Different Types Of Light Sources Research Articles

Evaluation of the degree of influence of different types of light source on the level of the output signal of the light sensor when its work on the reflected signal

The article considers the requirements for the characteristics of light sensors when they are used as part of an automatic control system for LED lamps, including options for their spatial arrangement in relation to the working surface. The results of experimental studies of the degree of influence of the type of light source on the output signal of the light sensor during its operation on the reflected signal are presented. A technique is described that allows minimizing the influence of the type of light source on the output signal of the light sensor when it operates on the signal reflected from the working surface. An example of the practical use of this technique as part of an existing automatic control system is given.

Endocrine effects of exposure to artificial light at night: A review and synthesis of knowledge gaps

Animals have evolved with natural patterns of light and darkness, such that light serves as an important zeitgeber, allowing adaptive synchronization of behavior and physiology to external conditions. Exposure to artificial light at night (ALAN) interferes with this process, resulting in dysregulation of endocrine systems. In this review, we evaluate the endocrine effects of ALAN exposure in birds and reptiles, identify major knowledge gaps, and highlight areas for future research. There is strong evidence for ecologically relevant levels of ALAN acting as an environmental endocrine disruptor. However, most studies focus on the pineal hormone melatonin, corticosterone release via the hypothalamus-pituitary-adrenal axis, or regulation of reproductive hormones via the hypothalamus-pituitary-gonadal axis, leaving effects on other endocrine systems largely unknown. We call for more research spanning a diversity of hormonal systems and levels of endocrine regulation (e.g. circulating hormone levels, receptor numbers, strength of negative feedback), and investigating involvement of molecular mechanisms, such as clock genes, in hormonal responses. In addition, longer-term studies are needed to elucidate potentially distinct effects arising from chronic exposure. Other important areas for future research effort include investigating intraspecific and interspecific variability in sensitivity to light exposure, further distinguishing between distinct effects of different types of light sources, and assessing impacts of ALAN exposure early in life, when endocrine systems remain sensitive to developmental programming. The effects of ALAN on endocrine systems are likely to have a plethora of downstream effects, with implications for individual fitness, population persistence, and community dynamics, especially within urban and suburban environments.

Attraction of Insects to Ornamental Lighting Used on Cultural Heritage Buildings: A Case Study in an Urban Area.

Artificial light at night (ALAN) reduces insect populations by altering their movements, foraging, reproduction, and predation. Although ALAN is mainly associated with streetlights and road networks, the ornamental illumination of monuments is making an increasing (but not well-studied) contribution. We compared insect attraction to two different types of light sources: a metal halide lamp (a type currently used to illuminate monuments) and an environmentally sound prototype lamp (CromaLux) comprising a combination of green and amber LEDs. The experiment was performed within the pilot CromaLux project in Santiago de Compostela (NW Spain). The abundance and diversity of the insects captured between June and October 2021 in the areas surrounding both light sources and in an unlit area were compared. By limiting the light emitted to amber and green, the CromaLux lamps reduced the number and diversity of insects, morphospecies, and orders attracted to the light, with similar numbers captured as in the unilluminated area, while a greater diversity of insects was captured beside the metal halide lamp. This effect has been demonstrated for almost all insect orders trapped, especially in Diptera, Lepidoptera, Coleoptera, Hemiptera, and Hymenoptera. On the contrary, Psocoptera showed a similar attraction to the CromaLux and metal halide lamps, a phenomenon whose causes deserve further investigation. As expected, Diptera were the most diverse and abundant insects in all samples, but the abundance of Lepidoptera was unexpectedly low (4%), which is in line with the worldwide evidence of the progressive decline of populations of this group. The study findings provide evidence that selecting specific wavelengths for ornamental lighting reduces the attraction of insects while maintaining adequate illumination of monuments for aesthetic purposes, resulting in a lower environmental impact on nocturnal insects. This study provides reference data for developing principles of good practices leading to possible regulatory and legal solutions and the incorporation of specific measures for artificial lighting of monuments and urban structures.

A Reliable Method of Measuring the Conversion Degrees of Methacrylate Dental Resins.

The main aim of the study was to implement the most reliable method of measuring the degrees of conversion during photopolymerization of dental fillings. Contrary to the methods used so far, the method is based only on comparison with the monomer absorbance spectrum without reference bands. Another aim of the study was to prepare a comparative analysis of the polymerization kinetics of dental resins under various light sources and different environmental conditions (irradiance, light dose, temperature), with estimation of the degrees of conversion (DC) of the resins being the main metric. HRi Universal Enamel (UE2) and HRi Universal Dentine (UD2) were examined under two different types of light sources used in dentistry, LED and halogen. DC was measured by Fourier transform infrared spectroscopy (FTIR) in transmission mode from 5 s up to 7 days. Spectra were recorded from the parallel optical layers of samples that were placed between the KBr crystals. The results are expressed by the changes in the absorbance spectrum during the polymerization and the calculated conversion rates. The results of each experiment were averaged from three separate measurements of three samples, during which the samples were illuminated under identical conditions. The data were analyzed by performing ANOVA test comparisons between sample groups at the significance level α = 0.05. The degree of conversion of the UD2 resin was higher than that of UE2 for each experimental condition, but there was no statistically significant difference between the DC of those materials (p > 0.05). There was statistically significant difference (p < 0.01) in the DC caused by LED and halogen light sources producing the same light doses (38 J/cm2). This was the result of different features of light transmission to the filler in the resin composite. The efficacy of the LED source is twice as high as that of the halogen light source. Maximal DC without any other differences in conditions, such as resin type or light source, reached around 70% for temperatures of 22–37 °C. For 37 °C, this took 24 h, which is a contrast to the 7 days it took for 23 °C. The influences of different conditions and factors on reaction kinetics are only strong in the early and the rapid stage of conversion. The optimal time of irradiance using either light source is 20 s for a monolayer, and its thickness should not exceed 2 mm.

Skin chromophore mapping by smartphone RGB camera under spectral band and spectral line illumination.

.Significance: Multispectral imaging enables mapping of chromophore content changes in skin neoplasms, which helps to diagnose a pathology. Different types of light sources can be used for the imaging. Design of laser-based illuminators is more complicated and, consequently, they are more expensive than LED-based illuminators. On the other hand, spectral line illumination has the advantage of less complicated calculations, since only the discrete maximum wavelengths need to be considered. Spectral band and spectral line approaches for multispectral skin diagnostics have not been compared so far. This can help to evaluate the accuracy and effectiveness of both approaches.Aim: To compare two specific illumination modalities—spectral band and spectral line illumination—from the point of performance for mapping of in vivo skin chromophores.Approach: Three spectral images of the same skin malformations were captured by a smartphone RGB camera with two different add-on illuminators comprising LED emitters and laser emitters, respectively. Five types of benign skin neoplasms were included in our study. Concentrations of skin melanin, oxy- and deoxy-hemoglobin at image pixel groups were calculated using the Beer–Lambert law.Results: Skin chromophore maps and statistical analysis of mean concentrations’ changes in the neoplasms compared to the surrounding skin are presented and discussed. The data of the laser emitters led to significantly higher ( times) increase of the oxy-hemoglobin values in vascular neoplasms and much lower deoxy-hemoglobin values, if compared to the data obtained by the LED emitters.Conclusions: Analysis of the obtained chromophore distribution maps and concentration variations in neoplasms led to conclusion that the spectral line illumination approach is more appropriate for this application. Considering only the peak wavelengths of illumination spectral bands leads to essentially different results if compared to those obtained by spectral line illumination and may cause misinterpretations in the clinical assessment of skin neoplasms.

Display illumination with modulated directional backlight

AbstractIllumination is essential for modern life as colorful world is perceived by human visionary system. Display technology has been developing rapidly in recent decades, and the basic principle is related to the way that the image is illuminated and light is emanated. Traditional illumination is provided by different types of light sources, and the display image is visible in large viewing space until the emanating light decays to zero. This work proposes and demonstrates a novel illumination scheme for a display in which the displaying images are visible only in specific spatial regions. The directional backlight ensures the image propagating to specific direction while imaging visibility can be controlled to terminate abruptly at certain distance from the display screen while exerting no influence to nearby regions. The working principle for such an illumination scheme is the use of the modulated coherent directional backlight through an axicon lens. It is shown that the illumination scheme can robustly deliver carried image information to the designated viewing region. This new illumination scheme has many advantages over conventional illumination, including its usage for personal display, very lower energy consumption, as well as minimizing light hazard pollution.

Measures to Improve the Energy Efficiency of Street Lighting Systems in the Kharkiv City

High-quality street lighting improves visual perception of the road and provides for a significant decrease in the number of road accidents. It has been established that the total number of accidents can be reduced by 30% for national roads and by 45% for especially hazard areas (e.g., at intersections). Doubling of the average luminance of the road surface significantly reduces the number of accidents in the dark and twilight. Sufficient street lighting contributes to: reducing electricity consumption; decreasing operating costs; improving the environmental situation; promoting business, tourism and investment activity; decreasing the number of criminal offenses. The analysis of recent research and publications helped choose the best European practices which can be used to improve the outdoor lighting in Ukraine. The street lighting network is continuously growing and being modernized. Different types of light sources are being used in the network to illuminate the city. Today, high-pressure lamps (HPS) are leading. They are increasingly replaced by LED light sources. Not a small share is accounted for by metal-halide lamps. The smallest number of light sources in the street lighting system, high-pressure mercury and compact fluorescent lamps (CFLs). To increase the efficiency of the street lighting system and reduce energy consumption for its operation, measures for its reconstruction and modernization are required. For this purpose, it is necessary to address the following problems: high level of obsolescence and physical wear and tear of system elements; inefficient use and high losses of electricity at the stages of transportation and consumption, due to the use of obsolete and worn-out equipment; suboptimal distribution of the utility capacity, which leads to ineffective use of the existing lighting system; low efficiency of the street lighting control system, due to the lack of electric meters and remote monitoring and control of the street lighting. Introduction of energy-saving types of light sources is one of the ways to modernize the existing street lighting system. It is necessary to replace old lighting fixtures, which have already exhausted their life span, by new energy-saving light sources (replace CFLs by LEDs), use automatic control systems. All this in turn will help reduce energy costs by 60%. To improve energy efficiency of the street lighting system, it is also recommended to carryout the replacement of electromagnetic ballasts by electronic ones. The employment of electronic ballasts, e.g., in case of using HPS 250 lamps, allows to save approximately 255 kWh/year. Considering that the price per kW of electric energy is UAH 2.68, one luminaire helps save the amount of UAH 683.4 per year.

Software Library For The Lighting Fixtures Optical characteristics Calculation By The Computer-aided design System Kompas 3D

The advantages and disadvantages of existing solutions for calculating lighting fixtures (LF) are discussed in the paper. The methods for solving the global illumination problem are demonstrated. The most important illumination models used to calculate LFs have been analyzed. The Torrance-Sparrow model is used as the primary model of reflective surface. The triangulation method based on approximation of the LF surface by a grid of triangles is used to increase the efficiency of LF design and computation. The optical ray propagation in a 3D optical system was modelled using classical laws of optics and the Monte Carlo method. The structure and the main steps of working with the library for CAD Kompas are described. The approximation of LF surface for different types of light sources and reflector parameters is presented. The implementation of approximations with subsequent ray tracing has demonstrated a good convergence of the problem solution. The results of the study have the potential to be useful for design engineers involved in the design and calculation of LFs, as well as developers of applied software in the field of computer graphics and computer-aided design systems.

Smart control methodology for light sources based on halogen lamp – a solution for eco- and user- friendly lighting in underground mining

Illuminance management of halogen lamp (HL) affects energy consumption and lighting effect. A smart control methodology of illuminance for light sources based on HL was described in this study. Based on the illuminance analysis model and experimental works, the relationship between power, illuminance and depth of light sources, i.e. single HL and combined HLs is obtained. The illuminance uniformity of different types of light source was calculated. The influence mechanism of interval distance between two HL modules (DBM) on illuminance uniformity was revealed. The energy conversion efficiency of single HL and combined HLs was discussed. By comparing the model measured results and the manual measured results, the measurement accuracy of the illuminance analysis model was analyzed. The results show that the image-based depth measuring method works well under the HL condition. For single HL, the farther away from the illuminance center, the lower the illuminance. It is found that there is a good correlation between power and illuminance, which verifies the feasibility of accurately changing HL’s illuminance by adjusting power. With the increase of DBM, the illuminance uniformity of HL increased at first and then decreased. The illuminance uniformity of HL at DBM 0.6 m is the highest, which is 66.1%. The illuminance measurement method is suitable for HL condition, which leads to the relative error between the model measured results and the manual measured results. The illuminance control of HL can be further realized based on high-precious illuminance measurement. Smart control of HL is not only conducive to providing appropriate illuminance for humans or machines in underground mining, but also can promote the balance between energy consumption and natural resources.

Low cost high intensity LED illumination device for high uniformity solar testing

Indoor testing of solar thermal absorbers requires an artificial light source with controlled emitted power and uniform illumination over the targeted sample. There are several devices described in literature which adopt different types of light sources and geometrical configurations, but they do not attain high uniformity, high power density, illumination of a large area and compactness simultaneously. The proposed solar simulator is composed of four identical high-power white LED arrays of 30 mm diameter each, placed on a supporting and cooling structure having a minimum volume of 26 cm × 26 cm × 8 cm. A numerical model has been developed, based on a ray tracing software, in order to define the optimal architecture. It has then been experimentally validated with measurements of the power density map, carried out with a 1% uncertainty pyranometer. Data shows that the built system is very stable over time and provides an illumination uniformity higher than 98% on a surface of 11 cm × 11 cm, which reduces to 95% on a surface of 15 cm × 15 cm. The power density can be adjusted within the 390–1360 W m−2 range without affecting uniformity, and the system is easily scalable to illuminate larger surfaces. It represents a suitable solution for various laboratory purposes requiring stable, uniform and high intensity illumination.

Features of Wall-Mounted Luminaires with Different Types of Light Sources

Features of Wall-Mounted Luminaires with Different Types of Light Sources

Performance of Scanning X-ray Back-Scattered Laue Diffraction Microscope with Different Types of Light Sources

Performance of Scanning X-ray Back-Scattered Laue Diffraction Microscope with Different Types of Light Sources

Experimental evaluation of the impact of the light source on the measurement of short-term average crosstalk in homogeneous single-mode multi-core fibers.

This work compares the random time-varying crosstalk in homogeneous multi-core fibers measured using different types of light sources with linewidths ranging from 100 Hz to 2.5 MHz. We show that the frequency stability of the light source plays a significant role on the quality of short-term average crosstalk measurements with no observable impact from laser linewidth. We also compare the use of filtered amplified spontaneous emission noise and coherent light sources for crosstalk measurements. The former are shown to enable average crosstalk measurements in short time periods. In contrast, measurements using coherent light sources require long measurement periods to reach similar results.

Performance Modeling of Ultraviolet Atmospheric Scattering of Different Light Sources Based on Monte Carlo Method

Since the atmosphere has a strong scattering effect on ultraviolet light, the transmission of non-line-of-sight (NLOS) signals can be realized in the atmosphere. In previous articles, ultraviolet (UV) light atmospheric scattering has been characterized by many scattering models based on spot light sources with uniformly distributed light intensity. In order to explore the role of light sources in atmospheric transmission, this work proposed a UV light atmospheric transport model under different types of light source, including light-emitting diode (LED), laser, and ordinary light sources, based on the Monte Carlo point probability method. The simulation of the light source in the proposed model is a departure from the use of a light source with uniform intensity distribution in previous articles. The atmospheric transmission efficiency of different light sources was calculated and compared with the data of existing models. The simulation results showed that the type of light source can significantly change the shape of the received signal and the received energy density. The Monte Carlo (MC) point probability method dramatically reduced the calculation time and the number of photons. The transmission characteristics of different ultraviolet light sources in the atmosphere provide a theoretical foundation for the design of ultraviolet detection and near-ultraviolet signal communication in the future.

Considerações sobre manchas de foxing em três colecções de papel dos séculos XVI a XX

Three surveys on the occurrence of foxing stains were carried out on papers dating from 1560 to 1975 in three Portuguese collections. Foxed papers were found to be more intensely and intrusively stained in certain time periods of each collection. Based on historical data and on the professional paper conservation experience, the authors linked the increased occurrence of foxing stains in certain time periods to the new papermaking processes and materials, which began to be introduced in the late 18th century, and in particular to a synergistic effect between three factors: the use of deficient gelatine sizing which began to present a poorer quality and homogeneity, the presence of iron-containing impurities throughout the paper leaf and a distinct sorbency of moisture. Observing batches of morphologically similar papers by using photographic imaging with different types of light sources and incidences, the authors verified that similar papers present similar foxing stains.

Obtaining high quality potato seed material on aerohydroponic installations

The results of the study on the production of potato minitubers by aeroponic and aero-hydroponic methods, which are non-substrate methods of growing plants, are presented. In order to develop technologies for growing virus-free potato seed material in closed systems, experiments on growing potato minitubers in multiuse aeroponic systems were conducted. Early-ripening potato varieties Rosara, Antonina and Yubilyar, mid-ripening Solnechny variety, and S-112 and Ch hybrids were used as the tested potato varieties. The plant growing cycle was divided into three phases: adaptation, growth, and tuberization. For each phase, different cultivation parameters were used. As a light source, highpressure sodium lamps DNaT 400 were used. The quantitative yield of potato minitubers per one plant on this type of systems was as follows: Antonina variety – 15.3 pcs., Yubilyar variety – 23 pcs., Hybrid Ch – 28.1 pcs., Hybrid S-112 – 30.2 pcs., Solnechny variety – 30.3 pcs., Rosara variety – 43.9 pcs. The effect of various light sources on the quantitative yield of potato minitubers of Nevsky and Yubilyar varieties was studied for this type of systems. Cultivation of potatoes in these systems was carried out according to the technology described, but using two different types of light sources. In the control variant, high-pressure sodium lamps DNaT 400 were used, in the experimental variant, LED lamps produced by CoB (full spectrum) technology with a passive cooling system were used. The use of LED lighting on Nevsky variety led to a statistically signifi cant increase in the quantitative yield of potato minitubers from one plant compared to the control, by 20.88%. The prospects of using Fagro aero-hydroponic systems for adaptation of potato microplants and for obtaining potato minitubers of Rosara and Solnechny varieties were shown. The quantitative yield of potato minitubers per plant on this type of installations was 46.9 pcs. for Rosara variety, and 56.7 pcs. for Solnechny.

Evaluation of dermoscopic criteria for seborrheic keratosis on non‐polarized versus polarized dermoscopy

The two dermoscopic methods, polarized dermoscopy (PD) and non-polarized dermoscopy (NPD), use different types of light sources. Here, we aimed to explore the differences between these two methods in the diagnosis of seborrheic keratosis (SK). The images of 121 cases of SK taken by a digital camera equipped with NPD and PD were evaluated against 14 dermoscopic criteria of SK. The agreement levels between NPD and PD were fair to perfect against the dermoscopic criteria of SK. Perfect agreement was observed in fingerprint-like structures (κ=0.812) and linear irregular vessels (κ=0.807). Substantial agreement was determined in comedo-like openings (κ=0.640), hairpin vessels (κ=0.609), a moth-eaten border (κ=0.642), sharp demarcation (κ=0.637), network-like structures (κ=0.662), and a mica-like pattern (κ=0.639). Moderate agreement was found in milia-like cysts (κ=0.550), fissures and ridges (κ=0.554), dotted vessels (κ=0.496), and color variability (κ=0.438). Fair agreement was obtained only in comma vessels (κ=0.340). Based on our results, we cannot recommend an absolute dermoscopic method for the diagnosis of SK; rather, we suggest that the methods are complementary.

Ứng dụng đèn led trong vi nhân giống cây gừng (Zingiber officinale Rosc.)

Currently, fluorescent lamps are often used as lighting systems in the tissue culture. These lamps consumed a lot of power. Recently, the use of LED lamp systems for planting was being noticed because LEDs were more conducive to tissue culture and less power consumption. In this study, the effects of mineral content, sugar concentration and monochromatic light on ginger’s growth were investigated. The results showed that ginger plant cultured in SH medium (Schenk and Hildebrandt, 1972) had higher height and diameter than in other media. The experiment using different sugar concentration, explants get the best growth when they were cultured in medium supplemented with 30 g/l sucrose. The next experiment, explants were placed in different types of light sources including, red LED, blue LED, or combination of red with blue light in 9: 1; 8: 2; 7: 3; 6: 4; 5: 5 ratios, fluorescent lamps, red fluorescent lamps, blue fluorescent lamps. The results showed that the red LED was suitable for the growth of ginger. The plant height (4.55 cm), leaf area (2.66 mm2) and root diameter (3.83 mm) was significantly higher than that of the other treatments. In the nursery, plants under cultivation of red LED were good growth and a survival plantlet ratio obtained over 96%.

Study on Influence of Lighting in the Detection System of Inner Wall

This paper introduces a method for detecting the inner wall image of small-diameter workpiece based on composite reflector. Theoretical analysis of annular light source used in the system is conducted. The optical system is modeled and simulated based on TracePro. The influence of different types of light source on visual detection is analyzed by changing the condition and parameters.

Examinations of the methods used to power supply of different light sources and their effect on bioelectrical brain activity

ObjectiveThe article represents the preliminary study, with the aim of the experiment being to examine whether different types of light sources used commonly in building interiors combined with various color temperature have an effect on EEG activity. The effect of frequency pulsation and color temperature on brain activity in EEG examinations in the beta 2 band was assumed. Material/participantsTwenty healthy men aged 19–25 years participated in the experiment. MethodsThe research stand was lit by: LED diodes with color temperatures of 3000K, 4200K, 6500K, with the power supplied using the pulse width modulation (PWM) method with the current frequency of 122Hz, linear fluorescent tubes (3000K, 6500K), with the power supplied with the frequency of 50Hz and 52kHz from the electromagnetic and electronic ballasts, and the conventional light bulb, with the power supplied directly from the mains electricity, used as a reference light. System Flex 30 apparatus with TrueScan software was used to record the EEG signal. The examination used two factors (speed and accuracy) of the Kraepelin's work curve to describe changes in work performance for various types of lighting. ResultsThe results demonstrate that the use of different types of emission of light and color temperature of the light have an effect on bioelectrical brain activity and work performance. ConclusionsThe highest activity of brain waves concerns the beta band in the frequency range of 21–22Hz, regardless of the type of the light source (LED, fluorescent tube). The methods used to supply power and color temperature of fluorescent tubes do not significantly affect bioelectrical brain activity during “work”, but previous lighting with fluorescent tubes during work has an essential effect on bioelectrical brain activity during rest. Regardless of the color temperature, LED lighting with PWM power supply leads to the highest bioelectrical activity (mainly in the range of 21–22Hz) in the brain during work and rest, which might suggests the usefulness of this method of supplying power for everyday work. Incandescent light does not affect the bioelectrical brain activity during work and rest.