Fringe Formation Research Articles

Modeling the Stress Field in MSLA-Fabricated Photosensitive Resin Components: A Combined Experimental and Numerical Approach

This study presents an experimental and numerical investigation into the stress field in cylinders manufactured from photosensitive resin using the Masked Stereolithography (MSLA) technique. For material characterization, tensile and bending test data from resin specimens were utilized. The stress field in resin disks was experimentally analyzed using photoelasticity and Digital Image Correlation (DIC) methods, subjected to compressive loads, according to the cylinder–plane contact model. Images were captured during the experiments using polarizing film and a low-cost CPL lens, coupled to a smartphone. The experimental results were compared with numerical and analytical simulations, where the formation of fringes and regions indicating the direction and magnitude of normal and shear stresses were observed, with variations ranging from 0.6% to 8.2%. The convergence of the results demonstrates the feasibility of using parts produced with commercially available photosensitive resin on non-professional printers for studying contact theory and stress fields. In the future, this methodology is intended to be applied to studies on stress in gears.

Tests of Uniaxial Compression of Single Grains.

Tests of the uniaxial compression of single grains were performed in a specially designed press, which allowed the recording of an applied load in regard to the time and observation of occurring phenomena in a polarization assay. Three types of grains were tested: quartz sand, glass granules, and crushed glass. The strength tests showed different mechanisms of grain damage depending on the type of grain. In addition, the formation and spread of interference fringes, forming "chains of force" in samples with a large number of grains, were observed by testing glass grains under the polarization assay. A more detailed understanding of the strength characteristics of single grains will allow the verification of the models most commonly used in DEM.

Transmission interference fringe (TIF) technique for the dynamic visualization of evaporating droplet

The transmission interference fringe (TIF) technique was developed to visualize the dynamics of evaporating droplets based on the Reflection Interference Fringe (RIF) technique for micro-sized droplets. The geometric formulation was conducted to determine the contact angle (CA) and height of macro-sized droplets without the need for the prism used in RIF. The TIF characteristics were analyzed through experiments and simulations to demonstrate a wider range of contact angles from 0 to 90°, in contrast to RIF's limited range of 0–30°. TIF was utilized to visualize the dynamic evaporation of droplets in the constant contact radius (CCR) mode, observing the droplet profile change from convex-only to convex-concave at the end of dry-out from the interference fringe formation. The TIF also observed the contact angle increase from the fringe radius increase. This observation is uniquely reported as the interference fringe (IF) technique can detect the formation of interference fringe between the reflection from the center convex profile and the reflection from the edge concave profile on the far-field screen. Unlike general microscopy techniques, TIF can detect far-field interference fringes as it focuses beyond the droplet-substrate interface. The formation of the convex-concave profile during CCR evaporation is believed to be influenced by the non-uniform evaporative flux along the droplet surface.

Geometrization of the Huygens–Fresnel principle: Applications to Fraunhofer diffraction

The classical wave theory can trace its historical origins to the seminal works of Christian Huygens, Thomas Young, and Augustin Fresnel. To explain some of light’s observed properties, such as rectilinear propagation, reflection, and refraction, Huygens proposed a simple geometrical construction of secondary spherical wavelets with centers of disturbance located on a primary wavefront. More than a century later, Young formulated the law of interference to both predict the formation of fringes in his now famous double slit experiment and also to estimate the wavelengths associated with different colors. A decade after that, Fresnel combined Huygens’ construction with Young’s interference law to qualitatively and quantitatively describe diffraction, which is the bending of light upon encountering an obstacle or an aperture. This grand synthesis, called the Huygens–Fresnel principle, acts as a powerful pictorial aid and conceptual tool that can describe a wide variety of complicated optical phenomena. However, the applications of the principle and its later developments, such as the Kirchhoff–Fresnel integral, are strewn with several simplifying assumptions and approximations that are aimed at minimizing the mathematical challenges involved. Consequently, two distinct formalisms are necessary to account for diffraction effects when the source of light or observation screen is placed nearby and far away from the aperture or obstacle. Recently, a hyperbola framework for analyzing wave interference at a multi-slit barrier was shown to successfully circumvent all conventionally imposed ad hoc conditions. The method commences directly from the Huygens–Fresnel principle and the ensuing predictions pertaining to the distribution of fringe characteristics, namely, positions, widths, and intensities on a detection screen can, therefore, justifiably claim accuracy in both the near field (Fresnel regime) and the far field (Fraunhofer regime). In this paper, the analysis that was previously carried out for the special case of slits of negligible widths is further extended to encompass slits of finite widths as well.

Measurements of the geometrical characteristics and refractive index of specimens made with X-ray interferometers

The theoretical background to the formation of interference fringes in a triple Laue X-ray interferometer by a specimen having plano-concave form is presented. The interference fringes in the general case have an elliptical form. The relation between the radius of the specimen, the refractive index and the radii of the interference fringes is established. For two epoxy lenses having different radii, the interference fringes are registered. The refractive index and the radii are determined by measuring the radii of the obtained interference fringes.

Simulation of the modes of appearance of "salt frame" during drip irrigation

The process of fertigation, which consists in providing plants with minerals contained in irrigation water, is widespread, despite a number of negative effects. The overwhelming majority of studies are aimed at studying the spatial distribution of salts during irrigation, in the interirrigation periods and at the end of the irrigation season, the processes of migration and salt concentration in the soil with a decrease in moisture (drying) are practically not considered. The purpose of this work is to simulate the modes of drying of light and dark gray forest soils of the Chuvash Republic (Russia) after fertigation. The studies were carried out in the period from 2020 to 2023. Since the state of the soil before the start of drip irrigation significantly affects the drying process, the paper considers situations that allow it to be influenced in terms of reducing negative effects. Modeling the movement of soil moisture both during and after the end of drip irrigation makes it possible to identify both cases in which the formation of a salt «border» does not occur or the effect is least pronounced, and those in which the formation of areas with a high salt concentration takes place with high intensity. The identification of such regimes allows, taking into account the characteristics of the initial distribution of moisture, to carry out preliminary preparation of the soil for fertigation. The paper shows that during drying, salts can mainly concentrate in areas with a sharp moisture gradient, that is, at the boundaries between dry and moist soil. This is due to the fact that soil moisture, due to the resulting pressure drop, enters an area with an already increased salt concentration. The developed model makes it possible to analyze the effect of salt fringe formation according to given initial and boundary conditions in the form of moisture gradients, porosity, specific soil surface, irrigation intensity and duration, and salt concentration.

Modeling process of salt fringe formation during fertigation

The introduction of mineral substances into the soil through fertigation ensures the localization of the nutrients necessary for the plant in the area of the root system. However, under certain conditions, this method leads to soil salinization. When the soil dries out, salts are predominantly concentrated at the boundary between dry and wet soil, forming a salt fringe. The article describes the results of experiments and a software tool designed to simulate the process of redistribution of salts during soil drying. The results of calculations for soils of central Russia are presented, taking into account the main hydrophysical characteristics of the soil and the function of hydraulic conductivity under various initial conditions in the form of moisture gradients depending on the depth of the soil, the intensity and duration of irrigation, and the concentration of nutrients. It is shown that by selecting the appropriate initial conditions and irrigation regimes, it is possible to significantly reduce the intensity of the formation of salt fringes.

Optical interference fringes in CsPbBr3 perovskite microplate

While high-reflectivity end faces have been used as resonant cavities to achieve low-threshold lasing in various micro-nano structures of all-inorganic perovskites, the specific influence of the natural surface cavity of a sample on its optical properties has rarely been reported. Herein, we systematically investigate the effect of interference effect induced by the surface cavity of wedge-shaped microplates on their optical properties. The competition between interference and re-absorption effects causes oscillation shifts in the fluorescence spectrum and the formation of interference fringes. Variations in the microplate’s thickness have a considerable impact on the interference effect, modifying the sample’s optical properties.

Nonlinear non-Hermitian Landau–Zener–Stückelberg–Majorana interferometry

In this work, we have studied the non-Hermitian nonlinear Landau–Zener–Stückelberg–Majorana (LZSM) interferometry in a non-Hermitian N-body interacting boson system in which the non-Hermiticity is from the nonreciprocal tunnelings between the bosons. By using the mean-field approximation and projective Hilbert space, the effect of nonreciprocity and nonlinearity on the energy spectrum, the dynamics, and the formation of the interference fringes have been studied. The different symmetries and the impact of the two different types of reciprocity, i.e. the in-phase tunneling and anti-phase tunneling, on the energy spectrum and the phase transition between the Josephson oscillations and the self-trapping have been investigated. For the LZSM interferometry, the strength of the nonreciprocity is found to take an essential role in the population of the projective state and the strengths of the interference patterns in the projective space. While the conditions of destructive and constructive interference under the weak-coupling approximation still only depend on the strength of nonlinearity. Our result provides an application of the nonlinear non-Hermitian LZSM interferometry in studying the parameters of a two-level system which related to the nonlinearity and the non-Hermiticity.

Modern branding in the digital economy

The article analyzes the impact of the dominant trends of qualitative changes in the modern economy on fringe formation. The trends of digitalization and personalization of nanoeconomy subjects are considered as such trends. Aspects of the digital economy and informatization are studied. Digital branding helps to establish a meaningful connection with the target audience, using a unique offer to highlight the brand and its distinctive competitive advantages. Innovations that increase the intensity of information flows shape and promote a digital brand. It has been established that modern branding is influenced by the relations born within the nanoeconomy. For example, a brand is an institution that depends on nano-actors, including owners, producers, and consumers. The institution of property implies that a person with savings can invest in a business that can develop its brand. A brand is subjective and reflects an individual approach to a product (good or service). The owner initiates the brand and becomes a reference from this owner to various consumers and business customers. The manufacturer is responsible for producing a particular product when the production conditions dictate the quality of the product or service, and the brand image is formed. The latest digital technologies affect economic processes, including the efficiency and stability of business processes. Digital technologies can improve the efficiency of targeting marketing strategies and increase the compliance of goods with consumer expectations. At the same time, it has been shown (proved) that the increase in the efficiency of economic processes under the influence of consumer activation is explained by the titles of the modern science of nanoeconomics. Nanoeconomic systems differ in peacetime and during military operations. Since Ukraine is going through difficult military times with aggression from Russia, it is necessary to consider the specifics of nanoeconomic development in these conditions and the post-war period. It is determined that the mental construction of a modern brand should include, in addition to product characteristics, elements of both digitalization and aspects of the behavior of individual economic agents, as opposed to the traditional neoclassical paradigm. Keywords: brand, trademark, nanoeconomy, digital communications, branding, brand management.

Liquid crystal based polarized low coherence interferometer for optical demodulation in sensors.

The resolution of the measurement detection and sensitivity of a polarized low coherence interferometer (PLCI) can be pre-engineered by optimizing the key parameters of the birefringent wedge, which is rarely reported. In this work, we introduce a liquid crystal (LC) wedge in the PLCI and use it to demodulate Fabry-Perot (FP) cavity length. The birefringence property of the nematic LC is used to convert the optical path difference (OPD) of the sensor into a spatial distribution. This results in the production of localized interference fringe patterns. The formation of PLCI fringes and the related shift of the interferogram with a variation in the displacement of the FP displacement sensor is explained with reference to the OPD matching between an LC wedge and the FP cavity. The displacement value is demodulated from the obtained fringe pattern by tracking the centroid position of the fringe envelope and also considering the birefringence dispersion. An additional simulation study shows that the spatial position of the interferogram signal coupled with the dispersion coefficient is almost identical to the experimental data. The demodulated results from both the simulation and experimental investigations are found to be consistent with each other and closely agree with the actual cavity length. Further, the possibility to enhance the sensing resolution is examined by modulating the interferogram fringes using an electric field. Compared to birefringent crystals, the LC wedge presented here is found to be advantageous for high precision and tunability of the measurement range, which is useful for robust fiber optic sensing applications.

Enhancement of mechanical, thermal and optical properties of TiO2 thin films using glancing angle deposition technique

RF Magnetron sputtering has been used to compare the mechanical, thermal, and electrical characteristics of titanium oxide (TiO2) thin films. The Glancing Angle Deposition methods (GLAD) have been implemented during the deposition of a thin film of TiO2. After annealing thin films on an ITO substrate, X-RD indicates the anatase phase, and SEM investigation confirms the deposition of TiO2 thin films and their surface morphology. The mechanical, thermal, and electrical properties of TiO2 thin films prepared by magnetron sputtering with RF supply have been investigated. Using GLAD deposition, a clear change in thermal conductivity and elastic properties has been observed. Experimental specific heat of thin film deposited at zero angles follows Debye and Einstein equation, while with GLAD deposition specific heat shows an increase in deviation as the angle of deposition increases. With a rise in inclination angle, a clear change in transmission spectra towards a higher wavelength has been observed. Following heat treatment, the optical transmission spectra of thin films with GLAD deposition confirm the formation of fringes and have been shifted towards the higher wavelength side to increase in inclination. Hence, using GLAD deposition on TiO2 plays an important role to change thermal conductivity, specific heat, elastic and electronic properties and which leads to many applications in thermal solar collectors, thermal sensors, thermo-optical switching, and sensing-based industries.

Demystifying speckle field interference microscopy

Dynamic speckle illumination (DSI) has recently attracted strong attention in the field of biomedical imaging as it pushes the limits of interference microscopy (IM) in terms of phase sensitivity, and spatial and temporal resolution compared to conventional light source illumination. To date, despite conspicuous advantages, it has not been extensively implemented in the field of phase imaging due to inadequate understanding of interference fringe formation, which is challenging to obtain in dynamic speckle illumination interference microscopy (DSI-IM). The present article provides the basic understanding of DSI through both simulation and experiments that is essential to build interference microscopy systems such as quantitative phase microscopy, digital holographic microscopy and optical coherence tomography. Using the developed understanding of DSI, we demonstrated its capabilities which enables the use of non-identical objective lenses in both arms of the interferometer and opens the flexibility to use user-defined microscope objective lens for scalable field of view and resolution phase imaging. It is contrary to the present understanding which forces us to use identical objective lenses in conventional IM system and limits the applicability of the system for fixed objective lens. In addition, it is also demonstrated that the interference fringes are not washed out over a large range of optical path difference (OPD) between the object and the reference arm providing competitive edge over low temporal coherence light source based IM system. The theory and explanation developed here would enable wider penetration of DSI-IM for applications in biology and material sciences.

Lensless light intensity model for quasi-spherical cell size measurement.

Quasi-spherical cell size measurement plays an important role in medical test. Traditional methods such as a microscope and a flow cytometer are either it depends on professionals and cannot be automated, or it is expensive and bulky, which are not suitable for point-of-care test. Lab-on-a-chip technology using the lensless imaging system gives a good solution for obtaining the quasi-spherical cell size. The diffraction effects and the low resolution are the two main problems faced by the lensless imaging system. In this paper, a lensless light intensity model for the quasi-spherical cell size measurement is given. First, the diffraction characteristics of a quasi-spherical cell edge are given. Then, a diffraction model at an arc edge is constructed based on the Fresnel diffraction at a straight edge. Using the diffraction model at an arc edge, we explained the mechanism of the formation of the quasi-spherical cell diffraction fringes. Finally, the light intensity of the first bright ring of the quasi-spherical cell diffraction pattern is used to achieve quasi-spherical cell size measurement. The required equipment and the measurement methods are extremely simple, very suitable for point-of-care test. The experimental results show that the proposed model can realize the statistical measurement of the quasi-spherical cells and the classification of the quasi-spherical cells with a difference of 1 [Formula: see text].

Ultrathin picoscale white light interferometer

White light interferometry is a well established technique with diverse precision applications, however, the conventional interferometers such as Michelson, Mach-Zehnder or Linnik are large in size, demand tedious alignment for obtaining white light fringes, require noise-isolation techniques to achieve sub-nanometric stability and importantly, exhibit unbalanced dispersion causing uncertainty in absolute zero delay reference. Here, we demonstrate an ultrathin white light interferometer enabling picometer resolution by exploiting the wavefront division of a broadband incoherent light beam after transmission through a pair of micrometer thin identical glass plates. Spatial overlap between the two diffracted split wavefronts readily produce high-contrast and stable white light fringes, with unambiguous reference to absolute zero path-delay position. The colored fringes evolve when one of the ultrathin plates is rotated to tune the interferometer with picometric resolution over tens of μm range. Our theoretical analysis validates formation of fringes and highlights self-calibration of the interferometer for picoscale measurements. We demonstrate measurement of coherence length of several broadband incoherent sources as small as a few micrometer with picoscale resolution. Furthermore, we propose a versatile double-pass configuration using the ultrathin interferometer enabling a sample cavity for additional applications in probing dynamical properties of matter.

Human Intestinal Spirochetosis Incompatible With Dysplastic Adenomatous Epithelium

Human intestinal spirochetosis (HIS) refers to the colonization of spirochetal bacteria in the human intestinal tract. HIS caused by Brachyspira spp. has been recognized for decades, but their pathological and clinical significance is largely unclear. The coincidence of dysplasia in adenoma or adenocarcinoma and HIS is very rare, and whether spirochetes can colonize on dysplastic epithelium remains controversial. Here, we report a case that showed abrupt abolition of mucosal surface fringe formation on a tubular adenoma (TA) and increased cytoplasmic MUC1 expression in the dysplastic epithelial cells compared with adjacent nondysplastic colonocytes. The findings support the hypothesis that the epithelial colonization of spirochetes is significantly reduced by dysplasia likely due to loss of microvilli, and an increase of epithelial MUC1 expression might contribute to reduced spirochetal colonization in colonic mucosa.

Stress distribution of multiple implant-supported prostheses: Photoelastic and strain gauge analyses of external hexagon and morse taper connections.

BackgroundTo evaluate the stress distribution of three-element prostheses on two different implant systems (External Hexagon (EH) or Morse Taper (MT)) and with two different retention mechanisms (screw-retained or cemented), by photoelastic analysis and strain gauge analyses. Material and MethodsFour photoelastic and 24 strain gauge models of a partially edentulous maxilla were made and were divided in four groups according to connection and retention system: Group I (EH-C) – external hexagon+cement-retained prosthesis; Group II (EH-S) external hexagon+screw-retained prosthesis; Group III (MT-C) – morse taper+cement-retained prosthesis; Group IV (MT-S) – morse taper+screw-retained prosthesis. The implants were installed in the axial position, the first in the region of element 15 and the distal implant in the region of element 17. Loads of 100 N were applied on the occlusal surface of the prosthesis for 10 seconds. For the photoelasticity analysis, photographic images were taken and were evaluated according to the number of high-intensity fringes. For the strain gauge analysis, the strain gauges were positioned on the marginal crest of the implants and on the apical region, being numbered for analysis of the stress distribution in each region. The electrical signals were captured and processed by specific software. ResultsHigher concentration of tension was observed in the apical region of the implants and mainly in the distal implant, where the formation of fringes was higher. The microstrain values obtained for each group were similar: EH-C (454±18,3 µɛ); EH-S (469±94 µɛ); MT-C (466±49,8 µɛ); MT-S (460±36,6 µɛ). It was observed that apical position had higher stress concentrations for all analyzed groups. ConclusionsThe different connections and fixation mode did not interfere in the amount of tension generated in the tissue adjacent to the implant, also the region that generated the greatest amount of tension was in the apical region of the anterior implant. Key words:Dental implants, biomechanics, fixed prosthodontics.

Thermal Fringe Formation during a Hologram Recording Using a Dry Photopolymer

In this study we investigated the undesired but possible fringe formation during the recording of large size holographic optical elements (HOE) using a dry photopolymer. We identified the deformation of the recording element during hologram exposure as the main source for this fringe formation. This deformation is caused mainly by the one-sided heating of the recording element, namely, the dry photopolymer–recording plate stack. It turned out that the main source for this heating was the heat of polymerization in the dry photopolymer released during the exposure interval. These insights were translated into a physical model with which quantitative predictions about thermal fringe formation can be made depending on the actual HOE recording geometry, recording conditions and characteristics of the dry photopolymer. Using this model, different types of large size HOEs, used as components to generate a steerable confined view box for a 23” diagonal size display demonstrator, could be recorded successfully without thermal fringe formation. Key strategies to avoid thermal fringe formation deduced from this model include balancing the ratio of lateral recording plate dimension R to its thickness h, recording the power density P or equivalently the exposure time texp at a fixed recording dosage E, and most importantly recording the the linear coefficient of thermal expansion (CTE) of the recording plate material. Suitable glass plates with extremely low CTE were identified and used for recording of the above-mentioned HOEs.

High photocatalytic efficiency of α-Fe2O3 - ZnO composite using solar energy for methylene blue degradation

The present report illustrates the photocatalytic degradation of methylene blue dye under solar energy through α-Fe2O3 - ZnO composite synthesized by adopting a facile and simple chemical method. Various characterization techniques particularly X-ray diffraction (XRD), Transmission electron microscopy (TEM), and Fourier transform infrared spectroscopy (FTIR), etc., have been employed to characterize the as-synthesized composite. The XRD reveals the successful formation of the as-synthesized sample. The TEM studies illustrate the agglomeration of particles with sizes in the range of ∼10–60 nm. HRTEM micrograph indemnifies the formation of lattice fringes pertaining to inter-planner spacing∼ 0.149 nm and ∼0.138 nm corresponding to (214) reflection plane of hematite and (112) reflection plane of ZnO, respectively. The as-synthesized α-Fe2O3 – ZnO composite shows double absorption edges which correspond to the bandgap of α-Fe2O3 (2.2 eV) and ZnO (3.2 eV). Furthermore, α-Fe2O3 - ZnO composite shows a remarkable enhanced degradation capacity than bare hematite nanoparticles and zinc oxide nanoparticles, and α-Fe2O3 – ZnO (1:2) composite demonstrates the best degradation performance among all the variants. Moreover, it clearly suggests that the UV part of solar light plays a vital role in the catalytic degradation of methylene blue whereas the visible part of light remains unresponsive.

Catalytic oxidative desulfurisation over Co/Fe-γAl2O3 catalyst: performance, characterisation and computational study.

The world faces the challenge to produce ultra-low sulfur diesel with low-cost technology. Therefore, this research emphasised on production of low sulfur fuel utilising nanoparticle catalyst under mild condition. A small amount of cobalt oxide (10-30 wt%) was introduced into the Fe/Al2O3 catalyst through the wet impregnation method. Cobalt modification induces a positive effect on the performance of the iron catalyst. Hence, the insertion of cobalt species into Fe/Al2O3 led to the formation of lattice fringes in all directions which resulted in the formation of Co3O4 and Fe3O4 species. The optimised catalyst, Co/Fe-Al2O3, calcined at 400 °C with a dopant ratio of 10:90 indicating the highest desulfurisation activity by removing 96% of thiophene, 100% of dibenzothiophene (DBT) and 92% of 4,6-dimethyl dibenzothiophene (4,6-DMDBT). Based on the density functional theory (DFT) on Co/Fe-Al2O3, two pathways with the overall energy of -40.78 eV were suggested for the complete oxidation of DBT.