Light Rays Research Articles

Fresnel lenses and auto tracking to increase solar panel output power

This solar panel, which is equipped with microcontroller-based auto tracking, is also equipped with a Fresnel lens to obtain more optimal power because the Fresnel lens has the property of bending or refracting light rays that pass through it so that it can focus sunlight. The Fresnel lens focuses sunlight radiation onto the solar panels. To determine the magnitude of the influence of Fresnel lenses on increasing the power produced by solar panels, two solar panels of the same size (11×11) cm were moved by auto tracking using the same axis. One solar panel is not fitted with a Fresnel lens, and the other is fitted with a Fresnel lens measuring 30×30 cm, where the distance between the Fresnel lens and the solar panel is 5 cm. Measurements of the output power of both solar panels were carried out simultaneously, namely from 08.00 to 18.00 WIB (West Indonesia time). The power output of both solar panels was measured in 30-minute intervals, resulting in 21 measurements. Solar panels using Fresnel lenses produce an output power that is 105.306% more significant than that of those without Fresnel lenses.

Retinal atrophy, inflammation, phagocytic and metabolic disruptions develop in the MerTK-cleavage-resistant mouse model

In the eye, cells from the retinal pigment epithelium (RPE) facing the neurosensory retina exert several functions that are all crucial for long-term survival of photoreceptors (PRs) and vision. Among those, RPE cells phagocytose under a circadian rhythm photoreceptor outer segment (POS) tips that are constantly subjected to light rays and oxidative attacks. The MerTK tyrosine kinase receptor is a key element of this phagocytic machinery required for POS internalization. Recently, we showed that MerTK is subjected to the cleavage of its extracellular domain to finely control its function. In addition, monocytes in retinal blood vessels can migrate inside the inner retina and differentiate into macrophages expressing MerTK, but their role in this context has not been studied yet. We thus investigated the ocular phenotype of MerTK cleavage-resistant (MerTKCR) mice to understand the relevance of this characteristic on retinal homeostasis at the RPE and macrophage levels. MerTKCR retinae appear to develop and function normally, as observed in retinal sections, by electroretinogram recordings and optokinetic behavioral tests. Monitoring of MerTKCR and control mice between the ages of 3 and 18  months showed the development of large degenerative areas in the central retina as early as 4 months when followed monthly by optical coherence tomography (OCT) plus fundus photography (FP)/autofluorescence (AF) detection but not by OCT alone. The degenerative areas were associated with AF, which seems to be due to infiltrated macrophages, as observed by OCT and histology. MerTKCR RPE primary cultures phagocytosed less POS in vitro, while in vivo, the circadian rhythm of POS phagocytosis was deregulated. Mitochondrial function and energy production were reduced in freshly dissected RPE/choroid tissues at all ages, thus showing a metabolic impairment not present in macrophages. RPE anomalies were detected by electron microscopy, including phagosomes retained in the apical area and vacuoles. Altogether, this new mouse model displays a novel phenotype that could prove useful to understanding the interplay between RPE and PRs in inflammatory retinal degenerations and highlights new roles for MerTK in the regulation of the energetic metabolism and the maintenance of the immune privilege in the retina.

CuS-CuO nanoparticles for antennas collect light through their conductivity by absorbing a single photon located at the wavelength of 254 nm

CuS-CuO nanoparticles were prepared by air annealing as-made CuS nanoparticles deposited using spray pyrolysis. The optical, structural, and morphological properties of samples were investigated by UV–VIS Spectroscopy, X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The XRD analysis of as-prepared sample include two phases CuS and Cu2S, while annealed films are a mixture of CuS and CuO phases. The dimensions of the CuS crystallites were estimated by Williamson's method on the diffraction peaks (81 nm) while the dimensions of the CuO ones were statistically evaluated via the SEM image (95 nm) and corroborated by Williamson's method on the diffraction peaks (98 nm). SEM study of annealed samples reveals that nanoparticles are monocrystalline. Optical analysis shows more than 80 % transmittance through sample thickness 164 nm in the infrared region and two energy bandgaps of 1.92 and 2.50 eV in the visible region associated with CuO and CuS, respectively. In addition, we observe after several optical excitations that only the UV wavelength of 254 nm gives a tangible electrical response. We understand from the literature that this is only possible through one interpretation of the antenna effect. Optical antennas aim to freely change light rays into local energy. In fact, our sample presents nanoparticles with sizes around 80 nm that show clear absorption through the development of their reproducible resistance that increases with polarization toward saturation after 5 V. Therefore, we propose using prepared nanoparticles in a light-harvesting antenna for artificial photodetector and other optoelectronic applications.

Dense viewpoint encoding of 3D light fields based on neural graphics primitives

The enormous rendering time is a challenge for generating the Projector Image Array (PIA) using parallax images. Based on Neural Radiance Fields (NeRF), a novel method for directly rendering sub-images of PIA is proposed to accelerate light field encoding. The method is a unique combination of 3D light field coding and recent instant Neural Graphics Primitives (NGP) technique, showing how to obtain high-quality PIA quickly. The NGP is used to accelerate the training and rendering of the NeRF, and to improve the quality of the rendered parallax images by utilizing a multi-resolution hash grid container. The light ray of the traditional light field coding method is viewed as the key object linking the display system and the implicit radiance field. By encoding the light field of the actual display system as input to the NGP network, the proposed method can directly obtain the sub-PIA displayed in a single projector. For a projector with a resolution of 720×1280, the sub-PIA rendering time is only 25ms. The PIA is then synthesized from all the sub-PIAs that have been rendered. Numerical simulation results show that this method runs faster than the traditional method with high-quality displays. Light field display experiments are conducted to demonstrate the method's feasibility.

A Review on Voice Navigation System for the Visually Impaired

A ground-breaking voice navigation system seems as a ray of light in a world where blind people must overcome enormous obstacles to navigate strange places. For those with vision impairments, safely and independently navigating in unfamiliar situations presents substantial obstacles. This system is a paradigm shift in providing safe and independent mobility assistance for the visually handicapped, as it makes use of cutting-edge technologies. The voice navigation system gives users the confidence to confidently navigate uncharted territory by seamlessly integrating computer vision and machine learning capabilities. With the use of real-time obstacle classification and recognition capabilities, the system can give users vital information about their surroundings, empowering them to make wise decisions while traveling. The system's smartphone-based platform, which provides an intuitive interface that can be accessed with voice commands, is its basis. By utilizing deep learning algorithms and pre-trained models, the system can precisely identify barriers and guide people across intricate environments. Precise positioning and route planning are made possible by the system's integration of GPS technology. Users receive up-to-date information on their location and the most efficient route to their destination via voice-activated instructions and advice. Individual user preferences are catered to by customizable options, which guarantee a tailored and user-friendly experience. A wider user base can utilize the system, democratizing access to necessary navigation tools, due to its affordability and interoperability with commonly available smartphone devices. The results of experimental tests highlight the effectiveness of the system, showing that it can reliably and accurately guide visually impaired people across a variety of surroundings. Through the promotion of increased autonomy and mobility, the voice navigation system enables users to move with unprecedented liberty and self-assurance, surmounting obstacles and opening up novel prospects. Key Words: : Voice navigation system, Machine learning, GPS technology, Deep learning algorithms, Navigation tools.

ДИСПЕРСТІ ОРТАЛАРДЫҢ ОПТИКАЛЫҚ ҚАСИЕТТЕРІ

The aim of the study is to study light scattering, one of the optical properties of dispersed media. A number of optical methods for determining the size, shape and concentration of colloidal particles and macromolecules are based on the Tyndall effect. A ray of light passing through a colloidal solution is visible as a result of scattering, this type of scattering is called opalescence. Scientific discovery new data on optical effects occurring on magnetic colloids under the influence of magnetic and hydrodynamic fields have been obtained. To create neutral light filters controlled by a magnetic field, it is possible to use established diffraction scattering models with a small angle. The article defines the correspondence and errors of the J.W. Rayleigh or Clausius equations of light scattering intensity for a collide sulfur solution obtained experimentally to solve the problem.

Kerr black hole shadows cast by extraordinary light rays with Weyl corrections

Kerr black hole shadows cast by extraordinary light rays with Weyl corrections

Observational signatures of Rotating compact objects in Plasma space–time

We have investigated the characteristics of shadows cast by the Kerr black hole in the presence of plasma and compared them to those of a rotating wormhole in a uniform plasma space–time for an observer at infinity. Interestingly, for the same uniform plasma density, the apparent shadow size of the rotating wormhole is always greater than that of the Kerr black hole. To further distinguish the two compact objects we studied the deflection angle and did a comparative study in the presence of the uniform and non-uniform plasma profiles. The goal of this whole exercise is to deepen our understanding of the observational phenomena of these astrophysical objects. The analysis reveals the importance of specific plasma distribution profiles, the impact of plasma on the shadow diameter, and the behavior of deflection angles in different plasma scenarios. We have calculated constraints on the plasma parameters by considering observational data and employing analytical formulations. Our work therefore provides valuable insights into the behavior of light rays near compact objects in plasma space–time.

Radiance-field holography for high-quality 3D reconstruction

Conventional light field-based computer-generated holograms, such as holographic stereograms, can provide nature parallax and accurate occlusion relation but are restricted by the inherent tradeoff concerning the angular and spatial resolution of the reconstructed optical field. In contrast, Wigner distribution function based light field generated holograms, also called non-hogel-based holograms, release this limitation by using basic ray-to-wave transformation frameworks. However, at present, this transformation framework is accurate only for generating holograms from orthogonal light field images of 3D scenes with a limited depth range and size. Thus, the radiance field holography method is proposed in this paper to generate high-quality 3D holograms for arbitrary scenes that can achieve high-resolution reconstruction within a deep depth range. In our method, a proposed radiance field is constructed from the perspective light field, which consists of multiple reference planes to resample and redistribute the light rays to represent the diffracted optical field of the 3D objects according to our developed sampling criterion. The complex optical field of the 3D object can be synthesized from these reference planes based on inverse Wigner transform and Fresnel propagation. As a result, both the numerical simulations and the optical experiments are implemented, and it is demonstrated that the high-quality 3D reconstruction of the synthesized hologram is achieved, which reflects the highest reconstruction resolution among the existing methods, the large depth range with accurate refocus and defocus, and the natural view-dependent effects.

Refractive index measurement deflectometry for measuring gradient refractive index lens.

A method based on deflectometry to measure the refractive index distribution of radial gradient refractive index (GRIN) lens is proposed in this paper. The method establishes the relationship between the refractive index distribution and the direction of light ray by deriving the propagation equation of light in a non-uniform medium. By measuring the deflection angle using the principle of deflectometry and the assumption of central refraction, the refractive index distribution of the radial GRIN lens is determined. The specific principle of refractive index measurement deflectometry (RIMD) is described in detail, and the correctness and accuracy of the method are verified through numerical simulations. Furthermore, the effects of calibration error, lens surface shape on the accuracy of the measurement results are analyzed. In the experimental section, the proposed method is applied to measure a radial GRIN lens, and the results are compared with the nominal parameters in terms of shape distribution and numerical values, demonstrating good consistency. The measurement error is controlled within the order of 10-3. This method enables rapid and convenient acquisition of full-field information of GRIN lens and holds promising potential for playing an important role in lens manufacturing and production.

Improving depth uncertainty in plenoptic camera-based velocimetry

This work describes the development of a particle tracking velocimetry (PTV) algorithm designed to improve three-dimensional (3D), three-component velocity field measurements using a single plenoptic camera. Particular focus is on mitigating the longstanding depth uncertainty issues that have traditionally plagued plenoptic particle image velocimetry (PIV) experiments by leveraging the camera’s ability to generate multiple perspective views of a scene in order to assist both particle triangulation and tracking. 3D positions are first estimated via light field ray bundling (LFRB) whereby particle rays are projected into the measurement volume using image-to-object space mapping. Tracking is subsequently performed independently within each perspective view, providing a statistical amalgamation of each particle’s predicted motion through time in order to help guide 3D trajectory estimation while simultaneously protecting the tracking algorithm from physically unreasonable fluctuations in particle depth positions. A synthetic performance assessment revealed a reduction in the average depth errors obtained by LFRB as compared to the conventional multiplicative algebraic reconstruction technique when estimating particle locations. Further analysis using a synthetic vortex ring at a magnification of − 0.6 demonstrated plenoptic-PIV capable of maintaining the equivalent of 0.1–0.15 voxel accuracy in the depth domain at a spacing to displacement ratio of 5.3–10.5, an improvement of 84–89% compared to plenoptic-PIV. Experiments were conducted at a spacing to displacement ratio of approximately 5.8 to capture the 3D flow field around a rotor within the rotating reference frame. The resulting plenoptic-PIV/PTV vector fields were evaluated with reference to a fixed frame stereoscopic-PIV (stereo-PIV) validation experiment. A systematic depth-wise (radial) component of velocity directed toward the wingtip, consistent with observations from prior literature and stereo-PIV experiments, was captured by plenoptic-PTV at magnitudes similar to the validation data. In contrast, the plenoptic-PIV did not discern any coherent indication of radial motion. Our algorithm constitutes a significant advancement in enhancing the functionality and versatility of single-plenoptic camera flow diagnostics by directly addressing the primary limitation associated with plenoptic imaging.Graphical abstract

Analysis of the Geodesic Motions of Massive Particles in Kerr–Sen–AdS4 Spacetime

We consider geodesic motions in Kerr–Sen–AdS4 spacetime. We obtain equations of motion for light rays and test particles. Using parametric diagrams, we show some regions where radial and latitudinal geodesic motions are allowed. We analyze the impact of parameters related to the dilatonic scalar on the orbit and find that it will result in more rich and complex orbital types.

A high resolution prism-grating panoramic imaging spectrometer based on occultation observations

Occultation observation is an important technique for shadow region detection and a significant complement to the illuminated region detection method. This technology will significantly reduce the impact of background light pollution and provide clearer occultation signals. In order to achieve high-resolution all-round detection in the shadow region, this paper introduces a proposal for a prism-grating panoramic imaging spectrometer based on occultation observations. It utilizes a panoramic annular lens to enable 360-degree occultation observations within the shadow region, combines a grating for spectral separation to obtain spectral information, and achieves an overall straight-line design for the system by adjusting the prism-grating surface's deflection angle. This paper, by analyzing the non-uniformity of light rays from different fields of view after dispersion by the grating, obtains the coordinate information of the spectrum on the image plane, significantly improving the accuracy of subsequent spectral calibration. The design results indicate that the optical system of this imaging spectrometer achieves a spectral resolution of 0.67 nm in the wavelength range of 365–770 nm. At a Nyquist frequency of 37.04lp/mm, the MTF across the entire bandwidth exceeds 0.6. The RMS of the point spread function is less than 9 μm across the full field of view, and aberration correction is excellent. This imaging spectrometer utilizes stellar occultations to achieve real-time 360-degree observations in the shadow region, and at the same time obtains total information on atmospheric components and contour information that varies with occultation height. This scheme offers a more comprehensive information for scientists in related fields.

Projection Mapping with a Brightly Lit Surrounding Using a Mixed Light Field Approach.

Projection mapping (PM) exhibits suboptimal performance in well-lit environments because of the interference caused by ambient light. This interference degrades the contrast of the projected images. Consequently, conventional methodologies restrict the application of PM to dimly lit settings, leading to an unnatural visual experience, as only the PM target is prominently illuminated. To overcome these limitations, we introduce an innovative approach that leverages a mixed light field, blending traditional PM with ray-controllable ambient lighting. This methodological combination, despite its simplicity, is effective because it ensures that the projector exclusively illuminates the PM target, preserving the optimal contrast. Precise control of ambient light rays is essential to prevent them from illuminating the PM target while adequately illuminating the surrounding environment. Furthermore, we propose the integration of a kaleidoscopic array with integral photography to generate dense light fields for ray-controllable ambient lighting. Additionally, we present an efficient binary-search-based calibration method tailored to this intricate optical system. Our optical simulations and the developed system collectively validate the effectiveness of our approach. Our results show that PM targets and ordinary objects coexist naturally in environments that are brightly lit as a result of our method, enhancing the overall visual experience.

21.83% incident light can circumvent a 6.6 × 6.6 cm2 obstruction by introducing a layer of bubbles into the photovoltaic glass.

Obstruction is inevitable and will significantly impact the actual output performance of photovoltaic modules, even jeopardize their operational safety. We introduced a layer of bubbles into photovoltaic glass. These bubbles can alter the path of incident light, while the internal reflection at the glass/air interface enables the redirected light rays to have longer lateral propagation distance, circumventing the obstructions. The optimized photovoltaic glass with a bubble diameter of 1.8 mm and a surface density of 16 cm-2 enables the light intensity underneath a 6.6 × 6.6 cm2 obstruction to reach 21.83% of the incident light intensity. This enhancement permits a partial shading of the photovoltaic module, increasing its output power by ∼20.8% and decreasing the reverse bias voltage on the shaded cell by ∼1.4 V.

The One-Cushion Escape from Snooker in a Circular Table

Abstract The one-cushion escape from snooker in a circular table can be viewed as a ge-ometric problem involving the reflection of a light ray in a circular mirror. There are at most four escapes in any given configuration. We will obtain specific configurations in which there are exactly 0, 1, 2, 3 or 4 escapes. The details consist in determining the number of real solutions in the interval (−1; 1) of certain polynomial equations, of degrees two, three or four.

Distortions of parabolic mirror optics for stereophonic lithography and prospects of compensations

The distortions of parabolic mirror optics used for stereophonic projection lithography were investigated. It has already been demonstrated that resist patterns are replicable on gently curved surfaces using mirror optics composed of faced paraboloids of revolution. However, it was found that replicated resist patterns were somewhat distorted from the original patterns. The distortions were caused by characteristics of projection optics. For this reason, the distortions were first calculated by tracing light rays. The calculation procedures are explained in detail. The calculated distortions almost coincide with the ones obtained by experiments. Next, the influences of distortions on the distributions of image intensity and replicated pattern widths were investigated. The maximum distortions reached 29% of the original size at the right-side corners of a 12 mm square, and the light intensity was lowered by 30%. For this reason, printed 200 μm pattern widths reached more than 500 μm on the right side. This was considered to be unfavorable for applying the method universally in various uses. For this reason, methods for compensating or modifying the optics distortions were investigated, and light intensity distributions were discussed.

Detection of atmospheric turbulence parameters in free space optical communication

Abstract These days usage of wireless communication has become vast compared to wired communication. The landline is replaced with a mobile, wi-fi with DAS. From the era of 1970 to the 1980s, wireless communication has evolved and wireless communication uses RF waves to communicate which is called RF communication. As the demand for the speed of data rate, the new technology is evolving in the unguided medium due to its range, cost, and availability. In this evolution, it first came with optical fiber and after RF wireless or electromagnetic wireless technologies. Later, researchers have been found optical communication. In present days it is facing a lot of challenges and trials. Optical communication means communication using the light ray or light spectrum which can achieve great speed and long distance with secure data transfer. The major challenge to achieve this communication is atmospheric turbulence. Although lots of experiments have been done still the problem is the detection of atmospheric conditions and making communication possible according to atmospheric turbulence. In this paper, we are going to discuss a few techniques to detect atmospheric turbulence.

Light field image coding using a residual channel attention network–based view synthesis

PurposeLight field images (LFIs) have gained popularity as a technology to increase the field of view (FoV) of plenoptic cameras since they can capture information about light rays with a large FoV. Wide FoV causes light field (LF) data to increase rapidly, which restricts the use of LF imaging in image processing, visual analysis and user interface. Effective LFI coding methods become of paramount importance. This paper aims to eliminate more redundancy by exploring sparsity and correlation in the angular domain of LFIs, as well as mitigate the loss of perceptual quality of LFIs caused by encoding.Design/methodology/approachThis work proposes a new efficient LF coding framework. On the coding side, a new sampling scheme and a hierarchical prediction structure are used to eliminate redundancy in the LFI's angular and spatial domains. At the decoding side, high-quality dense LF is reconstructed using a view synthesis method based on the residual channel attention network (RCAN).FindingsIn three different LF datasets, our proposed coding framework not only reduces the transmitted bit rate but also maintains a higher view quality than the current more advanced methods.Originality/value(1) A new sampling scheme is designed to synthesize high-quality LFIs while better ensuring LF angular domain sparsity. (2) To further eliminate redundancy in the spatial domain, new ranking schemes and hierarchical prediction structures are designed. (3) A synthetic network based on RCAN and a novel loss function is designed to mitigate the perceptual quality loss due to the coding process.

Geometric lightguide for near-eye light field displays.

Most near-eye displays with one fixed focal plane suffer from the vergence-accommodation conflict and cause visual discomfort to users. In contrast, light field displays can provide natural and comfortable 3D visual sensation to users without the conflict. This paper presents a near-eye light field display consisting of a geometric lightguide and a light field generator, along with a collimator to ensure the light rays propagating in the lightguide are collimated. Unlike most lightguides, which reduce thickness by employing total internal reflection that can easily generate stray light, our lightguide directly propagates light rays without total internal reflection. The partially reflective mirrors of the lightguide expand the exit pupil to achieve an eyebox of 13m m(h o r i z o n t a l)×6.5m m(v e r t i c a l) with an eye relief of 18mm. The collimator and the light field generator, both having effective focal lengths different in the horizontal and vertical directions, are designed to provide a 40-deg diagonal field of view. The working range of the light field generator, which is 30cm to infinity, is verified qualitatively and quantitatively by experiments. We optimize the illuminance uniformity and analyze the illuminance variation across the eyebox. Further, we minimize the ghost artifact (referring to the split-up of light fields replicated by the partially reflective mirrors) by orienting the partially reflective mirrors at slightly different angles to enhance the image quality for short-range applications such as medical surgery.