Refraction Of Light Research Articles

Influence of polyethylene content on preparation and properties of lead zirconate titanate piezoelectric ceramics via vat photopolymerization

Vat photopolymerization has garnered significant research interest due to its capabilities in achieving complicated designed structures and high resolution. However, there are still significant technical difficulties in manufacturing some piezoceramic parts because of the high refractive index and ultraviolet light absorptivity of these ceramic powders. Herein, we overcome this challenge for lead zirconate titanate (PZT) ceramics by introducing polyethylene (PE) additions with ultralow refractive index and UV light absorptivity into PZT slurries. As the PE content increases, the curing depth shows a clear upward trend. When the PE content is 30 vol%, the curing depth of PZT slurry could ensure the adequate interlayer combination. Besides, PZT ceramics with different volumes of porosity could be obtained by modulating PE content. The relative density of sintered PZT ceramics decreased from 83.12 % to 68.06 %. Furthermore, the samples with 30 vol% PE exhibited satisfactory dielectric and piezoelectric properties (ϵr =1911, tanδ=0.027, d33 = 308 pC/N, g33 = 1.82 × 10−2 Vm/N and d33g33= 5.61 × 10−12 m2/N). These results indicate that the addition of PE additives is an effective and universal approach to improve the curing depth of ceramic slurries and expand the range of processable materials for vat photopolymerization technologies.

Cross-medium imaging model and calibration method based on refractive optical path for underwater morphology measurement

Full-field optical morphology measurement methods are widely used in the shape measurement of underwater targets. The existing models and calibration methods in air could be invalid due to the refraction of light. To deal with these problems, this paper develops a cross-medium imaging model and a relative calibration method. In the modeling, the actual refraction optical path is considered when using arbitrary transparent structures. In the calibration, the accurate parameters of the model are first determined in the air environment and then updated by the refraction index replacement strategy. By using these methods, the accurate restoration of the morphology of objects in any medium is realized, and the inconvenience of underwater calibration process in prior methods can be avoided. The results of conducted experiments show that the accuracy of measurement can achieve 0.42%, which illustrates the validity of the proposed model and the precision of the proposed calibration method.

DIC measurement method based on binocular stereo vision for image 3D displacement detection

The deformation detection of large machinery is usually achieved using three-dimensional displacement measurement. Binocular stereo vision measurement technology, as a commonly used digital image correlation method, has received widespread attention in the academic community. Binocular stereo vision achieves the goal of three-dimensional displacement measurement by simulating the working mode of the human eyes, but the measurement is easily affected by light refraction. Based on this, the study introduces particle swarm optimization algorithm for target displacement measurement on Canon imaging dataset, and introduces backpropagation neural network for mutation processing of particles in particle swarm algorithm to generate fusion algorithm. It combines the four coordinate systems of world, pixel, physics, and camera to establish connections. Taking into account environmental factors and lens errors, the camera parameters and deformation coefficients were revised by shooting a black and white checkerboard. Finally, the study first conducted error analysis on binocular stereo vision technology in three dimensions, and the relative error remained stable at 1 % within about 60 seconds. At the same time, three algorithms, including the spotted hyena algorithm, were introduced to conduct performance comparison experiments using particle swarm optimization and backpropagation network algorithms. The experiment shows that the three-dimensional error of the fusion algorithm gradually stabilizes within the range of [–0.5 %, 0.5 %] over time, while the two-dimensional error generally hovers around 0 value. Its performance is significantly superior to other algorithms, so the binocular stereo vision of this fusion algorithm can achieve good measurement results.

Neutral density filter-based catadioptric optical design for thin virtual reality head-mounted device

Virtual reality (VR) has been a popular trending technology affecting the lifestyles of humans. Especially for near-eye displays, VR head-mounted devices (HMDs) are designed accordingly and widely used in different fields. Nowadays, small structure size is a challenge and an urgent need for the VR HMD, while catadioptric optics is an effective and promising approach to solving this problem. Thus, this paper develops three kinds of catadioptric optical systems for thin VR HMDs by adjusting the configuration positions of the light refraction module created by the aspheric lens and the light partial reflection module formed by the neutral density (ND) filter. The comparison results of the three designs in terms of structure size and imaging quality show that multiple reflections during the light divergence process can effectively reduce the thickness of the optical structure. Reasonable transmission during the reflection process is also favorable for size reduction. Based on the designed catadioptric optical module, a varifocal VR HMD is developed to mitigate the vergence-accommodation conflict, thereby improving the image quality and the sensory experience of users.

A refractive three-dimensional reconstruction method for fringe projection with a planar medium

In special measurement situations, a vision measurement system needs to measure objects through a viewing observation window made of a planar transparent medium. The refraction at the interface between a medium and air leads to large measurement errors in the pin-hole imaging model. Most existing solutions require complex processes of calculating refracted light equations and/or matching stereo images. Here, we propose a refractive three-dimensional (3D) reconstruction method for fringe projection with a planar medium. We derive a coordinate conversion relationship from a pseudo-object point caused by light refraction to a real-object point based on flat refractive geometry. Then, we integrate the relationship into regular fringe projection framework for unbiased 3D reconstruction. Two experiments, including 3D shape measurements of a step and a regular sphere are performed. The results verify the effectiveness and accuracy of the proposed refractive 3D reconstruction method.

Surgical Technique to Treat Presbyopic Inlay-Associated Corneal Haze With Sequential Excimer Photoablation: A Case Series.

To describe an approach using sequential excimer laser ablation of the stromal surface of the corneal flap with or without subsequent excimer ablation to the stromal bed to reduce presbyopic inlay-associated corneal haze. Twelve patients who underwent KAMRA inlay (Acufocus) explantation due to corneal haze were included. The mean interval between explantation and the primary surgery (phototherapeutic keratotomy [PTK] to corneal flap) was 16.2 ± 29.7 months (range = 1 to 83 months). The corneal flap was lifted and laid on an evisceration spoon and an excimer laser was used to ablate the flap stroma by 30 to 40 µm depth. Subsequently, an excimer laser was used to ablate and treat the stromal bed following a second flap lift according to the manifest refraction, leaving a minimal residual stromal bed thickness of greater than 300 µm. For both procedures, mitomycin C 0.02% was applied to the stromal bed before the flap was replaced and a bandage contact lens applied. Reductions in corneal haze were observed, following PTK to the corneal flap with or without photorefractive keratectomy (PRK) to the stromal bed, both clinically and on imaging. No significant changes in uncorrected distance visual acuity (P = .442) and corrected distance visual acuity (P = .565) were observed. Improvements were observed for both spherical equivalent refractive errors (P = .036) and corneal light backscatter (P = .019). There were significant improvements in spherical aberrations (P = .014) but no changes in total lower and higher order aberrations. PTK to the corneal flap with or without subsequent stromal bed PRK is an effective technique in treating corneal haze following presbyopic inlay explantation. [J Refract Surg. 2023;39(9):639-646.].

Geometrical optics of large deviations of Brownian motion in inhomogeneous media

Geometrical optics provides an instructive insight into Brownian motion, ‘pushed’ into a large-deviations regime by imposed constraints. Here we extend geometrical optics of Brownian motion by accounting for diffusion inhomogeneity in space. We consider three simple model problems of Brownian motion on the line or in the plane in situations where the diffusivity of the Brownian particle depends on one spatial coordinate. One of our results describes ‘Brownian refraction’: an analog of refraction of light passing through a boundary between two media with different refraction indices.

Refractive fringe projection profilometry for three-dimensional shape measurement.

Light emitted by an object placed in a transparent protective cover will change its original propagation direction before entering a fringe projection profilometry (FPP) system due to the influence of light refraction. This Letter proposes refractive FPP for accurate three-dimensional (3D) shape measurement. The method derives a coordinate mapping between a 3D measurement space and a 2D space formed by an incident ray, a normal of a refractive interface, and an emergent ray. Based on the coordinate mapping, the equation of the emergent ray in the 3D space can be directly determined with the equation of the incident ray and used for 3D measurement without refraction error. For validation, an FPP system through a planar glass was established and used for 3D shape measurements of a ring board, a regular sphere, and two objects with complex surfaces. Experimental results demonstrate the effectiveness and accuracy of the proposed refractive FPP.

MYOPIA AS A RISK FACTOR FOR OPEN-ANGLE GLAUCOMA : A SYSTEMATIC REVIEW

Introduction: In myopia, the eye has excessive light refraction power, refracting parallel rays in front of the retina when not accommodated. In myopia, the visual media focus is in front of the macula lutea. Too strong refraction, refractive myopia, or a lengthy eyeball can cause this. This condition produces long-distance hazy vision, or "nearsightness". Myopia is a natural eye growth variant that may or may not be inherited. Stress of accommodation and convergence and anomalies in the connective tissue linking the trabeculae cause myopia-related glaucoma.
 
 The aim: This article showed myopia as a risk factor for open-angle glaucoma.
 
 Methods: By comparing itself to the standards set by the Preferred Reporting Items for Systematic Review and Meta-Analysis (PRISMA) 2020, this study was able to show that it met all of the requirements. So, the experts were able to make sure that the study was as up-to-date as it was possible to be. For this search approach, publications that came out between 2013 and 2023 were taken into account. Several different online reference sources, like Pubmed and SagePub, were used to do this. It was decided not to take into account review pieces, works that had already been published, or works that were only half done.
 
 Result: In the PubMed database, the results of our search brought up 78 articles, whereas the results of our search on SagePub brought up 72 articles. The results of the search conducted for the last year of 2013 yielded a total 32 articles for PubMed and 19 articles for SagePub. In the end, we compiled a total of 16 papers, 10 of which came from PubMed and six of which came from SagePub. We included five research that met the criteria.
 
 Conclusion: Myopia has been identified as a potential risk factor for POAG and may also serve as a potential protective factor against the progression of POAG. The potential cause for the observed phenomenon could be attributed to the existence of myopia accompanied by a deficiency in the lamina cribrosa. This defect may contribute to a deceleration in the rate of visual field deterioration, as well as the advancement of POAG. Additional investigation into the underlying mechanisms is still required.

New ring shear deformation apparatus for three-dimensional multiphase experiments: first results

Abstract. Multiphase deformation, where a solid and fluid phase deform simultaneously, plays a crucial role in a variety of geological hazards, such as landslides, glacial slip, and the transition from earthquakes to slow slip. In all these examples, a continuous, viscous, or fluid-like phase is mixed with a granular or brittle phase, where both phases deform simultaneously when stressed. Understanding the interaction between the phases and how they will impact deformation dynamics is crucial to improve the hazard assessments for a wide variety of geohazards. Here, we present the design and first experimental results from a ring shear deformation apparatus capable of deforming multiple phases simultaneously. The experimental design allows for 3D observations during deformation in addition to unlimited shear strain, controllable normal force, and a variety of boundary conditions. To impose shear deformation, either the experimental chamber or lid rotate around its central axis while the other remains stationary. Normal and pulling force data are collected with force gauges located on the lid of the apparatus and between the pulling motor and the experimental chamber. Experimental materials are chosen to match the light refraction index of the experimental chamber, such that 3D observations can be made throughout the experiment with the help of a laser light sheet. We present experimental results where we deform hydropolymer orbs (brittle phase) and Carbopol® hydropolymer gel (fluid phase). Preliminary results show variability in force measurements and deformation styles between solid and fluid end-member experiments. The ratio of solids to fluids and their relative competencies in multiphase experiments control deformation dynamics, which range from stick–slip to creep. The presented experimental strategy has the potential to shed light on multiphase processes associated with multiple geohazards.

Image-Based Sensor for Liquid Level Monitoring during Bottling with Application to Craft and Home-Brewing.

Although craft and home brewing have fueled the beer renaissance in the last decade, affordable, reliable, and simple sensing equipment for such breweries is limited. Thus, this manuscript is motivated by the improvement of the bottle-filling process in such settings with the objective of developing a liquid level sensor based on a novel application of the known optical phenomena of light refraction. Based on the different refraction indices of liquid and air (and critical angle based on Snell's law), along with a novel LED light source positioning, a reliable liquid level sensor system was built with the aid of an embedded microcontroller. The used operating principle is general and can be used in applications other than the proposed one. The proposed method was extensively tested in a laboratory and limited production settings with a speed of 7 Hz using different liquids and container shapes. It was compared for accuracy to other sensing principles such as ultrasound, infrared, and time-of-flight. It demonstrated comparable or better performance with a height error ranging between -0.1534 mm in static conditions and 1.608 mm for realistic dynamic conditions and good repeatability on the production line with a 4.3 mm standard deviation of the mean.

The impact of a droplet's light refraction on the size enlargement of its internal objects

Liquid droplets are objects of study in many industries due to their wide range of applications, including in agriculture and energy. When studying a droplet with a deformed object inside it, the length or radius of the object inside it will not be directly measured by photographing of the side view due to the refraction effect. In order to solve this problem, this paper analyzes the magnification of the object inside the droplet by geometric optics theory, derives the formula of magnification, and verifies it using practical experiments and simulations to illustrate the validity of the formula. It is also found that the amplification effect decreases as the internal object increases. The conclusions of this paper can correct the size amplification effect of the object inside the droplet due to refraction, which is a guideline for experimental and computational analysis in the field of droplet-related research.

Sea Cucumber Identification Fishing System Based on Hog Super Pixel Feature Extraction

Due to the refraction, reflection and absorption of light induced by seawater and suspended particles, the image recognition of underwater vehicle has the problem of low accuracy and difficult localization, and to solve this one problem, an improved LSTM classification algorithm (CH-LSTM) based on CLAHE and HOG is given. First, the improved CLAHE algorithm is used to enhance image by image noise removal and de-fogging, the problems of underwater image distortion, fine lines, and abrupt changes are solved in the aquaculture waters image. Then, the Histogram of Orientation Gradient (HOG) operator is used for feature extraction to describe the shape of sea cucumbers and generate feature vectors; finally, the LSTM algorithm is used to classify the feature vectors and avoid overfitting through memory gates, so the generalization ability of the model was enhanced. The identification and sorting experiments of underwater fishing sea cucumbers show that the proposed algorithm is superior, especially in the environment of poor water quality, and the identification and localization accuracy of sea cucumbers is improved compared with the traditional ground SVM and BP neural network algorithms, and the identification accuracy is above 95.28%.

Comprehensive assessment of the anterior segment in refraction corrected OCT based on multitask learning.

Anterior segment diseases are among the leading causes of irreversible blindness. However, a method capable of recognizing all important anterior segment structures for clinical diagnosis is lacking. By sharing the knowledge learned from each task, we proposed a fully automated multitask deep learning method that allows for simultaneous segmentation and quantification of all major anterior segment structures, including the iris, lens, cornea, as well as implantable collamer lens (ICL) and intraocular lens (IOL), and meanwhile for landmark detection of scleral spur and iris root in anterior segment OCT (AS-OCT) images. In addition, we proposed a refraction correction method to correct for the true geometry of the anterior segment distorted by light refraction during OCT imaging. 1251 AS-OCT images from 180 patients were collected and were used to train and test the model. Experiments demonstrated that our proposed network was superior to state-of-the-art segmentation and landmark detection methods, and close agreement was achieved between manually and automatically computed clinical parameters associated with anterior chamber, pupil, iris, ICL, and IOL. Finally, as an example, we demonstrated how our proposed method can be applied to facilitate the clinical evaluation of cataract surgery.

Physics E-Module Development Based on Contextual Teaching and Learning on Reflection of Light and Refraction of Light

This study aims to develop an e-module based on Contextual Teaching and Learning (CTL) as a physics learning media and to test its feasibility. The study employed a research and development method (R & D). This research produces a digital learning media for the Physic topic of reflection of light and refraction of light, which can assist students in studying independently by following the syntax of CTL. The e-module combines video, audio, and interactive quiz features. The development process was conducted through the ADDIE model where the researcher evaluate every step in the development process. The e-module was developed according to the syntax of CTL. Validation of the e-module was conducted during the development steps. The validation results by the material expert gained a score of 85.09%, while the media expert gained a score of 82.14%. The e-module was implemented in a small group of nine students and gained a score of 84.71%. These scores mean that the e-module was considered feasible and very good.

Novel Peptides with Dual Properties for Treating Pseudomonas aeruginosa Keratitis: Antibacterial and Corneal Wound Healing.

The corneal epithelium is a layer in the anterior part of eye that contributes to light refraction onto the retina and to the ocular immune defense. Although an intact corneal epithelium is an excellent barrier against microbial pathogens and injuries, corneal abrasions can lead to devastating eye infections. Among them, Pseudomonas aeruginosa-associated keratitis often results in severe deterioration of the corneal tissue and even blindness. Hence, the discovery of new drugs able not only to eradicate ocular infections, which are often resistant to antibiotics, but also to elicit corneal wound repair is highly demanded. Recently, we demonstrated the potent antipseudomonal activity of two peptides, Esc(1-21) and its diastereomer Esc(1-21)-1c. In this study, by means of a mouse model of P. aeruginosa keratitis and an in vivo corneal debridement wound, we discovered the efficacy of these peptides, particularly Esc(1-21)-1c, to cure keratitis and to promote corneal wound healing. This latter property was also supported by in vitro cell scratch and ELISA assays. Overall, the current study highlights Esc peptides as novel ophthalmic agents for treating corneal infection and injury, being able to display a dual function, antimicrobial and wound healing, rarely identified in a single peptide at the same micromolar concentration range.

Physico-chemical properties of Ocimum americanum L. essential oil from Burkina Faso

The present study aims to determine physico-chemical and organoleptic properties of Ocimum americanum L. Essential oil (EO) extracted in Burkina Faso. The protocol described in ISO international standards and Gas Chromatography Mass Spectrometry (GC/MS) were used respectively to determine physico-chemical properties and chemical analysis of the EO. The physico-chemical parameters measured were the acid index, the miscibility with ethanol, the pH, the relative density, the refractive index and the rotatory power. The organoleptic properties studied on the essential oil were the odour, the colour and the appearance. The EO showed a relative density value less than 1, a low light refraction and found to be dextro-rotatory. The pH value obtained was tended towards acidity, the EO was soluble in 5 volumes of ethanol (70%) with a low content of free acids. O. americanum EO was fluid, colourless with a specific odour. The chemical analysis of the EO showed that the 1.8-cineole (51.8%) and the camphor (17.4%) were found to be the major constituents of the EO. These results could lead for the establishment of essential oil standards in Burkina Faso.

Study of optoelectronic, thermoelectric, mechanical, and thermodynamic properties of Cs2NaTlX6 (X = Cl, Br, I) for energy harvesting

The inorganic double perovskites are remarkable materials for renewable energy which can be realized through solar cells and thermoelectric generators. Here, we have comprehensively elaborated the stability, mechanical, thermodynamic, optical and transport characteristics. The formation energy is computed to ensure thermodynamic validity and the tolerance factor is assessed for structural existence. The elastic constants satisfied the Born criteria and mechanical stability. Naviera's velocities have been used to study the Debye temperature and directional lattice conductivity. Modifying the band gap from 3.1 to 0.58 eV by halide ions (Cl to I) probes the distinct optoelectronic characteristics. Absorption bands, dispersion of light energy, refraction, and optical loss explain the optical characteristics. In addition, the above thermoelectric factors like conductivities, Seebeck effect, and performance are studied in the temperature range of 100–600 K. Large figure of merit and extremely low lattice vibration at room temperature indicate their significance for thermoelectric devices.

Reading Teeth

While artifacts made of ivory fill the shelves and storage rooms of museum collections across the world, ever more stringent legal measures restricting or banning the ivory trade have turned these objects into troublesome treasures. Ivory is a biological material derived from the tusks and teeth of several extant and extinct animals. The physical and aesthetic properties of elephantine ivory in relation to its use and symbolic significance shaped the material cultures of classed whiteness at the turn of the twentieth century. Ivory from elephant tusks displays a characteristic macroscopic motif known as the Schreger pattern, which is often used by conservators and forensic researchers as an identifying characteristic. First described by German odontologist Bernhard Schreger in 1800, this pattern of crossing dark and bright lines is attributed to an optical phenomenon of light refraction. By proposing a refractive reading of ivory, this article explores the role of animal-derived materials in the construction of human identities. This method of analysis allows the properties of ivory—luster, brilliance, whiteness, and toughness—to be seen as agentive material properties that historically co-produced human racial and classed ideals. Analyzing nineteenth- and early twentieth-century sources in dental anatomy, ivory commerce, and technical microscopy permits an unraveling of this animal material’s ties to specific colonial regimes of trade and resource extraction, and its technical role in precursors to materials science. This paper is part of a special issue entitled “Making Animal Materials in Time,” edited by Laurence Douny and Lisa Onaga.

Development of Contextual Physics Teaching Materials Assisted by Virtual Lab Based-Android as Alternative Learning in Covid-19 Pandemic

This study aims to develop effective and efficient contextual physics teaching materials for students and teachers in the Covid-19 pandemic. The teaching materials are based on virtual lab-based Android so that they can be used in any conditions, including when applying physical distancing protocols at school or study from home (SFH). The teaching materials in the form of this application makes it easy for students to access the content on their mobile phones even when they cannot connect to the internet. Also, this application is very easy for teachers to be used. The research method used is based on the 4D model, that is define, design, develop and disseminate. The teaching materials that have been developed passed the first stage test with a Very Good result. The validity test is assessed by expert validators. The subject material used in this study is limited to Reflection and Refraction of Light. The response of students using the teaching materials is Good. According to the students, the teaching materials are easy to use, motivate learning, and deem effective in its implementation