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It was established that there is currently no information on the calculation and assessment of the main errors of ballistic laser gravimeters and recommendations for their reduction. Therefore, the purpose of this work is calculation and analysis of the main errors of the ballistic laser gravimeter. The test mass during the period of free fall is in interaction with all physical objects of the universe, which with the help of gravitational and other forces affect the law of motion of the test body. Eliminating the influence of inertial forces on the results of the gravimeter measurement is currently one of the main difficulties in improving the accuracy of determining the acceleration of gravity (AG). The path traveled by the test mass is measured relative to the inertial coordinate system, which is not absolutely inertial. Therefore, kinematic errors can be divided into two groups: those due to the influence of factors acting on the test body, and those acting on the inertial reference system of the test mass coordinates. The totality of indices of the specified errors allows determination of the structure of the indices of the ballistic gravimeter accuracy. The problem of reproducing the units of length and time in absolute gravimetry is mainly reduced to increasing the accuracy and long-term stability of their reproduction, since it is the errors of these units that are the main obstacle to increased accuracy of AG measurements. It was established that the accuracy of AG determination depends on the accuracy of measurement of the following quantities: the path of the test body; the degree of fixation of the inertial system relative to which the path is measured; time; gravitational forces; and inertial forces. It was determined that measuring the acceleration of gravity more precisely than 10-9 is fundamentally impossible due to quantum mechanical limitations, as well as fluctuations in length and time measures. [ABSTRACT FROM AUTHOR]

In this paper, diffraction of scalar waves by a screen with a circular aperture is explored, considering the incidence of either a collimated beam or a focused wave, a historical review of the development of the theory is presented, and the introduction of the Fresnel approximation is described. For diffraction by a focused wave, the general case is considered for both high numerical aperture and for finite values of the Fresnel number. One aim is to develop a theory based on the use of dimensionless optical coordinates that can help to determined the general behaviour and trends of different system parameters. An important phenomenon, the focal shift effect, is discussed as well. Explicit expressions are provided for focal shift and the peak intensity for different numerical apertures and Fresnel numbers. This is one application where the Rayleigh–Sommerfeld diffraction integrals provide inaccurate results. [ABSTRACT FROM AUTHOR]

The confocal probe is one of the most well-used optical sensors for displacement/position measurement as well as for mapping of three-dimensional microstructured surfaces and internal structures. A dual-detection configuration employing two detectors is often used in the state-of-the-art confocal probes to achieve wider measurement ranges, higher resolutions, better accuracies and faster measurement speeds. In this paper, the motivation and benefits for development and employment of the dual-detection confocal probes, as well as the investigation of the detector positions, are first presented. The signal processing methods associated with the dual-detection confocal probes are then categorized into the difference-type and the ratio-type, followed by descriptions on the features of each method. Finally, signal processing based on artificial intelligence and machine learning for the confocal probes are presented. [ABSTRACT FROM AUTHOR]

In several presentations of his latest documentary "Babi Yar. Context" (2021), the Ukrainian director Sergei Loznitsa has emphasized that reading Anatoly Kuznetsov's Babi Yar (1966) in his Soviet youth had a tremendous effect on his understanding of the Soviet oblivion regarding the Holocaust in Kyiv. In my paper, I examine the uses and misuses of history in Loznitsa's documentary film on the tragedy of Babyn Yar. The "context" — archival documentary footage of the preceding explosions of the administrative quarter in Ukraine's capital organized by the NKVD in September of 1941 and of the welcoming reception by Western Ukrainians of the German army's occupation of Lviv during the summer of 1941 — provide an important yet inconvenient historical framework for understanding the collective responsibility in mass execution of Kyivan Jews. However, when viewed within Loznitsa's cinematographic aesthetics, it becomes clear that Kuznetsov's literary representation of the unspeakable brutality of the Babyn Yar massacre served as a model for the director's film. Both — Kuznetsov in the 1960s and Loznitsa in the 2020s — used a wide array of artistic tools to communicate the long-lasting effect of the silenced tragedy on the human soul. [ABSTRACT FROM AUTHOR]

A detailed overview of the knowledge gaps in our understanding of the heliospheric interaction with the largely unexplored Very Local Interstellar Medium (VLISM) are provided along with predictions of with the scientific discoveries that await. The new measurements required to make progress in this expanding frontier of space physics are discussed and include in-situ plasma and pick-up ion measurements throughout the heliosheath, direct sampling of the VLISM properties such as elemental and isotopic composition, densities, flows, and temperatures of neutral gas, dust and plasma, and remote energetic neutral atom (ENA) and Lyman-alpha (LYA) imaging from vantage points that can uniquely discern the heliospheric shape and bring new information on the interaction with interstellar hydrogen. The implementation of a pragmatic Interstellar Probe mission with a nominal design life to reach 375 Astronomical Units (au) with likely operation out to 550 au are reported as a result of a 4-year NASA funded mission study. [ABSTRACT FROM AUTHOR]

Herbig Ae/Be stars are young contracting stars on the radiative track in the HR diagram on their way to the main sequence. These stars provide a valuable link between high and low mass stars. Here we review the progress that has been made in our understanding of these fascinating objects and their disks since the last major review on this topic published in 1998. We begin with a general overview of these stars and their properties. We then discuss the accretion of circumstellar material onto these stars. Next we discuss the dust and gas properties of the circumstellar disk before exploring the evidence for planet formation in these disks. We conclude with a brief discussion of future prospects for deepening our understanding of these sources and propose a new working definition of Herbig Ae/Be stars. [ABSTRACT FROM AUTHOR]

The essential purpose of this research study is to analyze the relationship among information technology, precision agriculture, and sustainability. This research study is related to primary data analysis, which determines the research used specific questions related to the variables. The open-ended and closed-ended questions are used for gathering the data, and these questions fulfill from different participants who have knowledge about sustainability, information technology, and agriculture. For measuring the data, used smart PLS software and generated different informative results such as indicator correlation, R square, F square, discriminant validity, and composite Reliability. Also, that smart PLS Algorithm model in between independent and dependent variables. Information technology is the main independent variable, and precision agriculture, also sustainability are both dependent variables. The overall result found that information technology positively relates to precision agriculture. The significant and direct relation with sustainability and information technology are positively associated with each other. [ABSTRACT FROM AUTHOR]

Much of the progress in astronomy has been driven by instrumental developments, from the first telescopes to fiber fed spectrographs. In this review, we describe the field of astrophotonics, a combination of photonics and astronomical instrumentation that is gaining importance in the development of current and future instrumentation. We begin with the science cases that have been identified as possibly benefiting from astrophotonic devices. We then discuss devices, methods and developments in the field along with the advantages they provide. We conclude by describing possible future perspectives in the field and their influence on astronomy. [ABSTRACT FROM AUTHOR]

The urgency of investigation lies in the urgent need to diversify models of higher education taking into account current modern trends and requirements, as well as the introduction of information and communication technologies in training of future physical culture teachers as flexible forms of educational process and innovative teaching means. The aim is to substantiate and experimentally test the effectiveness of web-quest as a means of preparation of future physical culture teachers to the conditions of blended learning. The object of the study was the 45 first-year students at speciality 014.11 Secondary Education (Physical Culture) of the first level of higher education. At the ascertaining stage it was found that 74.2% of respondents are familiar with the essence of blended learning, but only 38.7% have experience of such learning, it was discovered the insufficient skills of content search and analysis of information from the Internet (48.4%), project (16.1%) and problem-research (13%) training. At the formative stage, the obligatory discipline «History of Physical Culture» included a web-quest «Olympionic», which was to help to gain experience using various Web 2.0 services (video, multimedia, geoservices etc.). The effectiveness of the formative influence of the web-quest was ensured by the use of special methods: encouragement, support, gamification, competition, reflective analysis. The didactic possibilities of the web-quests lie in developing of students' research skills, forming of stable cognitive interest and positive attitude to future professional activities, improving the ability to use educational information resources and services in order to build and self-control of their own educational trajectory. The effectiveness of the web-quest as a means of adaptation of future physical culture teachers to the conditions of blended learning has been experimentally proved, it was discovered the improvement of the skills of using interactive exercises, problem-research and project training, content search and analysis of information from the Internet, online testing. [ABSTRACT FROM AUTHOR]

This paper presents an off-axis differential method for the improvement of a femtosecond laser differential chromatic confocal probe having a dual-detector configuration. In the proposed off-axis differential method employing a pair of single-mode fiber detectors, a major modification is made to the conventional differential setup in such a way that the fiber detector in the reference detector is located at the focal plane of a collecting lens but with a certain amount of off-axis detector shift, while the fiber detector in the measurement detector is located on the rear focal plane without the off-axis detector shift; this setup is different from the conventional one where the difference between the two confocal detectors is provided by giving a defocus to one of the fiber detectors. The newly proposed off-axis differential method enables the differential chromatic confocal setup to obtain the normalized chromatic confocal output with a better signal-to-noise ratio and approaches a Z-directional measurement range of approximately 46 μm, as well as a measurement resolution of 20 nm, while simplifying the optical alignments in the differential chromatic confocal setup, as well as the signal processing through eliminating the complicated arithmetic operations in the determination of the peak wavelength. Numerical calculations based on a theoretical equation and experiments are carried out to verify the feasibility of the proposed off-axis differential method for the differential chromatic confocal probe with a mode-locked femtosecond laser source. [ABSTRACT FROM AUTHOR]

This paper presents an improved data processing method, which is referred to as the tracking intersection method, for a fibre-based dual-detector differential chromatic confocal probe with a mode-locked femtosecond laser source. In the dual-detector differential confocal system, two fibre detectors of an optical spectrum analyzer are employed to detect the spectra of the confocal signals. One of the fibre detectors, referred to as the measurement detector, is located at the confocal position of the confocal system, and the other fibre detector, referred to as the reference detector, is located at a position with a certain offset from the confocal position. In the tracking intersection method, the Z-directional displacement of a measurement object is derived from tracking the wavelength at the intersection point of the two fibre detector outputs. A new algorithm is proposed to generate a normalized output with a sharp peak at the intersection wavelength, from which the intersection wavelength can be detected with a high-sensitivity while the influence of the non-smooth spectral distribution of the femtosecond laser source can be removed. Compared with the previous tracking local minimum method, the new tracking intersection method is more robust to noises in the fibre detector outputs and consequently can realize better performance such as higher resolution and larger range in measurement of the displacement of the object. The advantages of the new method are demonstrated by simulation and experiment. [ABSTRACT FROM AUTHOR]

An intentional investigation on the thermal stability of a mode-locked femtosecond laser chromatic confocal probe, which is a critical issue for the probe to be applied for long-term displacement measurement or surface profile measurement requiring long-time scanning, is carried out. At first, the thermal instability of the first prototype measurement setup is evaluated in experiments where the existence of a considerably large thermal instability is confirmed. Then the possible reasons for the thermal instability of the measurement setup are analyzed quantitatively, such as the thermal instability of the refractive index of the confocal lens and the thermal expansion of mechanical jigs employed in the probe. It is verified that most of the thermal instability of the measurement setup is caused by the thermal expansion of mechanical jigs in the probe. For the improvement of the thermal stability of the probe, it is necessary to employ a low thermal expansion material for the mechanical jigs in the measurement setup and to shorten the optical path length of the laser beam. Based on the analysis result, a second prototype probe is newly designed and constructed. The improved thermal stability of the second prototype probe is verified through theoretical calculations and experiments. [ABSTRACT FROM AUTHOR]

In the framework of the ALOHA project (Astronomical Light Optical Hybrid Analysis), devoted to high resolution imaging in the L band, we investigate in this paper the possibility to deploy fibre links between the telescopes of the CHARA Array. As a first step, we set up an outdoor hectometric fibre interferometer to measure the vibration environment at the Mount Wilson Observatory. The optical path difference of this interferometer has been actively stabilised within an accuracy better than 4 nmrms, a stability largely sufficient for any interferometric application. [ABSTRACT FROM AUTHOR]

A method is proposed to expand the Z-directional measurement range of a fiber-based dual-detector chromatic confocal probe with a mode-locked femtosecond laser source. In the dual-detector chromatic confocal probe, the Z-directional displacement of a measurement target is derived from the peak wavelength in the normalized intensity ratio from the two light intensities obtained by the two identical fiber detectors. In this paper, a new method utilizing the main-lobe and side-lobes of axial responses acquired from both the normalized intensity ratio Ia and the invert normalized intensity ratio In, which is the inverse of Ia, is proposed to obtain the seamless relationship between the peak wavelength and the Z-directional displacement of a measurement target. Theoretical calculations and experimental investigation are carried out to demonstrate the feasibility of the proposed measurement range expansion method. [ABSTRACT FROM AUTHOR]

Exo-zodiacal dust, exozodi for short, is warm (∼300 K) or hot (up to ∼2000 K) dust found in the inner regions of planetary systems around main sequence stars. In analogy to our own zodiacal dust, it may be located in or near the habitable zone or closer in, down to the dust sublimation distance. The study of the properties, distribution, and evolution of exozodis can inform about the architecture and dynamics of the innermost regions of planetary systems, close to their habitable zones. On the other hand, the presence of large amounts of exo-zodiacal dust may be an obstacle for future space missions aiming to image Earth-like exoplanets. The dust can be the most luminous component of extrasolar planetary systems, but predominantly emits in the near- to mid-infrared where it is outshone by the host star. Interferometry provides a unique method of separating the dusty from the stellar emission. We discuss the prospects of exozodi observations with the next generation VLTI instruments and summarize critical instrument specifications. [ABSTRACT FROM AUTHOR]

The development of high-contrast capabilities has long been recognized as one of the top priorities for the VLTI. As of today, the VLTI routinely achieves contrasts of a few 10− 3 in the near-infrared with PIONIER (H band) and GRAVITY (K band). Nulling interferometers in the northern hemisphere and non-redundant aperture masking experiments have, however, demonstrated that contrasts of at least a few 10− 4 are within reach using specific beam combination and data acquisition techniques. In this paper, we explore the possibility to reach similar or higher contrasts on the VLTI. After reviewing the state-of-the-art in high-contrast infrared interferometry, we discuss key features that made the success of other high-contrast interferometric instruments (e.g., integrated optics, nulling, closure phase, and statistical data reduction) and address possible avenues to improve the contrast of the VLTI by at least one order of magnitude. In particular, we discuss the possibility to use integrated optics, proven in the near-infrared, in the thermal near-infrared (L and M bands, 3-5 μm), a sweet spot to image and characterize young extra-solar planetary systems. Finally, we address the science cases of a high-contrast VLTI imaging instrument and focus particularly on exoplanet science (young exoplanets, planet formation, and exozodiacal disks), stellar physics (fundamental parameters and multiplicity), and extragalactic astrophysics (active galactic nuclei and fundamental constants). Synergies and scientific preparation for other potential future instruments such as the Planet Formation Imager are also briefly discussed. This project is called Hi-5 for High-contrast Interferometry up to 5 μm. [ABSTRACT FROM AUTHOR]

Both the vectorial diffraction theory and the Fraunhofer approximation method are used to calculate diffractive images. In those cases, 13.5 nm light is normally incident on Fresnel zone plates (FPZs) of which the focuses are all 0.3 mm. By investigating the calculations using the vectorial diffraction theory, the full width at half maximum (FWHM) intensities of the first-order diffraction along $$x$$ -axis ( $$\phi =0^{\circ }$$ ) are 17.2 and 8.7 nm for 2,000-zone and 10,000-zone FZPs, respectively. The comparison between two methods shows that FWHM errors along $$\phi =0^{\circ }$$ are 4.2 and 22.3 %, and along $$\phi =45^{\circ }$$ are 3.3 and 33.1 % for 2,000-zone and 10,000-zone FZPs, respectively. Furthermore, maximum intensity errors are 12.3 % for the 2,000-zone FZP and 33.5 % for the 10,000-zone FZP in our study cases. [ABSTRACT FROM AUTHOR]

In this paper, the problem to estimate the on-axis resolution in creating a desired field profile by radiation of an aperture A is addressed. The latter applies in both diffractive optics and antenna synthesis. This is because the 'aperture theory', A can schematize a source, for example, an antenna or a lens illuminated by an incident field radiating a significant field only on the same aperture. The analysis refers to a customary axicon geometry consisting of a circle aperture transverse to the observation domain. The aim was to find a resolution formula allowing to highlight the impact of aperture geometrical parameters for configurations that are below the Fresnel approximation. The results show that the aperture cannot approximate the target field with the same level of accuracy along with the observation domain. In particular, near the aperture, smaller details can be retrieved and as the distance increases this ability degrades. [ABSTRACT FROM AUTHOR]

The transverse focusing properties at the ‘pseudo-focal’ plane of coherent Bessel beams with angular momentum are analyzed in detail. The transverse magnification of the central dark region of Bessel beams at this pseudo-focal plane is derived for the first time by calculating the ratio of the magnitude of the transverse components of the corresponding wave vectors before and after the focusing lens. We test our results experimentally with coherent laser Bessel beams and excellent agreement is observed. Then, an LED light source is used to generate Bessel beams. By modifying the coherence of the LED light source, we observe that by reducing coherence a smaller and shallower central dark region of Bessel beams with angular momentum is produced at the pseudo-focal plane. This technique can be used as a method to characterize the degree of coherence of vortex beams. [ABSTRACT FROM AUTHOR]

The Fresnel diffraction of an aperture with a rough edge is studied in this paper. Circular and elliptical apertures with sinusoidal and random edges are chosen as examples to investigate the influence of the aperture edge on the diffraction. The numerical calculation results indicate intuitively the variations of the transverse and longitude diffraction intensity distributions with the edge parameters of the aperture. The data files of aperture models are obtained through the numerical calculations, and the aperture samples are obtained with the help of a liquid crystal light modulator (LCLM). Thus, the practical experiments of the diffractions of apertures with rough edges are carried out. The measured results are consistent with the calculated ones. The approximate analytic expressions of the diffraction by the modified aperture are deduced on the basis of the Fresnel diffraction theory and the statistic optics, and the reasonable explanations for the influence of edge parameters on the diffraction are given through the theoretical analysis. [ABSTRACT FROM AUTHOR]