in development, it is essential that we develop efficient methods to probe the radio transient sky. In this paper, we present results from a commensal short-duration transient survey, on time-scales of 8 s, 128 s, and 1 h, using data from the MeerKAT radio telescope. The data set used was obtained as part of a galaxy observing campaign, and we focus on the field of NGC 5068. We present a quick, wide-field imaging strategy to enable fast imaging of large data sets, and develop methods to efficiently filter detected transient candidates. No transient candidates were identified on the time-scales of 8 s, 128 s, and 1 h, leading to competitive limits on the transient surface densities of $6.7\, {\times }\, 10^{-5}$, $1.1\, {\times }\, 10^{-3}$, and $3.2\, {\times }\, 10^{-2}$ deg−1 at sensitivities of 56.4, 19.2, and 3.9 mJy following primary beam correction for the respective time-scales. We find one possible candidate that could be associated with a stellar flare, which was rejected due to strict image quality control. Further short time-scale radio observations of this candidate could give definite results about its origin.

Optical Feedback FM-to-AM Conversion with integrated Micro-Ring Resonator for Displacement Sensing Applications

In this study, we show the capability of integrated Micro-Ring Resonators (MRRs) to perform frequency-to-amplitude (FM-to-AM) conversion of optical feedback interferometry (OFI) signals with improved signal-to-noise ratio compared to conventional AM OFI signals. Further, contrary to traditional OFI FM-to-AM conversion techniques using gas cell-based edge filters and free-space or fiber Mach-Zehnder Interferometers (MZI), integrated photonic processing offers greater compactness and perturbation resilience, enhancing noise performance through improved temperature control and immunity to parasitic mechanical vibrations. The OFI FM-to-AM conversion was performed with a fabricated silicon nitride MRR of radius 120 μm and a quality factor of 130,000. The FM-to-AM conversion factor achieved was 0.61 GHz−1, with a noise equivalent displacement of only 4.9 nm for a 1 kHz bandwidth. This demonstration highlights the potential of integrated edge filters to replace traditional freespace and fiber architectures, more prone to environmental perturbations, in OFI signal processing for vibrometric applications.

An ERPNS Technology Based on OFDR for Accurate Arm-Length Difference Measurement of Optical Fiber Interferometer Under Dynamic Environment

An ERPNS Technology Based on OFDR for Accurate Arm-Length Difference Measurement of Optical Fiber Interferometer Under Dynamic Environment

Real-time tracking of the adsorption of bovine serum albumin on lipid layer and its effect on lipolysis by optical interferometry

The model proteins bovine serum albumin (BSA) and lipid layer were used to study the effect of proteins on lipolysis. A lipid layer with an interference effect was constructed by loading the triolein into the silica colloidal crystal (SCC) film. The ordered porous layer interferometry (OPLI) system was used to track the changes in lipid layer mass caused by lipase hydrolysis to achieve real-time lipolysis detection. The real-time tracking of the adsorption of BSA on the lipid layer by converting the migration of interference fringes caused by the change of the lipid layer into the optical thickness change (ΔOT). The effect of BSA on the early and late stages of lipolysis was studied, and lipases containing 5 mg/mL BSA degraded the lipid layer 3.4 times faster than lipases containing 0.1 mg/mL BSA in the later stages. This study deepens the understanding of protein-lipid interactions in complex digestive environments.

Single‐shot phase‐shifting on Michelson interferometry for incoherent digital holography

AbstractA single‐shot phase‐shifting method in incoherent digital holography (IDH) based on Michelson interferometry is proposed herein. The proposed method uses polarization‐modulating optical elements and a polarization sensor in the Michelson interferometer optics to induce a geometric phase shift. It acquires four holograms with different geometric phase retardations in a single exposure to eliminate the bias and conjugate noise using a phase‐shifting technique. The proposed optical system enables real‐time bias and conjugate term removal from a recorded hologram without requiring sequential recording for phase shifting. Furthermore, because it is based on Michelson interferometry, it can be implemented using simple reflective optics without expensive or difficult‐to‐produce optical elements for single‐shot phase shifting. The principles of self‐interference and geometric phase shifting in the proposed optical structure were analyzed mathematically. A real‐time IDH‐recording experimental setup was constructed to verify the proposed method. The experimental results of single‐shot phase‐shifting IDH and hologram movie recordings confirm the feasibility of the proposed method.

Three-dimensional imaging of acoustic pressure by tomography applied to optical feedback interferometry

This paper presents a novel experimental technique for three-dimensional imaging of acoustic pressure waves by means of an optical feedback interferometer associated to standard Radon transformation algorithm for tomography. The imaging system is based on the sensing of the optical refractive index changes induced by the pressure variation in the medium where the acoustic wave propagates. Thanks to the compactness allowed by the laser optical feedback interferometer, this technique allows to image in three dimensions the variations of pressure of any acoustic source without any displacement of the source.

Talbot-Lau devices: a reappraisal

The Talbot effect and the Lau effect have been usefully applied in optical interferometry, and for designing novel X-ray devices, as well as for implementing useful instruments for matter waves. In temporal optics, the above phenomena play a significant role for reconstructing modulated, optical short pulses that travel along a dispersive medium. We note that the Talbot-Lau devices can be spatial frequency tuned if one employs varifocal lenses as a nonmechanical technique. Thus, we identify a pertinent link between the Talbot-Lau sensors and the development of artificial muscle materials, for generating tunable lenses. Our discussion unifies seemly unrelated topics, for providing a global scope on the applications of the Talbot-Lau effect.

Mapping a Lower Limit on the Mass Fraction of the Cold Neutral Medium Using Fourier-transformed H i 21 cm Emission Line Spectra: Application to the DRAO Deep Field from DHIGLS and the HI4PI Survey

We develop a new method for spatially mapping a lower limit on the mass fraction of the cold neutral medium by analyzing the amplitude structure of Tˆb(kv) , the Fourier transform of T b (v), the spectrum of the brightness temperature of the H i 21 cm line emission with respect to the radial velocity v. This advances a broader effort exploiting 21 cm emission line data alone (without absorption line data, τ) to extract integrated properties of the multiphase structure of the H i gas and to map each phase separately. Using toy models, we illustrate the origin of interference patterns seen in Tˆb(kv) . Building on this, a lower limit on the cold gas mass fraction is obtained from the amplitude of Tˆb at high k v . Tested on a numerical simulation of thermally bi-stable turbulence, the lower limit from this method has a strong linear correlation with the “true” cold gas mass fraction from the simulation for a relatively low cold gas mass fraction. At a higher mass fraction, our lower limit is lower than the “true” value, because of a combination of interference and opacity effects. Comparison with absorption surveys shows a similar behavior, with a departure from linear correlation at N H I ≳ 3–5 × 1020 cm−2. Application to the DRAO Deep Field from DHIGLS reveals a complex network of cold filaments in the Spider, an important structural property of the thermal condensation of the H i gas. Application to the HI4PI survey in the velocity range −90 < v < 90 km s−1 produces a full sky map of a lower limit on the mass fraction of the cold neutral medium at 16.′2 resolution. Our new method has the ability to extract a lower limit on the cold gas mass fraction for massive amounts of emission line data alone with low computing time and memory, pointing the way to new approaches suitable for the new generation of radio interferometers.