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Fresnel incoherent correlation holography (FINCH) can achieve high-precision and non-scanning 3D imaging. However, as a holographic imaging technology, the huge bandwidth requirements and the amount of holographic data transmitted have always been one of the important factors limiting its application. In addition, the hardware cost of pixel array-based CCD or CMOS imaging is very high under high resolution or specific wavelength conditions. Accordingly, a single-pixel Fresnel incoherent correlation holography (SP-FINCH) compressed imaging method is proposed, which replaces pixel array detector with single-pixel detector and designs a Trumpet network to achieve low-cost and high-resolution imaging. Firstly, a modified FINCH imaging system is constructed and data acquisition is carried out using a single-pixel detector. Secondly, a Trumpet network is constructed to directly map the relationship between one-dimensional sampled data and two-dimensional image in an end-to-end manner. Moreover, by comparing the reconstructed images using neural network with that using commonly used single-pixel reconstruction methods, the results indicate that the proposed SP-FINCH compressed imaging method can significantly improve the quality of image reconstruction at lower sampling rate and achieve imaging without phase-shifting operation. The proposed method has been shown to be feasible and advantageous through numerical simulations and optical experiment results. [ABSTRACT FROM AUTHOR]

Seismic interferometry can obtain a new record by correlating original response received at two different stations. In the record, one station acts as the virtual source, while the other is regarded as the receiver. However, conventional cross-correlation interferometry calculations may yield inaccurate imaging results for virtual source records due to non-stationary phase region influences from the source. To solve this problem, we propose a new calculation method. In this method, for the traditional correlation result, the virtual event is selected through a time window and the correlation coefficients are calculated with the real data. Finally, by selecting the appropriate coefficient range, the source that needs to participate in the superposition calculation is determined. To verify the accuracy of this method, it is combined with conventional interferometry to process both the marine vertical cable seismic (VCS) model and actual data. By comparison, the profile obtained by the improved method are more accurate. [ABSTRACT FROM AUTHOR]

The accurate extraction of useful signals from the measurement data is one of the important parts and challenges of the understanding of subsurface information. The desired signal is usually hidden in the background noise, and the amplitude is weak due to the particular geological environment of the subsurface or the consistency of the measuring instrument. By extending the theory of seismic interferometry to include the effects of adjacent virtual channels and by combining super- and reverse-virtual interferometry, we obtain a hybrid virtual interferometry technique based on stacking neighboring virtual traces for wave reconstruction. We have verified the effectiveness of the processing method in suppressing noise interference and extracting useful signals using synthetic data tests. The method is applied to the processing and interpretation of acoustic measurements acquired in a cased borehole of a coal formation and an open hole of an igneous formation, where the processed waveforms are finely reconstructed, and the estimated slowness results are in good agreement with other measurements, thus providing an effective tool for data analysis. [ABSTRACT FROM AUTHOR]

The estimation of elastic properties of thin-bed formations from sonic logging is challenging. Standard slowness processing of sonic logging waveforms typically yields an average slowness log profile over the span of the receiver array, obscuring thin-layer features smaller than the array aperture. In order to enhance vertical resolution of the slowness logs, the subarray processing techniques have been developed. However, for the subarrays with smaller aperture, the semblance from subarray waveforms becomes susceptible to noise, which results in a low signal-to-noise (S/N) ratio for the processing slowness logs. To overcome the above drawbacks, we propose a slowness estimation method with the enhanced resolution ranging from the conventional array aperture resolution to the inter-receiver spacing based on the reconstruction of neighboring virtual traces (RNVTs). The method utilizes super-virtual interferometry to reconstruct a large number of waveforms for slowness extraction using redundant information from overlapping receiver subarrays. We validate the feasibility and effectiveness of the proposed method using synthetic numerical experiments. By adding different levels of noise to synthetic data, we conclude that the new method has better noise robustness. Finally, we apply this method to field data, and the estimated high-resolution slowness logs show good agreement in interbedded sand-shale sequences. Both numerical tests and examples of field data show that, the slowness logs estimated by the new method can be obtained with a high resolution as well as with a high S/N ratio, providing an effective method for assessing slowness properties from a borehole. [ABSTRACT FROM AUTHOR]

Snakes in the family Elapidae largely produce venoms rich in three-finger toxins (3FTx) that bind to the α 1 subunit of nicotinic acetylcholine receptors (nAChRs), impeding ion channel activity. These neurotoxins immobilize the prey by disrupting muscle contraction. Coral snakes of the genus Micrurus are specialist predators who produce many 3FTx, making them an interesting system for examining the coevolution of these toxins and their targets in prey animals. We used a bio-layer interferometry technique to measure the binding interaction between 15 Micrurus venoms and 12 taxon-specific mimotopes designed to resemble the orthosteric binding region of the muscular nAChR subunit. We found that Micrurus venoms vary greatly in their potency on this assay and that this variation follows phylogenetic patterns rather than previously reported patterns of venom composition. The long-tailed Micrurus tend to have greater binding to nAChR orthosteric sites than their short-tailed relatives and we conclude this is the likely ancestral state. The repeated loss of this activity may be due to the evolution of 3FTx that bind to other regions of the nAChR. We also observed variations in the potency of the venoms depending on the taxon of the target mimotope. Rather than a pattern of prey-specificity, we found that mimotopes modeled after snake nAChRs are less susceptible to Micrurus venoms and that this resistance is partly due to a characteristic tryptophan → serine mutation within the orthosteric site in all snake mimotopes. This resistance may be part of a Red Queen arms race between coral snakes and their prey. [ABSTRACT FROM AUTHOR]

This paper introduces a novel application of the laser speckle technique in dentistry, focusing on assessing the efficiency of dental excavation methods used to remove decayed tooth structure. The aim is to evaluate the efficiency of two chemo-mechanical agents and the high-speed drill using the laser speckle technique, which offers objective, non-invasive, and real-time evaluation capabilities. Extracted human primary molars with active occlusal carious lesions were sectioned into three parts, with each part allocated to one of three groups: Group 1 (Brix3000®), Group 2 (Papacarie DUO®), and Group 3 (High-speed drill mechanical caries removal). Caries removal was performed using the designated agent or method for each group. After caries excavation, speckle imaging using a 632.8 nm laser was conducted. Additionally, SEM was used to acquire micro-photographs of the surface morphology of the treated samples. The findings reveal insights into the comparative efficiency of the three dental excavation agents and methods using the laser speckle technique. The speckle parameters extracted from speckle patterns generated by treated teeth provide valuable information for evaluating the performance of the excavation methods. The scanning electron microscopy images also offer detailed visual evidence to support the analysis. This paper demonstrates the potential of the laser speckle technique for assessing the efficiency of dental excavation methods. The objective, non-invasive, and real-time evaluation provided offers advantages over subjective visual assessment and manual measurements. [ABSTRACT FROM AUTHOR]

On February 22, 2023, a devastating landslide occurred on the mining slope of an open-pit coal mine in Inner Mongolia, China, leading to the mining area being buried and 53 fatalities. The source area of the landslide measured approximately 500 m in both length and width, with an estimated volume of the deposited material reaching approximately 5 million cubic metres. Based on the severe impact of this incident, our study conducted preliminary research using a combination of methodologies, including particle image analysis, synthetic aperture radar interferometry, interpretation of optical remote sensing data, and post-event news reports analysis. The results indicated that the landslide lasted 23 s from initiation to cessation of movement. The historical deformation indicated that prior to the resumption of the mining activities, only localized deformation was observed at the rear edge of the landslide. However, when mining activities resumed in April 2021 and extended to the vicinity of the north slope, the deformation range and rate in the source area of the landslide rapidly increased. The investigation deduced that the soft foundation at the slope bottom and mining activities are the primary causative factors of this event. Mining activities, which stripped coal seams within the slope and surface rock masses, led to the expansion of tension cracks within the landslide body, weakening resisting forces at the leading edge and thus playing a significant role in destabilizing the landslide body. The evolution of the landslide from incubation to instability could be divided into four stages: early microcrack development, slow creep, accelerated deformation after resumption of mining, and ultimate instability. Therefore, it is of great significance to advance real-time deformation monitoring and early warning systems specifically those designed for mining slope areas by comprehensive measures. Furthermore, enhancing the high-frequency monitoring capabilities of synthetic aperture radar satellites is crucial to reducing the occurrence of these catastrophic events. [ABSTRACT FROM AUTHOR]

Quantitative phase imaging (QPI) has become a vital tool in bioimaging, offering precise measurements of wavefront distortion and, thus, of key cellular metabolism metrics, such as dry mass and density. However, only a few QPI applications have been demonstrated in optically thick specimens, where scattering increases background and reduces contrast. Building upon the concept of structured illumination interferometry, we introduce Gradient Retardance Optical Microscopy (GROM) for QPI of both thin and thick samples. GROM transforms any standard Differential Interference Contrast (DIC) microscope into a QPI platform by incorporating a liquid crystal retarder into the illumination path, enabling independent phase-shifting of the DIC microscope's sheared beams. GROM greatly simplifies related configurations, reduces costs, and eradicates energy losses in parallel imaging modalities, such as fluorescence. We successfully tested GROM on a diverse range of specimens, from microbes and red blood cells to optically thick (~ 300 μm) plant roots without fixation or clearing. [ABSTRACT FROM AUTHOR]

More than a century ago, Albert Einstein presented his general theory of gravitation (GR) to the Prussian Academy of Sciences. One of the predictions of the theory is that not only particles and objects with mass, but also the quanta of light, photons, are tied to the curvature of space-time, and thus to gravity. There must be a critical compactness, above which photons cannot escape. These are black holes (henceforth BH). It took 50 years after the theory was announced before possible candidate objects were identified by observational astronomy. And another 50 years have passed, until we finally have in hand detailed and credible experimental evidence that BHs of 10 to 10 10 times the mass of the Sun exist in the Universe. Three very different experimental techniques, but all based on Michelson interferometry or Fourier-inversion spatial interferometry have enabled the critical experimental breakthroughs. It has now become possible to investigate the space-time structure in the vicinity of the event horizons of BHs. We briefly summarize these interferometric techniques, and discuss the spectacular recent improvements achieved with all three techniques. Finally, we sketch where the path of exploration and inquiry may go on in the next decades. [ABSTRACT FROM AUTHOR]

A 3D nano-displacement measurement method, where the difference in phase between the beams in a four-beam laser interference is changed, is proposed. Simulation results demonstrate that the variation of phase difference causes the deviation of the interference pattern in the laser interference system. Based on this theory, we design and build a four-beam laser interference system. The corner cube prism in the optical path is shifted, and the phase of the beam is changed by applying different voltages to a piezoelectric stage. The phase difference is obtained by analyzing the lattice pattern with subpixel precision, and then the displacement is determined by correlation operation. The experimental measurement results are consistent with the theoretical analysis, thereby verifying the feasibility of this measurement method. Highlights: The four-beam laser interference lattice pattern can achieve higher precision displacement measurement. The 3D displacement measurement system of the four-beam laser interference can realize single-dimensional or multi-dimensional displacement measurement. At the same time, it provides a basis for micro-displacement measurement in various applications. The specific pixels of the interference pattern are accurately located using the correlation operation to achieve precise measurement results and minimize errors. [ABSTRACT FROM AUTHOR]

In the framework of the ALOHA (Astronomical Light Optical Hybrid Analysis) project, dedicated to high resolution imaging in the L-band using optical fibre and nonlinear optics, we have implemented a servo controlled hectometric outdoor fibre link between two telescopes and the recombination beam facility of the CHARA telescope array. A two-stage servo system using optical fibre modulator, fibre delay line, and a metrology laser at 1064 nm allows to stabilise the optical path difference within 3 nm RMS over a 3000 s record. Using an internal source at 810 nm, the signal-to-noise ratio of the fringe modulation peak is enhanced by a factor better than two when the servo control is switched on. This study can be also considered as a seminal work towards very long base fibre linked telescope arrays and allows to scale the perturbative environment of an outdoor fibre link. [ABSTRACT FROM AUTHOR]

The retrieval of surface waves from ambient noise is important for delineating the solid earth's near-surface structures, especially in urban environments. Seismic interferometry (SI) with linear arrays is becoming popular in urban areas with abundant anthropogenic noise. However, retrieving the noise correlation functions (NCFs) is usually challenging for a dense linear array under the demand of short-time recordings and the limited number of stations in urban environments. We comprehensively compare the SI and three-station interferometry, and the results show that the convolution-based three-station interferometry can accurately retrieve the NCFs using short-time recordings for dense linear arrays from traffic-induced noise. A synthetic example demonstrates the superiority of the convolution-based three-station interferometry over the traditional SI and the correlation-based three-station interferometry. Results from two field examples validate the convolution-based three-station interferometry for linear arrays deployed synchronously and asynchronously and confirm its advantage for multi-component data. We conclude that the convolution-based three-station interferometry performs better because it makes better use of linear arrays with short-time recordings and retrieves higher-quality NCFs. [ABSTRACT FROM AUTHOR]

Morphology and function in a fetal heart with severe tricuspid regurgitation remains challenging. The aim of this study was to assess cardiac morphology and function in fetuses with severe tricuspid regurgitation by fetal heart quantification (HQ) and to assess the practical value of fetal HQ. Clinical information was analyzed for 63 pregnant women who underwent fetal cardiac ultrasonography. The women were divided into those who had a fetus with severe tricuspid regurgitation (n = 20) and those with a normal fetus (n = 40). The global sphericity index (GSI), fractional area change (FAC), and global longitudinal strain (GLS) of both ventricles and the sphericity index (SI) and fractional shortening (FS) of 24 segments were quantified by fetal HQ using speckle tracking imaging. Fetuses with severe tricuspid regurgitation had a significantly lower GSI (1.14 ± 0.10 vs. 1.26 ± 0.08, p < 0.001) and a higher GSI Z-score (-0.98 ± 1.01 vs. 0.25 ± 0.87, p < 0.001) as well as a significantly lower right ventricular FAC (36.50 ± 7.34% vs. 45.19 ± 3.39%, p < 0.001), FAC Z-score (-1.02 ± 1.41 vs. 0.49 ± 0.74, p < 0.001), and GLS (-21.01 ± 5.66% vs. 45.19 ± 3.49%, p < 0.001). The SI and SI Z-score were significantly lower in segments 1–18 of the right ventricle in fetuses with severe tricuspid regurgitation (p < 0.05); furthermore, FS of segments 1–12 and 19–24 and the FS Z-score of segments 18–24 were significantly lower in fetuses with severe tricuspid regurgitation (p < 0.05). Fetal HQ is useful for evaluation of cardiac morphology and function in fetuses with severe tricuspid regurgitation and can provide important reference information for both clinical diagnosis and treatment. [ABSTRACT FROM AUTHOR]

A conceptual design for diagnosing erosion of the first wall and divertor plates of a tokamak with reactor technologies TRT is proposed. The principles of constructing a diagnostic complex based on the following systems are developed: laser radar, dual-wavelength digital holographic interferometry and active laser IR thermography. An optical scheme is developed for combining the optical paths to input laser radiation and collect scattered light from diagnostic systems. To view the maximum area of the first wall, a scheme for optical scanning of the surface of the first wall and divertor is proposed. Based on optical simulation, the spatial distribution of the power density and phase of interferometry laser radiation in the illuminated region of the first wall is constructed, and the dimensions of the light fields and power density for IR thermography and laser radar diagnostics are determined. An image formation scheme is proposed and the spatial resolution is determined for interferometry and IR thermography methods. The light scattering function on models of the ITER divertor cladding is studied experimentally. The energy of the collected signal is calculated on the basis on the experimental data for all three diagnostic methods and the requirements for the diagnostic equipment are formulated. [ABSTRACT FROM AUTHOR]

To resolve high-precision deformation from low-quality speckle images, a high-order time-domain digital image correlation algorithm is proposed. This algorithm is based on the nonlinear optical flow equation for low-quality speckle images collected in extreme testing environments. A subpixel displacement image containing Gaussian white noise is established by using the simulated speckle method. The displacement of the high-order time-domain digital image correlation algorithm is solved by the least squares iteration method, and the test accuracy of the proposed algorithm is analyzed. The results show that the nonlinear optical flow equation can describe the time continuity of pixel gray level changes before and after deformation. The proposed algorithm can also analyze the velocity and acceleration term of deformation. The high-order time-domain digital image correlation algorithm is insensitive to the change in image grayscale and has high measurement accuracy. Therefore, this method can solve the problem of resolving high-precision deformation from low-quality speckle images. [ABSTRACT FROM AUTHOR]

We present an efficient construction method for object recognition based on speckle learning using the optical memory effect. An object classifier based on speckle learning without the process of reducing or eliminating scattering and with a simple optical setup has been previously reported, but it requires a large number of training images to improve the performance of the classifier. This method is not applicable for bioimaging because of the difficulty of collecting training images caused by position control and phototoxicity of target cells. In our method, a wide variety of training images are augmented by a computer from a few speckle intensity images in the working range of the optical memory effect. We experimentally demonstrated our method with a 4f-optical system implementing the optical memory effect. As a result, the constructed binary classifier showed high accuracy under various scattering conditions and resolutions of the test image. [ABSTRACT FROM AUTHOR]

Recurrence of large-scale ancient landslides often manifests as catastrophic events, so it is important to assess their stability by monitoring the deformation process. In this study, the Da'ao ancient landslide along the Jinsha River in China was investigated and analyzed. Field investigation showed that the landslide body is being experienced deforming with many new failures. Three sliding events can be identified according to different main scarps. The Permanent Scatterer Synthetic Aperture Radar Interferometry (PS-InSAR) data further revealed that the most obvious deforming area is in the middle and toe part of the sliding body with the largest cumulative displacement of 55 mm during 2017 to 2021. Additionally, the relatively stable zone and the accelerating deforming zone are divided by displacement rate. This indicates that the Da'ao landslide is becoming unstable. At the same time, the Particle Flow Code (PFC) simulation verified that the risk of landslide recurrence is likely when subjected to strong earthquakes or heavy rainfall, and the resulting sidings could dam the Jinsha River. In addition, the analysis results suggested that the displacement rates were approximately 5 mm/year and 13.3 mm/year before and after the Ms 5.2 earthquake, respectively, which occurred on 04/21/2019. The deformation changed with seasonal variation during 2017–2021 and lagged behind precipitation, while the earthquake can increase the amount and rate of displacement. The results presented here can help us to understand how landslides recur over time and their deformation and failure mechanisms, which is useful for disaster prevention and mitigation. [ABSTRACT FROM AUTHOR]

Aptamers are increasingly employed in SARS-CoV-2 theragnostics in recent years. Characterization of aptamers, testing affinity and kinetic parameters (e.g., equilibrium dissociation constant (KD), kon, and koff), can be done by several methods and influenced by many factors. This study aims to characterize the binding of aptamers to SARS-CoV-2 nucleocapsid (N) protein using capillary electrophoresis (CE) and bio-layer interferometry (BLI). These two analytical methods differ by how the aptamer binds to its target protein once the aptamer, as a capture ligand, is partitioned in solution (CE) or immobilized on the biosensor (BLI). With CE, the KD values of the N-binding aptamers (tNSP1, tNSP2, and tNSP3) were determined to be 18 ± 4 nM, 45 ± 11 nM, and 32 ± 7 nM, respectively, while the KD measurements by BLI yielded 4.8 ± 0.6, 4.5 ± 0.5, and 2.9 ± 0.3 nM, respectively. CE results showed a higher KD across all aptamers tested. The differences in the steric hindrance and confirmational structures of the aptamers immobilized on the BLI biosensors versus those suspended in the CE sample solution affect the molecular interactions between aptamers and the target proteins. Moreover, the buffer composition including pH and ionic strength can influence the stability of aptamer structures, or aptamer-protein complexes. All these variables affect the binding and calculated KD. In this sense, a KD value alone is not sufficient to make comparisons between aptamers; instead, the entire experimental setup should also be considered. This is particularly important when implementing aptamers in different bioanalytical systems. [ABSTRACT FROM AUTHOR]

The impact of cutting the f-holes in a completed violin was investigated based on two measurable characteristics of the instrument. One of these aspects focused on the signature modes, while the other involved monitoring the graph of the bridge mobility. A particular emphasis was placed on analyzing this graph due to existing literature suggesting the connection of the bridge hill to the presence of f-holes. In the case of two real violins, bridge mobility was measured using an ultra-miniature accelerometer and an impact hammer. Concurrently, signature modes were recorded using Electronic Speckle Pattern Interferometry, an optical technique that performs well on rough surfaces; hence, the violins employed were intentionally left unvarnished. One of the violins lacked f-holes but included the rest of the structural elements. It was measured in stages as the f-holes were cut. The second violin adhered to a standard design but featured slightly wider f-holes, serving as a reference. Additionally, bridge mobility and signature modes were simulated for a finite element violin soundbox both with and without f-holes. Contrary to expectations, both the experiments and simulations revealed the emergence of the Bridge Hill even in the absence of f-holes. However, the alteration of the middle and high-frequency response was evident during the f-hole cutting process, accompanied by the observation of CBR as well as B 1 - and B 1 + modes. [ABSTRACT FROM AUTHOR]

The detection of weak time-dependent alternating signals in a strongly noisy background is an important problem in physics and a critical task in metrology. Quantum lock-in amplifier can extract alternating signals within extreme noises by using suitable quantum resources, which has been widely used for magnetic field sensing, vector light shift detection, and force detection. In particular, entanglement-enhanced quantum lock-in amplifier can be realized via many-body quantum interferometry. The many-body lock-in measurement provides a feasible way to achieve high-precision detection of alternating signals, even in noisy environments. In this article, we review general protocol, experiment progresses and potential applications of quantum lock-in measurements. [ABSTRACT FROM AUTHOR]

In this paper we report an improved method of coherent sensing through the use of a generalized phase-stepping algorithm to extract magnitude and phase information from interferometric fringes acquired by laser feedback interferometry (LFI). Our approach allows for significantly reduced optical sampling and acquisition times whilst also avoiding the need for fitting to complex models of lasers under optical feedback in post-processing. We investigate theoretically the applicability of this method under different levels of optical feedback, different laser parameters, and for different sampling conditions. We furthermore validate its use experimentally for LFI-based sensing using a terahertz (THz)-frequency laser in both far-field and near-field sensing configurations. Finally we demonstrate our approach for two-dimensional nanoscale imaging of the out-of-plane field supported by individual micro-resonators at THz frequencies. Our results show that fully coherent sensing can be achieved reliably with as little as 4 sampling points per imaging pixel, opening up opportunities for fast coherent sensing not only at THz frequencies but across the visible and infra-red spectrum. [ABSTRACT FROM AUTHOR]

The electro-brush plating process is flexible, and its deposition rate is relatively fast. However, the pretreatment process of brush plating is cumbersome, which leads to many problems in practical applications. The impact of different pretreatment techniques on the surface quality and the related properties of Ni-Co-Al2O3 nanocomposite coatings electro-brushed on 45 steel substrates were studied in this paper. The surface roughness, morphology, cross-sectional morphology, and the thickness of deposited layers were analyzed by white-light interferometry, SEM, and metallographic microscopy. The adhesion, hardness, and elastic-plastic mechanical properties of Ni-Co-Al2O3 nanocomposite coatings were discussed in-detail by scratch tester, hardness tester, and nanoindenter. The results show that the two-step method of alkali solution–hydrochloric acid not only has a simple process but also a good pretreatment effect. The Ni-Co-Al2O3 nanocomposite coating obtained by this method is flat, uniform, and has fewer defects. The prepared coating thickness reaches 11.68 µm, the average hardness value is 630 HV, and the elastic recovery ratio he/hmax value is 0.28. The adhesion between the coating and the substrate is significantly better than that of the traditional electro-brush plating process. This is expected to open a new path for the optimization and industrial application of the electro-brush plating process. [ABSTRACT FROM AUTHOR]

Based on the speckle observations of the wide double star ADS 15571 with the 6-m BTA telescope at the Special Astrophysical Observatory of the Russian Academy of Sciences in 2014, we have confirmed the existence of a close companion to component A that was previously detected from astrometric observations at the Pulkovo Observatory. An extension of the BTA observations from 2014 to 2022 has allowed 28 positions of the companion relative to the primary star to be obtained. From this series we have constructed the relative orbit of the companion and determined the sum of the masses of subsystem A ( ). A comparison of this orbit with the orbit of the photocenter of component A constructed from Pulkovo photographic observations has also allowed the mass ratio of the primary star and the companion and their individual masses to be estimated: and . Based on the estimates of the magnitude difference between the two stars of the system ADS 15571A, we have estimated the spectral types of the components: ADS 15571Aa—F8V; ADS 15571Ab—K5V–K5.5V. The speckle observations of component B have shown that it has no resolvable companions. [ABSTRACT FROM AUTHOR]

An empirical study assessing the suitability of laser speckle patterns for use in experimental mechanics research conducted at hypersonic conditions is presented. Speckle patterns generated via coherent optical scattering from a gold-coated graphite surface inserted into a Mach 10 air stream were collected and analyzed using Computer-Aided Speckle Interferometry using two methodologies: a typical spanwise approach involving increasing temporal span between image pairs, and a sequential approach that utilizes a combination of temporal re-referencing and spatial resampling. Results were characterized for spatial-temporal stability and variance. Our observations demonstrate that optical methods relying on stable and properly formed speckle patterns can be used in a hypersonic regime at various Reynolds numbers and common camera frame rates, but the technique is sensitive to the conditions of the airflow and the processing methodology chosen. [ABSTRACT FROM AUTHOR]

This paper proposes a solution to the need for appropriate methods to control the health of the final product which is among the challenges of applying three-dimensional (3D) printers in mass production. Sheared laser interferometry so-called shearography is considered a proper option for this aim. The main objective of this paper is to inspect defective 3D-printed polymer parts. In addition, this study explores the influence of the infill percentage of the samples on the defect detectability as well as the shearography setup parameters. To this aim, three samples of Polylactic-acid (PLA) with different infill percentages were printed by the fused deposition modeling (FDM) method. Burnt filament defects were deliberately created inside the samples during printing. Shearography tests were carried out applying thermal excitation. Based on the results, the infill percentage directly affects the defect detectability as well as the shearography parameters. Accordingly, an increase in infill percentage enhanced the quality of shearography resultant fringe patterns. Additionally, it significantly leads to an increase in the detectable range of loading size and shear distance. Therefore, shearography was regarded as appropriate for detecting burnt filament defects, especially in high infill percentages. [ABSTRACT FROM AUTHOR]

The difference between observed and modelled precession/nutation reveals unmodelled signals commonly referred to as Celestial Pole Offsets (CPO), denoted by dX and dY. CPO are currently observed only by Very Long Baseline Interferometry (VLBI), but there is nearly 4 weeks of latency by which the data centers provide the most accurate, final CPO series. This latency problem necessitates predicting CPO for high-accuracy, real-time applications that require information regarding Earth rotation, such as spacecraft navigation. Even though the International Earth Rotation and Reference Systems Service (IERS) provides so-called rapid CPO, they are usually less accurate and therefore, may not satisfy the requirements of the mentioned applications. To enhance the quality of CPO predictions, we present a new methodology based on Neural Additive Models (NAMs), a class of interpretable machine learning algorithms. We formulate the problem based on long short-term memory neural networks and derive simple analytical relations for the quantification of prediction uncertainty and feature importance, thereby enhancing the intelligibility of predictions made by machine learning. We then focus on the short-term prediction of CPO with a forecasting horizon of 30 days. We develop an operational framework that consistently provides CPO predictions. Using the CPO series of Jet Propulsion Laboratory as the input to the algorithm, we show that NAMs predictions improve the IERS rapid products on average by 57% for dX and 25% for dY under fully operational conditions. Our predictions are both accurate and overcome the latency issue of final CPO series and thus, can be used in real-time applications. [ABSTRACT FROM AUTHOR]

Adenosine induced cardiac arrest (AiCA) is one of the methods used to facilitate microsurgical aneurysm clipping by providing more visibility and less pressure in the aneurysmal sac and neighboring vessels. We report the use of laser speckle contrast imaging (LSCI) during AiCA to monitor the changes in pulsation and perfusion on the cortical surface during adenosine induced cardiac arrest for aneurysm clipping surgery. Application of this technology for perfusion monitoring may improve workflow and surgical guidance and provide valuable feedback continuously throughout the procedure. ClinicalTrials.gov identifier: NCT0502840. [ABSTRACT FROM AUTHOR]

Backscatter interferometry (BSI) is a refractive index (RI) detection method that is easily integrated with capillary electrophoresis (CE) and is capable of detecting species ranging from inorganic ions to proteins without additional labels or contrast agents. The BSI signal changes linearly with the square of the separation voltage which has been used to quantify sample injection, but has not been explored as a potential signal enhancement mechanism in CE. Here we develop a mathematical model that predicts a signal enhancement at high field strengths, where the BSI signal is dominated by the voltage dependent mechanism. This is confirmed in both simulation and experiment, which show that the analyte peak area grows linearly with separation voltage at high field strengths. This effect can be exploited by adjusting the background electrolyte (BGE) to increase the conductivity difference between the BGE and analyte zones, which is shown to improve BSI performance. We also show that this approach has utility in small bore capillaries where larger separation fields can be applied before excess Joule heating degrades the separation. Unlike other optical detection methods that generally degrade as the optical pathlength is reduced, the BSI signal-to-noise can improve in small bore capillaries as the larger separation fields enhance the signal. [ABSTRACT FROM AUTHOR]

Although our every-day experience rejects it, the quantum Cheshire Cat suggests a potential spatial separation between different properties of a single particle in an interferometer. The first experiment with neutrons confirmed the quantum Cheshire Cat effect by using the path and spin degrees of freedom. The locations of each property are determined qualitatively through reactions to locally applied perturbations. Yet, no consensus on the interpretation has been reached. To clarify the origin of the effect, in the present experiment the energy degree of freedom is used as the third property; the three properties of neutrons appear to be separated in different paths in the interferometer. The analysis of the experiment suggests the strong involvement of the inner product between the state vectors, one evolved from the initial state through the perturbation and the other being the final state. The inner product results in amplitudes from two sub-beams which contribute to the intensity. The cross-term between amplitudes gives rise to the quantum Cheshire Cat. The Cheshire Cat phenomenon in quantum mechanics refers to a captivating observation where a particle and its properties behave as if they were separated. Here, the authors show the possibility of observing the Cheshire Cat phenomenon via interferometric neutron experiments in agreement with a weak measurement theoretical approach. [ABSTRACT FROM AUTHOR]

The results of an experimental study of the operation of fiber optic sensors (FOS) of acoustic emission introduced into the structure of polymer composite materials (PCM) are presented. The reliability and fault tolerance of FOS under critical mechanical loads on PCM was assessed, and the influence of the presence of FOS embedded into the structure of PCM on the mechanical characteristics of the material was investigated. For demodulation of FOS output signals, the principles of adaptive holographic interferometry based on two-wave mixing at dynamic hologram formed in a photorefractive crystal are used. [ABSTRACT FROM AUTHOR]

Interferometers used for high-precision spectroscopic measurements are considered. The choice of a holographic interferometer is supported because of it implements the spatial-spectral method of holographic interferometry. With this holographic interferometer one can measure in real time the displacements of the phase center of a coherent light flux over a wide dynamic range and record the measured data in digital form. Based on the mathematical relations elucidated by the authors in previous publications, and based on the results of experimental studies, we have been able to numerically estimate the sensitivity of a holographic interferometer to spatial movements of phase centers (focus points) of light fluxes—point light sources that form a holographic interferogram. We establish the dependence of the normalized level of light flux intensity in the central region of the holographic interferogram on the displacement of a real point light source along the normal to the plane of the Fourier hologram. From the results of mathematical simulation we show that the sensitivity of a holographic interferometer to the movements of a real point light source normal to the plane of the Fourier hologram depends on the optical circuit parameters of the holographic interferometer when exposing the hologram and on the measurement parameters. In this case, the sensitivity of a holographic interferometer to specific movements of a real point light source can only be estimated experimentally. We propose to increase the sensitivity of a holographic interferometer by using a thin converging lens in its optical design. A mathematical relation has been obtained and studied for the gain coefficient of the phase advance of a light flux with a spherical wavefront. Given the known parameters of the thin converging lens in the optical circuit, we can use this relationship to numerically estimate the increase in sensitivity of a holographic interferometer that implements the spatial-spectral method of holographic interferometry. It is shown that the sensitivity of the holographic interferometer to the displacement of an imaginary point light source normal to the plane of the Fourier hologram is 2.86 times greater than its sensitivity to the same movement of a real point light source. It has been established that the sensitivity of holographic interferometer with a volumetric Fourier hologram and a thin converging lens in its design can be increased by no less than an order of magnitude compared with the sensitivity of known optical interferometers. The results of assessing the sensitivity of the holographic interferometer implementing the spatial-spectral method of holographic interferometry to displacement of point sources of real and imaginary light fluxes, as well as the resulting ratio for the gain coefficient of the phase advance of the light flux by the thin converging lens, will be useful for high-precision measurements of linear and angular movement of objects, as well as in the construction of photonic device structures. From the results of the study based on the holographic interferometer, an experimental sample of an acousto-electric transducer has been developed and manufactured, which has high sensitivity over wide dynamic and frequency ranges and is intended for use in acoustic locations of unmanned aerial vehicles. [ABSTRACT FROM AUTHOR]

Cellulose, the basic biopolymer of plants, has unique optical characteristics due to its inherent birefringence. In this review, we summarize reported birefringence values for cellulose from the literature and describe its measurement techniques, including ellipsometry, interferometry, spectrophotometry and photothermometry. We also discuss the main dispersion models that have been proposed to explain the wavelength dependence of cellulose birefringence. Furthermore, we outline the diverse applications of cellulose birefringence, with a particular focus on biomedicine. Finally, we discuss the future prospects for cellulose birefringence. Overall, this review provides valuable insights into the basic research and practical application of cellulose birefringence and will stimulate new research and innovation in various fields. [ABSTRACT FROM AUTHOR]

The magnitude (spatial location, area, and volume) of landslides is a crucial parameter for estimating the quantitative risk and preventing landslide hazards. This study proposes a novel approach to forecast the volume of potential landslides in alpine-canyon terrain by combining the empirical relationship linking landslide volume (V) to characteristics and synthetic aperture radar interferometry (InSAR) technology in the northeast of the Qinghai-Tibet Plateau, China. First, a historical landslide inventory with detailed characteristics was established by reviewing literature and field investigation. Then, the relationship between volume and characteristics of landslides was analyzed based on the least-squares linear regression of the logarithmic transformation. Finally, the relationships of the colluvial landslides (V = 0.170 × L 0.982 × W 1.589 × H 0.471) and loess landslides (V = 0.170 × L 0.796 × W 2.151 × H 0.048) were obtained after verifying several landslides. The ground deformation rate was generated, and 217 potential landslides were detected using 47 descending Sentinel-1A images acquired from January 11, 2020, to July 16, 2021, and 40 ascending Sentinel-1A images acquired from January 11, 2020, to April 23, 2021. Through the established relationships, the total volumes of all potential colluvial and loess landslides were estimated to be 8.77 × 108 m3 and 5.74 × 108 m3, respectively. This study provides an improved empirical relationship to better forecast the volume of potential landslides in alpine-canyon terrain. Furthermore, the study helps in understanding the future dynamic evolution of potential landslides using InSAR technology, which provides scientific understanding to assess and prevents potential landslide hazards and risks in the Bailong River basin. [ABSTRACT FROM AUTHOR]

An analysis of the results of repeated geodynamic observations at the Buzachi peninsula field are presented. Comprehensive geodynamic monitoring includes leveling and gravimetric observations, GPS measurements, and repeated satellite radar interferometry data. A comprehensive analysis of the results shows the presence of systematic subsidence of the earth's surface in the central part of the field territory, induced by development. Based on leveling and gravimetric observations, two areas of local anomalies are identified, which are localized in zones of anomalous deformation activity of faults. Dangerous manifestations of gas gryphons have been repeatedly recorded at the field, which occurred in the area of the dynamic influence of fault zones. Deformations of the earth's surface alternating in sign (uplift and subsidence) are revealed, which precede the process of active formation of gryphons. Mathematical modeling of these processes is carried out and a generalized geomechanical model of the formation of anomalous and negative fluid dynamic manifestations is proposed. A calculation of local horizontal stresses shows that they are concentrated near active faults, forming paths for subvertical fluid migration and creating conditions for the formation of gryphons. A complex parameter is proposed to assess the level of geodynamic hazard of the field territory, and areal distribution diagrams of this parameter by year are constructed. Potentially dangerous zones of anomalous manifestation of recent deformation and fluid dynamic processes have been identified. [ABSTRACT FROM AUTHOR]

Displacement velocity fields of the block-fault structure are constructed and the main geodynamic processes in the area of the East Anatolian Fault (EAF) are revealed based on the results of the processing of 437 radar interferograms obtained from the Sentinel-1 radar in the period from early 2018 until the beginning of the destructive seismic activity in February 6, 2023 in Turkey by the Stacking-InSAR method. Anomalous block displacements along this fault have been identified; they are timed to the earthquake of January 24, 2020 (Mw = 6.7). Zones of stress–strain state of the main blocks in the period preceding the earthquake have been determined using the cluster analysis of time series of velocity fields. It is shown that the epicenters of the February 2023 earthquakes are located in these zones. A conclusion is made about the necessity of using such a technique to estimate the stress–strain state in order to predict seismic activity. [ABSTRACT FROM AUTHOR]

We theoretically describe a driven two-electron four-level double-quantum dot (DQD) tunnel coupled to a fermionic sea using the rate-equation formalism. This approach allows to find occupation probabilities of each DQD energy level in a relatively simple way, compared to other methods. Calculated dependencies are compared with the experimental results. The system under study is irradiated by a strong driving signal, and as a result, one can observe Landau–Zener–Stückelberg–Majorana (LZSM) interferometry patterns which are successfully described by the considered formalism. The system operation regime depends on the amplitude of the excitation signal and the energy detuning, so one can transfer the system to the necessary quantum state in the most efficient way by setting these parameters. Obtained results give insights about initializing, characterizing, and controlling the quantum system states. [ABSTRACT FROM AUTHOR]

Currently, one of the rapidly developing optical methods is the digital version of shear interferometry (shearography). The advantages of the method are: contactless method of obtaining data; low dependence on the shape and surface of the material being studied; determination of gradients of movements of surface points, manifested in the form of anomalies in the pattern of interference fringes, which are associated with areas of deformation. Experiments were carried out to obtain shearograms using a Michelson interferometer. An optical scheme for forming an image shift was tested. A scheme of a compact speckle interferometer for digital shearography has been proposed and implemented. A software algorithm for obtaining shearograms has been implemented. The device was tested to determine out-of-plane deformations on samples such as a round thin membrane. Experiments were carried out to detect defects in welds as zones with nonuniform deformation. [ABSTRACT FROM AUTHOR]

The dependence of the change in the components of the inverse permittivity tensor of a cubic photorefractive Bi12SiO20 crystal on the direction of the wave vector of holographic grating in the crystal coordinate system has been studied. It is shown that, when recording a phase hologram, the largest change in the refractive index of Bi12SiO20 crystal is attained when the holographic grating wave vector is oriented along symmetrically equivalent 〈111〉 directions. The maximum possible modulation amplitude of the refractive index of a holographic grating with the wave vector oriented along the 〈110〉 directions is found to exceed that in the case of orientation along the 〈100〉 directions. The components of the inverse permittivity tensor of Bi12SiO20 crystal were calculated taking into account that a phase hologram is recorded under linear electro-optic, photoelastic, and inverse piezoelectric effects. [ABSTRACT FROM AUTHOR]

To establish a relatively stable internal haemorrhoid model in rats. A total of 48 SPF SD rats were selected and randomly divided into a blank group of 16 and a model group of 32. The model was created by croton oil-mixed liquid stimulation combined with standing and swimming experiments, and the modelling times were 1 week and 2 weeks, respectively. By observing the symptoms and signs of rats, pathological morphology and immunohistochemical staining of anorectal tissue, anorectal laser speckle blood-flow imaging and defecation contrast, etc., the effect of different modelling times was evaluated. The stability of the model was evaluated after feeding for 2 weeks. Both model-formation times caused rats to produce local symptoms of tissue bulging in the haemorrhoid area. Microscopy showed that the rectal submucosal interstitial blood vessels were dilated, and inflammatory cell infiltration and other manifestations were observed. Laser speckle blood-flow imaging revealed increased anorectal blood perfusion and capillary dilatation, and defecography showed a longitudinal and continuous rectal mucosa. After 2 weeks of normal feeding, lifting of the haemorrhoidal tissue was still present. The effect of modelling for 1 week was most in line with the clinical manifestations of internal haemorrhoids. The 1-week modelling scheme in this study can effectively establish a rat internal haemorrhoid model that closely approximates clinical internal haemorrhoid symptoms and pathological manifestations. The operation is simple, the success rate is high, and the model has certain stability. This model can be used as an important basis for studying various treatment methods for internal haemorrhoids. [ABSTRACT FROM AUTHOR]

In high-sensitive laser interferometers, such as the gravitational-wave detector KAGRA, ultra-high-quality mirrors are essential. In the case of KAGRA, where cavity mirrors are cooled down to 20 K, large-size Sapphire crystals are used as the substrate for the main mirrors to achieve both a good optical quality (i.e., low absorption and uniform refractive index) and optimized thermal behavior under cryogenic temperatures. To implement the very tight optical specifications required by this demanding application, it is mandatory to test the optical homogeneity of different substrates. In order to characterize refractive-index inhomogeneities of large-size uniaxial samples such as the KAGRA Sapphire test masses, we developed a dedicated setup, allowing to resolve birefringence changes with a sensitivity in the order of Δ n ≈ 2 × 10 - 10 and a spatial resolution of 1 mm 2 . Moreover, the same setup allows us to simultaneously record residual absorption maps, thus allowing for a comparison between birefringence and absorption features. In this paper, we will present for the first time measurements on a KAGRA-sized Sapphire substrate which has been characterized in terms of absorption already in an earlier work. Both birefringence inhomogeneities and absorption distributions will be compared and correlations discussed. [ABSTRACT FROM AUTHOR]

The field of nanowire (NW) technology represents an exciting and steadily growing research area with applications in ultra-sensitive mass and force sensing. Existing detection methods for NW deflection and oscillation include optical and field emission approaches. However, they are challenging for detecting small diameter NWs because of the heating produced by the laser beam and the impact of the high electric field. Alternatively, the deflection of a NW can be detected indirectly by co-resonantly coupling the NW to a cantilever and measuring it using a scanning probe microscope. Here, we prove experimentally that co-resonantly coupled devices are sensitive to small force derivatives similar to standalone NWs. We detect force derivatives as small as 10−9 N/m with a bandwidth of 1 Hz at room temperature. Furthermore, the measured hybrid vibration modes show clear signatures of avoided crossing. The detection technique presented in this work verifies a major step in boosting NW-based force and mass sensing. Flexural oscillations of singly-clamped nanowires can be detected by interferometry for diameters above 50 nm, while below such diameter the detection becomes challenging. The authors detect force derivatives as small as 10-9 N/m at room temperature by measuring hybrid vibration modes originated by coupling a nanowire and a cantilever. [ABSTRACT FROM AUTHOR]

The paper presents the results of the processing of satellite radar images acquired by the TerraSAR-X satellite using the persistent scatterer method for analyzing the subsidence of the earth's surface over potash mines in the city of Berezniki, Perm Krai. A sequence of processing procedures in the GAMMA Software package (Gamma Remote Sensing AG, Switzerland) is presented, which showed good results in the conditions of this territory. A comparison is made with the results obtained earlier by summation of interferograms. In contrast to the methods of persistent scatterers, the summation is performed without analyzing displacements in time. The noisy time series obtained by the summation are not rejected, so the displacement maps cover the study area more evenly. In the persistent scatterer method, the time series is analyzed using a variety of criteria, so the subsidence rates are estimated more reliably. In the areas where the results were obtained by summation and the persistent scatterer method, the subsidence rates are in good agreement. The persistent scatterer method has made it possible to estimate displacements in certain areas separated by vast incoherent woodlands, on which interferograms lose their coherence. At the same time, a new subsidence area was identified with an average rate of subvertical displacements up to 75 mm/year and, in some areas, up to 100 mm/year, which, according to data for 2020 and 2018, was not detected. The subsidence here should be clarified based on the images for subsequent years or using surface thechniques. The time series also show the deceleration of subsidence in spring on persistent scatterers located on buildings and infrastructure. We associate the total spring deceleration of subsidence by 3–5 cm not with underground but with seasonal factors, specifically with the heating of buildings in the spring. Other reasons are also possible, but the main one is that, in areas with a moderate subsidence rate, this effect can lead to some underestimation of the average subsidence rate. A detailed study of the time series for subsidence makes it possible to identify areas requiring special attention. Most of the subsidence occurs more or less evenly; in a significant part of the territory, the subsidence rate in 2021 has decreased. This indicates the effectiveness of the measures taken to protect the ground infrastructure. Within the city area, the acceleration of subsidence was found only at the beginning of Lenin Avenue. SAR interferometry is an effective tool for studying subsidence processes in the city of Berezniki. This method significantly complements geodetic works, since it provides data on vast areas that cannot be covered by detailed ground measurements. In addition, part of the closed territories becomes dangerous for ground works, so there is no alternative to satellite technologies. [ABSTRACT FROM AUTHOR]

Using different methods for processing SAR images from the Sentinel-1A satellite, the displacement fields were determined in the region of the East Anatolian Fault Zone (EAFZ) and the Sürgü-Çardak faults, as well as a small fault on the continuation of the East Hatay fault zone, which rupture initiated a series of catastrophic earthquakes in Turkey on February 6, 2023. DInSAR and offset methods were applied. The most detailed data on the displacements were obtained by the offset method using images from the descending orbit. When constructing the model from the available SAR data, the data with the maximum signal-to-noise ratio were selected. For the northern part of the region, above 37.4° N, the range displacements obtained by the offset method from a descending orbit were used. South of parallel 37.0° N, we used azimuth displacements from the same descending orbit. The model of the seismic rupture was constructed on the basis of solution of (Pollitz, 1996) of the problem of deformations at the surface of a layered spherical Earth caused by along dip and strike displacements on a rectangular fault located inside the planet. Pollitz (1996) demonstrated that ignoring the radial layering of the planet leads to errors up to 20%, with the largest errors occurring in the presence of a large strike-slip component. Ignoring sphericity also introduces an error when using the solution in the framework of the idealization of an elastic homogeneous half-space with a flat free surface (Okada, 1985) which was used when constructing USGS and (Barbot et al., 2023) models. In our model the surfaces of seismic rupture are approximated by 19 rectangular elements along the strike, divided into three levels along the dip. Another element approximated a rupture along the extension of the East Hatay Fault Zone. As in the models of other authors (USGS; Barbot et al., 2023), in our model in the southern part of the EAFZ, the displacements increase from south to north, and are mainly concentrated in the upper part of the Earth's crust to a depth of 10 km. At the southern end of this rupture, displacements in our model with an amplitude of up to 2 m are obtained at the lower levels of the model, and at its upper level, the displacements were only 0.11 m, and in this area on February 20, 2023 an earthquake of magnitude 6.3 occurred with a hypocenter depth of 11.5 km. The main displacements on the EAFZ are determined on its central segment. Here, the displacements go to a greater depth, their value reaches 10.2 m. On the Sürgü-Çardak fault, significant displacements occurred down to a depth of 20 km; displacements exceeded 10.2 m. In our model, at the northeast end of the seismic rupture along the EAFZ, a displacement area of 6.8 m overlaps with the southwest end of the seismic rupture model of the Doğanyol-Sivrice earthquake of January 24, 2020 with Mw 6.7, published on the USGS website. Therefore, our model does not confirm the hypothesis of the presence of a seismic gap here, which, according to (Barbot et al., 2023), is a zone of a possible nearest earthquake. [ABSTRACT FROM AUTHOR]

The latest results of the most detailed analysis of multi-epoch polarization-sensitive observations of active galactic nuclei (AGN) jets at parsecs scales by very long baseline interferometry (VLBI) reveal several characteristic patterns of linear polarization distribution and its variability [1, 2]. Some of the observed profiles can be reproduced by a simple model of a jet threaded by a helical magnetic field. However, none of the models presented to date can explain the observed polarization profiles with an increase in its degree towards the edges of the jet, and accompanied by a "fountain" type electrical vector pattern and its high temporal variability in the center. Based on simulations of the VLBI observations of relativistic jets, we show here that the observed transverse linear polarization profiles can be naturally produced in a model of jets precessing on ten-years scales. In this scenario, due to the finite resolution of VLBI arrays, the initially strong polarization along the jet axis is blurred due to the superposition of regions whose polarization angle changes significantly when projected onto the sky plane. In our simulations, we qualitatively reproduce the distribution of the electric vector and its variability, though the polarization distribution images are characterized by a bright spine due to weak suppression of polarized emission, which is poorly consistent with observations of quasars. More effective depolarization can be obtained in models with the suppressed emission of the jet spine. [ABSTRACT FROM AUTHOR]

This article discusses a measurement module of a dispersion interferometer based on a CO2 laser for integral plasma density measurements with a resolution of 4 × 1011 cm–2 with a time discreteness of 4 µs. Such characteristics of the device make it possible to use the results of its measurements in feedback loops for plasma density control. The main elements of the measurement module are crystals of analog-to-digital converters (ADCs) and a digital streaming data processing node based on a field-programmable gate array (FPGA). The algorithm for calculating the plasma density implemented in the digital node is based on the harmonic analysis of interferometer signals and is resistant to noise and changes in the modulation depth. The measurement module under consideration is a prototype of the system of monitoring and automatic control of plasma density at the Globus-M2 facility (St. Petersburg, Russia). [ABSTRACT FROM AUTHOR]

Planetary Radio Interferometry and Doppler Experiment (PRIDE) is a multi-purpose experimental technique aimed at enhancing the science return of planetary missions. The technique exploits the science payload and spacecraft service systems without requiring a dedicated onboard instrumentation or imposing on the existing instrumentation any special for PRIDE requirements. PRIDE is based on the near-field phase-referencing Very Long Baseline Interferometry (VLBI) and evaluation of the Doppler shift of the radio signal transmitted by spacecraft by observing it with multiple Earth-based radio telescopes. The methodology of PRIDE has been developed initially at the Joint Institute for VLBI ERIC (JIVE) for tracking the ESA's Huygens Probe during its descent in the atmosphere of Titan in 2005. From that point on, the technique has been demonstrated for various planetary and other space science missions. The estimates of lateral position of the target spacecraft are done using the phase-referencing VLBI technique. Together with radial Doppler estimates, these observables can be used for a variety of applications, including improving the knowledge of the spacecraft state vector. The PRIDE measurements can be applied to a broad scope of research fields including studies of atmospheres through the use of radio occultations, the improvement of planetary and satellite ephemerides, as well as gravity field parameters and other geodetic properties of interest, and estimations of interplanetary plasma properties. This paper presents the implementation of PRIDE as a component of the ESA's Jupiter Icy Moons Explorer (JUICE) mission. [ABSTRACT FROM AUTHOR]

A new era of lunar exploration has begun bringing immense opportunities for science as well. It has been proposed to deploy a new generation of observatories on the lunar surface for deep studies of our Universe. This includes radio antennas, which would be protected on the far side of the Moon from terrestrial radio interference, and gravitational-wave (GW) detectors, which would profit from the extremely low level of seismic disturbances on the Moon. In recent years, novel concepts have been proposed for lunar GW detectors based on long-baseline laser interferometry or on compact sensors measuring the lunar surface vibrations caused by GWs. In this article, we review the concepts and science opportunities for such instruments on the Moon. In addition to promising breakthrough discoveries in astrophysics and cosmology, lunar GW detectors would also be formidable probes of the lunar internal structure and improve our understanding of the lunar geophysical environment. [ABSTRACT FROM AUTHOR]

We compare two methods of millimeter radio interferometry with and without frequency conversion using as an example experimental measurements of the transverse deformation magnitude of a metal rod under dynamic load. We reveal a good agreement between the results, demonstrating a possibility of measuring the surface deviations within times of about 1 μs with micron precision. [ABSTRACT FROM AUTHOR]

Optics with high-precision height and slope are increasingly desired in numerous industrial fields. For instance, Kirkpatrick–Baez (KB) mirrors play an important role in synchrotron X-ray applications. A KB system is composed of two aspherical, grazing-incidence mirrors used to focus an X-ray beam. The fabrication of KB mirrors is challenging due to the aspherical departure of the mirror surfaces from base geometries and the high-quality requirements for slope and height residuals. In this paper, we present the process of manufacturing an elliptical cylinder KB mirror using our in-house-developed ion beam figuring (IBF) and metrology technologies. First, the key aspects of figuring and finishing processes with IBF are illustrated in detail. The effect of positioning error on the convergence of the residual slope error is highlighted and compensated. Finally, inspection and cross-validation using different metrology instruments are performed and used as the final validation of the mirror. Results confirm that relative to the requested off-axis ellipse, the mirror has achieved 0.15-µrad root mean square (RMS) and 0.36-nm RMS residual slope and height errors, respectively, while maintaining the initial 0.3-nm RMS microroughness.Highlights: Demonstrated our in-house developed, high-performance Kirkpatrick–Baez mirror manufacturing solution. Highlighted the key factors and strategies in achieving stringent mirror design specifications. Achieved excellent slope error (0.15 µrad RMS), height error (0.36 nm RMS), and microroughness (0.3 nm RMS). [ABSTRACT FROM AUTHOR]

The growing demands of optical systems have led to increasingly complex aspheres and freeforms. In this paper, an established measurement system in asphere production, which is also a promising approach in high-precision freeform metrology, is presented. It is based on a scanning-point multiwavelength interferometer approach. The scanning principle enables great flexibility, reduces setup time and costs, and has almost no limitations in spherical departure. Due to the absolute measurement capability, the utilized multiwavelength approach is beneficial for segmented, annular, and discrete surfaces, which are common designs of modern applications’ optical elements. The metrology system enables measurements on a nanometer scale on a great variety of apertures—from 1 to 1000 mm. Recently, a new short-coherence multiwavelength interferometer operating in the visible domain has been developed. It enables the high-precision measurement on silicon-coated surfaces, which can be found in space applications and are also commonly used for extreme-ultraviolet (EUV) lithographic setups, which will be used as an example throughout this work. Owing to the large absolute measurement capability, applied grating structures for suppressing infrared light in the EUV process can easily be measured. This paper summarizes the basic working principles of the proposed metrology system, explains the special requirements for different fields of application, highlights the capabilities of the visible multiwavelength approach, and shows the measurement results.Highlights: Modern applications, like extreme-ultraviolet lithographic setups, require new and flexible metrology tools. A scanning-point interferometer, working in the visible domain, is presented. The first measurement results on demonstrators prove the capability. [ABSTRACT FROM AUTHOR]