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In this work, a scheme of combining an aspheric reflector and a primary packaging freeform lens in phosphor-converted lighting-emitting diode (pc-LED) based lighting system design was developed. In contrast to most of previous works in which the color and illumination uniformity of the pc-LED lighting systems were improved one by one, the developed scheme can improve both indicators simultaneously. To demonstrate the feasibility of the developed design scheme, an initially designed pc-LED optical model, with an average correlated color temperature (CCT) of about 5000 K, was constructed as the light source of the illumination system. The key ingredient to the color uniformity of the illumination system was investigated at first, and then several instances with the cut-off angle ranging from 40 to 60 degrees were further discussed. Detailed analysis shows: for each case, the CCT variation decreases from over 4000 K to smaller than 300 K and the illumination uniformity increases from a very low level to better than 80% on the target region.

The purpose of the work is to study the development of concepts and technologies for the manufacture of ceiling fixtures to light the interior of buildings – office, public and administrative ones, etc. It is known that fluorescent lamps have long been used for interior lighting. Massive diffusers made of matte polycarbonate sheets were used to smooth the light intensity curve of such luminaires and bring it to the cosine light distribution. Due to the matte coating of the diffuser, the luminous part of the light fixtures acquired, with a fairly good approximation, the properties of an equally bright surface. Such surfaces are known to have a cosine light distribution and are very convenient for lighting. In the early 2000s, the problem of energy saving worsened, which led to a significant reduction in the number of luminaires of this type. These changes have also affected the approaches to the design of indoor light fixtures. The major difference of the new modifications of fluorescent fixtures is the absence of a matte reflector, which is very uneconomical in terms of energy saving, since it significantly decreased the luminous flux. The refusal to use the diffuser led to the emergence of fluorescent fixtures with a specular reflection system and shutters, which limited the dazzling effect of such lamps. However, with the parallel development of LED technology, the concept of choosing a light source in indoor lighting fixtures began tochange. In grille fixtures, LEDs were gradually replacing fluorescent ones. Nowadays, manufacturers' websites offer a fairly wide selection of LED fixtures. They differ in the price, quality of LEDs used, design and technological solutions. Recently, the volume of production and range of LED light bars has been increasing. The article presents an attempt to consider which fixtures offered on the modern market are the most balanced in terms of engineering solution in the context of lighting, operational, pricing, technological and certification characteristics. Based on the analysis of fixtures of different types and modifications, the authors concluded that the most optimal engineering solution is ceiling LED light bars and developed a method of their design and certification.

The light organ is an electronic device that can emit light. However, there are light organs in animals that can produce light naturally. Loligo duvaucelii is a species whose biolumenesence comes from fluorescent bacteria that live in symbiosis in its ink sacs. This study aims to determine in detail the construction of the squid light organ using the transmission electron microscopy (TEM) method. The results showed that this type of squid has a pair of light organs attached to the dorso-lateral ink sac. The light organ is spherical, some are found on the surface and some are embedded on the wall of the ink sac. It consists of a lens that is located on the outer surface of the ink sac, and a sac of light organs (embedded on the wall of the ink sac) with channels connecting the pocket to the mantle cavity. The wall of the sac of the light organ consists of three layers, namely the innermost layer which is multi-fold with microvilli on the cell surface and between the folds of the sac populated with bacteria, the dense layer that acts as a reflector, and the pigment layer. Cilia are observed on the surface of the duct connecting the sac with the mantle cavity. This study concluded that the construction of the squid light organ has a convex-shaped lens structure and is muscular. In the pockets of light organs, a dense population of bacteria is found. The reflector consists of many layers, and the pigment layer contains many granules.

This research paper demonstrates the importance of Parabolic Solar Cooker both for developing countries and for refugee camps. This cooker's main purpose was to concentrate the solar radiation and convert it to heat using different reflective materials. Some essential factors were considered as the surface of the reflector must be smooth and shiny, and control (loading, tracking, temperature sensing.) variables and uncontrolled (wind, ambient temperature) variables also need to consider. Several Parabolic Solar cookers had designed various reflective materials such as Stainless Steel, Aluminum Foil, and Mylar Tape. Additionally, multiple testing had done with those Parabolic Solar cookers. Besides, in this research three different forms of temperature were measured: Concentrating surface temperature, vessel temperature, and water temperature. The notable success of this research work was the third design. The third design was implemented with Mylar Tape as a reflective material. Boiled Rice, Fried egg and Fried potato had cooked within a short period with the third design. Firstly, stainless steel as a reflective material was used to construct the first prototype. Moreover, 58.2 °C maximum water temperature was achieved from the first prototype. After that, the second prototype was used aluminum foil as reflective material. Besides, 74.5 °C maximum water temperature was achieved from the second prototype. Finally, the third prototype was used Mylar tape as a reflective material. Alongside, 74.5 °C maximum water temperature was achieved from the third prototype. Moreover, in the wood we got 239 °C as well as in paper we got 105.4 °C.

Reflective assemblies of high refractive index organic crystals are used to produce striking optical phenomena in organisms based on light reflection and scattering. In aquatic animals, organic crystal-based reflectors are used both for image-formation and to increase photon capture. Here we report the characterization of a poorly-documented reflector in the eye of the shrimp L. vannamei lying 150 μm below the retina, which we term the proximal reflective layer (PR-layer). The PR-layer is made from a dense but disordered array of polycrystalline isoxanthopterin nanoparticles, similar to those recently reported in the tapetum of the same animal. Each spherical nanoparticle is composed of numerous isoxanthopterin single crystal plates arranged in concentric lamellae around an aqueous core. The highly reflective plate faces of the crystals are all aligned tangentially to the particle surface with the optical axes projecting radially outwards, forming a birefringent spherulite which efficiently scatters light. The nanoparticle assemblies form a broadband reflective sheath around the screening pigments of the eye, resulting in pronounced eye-shine when the animal is viewed from a dorsal-posterior direction, rendering the eye pigments inconspicuous. We assess possible functions of the PR-layer and conclude that it likely functions as a camouflage device to conceal the dark eye pigments in an otherwise largely transparent animal.

In this paper, a design scheme of an automobile low-beam light illumination system with a reflector free-form surface is presented. Per the energy grid mapping theory and edge ray theory, an oblique triangular energy mapping scheme was proposed, and the free-form reflector was obtained by geometric iterative calculation. The Monte Carlo ray tracing method was used to simulate the system. The simulation results met the regulatory requirements of ECE R112, and the light efficiency could reach 81%. The length, width, and height of the reflector were 55.61 m m × 22.02 m m × 23.70 m m . The reflector achieves a special light type through precise light distribution, does not need other shielding objects, and has the advantage of small size.

We introduce a current development in optical design for vehicle forward lighting based on solid-state lighting, in particular, phosphor-converted white LEDs. The vehicles include bicycles, bikes, and automobiles. Although the requirements regulating different vehicles are different, the low beam always requires a high-contrast cutoff line. Three optical design approaches are discussed; these include a projection lens incorporated with a baffle or beam shaper, multisegment reflectors, and complex lenses. A new design approach called light field management technology for the multisegment reflector is introduced. In addition, the possible related manufacturing errors and the robustness of different optical approaches are analyzed. Finally, we introduce three approaches to adaptive forward lighting that provide a driver with brighter and clearer vision without inducing glare to people on the roadway. The application of video projection technology to roadway illumination could be a trend of vehicle forward lighting based on solid-state lighting.

We demonstrate an iterative and inverse design of a segmented reflector used to illuminate the road with a uniform light distribution and reduced glare to the oncoming traffic. Design is set to meet the StVZO standard. The maximum brightness obtained is 1460 candela, which is five times brighter than a conventional headlamp of urban shared electric scooters and bicycles, resulting in improved visibility in dark environments. A prototype was built and tested at various environments. The tolerance analysis showed no negative influence on the desired standard light distribution. In addition to this iterative approach, a ray tracing code has been developed for inverse design and to map a desired uniform road illumination pattern back to the candela sensor for corresponding reflector design.

Leaves have evolved to effectively harvest light, and, in parallel, to balance photosynthetic CO2 assimilation with water losses. At times, leaves must operate under light limiting conditions while at other instances (temporally distant or even within seconds), the same leaves must modulate light capture to avoid photoinhibition and achieve a uniform internal light gradient. The light-harvesting capacity and the photosynthetic performance of a given leaf are both determined by the organization and the properties of its structural elements, with some of these having evolved as adaptations to stressful environments. In this respect, the present review focuses on the optical roles of particular leaf structural elements (the light capture module) while integrating their involvement in other important functional modules. Superficial leaf tissues (epidermis including cuticle) and structures (epidermal appendages such as trichomes) play a crucial role against light interception. The epidermis, together with the cuticle, behaves as a reflector, as a selective UV filter and, in some cases, each epidermal cell acts as a lens focusing light to the interior. Non glandular trichomes reflect a considerable part of the solar radiation and absorb mainly in the UV spectral band. Mesophyll photosynthetic tissues and biominerals are involved in the efficient propagation of light within the mesophyll. Bundle sheath extensions and sclereids transfer light to internal layers of the mesophyll, particularly important in thick and compact leaves or in leaves with a flutter habit. All of the aforementioned structural elements have been typically optimized during evolution for multiple functions, thus offering adaptive advantages in challenging environments. Hence, each particular leaf design incorporates suitable optical traits advantageously and cost-effectively with the other fundamental functions of the leaf.

We propose a design method of asymmetric double freeform surface lens for an integrated LED automobile headlamp and develop an integrated LED automobile optical system. A single asymmetric double freeform surface lens is designed to redistribute rays emitting from the light source for realizing both low and high beams. Moreover, a freeform surface reflector is used to improve the energy efficiency of high beams. The prism placed in the optical path can suppress chromatic dispersion on the edge of the target plane. Simulation and experimental results show that the illumination values and color temperature of the key points can fully meet the requirements of United Nations Economic Commission for Europe vehicle regulations (ECE) R112, 48, and 128. The volume of the whole optical system comprised of freeform surface elements is smaller than that of the low beam system of a traditional headlamp, resulting in saved space, in which other electronic devices can be installed for the safety of the driver, which indicates that the proposed method is practical in the field of automobile lighting.

With the advantage of low etendue and no efficiency droop, phosphor-converted white laser diode (pc-WLD) has been a very promising candidate in future high-luminance solid-state lighting. To obtain high brightness, the blue laser beam is usually collimated or focused onto a yellow phosphor layer, which may result in poor angular color uniformity (ACU). In this study, we observed the blue spot and yellow ring phenomenon of the transmissive pc-WLD, which is attributed to the mismatch between the focused intensity distribution of the blue light and the divergent intensity distribution of the yellow light. Then, we proposed a secondary optics consisting of a parabolic reflector coupled with a freeform lens to enhance the ACU by collimating all the rays emitting from the phosphor, which is located at the focus of the reflector. Through this design, we achieved the match of the intensity distribution of the blue and yellow lights, resulting in a high ACU of 0.85 with a view angle of ±10° by simulation. Moreover, the luminance of the pc-WLD can be enhanced by about four times using this method. Finally, we fabricated a prototype of the designed secondary optics and validated the effectiveness of the proposed method in achieving small-divergent-angle uniform illumination with enhanced luminance of the transmissive pc-WLD.

Livestock rooms with systems for feeding dry feeds with feeder pipelines are characterized by a relatively high concentration of dust. Studies on the shaping of artificial lighting intensity were carried out in an experimental, non-bedding pig fattening house. In order to improve the lighting, the animal room was modernized by lining the ceiling and walls with aluminum foil. It was a reflector screen when light was on, which, however, over time covered with dust coming from the mechanically fed dry feeders. For the assessment of brightness in the production hall, five equally spaced measuring stations were placed in the pens and five similarly spaced stations were set in the corridor. The intensity of lighting (brightness) was measured with the L-20A lux-meter. The measurements were carried out after a six-month use of the liner, when it was significantly contaminated with dry fodder particles. As part of operational tests, the differentiation of brightness between the individual stands and gradual changes in lighting at various stages of aluminum foil cleaning were checked: washing the external wall with detergents, washing all the walls in the room and washing the entire interior, including the ceiling. Before wet cleaning the reflector screens, a significant differentiation of the brightness between the stands in the pens was observed - it ranged from 134.1 Lx to 176.0 Lx, which indicates uneven pollution of the internal surfaces of building partitions. Similarly, significant discrepancies in the lighting intensity were found on the corridor floor. Values ranged between 50.3 Lx and 65.8 Lx. When washing the next partitions, the average illumination values in the pen area dropped unexpectedly, and the final drop after removing the dust from all the walls and ceiling was 2.8%. Similar tendency was observed in the communication-drive corridor. In this area, the brightness decreased by as much as 4.1%. The reason for the decrease in visual comfort was the matting of screens caused by grinding of particles during the washing. Therefore it would be necessary to undertake research on the removal of dust from the reflector screens using another method, for example mechanical dusting.

In this paper, an achromatic LED projection headlamp (ALPH) is proposed for compensating color dispersion on the cut-off line of the light pattern. The ALPH consists of a white light LED, an elliptical reflector, a stop, an achromatic doublet lens (ADL). The ALPH is optimized and designed by computer programs firstly and its prototype is verified in experiments. According to the simulation results, the distance between the cut-off lines of the red light and the blue light is about 5.4 mm at 25 m and much less than that of the conventional LED projection headlamp. The measurements of the spectrometer and the illuminometer show that the ALPH can effectively enhance the consistency of the light pattern of the red and blue light and reduces the color dispersion near the cut-off line simultaneously. Moreover, all test points conform with the ECE R112 regulation except for only one point. By the determination of the integrating sphere, the optical efficiency of the prototype is 59%.

Digital pulse processing methods have various applications in radiation spectroscopy due to their unique properties. Here, the effect of light reflector on the response of a large plastic scintillator with different reflective coverings (Teflon tape, aluminum foil and black tape) coupled to a fast photomultiplier tube is investigated based on some extracted anode pulse features. Results showed that the pulse features were changed according to the reflection coefficient of the covering. For instance, the fall time of the average anode pulse shape for Teflon tape, aluminum foil and black tape coverings are 10.46, 6.88 and 3.65 ns, respectively.

Silver tinted multi-folded reflector sheet was additionally used in the newly designed LED-PBR setup to study the growth performances and resultant lipid production in Chlamydomonas reinhardtii. The experiment was also carried out to compare the algal growth under various LED light qualities with a white fluorescent lamp (FLs). The synergistic effect of the direct and reflected light provided more efficiency and light penetration that improved the cell concentration (77.5 × 106 cells mL−1), specific growth rate (0.514 d−1), total pigments (12.876 ± 0.673 mg L−1) and lipid content (39.4%) of C. reinhardtii under blue illumination than FLs. Interestingly, green light exhibited remarkable changes in lipid content (27.9%) on the 10 d of cultivation than white, red and FLs. Nile red analysis of neutral accumulation and FTIR analysis of fatty acid contents of C. reinhardtii under different light condition significantly varied. This modified RC-PBR setup can be utilized to increase the light intensity in algal culture and thereby minimize energy consumption and culture duration compared to FLs.

A concept of indoor solar illumination is described and simulated. The solar illumination system is composed of a tracking primary reflector, a selective secondary reflector, a visible light guide and a scattering solid glass tube fixture. Each part of the solar illumination system is optically suited and compatible with other parts to realize high efficiency. The simulation is conducted for Baghdad city for a library hall. Two major days over a year are chosen to investigate the illumination system for acceptable visible light level for reading hall. The two days are: summer solstice day and winter solstice day at 8:00 AM and 12:00 PM for each. Research results showed that the design of the solar system is achieved on the base of minimum solar illuminance level at the starting day for office work at 8:00 AM on 21 December. Aluminum coated dish is the preferred comparing with silver coated dish which their solar illuminance for one meter dish diameter are so close for reading hall visible light level. Their values are 538Lux for Aluminum and 589Lux for Silver.

The present work describes the design and development of a dedicated illumination system for application to high-speed digital image correlation. This type of application requires image acquisition to be performed with very short shutter times. This means that there is less time to integrate the incoming light and, as such, it is necessary to have significant light flux to acquire quality images. As such, illumination is usually the major concern in such high-speed imaging applications. The developed system uses a strobing high-power LED light source to tackle this issue, and illuminate the specimen with a large light flux during a very short period. This reduces the amount of heat that the specimen receives from the lighting source and has the advantage of enabling the use of cameras that would otherwise be unable to use such short shutter times effectively. In this paper, the whole design of the device is described. From the control electronics to the mechanical design, including the optical design of an appropriate reflector.

Road infrastructure has witnessed incremental changes in the past as compared to the immense development witnessed by the vehicle’s safety technology. Bott’s dots and other reflector devices are extensively used on the road infrastructure for lane separation and for improving edge detection. These devices come in a large variety of shapes and sizes, however, all of them fall under the category of retroreflectivity since they depend on vehicle lights to provide reflection. Glow-in-the-dark (GiD) material has the benefit that it can store energy during the presence of light and can emit the stored energy in the form of visible light in the absence of an external light source. In this regard, the presented research work details the development and testing of GiD concrete based markers that can be used for lane separation and edge detection. The benefit of the presented innovation is that GiD concrete based markers can be used for visible light instead of retroreflectivity in addition to acting as a driver alertness tool. The durability performance of the presented innovative GiD based raised pavement markers has been presented along with cost comparison to traditional Bott’s dot. In addition, the presented prototype can be adopted for various architectural and esthetical applications in buildings, parks, walkways and bicycle lanes etc.

Soiling effects influence the output of solar thermal plants, significantly causing unwanted transmittance, reflectance, and absorbance losses. Research is needed to identify what type of reflective surfaces are best suited for semitropical climates, such as the southeastern United States. This paper initially presents a review of several concentrating solar power (CSP) reflector testbeds used to analyze the soiling effects of various reflective materials. A soiling testbed is developed for this study that comprised six sets of reflective surfaces mounted at a fixed tilt of 30 degrees: three sets of thin-film surfaces and three sets of glass types. Two generations of 3M solar mirror film (SMF), 3M SMF 1100 and 3M SMF 2020, were used along with Konica Minolta SMF, silvered Corning Willow Glass, a dichroic cold mirror, and a standard mirror. Results show that the 3M SMF 2020 and Konica Minolta SMF performed the best during regular cleaning intervals, whereas the silvered Corning Willow Glass gave the best performance if only cleaned naturally. The other glass types showed the least average loss due to soiling throughout this study but gave the lowest performance for specular reflection.

With the rapid advancement of light-emitting diodes (LEDs), front fog lamps using LEDs have become a main emphasis for vehicle lighting. For vehicle lighting, the front fog lamps should provide a bar-shaped beam of light with a sharp cutoff at the top and are designed to increase the illumination directed toward ground at a sharp angle. In this study, an innovative lens design based on a freeform surface responding to the requirements of the vehicle lighting is proposed. The design of the two-axis asymmetric freeform lens for LED front fog lamp can meet ECE R19 class F3 regulation without any other lens or reflector.

A luminous reflective display can be constructed by placing an electro-optic shutter on the stack of a luminescent layer, a color filter, and a reflector in this order. The luminescent materials convert a part of the incident light to photoluminescence photons. The reflector redirects the downward photon flux toward an observer. The color filters prevent the photons with unwanted wavelengths from being reflected. The upward spectral flux from this multi-layer structure is formulated. Experiments with off-the-shelf components revealed more than three-fold increase in spectral flux and up to 55% color gamut extension, compared with a control device without luminescent materials.

This paper describes a qualitative study on user opinion of daylight supplementation via a horizontal light pipe (HLP) applied in a test office in a building located in southern Norway. The study is part of a full-scale long-term study analysing lighting energy consumption and the photometry of supplemented light. This study employs a custom-made reflector for daylight distribution via HLP to preserve the features of natural light, noted as the primary human association with daylight, and is, as such, first of its kind. The main research aim was to find out if noticeable daylighting provision from the HLP leads to a positive user perception of the space when compared to a situation without a HLP. The study collects user responses to a new illumination solution using a user-survey method based on exposure to the visual environment of an experimental office. Statistical correlation and a t-test were used to analyse the results. The paper concluded that the user appraisal of the office was more positive when there was a noticeable daylight supplement from the HLP in the space, but the appraisal was negative for the higher light variability in the illuminance level both indoors and outdoors. The conclusion serves as an additional argument for the implementation of the HLP in building design, besides its energy saving potential.

The lighting quality of educational buildings needs to be improved caused the most classrooms show that intense light near the windows but insufficient in the interior. The average daily learning time of primary and secondary school students is more than 9 hours, which puts forward higher requirements for lighting, including illumination and daylighting uniformity. In some cases of leading edge, using reflector as shading method can shade and improve the uniformity of lighting. Taking Guangzhou as the breakthrough point, this paper studies the shading and daylighting problems of educational buildings in hot and humid areas. Using grasshopper software to analyze the climate in Guangzhou, optimize the reflective sunshade component, not only improve the lighting quality, but also enhance the ventilation and heat dissipation. Moreover, the optimal evaluation is determined by the illumination analysis of Ecotect software. The research results actively explore the combination of architectural design and energy-saving means, providing a convenient sunshade method for classrooms in Guangzhou, which has reference for high temperature and high humidity areas.

Smart traffic automation is an integral part of smart cities in recent days. Huge amount of energy and power is consumed by the usage of high end computers and electronic devices. An energy optimization technique is proposed in this paper to minimize energy dissipation and power consumption by the existing traffic systems. Green computing concept is implemented in automated traffic system. It is observed that a remarkable amount of energy is dissipated and eventually wasted due to the use of regular electric lights at traffic points. ‘Traffic Reflector’ concept is introduced in place of regular traffic lights. LED lights or incandescent bulbs in the traffic signal posts would be replaced by the reflectors. Sunlight would be focused on these reflectors by properly placed mirrors. Mirrors would be adjusted automatically to change their angles according to sun's position. Light source would be replaced by solar panel driven light in the absence of sunlight at night or other weather conditions. Energy consumption by traffic signal lights at traffic signal points is minimized by our proposed approach.

Visual comfort and energy consumption for lighting in large office buildings is an area of ongoing research, specifically focusing on the development of a daylight control technique (light shelf) combined with solar energy. This study aims to investigate the optimum performance of light shelf photovoltaics (LSPV) to improve daylight distribution and maximize energy savings for the hot desert-like climate of Saudi Arabia. A radiance simulation analysis was conducted in four phases to evaluate: appropriate height, reflector, internal curved light shelf (LS) angle, and the integrated photovoltaic (PV) with various coverages (25%, 50%, 75%, and entirely external LS). The results revealed that the optimum is achieved at a height of 1.3 m, the addition of a 30 cm reflector on the top of a window with an internal LS curved angle of 10&deg, with 100% coverage (LSPV1, LSPV2). Such an arrangement reduces the energy consumption by more than 85%, eliminates uncomfortable glare, and provides uniform daylight except for during the winter season. Hence, the optimization of the LSPV system is considered to be an effective solution for sustainable buildings.

In recent years, the need for comfortable visual environments in indoor spaces has increased energy use in buildings. There have been diverse studies on using a light shelf to solve this problem. It is an effective system that allows external natural light deep into indoor spaces through reflection. However, prior studies have used light shelves with a fixed reflectivity, and there are few studies on improving the visual environment through light shelf control. Therefore, this study proposes a movable light shelf with a rolling reflector that can change the reflectivity. To achieve these objectives, we conducted a performance evaluation of the system&rsquo, s ability to save energy and improve the visual environment. This study built a real scale testbed and conducted a performance evaluation by deriving values for lighting energy consumption, uniformity, and luminance contrast depending on the light shelf variables. We conclude that (1) the light shelf system achieved an energy savings of 13.6% and 5.7%, respectively, compared to a fixed type light shelf, whose reflectivity cannot be changed, and a traditional movable light shelf, (2) in terms of improving the visual environment, results suggest that the visual environment could be improved using a light shelf by deriving light shelf variables that disturb indoor uniformity, and (3) the results verified glare generation conditions by deriving luminance contrast caused by the variables of light shelf angle and its reflectivity.

Accidents often occur at night due to a lack of light. With the low-light conditions, a lot of drivers who use high beam headlight forgot to switch to low beam headlight. That action can cause temporary blindness to the driver in front of him because of the glare. Automatic Headlight can change the mode of lights and reflector lights when passing move uphill or downhill roads using the accelerometer sensor MPU6050. The automatic headlight can also change the mode of light based on the light in front of him using the BH1750 lux meter sensor so that the path illuminated by the headlight to be quite and do not endanger other drivers. Laboratory testing has a success rate of 97%, with 260 trials in 13 conditions. And on real testing, the automatic headlight can switch modes automatically when going uphill and downhill. The headlight can change modes automatically when passing through roads with adequate lighting or when passing other vehicles.

We present a design for a cost-effective low-beam automotive headlamp with a single light-emitting diode (LED) light source. The proposed design consists of a white LED, an elliptical reflector, a parabolic reflector, a toric lens, a filter, and a prism array. The white LED had a luminous flux of 146 lm. Non-sequential rays were used to improve the efficiency and a toric lens was employed to optimize the light pattern on a 25 m screen which appeared as rectangular with a high degree of uniformity. In addition, the filter and the prism array were modified to correct the measured light pattern results to meet the requirements of ECE R112. We set the reflectivity of the elliptical and parabolic reflectors for the compound reflectors to be 95%. The transmittance of each surface of the toric lens is 98%. The total received lumens was 80.62 lm, and the overall efficiency was 55.22%.

This paper is on the implementation of a system that monitors and controls a smart farm using Arduino and DC motors. Light control in traditional smart farms uses artificial light such as LED lights to control brightness. However, this traditional method has high maintenance cost for continuously turning on artificial light. In this paper, we develop a system to control the amount of light inflow using the angle control of the reflector. Also, we monitor environmental information such as temperature, humidity, carbon dioxide(Co2), and light value for the optimum smart farm environment. The temperature is controlled using the ventilator and heater. Also, environmental data can be uploaded to the server in real-time to check the accumulated data on a chart, and we accumulate the optimal reflector angle data for more than one year. Since solar motion repeats every year, we can control the reflector according to this accumulated data. This system has been implemented as a server and mobile application that provides various sensors for environmental control, Arduino, Wemos for Wifi server upload, and a monitoring UI.

Considering the dark matter as self-gravitating Bose-Einstein condensate in a gravito-chemical equilibrium state, we have studied the light trajectory through the halo. Found that depending on the initial direction cosine of the light ray, there are three types of trajectories: (a) the refracted light i.e. light which can refracts away from the halo to the out side, (b) the trapped light i.e. light that is trapped into the halo i.e. an observer, situated outside of the halo, can not observe it and (c) the reflected light: in this case the halo behaves as a perfect reflector to the outside light. The light trapping can introduce asymmetry in the observed spectrum and modify the apparent number of stars in a dark matter dominated galaxy.

The study aimed to evaluate the influence of reflective materials on the cultivation bench and the use of rice husks over the substrate in the formation of Dipteryxalata seedlings. The experiment was carried out in the experimental area of the Mato Grosso do Sul State University, in Cassilândia-MS, from November 1st, 2016 to January 26th, 2017. A completely randomized design in a 5 x 2 factorial scheme was used, with five replications and five plants per plot. Four reflective material for the cultivation bench and treatment without reflective material (control), combined with or without rice husks over the substrate (0.5 cm layer), were evaluated. Laminated paper tray, mirror, reflective fabric (known as “fake sequin fabric”), and aluminum foil were used as reflective materials. The reflecting materials did not differ in the reflectance of photosynthetically active radiation. However, the mirror and the aluminum foil reflected more than the control. The use of rice husk over the substrate did not increase the Dipteryxalata seedlings' quality. The mirror as a reflective material produced Dipteryxalata seedlings of higher quality than the system without material reflector called control. El estudio tuvo como objetivo evaluar la influencia de los materiales reflectantes en el banco de cultivo y el uso de cáscaras de arroz sobre el sustrato en la formación de plántulas de Dipteryx alata. El experimento se llevó a cabo en el área experimental de la Universidade Estatal de Mato Grosso do Sul (UEMS), en Cassilândia-MS, del 1 de noviembre de 2016 al 26 de enero de 2017. Un diseño completamente al azar en una factorial de 5 x 2 esquema fue utilizado, con cinco repeticiones y cinco plantas por parcela. Se evaluaron cuatro materiales reflectantes en el banco de cultivo y tratamiento sin material reflectante (control), combinado con o sin cáscaras de arroz sobre el sustrato (capa de 0,5 cm). Bandeja de papel laminado, un espejo, tela reflectante (conocida como "fake sequin fabric"), y se utilizó una lámina de aluminio como materiales reflectantes. Los materiales reflectantes no diferían en la reflectancia de la radiación fotosintéticamente activa, sin embargo, el espejo y la lámina de aluminio reflejaban más que el control. El uso de cáscara de arroz en el sustrato no aumentó la calidad de las plántulas de Dipteryx alata. El espejo como material reflectante produjo plántulas Dipteryx alata de mayor calidad que el sistema sin material reflector, llamado control. O estudo teve como objetivo avaliar materiais refletores sobre a bancada de cultivo e a proteção do substrato com palha de arroz na formação de mudas de Dipteryx alata. O experimento foi conduzido na área experimental da Universidade Estadual de Mato Grosso do Sul, em Cassilândia, no período de 01 de novembro de 2016 a 26 de janeiro de 2017. Foi utilizado o delineamento inteiramente casualizado em esquema fatorial de 5 x 2, com cinco repetições e cinco plantas por parcela. Quatro materiais reflexivos sobre a bancada e um tratamento sem material reflexivo (controle), combinados com e sem cascas de arroz sobre o substrato (camada de 0,5 cm). Os materiais refletores utilizados foram a bandeja de papel laminado, o espelho, um tecido denominado de “falso paetê” e o papel alumínio. Os materiais refletores não diferiram entre si na reflectância da radiação fotossinteticamente ativa, contudo, o espelho e o papel alumínio refletiu mais que o controle. O uso de casca de arroz sobre o substrato não aumentou a qualidade das mudas de Dipteryx alata. O espelho como material refletor produziu mudas de Dipteryx alata de maior qualidade que o sistema sem refletor material, denominado controle.

This paper presents a design for a high-efficiency, low-beam headlamp with Oliker’s ellipses technology [Computing Lett. 2, 29 (2006)1574-040410.1163/157404006777491981]. In addition to the one-time intrinsic light absorption of reflection, the designed low-beam lampshade can reflect all the light from the LED in the on-demand illumination range. This study proposes and adopts a matrix calculation method to accelerate the calculation speed of constructing an Oliker’s composite ellipsoidal reflector, which in turn increases the ellipsoidal facet number of the compound ellipsoidal reflector. In the design of the low-beam headlamp, the illumination weight on the target plane is defined by the method of curve fitting, which ensures that the light-field pattern of the low-beam headlamp changes smoothly rather than in a patchy distribution. The content of this study itself also provides a design method and example for applying Oliker’s ellipses technology to on-demand spatial lighting.

The FDTD simulation is performed with a system in which the front-surface is a concave lens, the inside of bulk is a zero refractive index medium in which positive and negative refractive index cells are randomly arranged, and a reflector is placed over the back-surface plane. In a zero-index medium, an outgoing wavefront is always parallel to the outgoing-surface, is independent of either the incident wavefront or the shape of the incoming-surface. After waiting for a while after entering pulsed light into this structure, the light reflected from the back-surface is focused at the focal point of the concave lens over the front-surface.

Packaging materials usable for DUV-LEDs are limited as most organic materials are affected by DUV radiation. Packages used are TO-packages or 3D-structured ceramic housings with quartz lid. Due to DUV-LEDs radiating up to 50% of their light to the sides a significant share is lost. This paper describes a hermetic SMD-compatible packaging approach that integrates reflectors into a quartz window to maximize the light extraction. Side emitted and otherwise wasted light is redirected towards the surface. It avoids costly 3D-structured ceramics and improves the overall thermal performance. Design choices of the reflector structures allow to tailor the radiation patterns of the LEDs.

The field of indoor lighting covers a wide range of lighting uses with varying requirements for lighting conditions to be satisfied by properly selected lighting equipment. The need to frequently change the arrangement of useable areas entails the necessity to adapt the lighting to new requirements. A good solution for reducing costs and saving time is a luminaire adjusting the luminous flux and spatial luminous intensity distribution in a wide range. The authors present the concept of an adaptive luminaire and its construction assumptions. In addition, the results of studies on the development of the concept are shown together with conditions and limitations that influenced the construction of the luminaire. The analysis of the surface of the moveable reflector is presented, and the results of testing the luminaire prototype are compared with the results of simulation tests.

Whiteness is one of the most important characteristics of a printing paper. There is a stable relationship between the printed and optical properties of the paper. At the same time, the understanding of whiteness in the papermaking and printing industries is significantly different. Such miscommunication negatively affects the quality of printed products, since the choice of a suitable paper (or cardboard) is difficult to a certain extent. One of the ways to get out of this situation is to create a simple and clear computational model of the white paper, which would not depend on any physical standards. The model would help when conducting the input control in printing plants and would allow one to establish communication between industries. This work is devoted to the description of such a model. © 2020 American Institute of Physics Inc.. All rights reserved.

A reflector-based light-emitting diode (LED) luminaire structure that can achieve a large cut-off angle for general lighting is presented in this work. The proposed lighting unit mainly consists of a spherical reflector and a primary packaging lens that contains an aspheric surface and a spherical surface. The light rays emitted from the LED light source are well controlled by the spherical reflector and the aspheric surface of the lens for the purpose of obtaining a uniform illumination on the target surface. Both the ideal Lambertian LED and non-Lambertian LED light sources were employed to validate the proposed structure and the performance of the designed lighting units was analyzed by optical simulation. The results show that the light utilization efficiencies and the estimated uniformities are 92.96% and 91.11% for ideal Lambertian LED-based lighting unit and 93.31% and 91.64% for non-Lambertian LED-based lighting unit, respectively. Further analysis shows that the tolerances of horizontal, vertical, and rotational deviation of the both lighting units were about 2.0 mm, 1.0 mm, and 1.0°, respectively.

Hundreds of high-quality 25 mm $\times $ 25 mm $\times \,\, 600$ mm Bi4Ge3O12 single crystals were industrially grown by the Bridgman method for the DArk Matter Particle Explorer (DAMPE) project. With respect to the crystals with the best optical quality, the optical transmittance along the longitudinal and transversal directions can achieve 72% and 76% at 480 nm, respectively. Most of the grown crystals satisfied the light output uniformity requirement of the DAMPE calorimeter. For the remaining crystals, the effects of air annealing, reflector materials, and surface treatment on the improvement of light response uniformity were also studied.

Heliostat daylighting systems, used to transmit sunlight deep into rooms where natural light cannot reach, are increasingly applied in buildings. A roof-mounted heliostat with an area of 22.95 m2 was developed in this work to verify the feasibility of high flux and long distance daylighting in large building interior. The developed heliostat system consists of a heliostat, a secondary reflector, and glass windows forming the light path within the building. The problem of gravitational deformation of the steel beams base of the heliostat was solved by a rectification algorithm embedded into the computer program, to realize vertical daylighting. The spectrum and chromaticity of the heliostat daylighting system developed was measured, and the results verify the good visual quality of the interior illumination. The light transmission distance is more than 70 m, and the system can provide a level of 20–80 klux daylighting illuminance in the daytime. An economic analysis was carried out, and data indicates a good cost-effectiveness of the heliostat daylighting system developed. It is hoped that this research will be of some reference value to the design of heliostat daylighting systems in large buildings.

This paper presents optimisation of rear Si texturing by KOH-based solution for enhanced light-trapping in liquid-phase crystallised Si thin-film solar cells on glass. Texturing with 3 µm Si removal exhibits the largest absorption enhancement (compared with 1 and 2 µm Si removal) due to the enhanced light scattering by the rear pyramidal features. In the solar cells with SiOx/SiNx/SiOx buffer layer (with anti-reflection effect), the Jsc is found to increase from 20.4 (planar reference) to 22.6 mA/cm2 (10.8% enhancement) with the optimised rear Si texturing. The Voc and pFF are not degraded. After incorporating white paint back surface reflector and front anti-reflection foil to the rear-textured solar cells, Jsc up to 25.4 mA/cm2 (24.5% relative enhancement) is achieved.

Windshield-type vehicle head-up displays (HUDs) are increasingly popular and stepping forward augmented reality; however, the windshield causes an annoying problem-ghost images. By now, the maximal extent of ghost images has not been determined for an HUD with an acceptable legibility. In this paper, to find the quantitative criterion of ghost images regarding subjective perceptions, we first design an HUD using a rotatable aspheric reflector and a wedge-glass windshield. Optical design of the HUD and experimental results of high-quality images are discussed. Next, eight different disparity angles between the primary and ghost images are controllably generated by rotating the aspheric reflector. Based on this HUD platform, human factor experiments utilizing a simulative automotive driving environment are conducted, in which the eight disparity angles are provided to 12 subjects under three ambient contrast ratios (ACRs). The human factor experiments demonstrate that the maximal disparity angles for an acceptable legibility under the ACRs of 3.90, 2.49, and 1.80 are 0.006°, 0.017°, and 0.024°, respectively. These maximal acceptable disparity angles are important references for quantitatively and efficiently evaluating the optomechanical system of an HUD. In addition, they can help to make vehicle laws and regulations for HUDs.

Objectives: Recently in the gaming industry, multiple games for different consoles and machines are being introduced and their sole focus is to bring the player closer to its avatar. Methods/Statistical Analysis: In the past, such avatar was achieved through the motion detection cameras such as Kinect by Microsoft and the introduction of virtual reality in games. Even with all these, the games are still not well connected with the players because the player do not feel the outcomes of the game in a way that if player’s character gets hurt, simultaneously the player should also physically experience the action. Findings: This research is based upon the use of Kinect as an input device which will detect the player and record its movements in the game developed through Unity 3D. The game developed is based upon boxing. There are two characters controlled by two players and the concept is that when a player’s character gets punched, the player also gets a feel through vibration motors attached to the player’s suit. Application/Improvements: This virtual gaming suit will ensure that a gaming player must be the part of the game and will feel the action and sensation of the game in real time. Keywords: Arduino; Boxing; Gaming Suit, Microsoft Kinect, Unity 3D

A busca por ambientes construídos com melhor climatização para o usuário é um interesse crescente na construção civil, além de garantir um ambiente com estanqueidade, sem infiltrações e poder proporcionar ambientes com temperaturas mais amenas. Neste sentido, o objetivo deste trabalho foi avaliar se a utilização de manta impermeabilizante de PVC melhora o conforto térmico em edificações. Os ensaios foram realizados em laboratório e em campo, avaliando a variação de temperatura nas faces opostas de telhas com e sem revestimento em manta impermeabilizante de PVC. Em laboratório as temperaturas superficiais foram avaliadas sob a incidência de luz de um refletor. Em campo, fez-se a medição sobre incidência direta do sol. Os resultados permitiram concluir que a manta não atua somente como impermeabilizante, mas como refletor da radiação solar, proporcionando uma diferença entre a temperatura externa e interna na telha de até 20°C. O uso de mantas impermeabilizantes de PVC para a melhora térmica em edificações é efetivo, acarretando reflexão de parte da radiação solar incidente sobre a superfície de cobertura da edificação, dificultando a passagem de calor para a área interna.

The performance of the amorphous silicon a-Si:H pin diode with respect to the wavelength, the incident direction, and the absorption of the light has been studied. Three types of LED lights, i.e., red, green, and blue, were used as the incident lights. The aluminum film was deposited above or below of the ITO electrode as the light reflector. The diode was exposed to the illumination light through the p+ or n+ layer. The external quantum efficiency was used as the reference to discuss the device performance.

The establishment of an uniform color space mostly based on the reflector, and few researchers have been tried the establishment of the monitor uniform color space. To make sure a better color reproduction on the monitor,and ensure an accurate color transformation among monitors. It is necessary for us to establish an uniform monitor color space. In this paper, We used the Munsell color chips under the condition of C light. then processed the Munsell color chips on the monitor in the Lab color space. Finally, a set of uniform color data based on monitor is acquired called Lab-m3.