Size Of Light Source Research Articles

HARMONY OF LIGHT AND SHADOW: KEY ASPECTS OF LIGHTING IN PORTRAIT PHOTOGRAPHY

The article analyzes the role of lighting in portrait photography, emphasizing how the harmony between light and shadow can affect the emotional depth and visual appeal of an image. Photography, presented as an art and science of light, requires not only professional skills, but also the talent and skill of the photographer. The skill of a photographer lies not only in technical execution, but also in the ability to convey life and emotions through the image, revealing the true character of a person. Thus, a portrait photographer should be able to capture the soul and inner world of the model, which is a sign of his or her true skill. The article pays special attention to lighting under artificial lighting. It further discusses such aspects as distance between the subject and the light source, directionality of light, the size of light source and the distance to the subject, as well as the importance of shape of reflector. The different types of lighting in portrait photography are also discussed: back, side, front, diffused, and hard light, each of which affects the final image. The study includes analysis of current trends and innovative lighting techniques in portrait photography. It emphasizes the importance of the photographer’s ability to use different light sources to create images that reflect uniqueness and personality of the model. This study aims to expand the theoretical knowledge and practical skills of photographers, striving to improve the quality and expressiveness of portrait images.

Size characterization of x-ray tube source with sphere encoded imaging method.

In x-ray imaging, the size of the x-ray tube light source significantly impacts image quality. However, existing methods for characterizing the size of the x-ray tube light source do not meet measurement requirements due to limitations in processing accuracy and mechanical precision. In this study, we introduce a novel method for accurately characterizing the size of the x-ray tube light source using spherical encoded imaging technology. This method effectively mitigates blurring caused by system tilting, making system alignment and assembly more manageable. We employ the Richardson-Lucy algorithm to iteratively deconvolve the image and recover spatial information about the x-ray tube source. Unlike traditional coded imaging methods, spherical coded imaging employs high-Z material spheres as coding elements, replacing the coded holes used in traditional approaches. This innovation effectively mitigates blurring caused by system tilting, making system alignment and assembly more manageable. In addition, the mean square error is reduced to 0.008. Our results demonstrate that spherical encoded imaging technology accurately characterizes the size of the x-ray tube light source. This method holds significant promise for enhancing image quality in x-ray imaging.

Reconstruction based on adaptive group least angle regression for fluorescence molecular tomography.

Fluorescence molecular tomography can combine two-dimensional fluorescence imaging with anatomical information to reconstruct three-dimensional images of tumors. Reconstruction based on traditional regularization with tumor sparsity priors does not take into account that tumor cells form clusters, so it performs poorly when multiple light sources are used. Here we describe reconstruction based on an "adaptive group least angle regression elastic net" (AGLEN) method, in which local spatial structure correlation and group sparsity are integrated with elastic net regularization, followed by least angle regression. The AGLEN method works iteratively using the residual vector and a median smoothing strategy in order to adaptively obtain a robust local optimum. The method was verified using numerical simulations as well as imaging of mice bearing liver or melanoma tumors. AGLEN reconstruction performed better than state-of-the-art methods with different sizes of light sources at different distances from the sample and in the presence of Gaussian noise at 5-25%. In addition, AGLEN-based reconstruction accurately imaged tumor expression of cell death ligand-1, which can guide immunotherapy.

Design of optical elements for an extended light source

Using the previously developed optimization method for an extended light source [Byzov EV, Kravchenko SV, Moiseev MA, Bezus EA, Doskolovich LL. Optimization method for designing double-surface refractive optical elements for an extended light source. Opt Express 2020; 28(17): 24431-24443. DOI: 10.1364/OE.400609], we designed a compact refractive optical element (the ratio of the element height to the light source size being 1.55) providing a uniform illuminance distribution in a shifted rectangular region. An application of the optimization method for calculating the so-called TIR-elements, exploiting the phenomenon of the total internal reflection of rays, is considered. For an extended light source, compact TIR-elements with freeform exit surfaces that generate uniform illuminance distributions in a rectangular region are designed. The results of the work show promise for a wide class of problems of designing compact optical elements for light-emitting diodes.

A portable illumination device for photodynamic therapy of the oral cavity

Photodynamic therapy (PDT) is a minimally invasive method for treating oral leukoplakia. In this paper, we propose a portable PDT device consisting of a flexible circuit board with a liquid flow cooling module on the back. The light source size was 17[Formula: see text][Formula: see text][Formula: see text]mm, and the irradiation area of the light source was up to 100[Formula: see text]mm2. The irradiance range of this device was from 10[Formula: see text]mW/cm2 to 100[Formula: see text]mW/cm2. Simulation and experimental results showed that the irradiance coefficient variation for a treatment area of 81[Formula: see text]mm2 was less than 7%. At an irradiance of 100[Formula: see text]mW/cm2, a device surface temperature of lower than 42∘C can be achieved to satisfy the safety requirements under the conditions that the temperature of cooling liquid is 10∘C and the liquid flow speed is above 12[Formula: see text]mL/min.

Flexible Light Sources.

Various light sources have been developed for the application of optical stimulation in the optogenetics field. Light transmission inside living tissue is limited to a distance of a few millimeters; hence, it is necessary to insert the light source near the nerve tissue to be stimulated. If a device is rigid, it causes mechanical stimulation to act on the nerve tissue. The application of mechanical stimulation may induce inflammation, obstructing neural activity. Fabricating such a device out of a soft material can prevent mechanical stimulation of cells and mitigate biological reactions such as inflammation or encapsulation. Minimizing the sizes of LED and other light sources as much as possible and mounting them on a flexible substrate can provide the entire device with flexibility. Micro-LEDs can be reduced to a size almost comparable to that of a cell and it has even been reported that some have been mounted on the tip of needle-shaped devices inserted into living tissue. A device using organic semiconductors is sufficiently soft to be bent, which is a characteristic not observed in inorganic semiconductors. Using organic LEDs can realize wide-area flexible light-emitting surfaces and they are widely anticipated to be the next generation of light sources. This chapter introduces technologies used to manufacture these soft light sources and examples of optical stimulation devices that incorporate them.

An artefact-resist optrode with internal shielding structure for low-noise neural modulation

Objective. The combination of optical manipulation of neural activities with electrophysiology recording is a promising technology for discovering mechanisms of brain disorders and mapping brain networks. However, fiber-based optrode is limited by the large size of light source and the winding of optical fiber, which hinders animal’s natural movement. Meanwhile, the laser diode (LD)-based optrode restricted to the stimulation-locked artefacts will contaminate neural signal acquired from recording channels. Approach. Here, a reformative low-noise optrode with internal grounded shielding layer is proposed to mitigate the stimulus-locked artefacts generated during LDactivation for the application of optogenetics. Main results. The artefact mitigation capacity of grounded shielding was verified via simulation and experiments with transient amplitude of artefacts declined from over 5 mV to approximately 200 µV in-vitro. Meanwhile, the stimulation parameters were used based on previous studies by which neurons were activated without over heating the tissue as characterized by in-vitro studies (the output optical intensity is 823 ± 38 mW mm−2). Furthermore, the microelectrodes were modified with Poly (3, 4-ethylenedioxythiophene)-poly (styrenesulfonate) (PEDOT: PSS) to increase the signal recording quality of the optrode. Finally, in-vivo optogenetics experiments were carried in the hippocampus of one mouse and the results showed our low-noise optrode was qualified to achieve high-quality neural recording (signal-to-noise ratio about 13) and specific neuron stimulation simultaneously. Significance. These results suggest the low-noise optrodes exhibit the ability of manipulating and recording neural dynamics and they are excellent candidates for neuroscience research.

Analysis of Gloss Constancy in Light Source Size Change

Analysis of Gloss Constancy in Light Source Size Change

Ghost Imaging with Different Speckle Sizes of Thermal Light

In this paper, we theoretically and experimentally analyze the impact of speckle size of pseudo-thermal light source on ghost imaging. A larger size of speckle can bring improvements in SNR and visibility. At the same time, the edge blur of the retrieved image will become more serious. We also present a setup which can mitigate the edge blur of larger speckle while maintaining the advantages of higher SNR and visibility by changing the speckle size of the object beam with a concave lens.

Optimization of resolution by FDTD analysis in aligner lithography

A mask aligner can transcribe a pattern from a photomask to an exposure substrate by Fresnel diffraction. A diffraction fringe, specific to Fresnel diffraction, appears on a light intensity distribution of the pattern (a diffraction pattern image), and the formation of the pseudo-pattern restricts the resolution performance. The diffraction fringe can be smoothened by expanding the spread of the illumination source, and thus, the pseudo diffraction can be attenuated. However, this also causes a change in light intensity at the pattern edge to be attenuated, and the error of pattern line width to process change becomes large. Since edge diffraction patterns can be calculated by finite difference time domain (FDTD) analysis, the size of light source providing optimum resolution can be predicted by calculating and comparing pattern images corresponding to the size of the light source using this analysis. Therefore, by introducing an illumination optical system that can arbitrarily set the size of a light source to a predicted value, optimum resolution can be obtained without prior trial exposure. This study shows that the resolution of an aligner can be optimized by prior prediction, by introducing a multiple smoothing optical system that has been developed as an illumination system. This system realizes uniform illumination distribution on both a pupil plane and photomask plane and has an adjustable aperture mechanism that, by combining it with FDTD analysis, can arbitrarily set the size of the light source.

Gloss and Material Constancy in the Change of Light Source Size

It is well-known that gloss appearances are observed as the results of association among various physical factors. In order to analysis this association, perception for constancy is very important characteristic features. In this paper, therefore, we verify the influence in gloss and material constancy under the artificial environment by changing the shape and size of light source. We performed two type observations in subjective evaluation, one is the “gloss appearance” which is mainly observed the distribution of specular reflection, and the other is “material appearance” which is mainly observed all distribution of specular and diffuse reflection influenced roughness as whole appearance of object. We prepared two kinds of object which has different roughness, and four kinds of light image generated by LCD projector. A paired comparative experiment was performed under different light source with real object. As the result, there was no obvious gloss constancy when we observed only the distribution of specular reflection, since the shape and size of light source gave a great influence to the gloss perception. On the other hand, an effect of material constancy appeared when we observed all distribution of specular and diffuse reflection influenced roughness as whole appearance of object.

Optimized lens design for small angle uniform illumination from an extended source

Based on the edge-ray principle of non-imaging optics, an optical design method for a lens producing small angle, uniform illumination from a high-power light-emitting diode light source has been developed. The energy correspondence between the light-emitting diode light source and the illuminance distribution on a target plane was established, and a number of discrete points for freeform profile curves which could achieve uniform illumination over a small angle were calculated and fitted to create a lens. Finally, simulations were performed using software. The influence of the size of light source on the emitting angle under uniform illumination was also investigated. The results show that the optical system can achieve uniform illumination with an extended source, the divergence angle being controlled within a minimum range by the optical design method.

Focus tolerance influenced by source size in Talbot lithography

Abstract Using a simulation, we investigate the effects of the light source size and derive an effective method for suppression of the subfringes that appear in ArF Talbot lithography, which has been proposed for submicron pattern transfer applications. The appearance of the subfringes, which were caused by interference, was related to the size of the light source. If an appropriate light source size is chosen, then, a large process window can be obtained. Guidelines for source size selection are given.

GEARS: A General and Efficient Algorithm for Rendering Shadows

AbstractWe present a soft shadow rendering algorithm that is general, efficient and accurate. The algorithm supports fully dynamic scenes, with moving and deforming blockers and receivers, and with changing area light source parameters. For each output image pixel, the algorithm computes a tight but conservative approximation of the set of triangles that block the light source as seen from the pixel sample. The set of potentially blocking triangles allows estimating visibility between light points and pixel samples accurately and efficiently. As the light source size decreases to a point, our algorithm converges to rendering pixel accurate hard shadows.

基于扩展光源的LED小角度自由曲面透镜设计

A design algorithm of free surface lens based on extended source that can realize uniform illumination with small angle is presented.The energy correspondence between the extended source and the target plane is established.Using the edge-ray principle of nonimaging optics,a number of discrete points of the freeform profile curve is calculated and fitted to lens entity.By using non-sequential ray tracing to simulate lens with different light source size,under the premise of uniform illumination,the impact of the size of the light source for emitting angle is discussed.The simulation results show that the optical system can achieve uniform illumination with extended source and divergence angle can be controlled to its minimum angle.

Scattering Intensity of Floor Illuminance and Surface Luminance of Smoldering Smoke Layer

This paper examines the relationship between smoke layer properties and luminous quantities such as floor illuminance and surface luminance of smoke layer by conducting photometrical experiments under a smoke layer configuration with white smoke from smoldering fire source. The floor illuminance and surface luminance on the smoke layer in the model test compartment are found to be dependent upon the size of light source, the distance between light source and the observed location, the smoke layer thickness ZCs and optical smoke density Cs. The scattering intensity of white smoke from smoldering fire increases as the Cs and ZCs increased and the extent of the increase is affected by size of light source and measurement points of floor illuminance. The surface luminance of the smoke layer has a distribution and the luminance at the light source center decreases with the increase of CsZCs, while the surface luminance to the ceiling increased with CsZCs.

Optical detection sensitivity of area light source in optical read-out IR imaging

In the theoretical analysis of the optical readout IR imaging, the incoherent area light source with a certain size is typically simplified into an ideal point light source, which leads to analytical errors. In this paper an area light source model is established, and using the Fraunhofer diffraction theory the influence of the optical detection sensitivity on area light source is studied. The dependence of the optical detection sensitivity on light source radius and reflector length of the focal plane array is found. And optimized design criteria for the size of light source and the length of the reflector are proposed. According to theoretical analysis, the experimental verification is carried out, and the results are consistent with theoretical analyses.

Application of Optical Fiber Made of Various Materials with Composite Properties of Materials in Laser Medical Treatment

Though introducing the optical fiber in a laser medical treatment made ​​of different materials, contrast expounded integrated characteristic of the different materials in manufacturing an optical fiber material, summed four aspects need to be considered in the choice of the optical fiber manufacturing material. First, the laser parameters, such as maximum laser power, the wavelength, the transmission distance, the laser beam spot size and numerical aperture of the laser light source. Second, according to the optical fiber light transmittance curve, to identify the optimum transmittance of the application wavelength. Third, determining transmission optical slender core diameter, typically a core diameter is greater than the laser spot size of 2/3; decision sets of plastic material finally.

Effect of light source size on discomfort glare thresholds

AbstractPurpose Bright light sources, such as car headlamps or residential street lights, can cause visual discomfort. The origins of discomfort glare (DG) or the factors that contribute to it remain poorly understood, even after 50 years of multidisciplinary research [American Journal of Ophthalmology, 153(4):587‐593(2012)]. This study examined the effect of the light‐source intensity, size, surround luminance and pupil size on DG thresholds.Methods The pupil was measured in real time to calculate retinal illuminance, a more pertinent parameter in studies of DG. DG thresholds were estimated with a staircase procedure: the retinal illuminance was increased or decreased based on whether the participant indicated the absence or presence of DG, respectively. The subjects were required to view a source of light presented against a simulated residential street background. The size of the disc source was selected randomly under computer control. Five different source sizes were used to produce a 40 fold variation in stimulus area. The light source behind the aperture disc was designed to produce uniform flashes of light of varying intensity, while the surround light level remained unchanged.Results It was found that at the threshold for DG, the retinal illuminance is approximately constant and independent of source size. On the other hand, pupil plane illuminance increases as source size increases.Conclusion These findings suggest that DG depends mostly on localised retinal illuminance, rather than the total amount of light entering the eye. DG therefore appears to be largely related to saturation of photoreceptor signals. The results also suggest that higher levels of street illumination can be achieved by increasing the size of light source without causing any increase in DG.

Color of Light-Source and Background Luminance on Perceived Convexity and Concavity of a Blurred 3-D Hemisphere

In the present study, the effect of light-source color, size, background luminance, and blur on the perceived convexity and concavity of a 3-D hemisphere was investigated. The sample consisted of 84 undergraduates divided into Experience and No-experience groups based on experience working with 3D software. Participants were asked to adjust the angle of light in a clockwise direction until a convex hemisphere appeared concave. Analysis indicated that the color of light had a statistically significant effect on the angle of adjusted light, and the Experience group adjusted the angle of light less than did the No-experience group. The angle of the adjusted light was significantly smaller under the high background luminance condition compared with the medium and low luminance conditions. The angle of adjusted light under the low blur condition was greater than that under the high and medium blur conditions. These results have implications for graphics-based interface design.