scholarly journals Quantitative express estimation of humine and fulvo acids content in aqueous solutions by photo-stimulated luminescence

2018 ◽  
Keyword(s):  
Quantum Yield ◽  
Dynamic Range ◽  
Light Flux ◽  
Low Noise ◽  
Light Sources ◽  
Colloidal Systems ◽  
Colloidal Solutions ◽  
Measuring Device ◽  
Light Emitting ◽  
Quantum Yield Of Luminescence

The work substantiates the expediency of using the methods of recording the quantum yield of luminescence of humic and folic compounds in the process of determining the relative concentrations of these substances in aqueous and colloidal solutions. The efficiency of using modern high-power ultraviolet semiconductor light sources with high monochromaticity of light flux has been proved, followed by the registration of reviews of the samples under investigation with the help of a low-noise semiconductor photodetector with a connected operational amplifier, which allows to provide a wide dynamic range of current and voltage measurements. The subject of the study is the process of recording the quantitative and qualitative parameters of the se- lected chemical compounds in colloidal systems in the liquid phase developed in the course of research by the model of the measuring instrument. The novelty of the work is to improve the classical methods for recording the quantum yield of lumines- cence, using a modern element base and testing the model of a measuring device with powerful ultraviolet light-emitting diodes as a light source and low-noise photodetector with a clear dynamic range designed for recording the quantum yield of luminescence of the samples under investigation.

scholarly journals Elimination of the blinding effect in landscape luminaires

2018 ◽  
Vol 7 (2.13) ◽  
pp. 252
Author(s):  
Albert Ashryatov ◽  
Dinara Churakova
Keyword(s):  
Light Curve ◽  
Light Source ◽  
Light Flux ◽  
Light Distribution ◽  
Light Sources ◽  
Mirror Surface ◽  
Light Emitting ◽  
Lighting Technology ◽  
Initial Task ◽  
Flat Beam

The article presents one of the possible options for implementing the lighting technology "Flat beam" for landscape lighting purposes. One of the possible ways to control the light distribution of a number of light sources based on LEDs with different radiation patterns is considered. As a secondary optics, it is proposed to use a mirror surface that redistributes the light flux of an LED light source. It is indicated that, depending on the initial type of the light-emitting diodes light curve and the features of mounting the mirror surface, the resulting light distribution can vary widely, depending on the initial task that the designer sets for himself.  

scholarly journals Development of portable device for measurement of dynamic and static light-emission WOLED characteristics

2021 ◽  
Vol 1 (1(57)) ◽  
pp. 30-33
Author(s):  
Ihor Helzhynsky ◽  
Stepan Kutsiy ◽  
Andriy Veryha ◽  
Khrystyna Ivaniuk ◽  
Taras Dudok
Keyword(s):  
Light Source ◽  
Data Exchange ◽  
Light Emission ◽  
Spectral Characteristics ◽  
Light Flux ◽  
Luminous Flux ◽  
Visible Range ◽  
Light Sources ◽  
Measuring Device ◽  
Routine Work

The research object of this work is the parameters of organic light-emitting diodes, namely power and luminous flux. Determination of these parameters can be carried out using a photodiode and requires measuring the dark current of the sensor (photodiode), measuring the current of the photodiode when illuminated by the LED under investigation. And also take into account the relationship between the light flux received by the sensor and its output current, and take into account the spectral characteristics of the sensor. Calculate the investigated parameters of the LED based on the measurements. Carrying out these measurements requires laboratory instruments and workplace organization, and further calculations are routine work. It is possible to increase the measurement accuracy by improving the existing methods for measuring the required parameters, and it is possible to automate the process of measurements and calculations using a modern microprocessor radioelement base. Microcontrollers are widespread such radioelements. They have the necessary peripherals for independent operation and have sufficient computing power to implement the required measuring device. Its application makes it possible to automate the measurement process, carry out the necessary calculations, save correction constants, accumulate and process the obtained data, analyze these received data, exchange data with a computer, etc. So, the work is aimed at developing a methodology that will allow the simultaneous measurement of power and luminous flux of planar light sources. And also on the feasibility of this technique in the device and software with the ability to measure the power of the light source in an arbitrary band of the spectral visible range. Thus, it is possible to determine what power in watts a light source emits with the dynamics of supply currents in the optical bands, knowing the spectrum of this source without using glass filters. So, the result of applying the technique is to determine the power of light radiation (in watts) or the luminous flux (in lumens) of the emitter (light sources).

scholarly journals Photometer for Measuring the Characteristics of the Light Source with Directed Light Radiation

2018 ◽  
pp. 27-32
Author(s):  
P. Neyezhmakov ◽  
E. Tymofeiev ◽  
О. Lyashenko
Keyword(s):  
Real Time ◽  
Near Field ◽  
Light Flux ◽  
Temperature Fluctuations ◽  
Light Distribution ◽  
Light Sources ◽  
Light Emitting ◽  
Temperature Changes ◽  
Total Light ◽  
Photometric Characteristic

The accuracy of the measurement of the main photometric characteristic of the emitter determines the error for determining the total light flux of the light sources, especially light emitting diodes, for which it should not exceed 5 per cent. Existing measurement methods with the use of integrated spheres, goniophotometers and goniophotometers of the near field require a great deal of time and have a great deal of value. To eliminate these shortcomings, a method for measuring the characteristics of light sources with directed light distribution is proposed based on the use of a set of meters located in a plane perpendicular to the main direction of the source radiation propagation. On the basis of this method, a photometer for measuring the characteristics of the directional light sources is developed, which allows to quickly, in real time, determine the characteristics of the emitters. The method of determining the parameters of light distribution of directed sources of light for the construction of its photometric body is not required to use a rotary means. Taking into account the significant influence of temperature fluctuations on the characteristics of LED light sources, it is possible will upgrade the proposed method for determining the photometric body of the radiation source in real time and when the temperature changes due to the introduction of additional elements in the future.

scholarly journals Lifetime Prediction method of LED Light-emitting Device Based on Approximate Analysis

2021 ◽  
Vol 271 ◽  
pp. 01031
Author(s):  
Cai Wenting ◽  
Li Sheng ◽  
Meng Qinghui ◽  
Huang Haisong
Keyword(s):  
Approximate Method ◽  
Light Source ◽  
High Efficiency ◽  
Light Flux ◽  
Prediction Method ◽  
Light Sources ◽  
Light Emitting ◽  
Led Light ◽  
Long Life ◽  
Application Requirements

Compared with other light sources, LED light source has a longer service life and will not suddenly fail. Due to its high efficiency, energy saving and long life, LED has become the most popular light source at present. However, it is no longer considered to meet the application requirements, and the time that the light flux decays to this level is considered to be the life of the LED. This paper introduces the approximate method used to predict the lumen maintenance life of LED lamps. The experimental results obtained by the approximate method are compared with the TM-21 standard. Eventually, it is concluded that the approximate method provides more reliability information than the original TM-21 standard, and the obtained results are more reference, more accurate and more reliable.

Organic Light Emitting Diodes - Innovative Light Sources

2019 ◽  
pp. 101-107
Author(s):  
Sergei A. Stakharny
Keyword(s):  
Light Source ◽  
Organic Light Emitting Diodes ◽  
Organic Leds ◽  
Light Sources ◽  
High Quality ◽  
Light Emitting ◽  
Organic Light ◽  
Lighting Systems ◽  
Physical Principles ◽  
Prospects Of Application

This article is a review of the new light source – organic LEDs having prospects of application in general and special lighting systems. The article describes physical principles of operation of organic LEDs, their advantages and principal differences from conventional non-organic LEDs and other light sources. Also the article devoted to contemporary achievements and prospects of development of this field in the spheres of both general and museum lighting as well as other spheres where properties of organic LEDs as high-quality light sources may be extremely useful.

Superior Stable and High Quantum Yield Phosphor Na2BaSr(PO4)2: Eu2+ for Plant Growth LEDs

2021 ◽  
Author(s):  
Jinmeng Xiang ◽  
Xiaoqi Zhao ◽  
Hao Suo ◽  
Minkun Jin ◽  
Xue Zhou ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Plant Growth ◽  
Light Emitting Diodes ◽  
Light Environment ◽  
High Quantum Yield ◽  
Light Emitting ◽  
Growth Rhythm ◽  
High Quantum ◽  
Violet Light ◽  
Important Means

Controlling the light environment of plant growth using phosphor-converted light-emitting diodes (pc-LEDs) is an important means to regulate the growth rhythm and enhance the yield, in which bluish violet light...

scholarly journals Red Light-Emitting Diodes with All-Inorganic CsPbI3/TOPO Composite Nanowires Color Conversion Films

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Lung-Chien Chen ◽  
Yi-Tsung Chang ◽  
Ching-Ho Tien ◽  
Yu-Chun Yeh ◽  
Zong-Liang Tseng ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diode ◽  
Red Light ◽  
Trioctylphosphine Oxide ◽  
Optical And Electrical Properties ◽  
Colloidal Solutions ◽  
High Quality ◽  
Light Emitting ◽  
Hot Injection ◽  
Color Conversion

AbstractThis work presents a method for obtaining a color-converted red light source through a combination of a blue GaN light-emitting diode and a red fluorescent color conversion film of a perovskite CsPbI3/TOPO composite. High-quality CsPbI3 quantum dots (QDs) were prepared using the hot-injection method. The colloidal QD solutions were mixed with different ratios of trioctylphosphine oxide (TOPO) to form nanowires. The color conversion films prepared by the mixed ultraviolet resin and colloidal solutions were coated on blue LEDs. The optical and electrical properties of the devices were measured and analyzed at an injection current of 50 mA; it was observed that the strongest red light intensity was 93.1 cd/m2 and the external quantum efficiency was 5.7% at a wavelength of approximately 708 nm when CsPbI3/TOPO was 1:0.35.

Room temperature synthesis of Sn2+ doped highly luminescent CsPbBr3 quantum dots for high CRI white light-emitting diodes

Nanoscale ◽  
2021 ◽  
Author(s):  
Dongdong Yan ◽  
Qionghua Mo ◽  
Shuangyi Zhao ◽  
Wensi Cai ◽  
Zhigang Zang
Keyword(s):  
Quantum Dots ◽  
Quantum Yield ◽  
White Light ◽  
Room Temperature ◽  
Temperature Synthesis ◽  
Light Emitting ◽  
Photoluminescence Quantum Yield ◽  
Hot Injection ◽  
White Light Emitting Diodes ◽  
Cspbbr3 Quantum Dots

With a high photoluminescence quantum yield (PLQY) being able to exceed 90% for those prepared by hot injection method, CsPbBr3 quantum dots (QDs) have attracted intensive attentions for white light-emitting...

scholarly journals Application of Light-Emitting Diodes for Improving the Nutritional Quality and Bioactive Compound Levels of Some Crops and Medicinal Plants

Molecules ◽  
2021 ◽  
Vol 26 (5) ◽  
pp. 1477
Author(s):  
Woo-Suk Jung ◽  
Ill-Min Chung ◽  
Myeong Ha Hwang ◽  
Seung-Hyun Kim ◽  
Chang Yeon Yu ◽  
...  
Keyword(s):  
Plant Growth ◽  
In Vitro Culture ◽  
Light Emitting Diodes ◽  
Photosynthetic Pigment ◽  
Antioxidant Properties ◽  
Light Sources ◽  
Light Emitting ◽  
Cell Defense ◽  
Led Irradiation

Light is a key factor that affects phytochemical synthesis and accumulation in plants. Due to limitations of the environment or cultivated land, there is an urgent need to develop indoor cultivation systems to obtain higher yields with increased phytochemical concentrations using convenient light sources. Light-emitting diodes (LEDs) have several advantages, including consumption of lesser power, longer half-life, higher efficacy, and wider variation in the spectral wavelength than traditional light sources; therefore, these devices are preferred for in vitro culture and indoor plant growth. Moreover, LED irradiation of seedlings enhances plant biomass, nutrient and secondary metabolite levels, and antioxidant properties. Specifically, red and blue LED irradiation exerts strong effects on photosynthesis, stomatal functioning, phototropism, photomorphogenesis, and photosynthetic pigment levels. Additionally, ex vitro plantlet development and acclimatization can be enhanced by regulating the spectral properties of LEDs. Applying an appropriate LED spectral wavelength significantly increases antioxidant enzyme activity in plants, thereby enhancing the cell defense system and providing protection from oxidative damage. Since different plant species respond differently to lighting in the cultivation environment, it is necessary to evaluate specific wavebands before large-scale LED application for controlled in vitro plant growth. This review focuses on the most recent advances and applications of LEDs for in vitro culture organogenesis. The mechanisms underlying the production of different phytochemicals, including phenolics, flavonoids, carotenoids, anthocyanins, and antioxidant enzymes, have also been discussed.

scholarly journals Air stable and highly efficient Bi3+-doped Cs2SnCl6 for blue light-emitting diodes

RSC Advances ◽  
2021 ◽  
Vol 11 (42) ◽  
pp. 26415-26420
Author(s):  
Yue Yao ◽  
Si-Wei Zhang ◽  
Zijian Liu ◽  
Chun-Yun Wang ◽  
Ping Liu ◽  
...  
Keyword(s):  
Quantum Yield ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Color Coordinates ◽  
Blue Led ◽  
Highly Efficient ◽  
Photoluminescence Quantum Yield ◽  
Long Life

A Bi3+-doped Cs2SnCl6 exhibits photoluminescence at around 456 nm and a photoluminescence quantum yield of 31%. The blue LED based on the Bi3+-doped Cs2SnCl6 phosphor exhibits a long life of 120 hours and a CIE color coordinates of (0.14, 0.11).

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