The spotlight development on the solid-state laser light source is considered in this scientific article. The light sources characteristics are as close as possible to the characteristics and parameters of modern LED light sources. The main aim is to reach the luminous flux value of 3000 lm. That is analogues with the luminous flux of modern LED searchlights. As well as the photometric and electrical parameters, values and determination of the measures to improve the design of the spotlight are of the interest.
The spotlight sample has been tested. And the test results show that after the value of 3000 lm reached the main failing of light source is the low value of its luminous efficacy, equal to 57 lm/W. In order to increase the light output of the searchlight, there are the ways of modernization of its construction suggested in the article. The previous results show that the measures suggested will allow us to increase the value of luminous efficacy to 100 lm/W. Besides that, such parameters and characteristics of the spotlight as the correlated colour temperature (CCT), colour rendering index (CRI), wattage, luminous intensity and spectral light distribution are measured and submitted in the article.
The obtained energetic characteristics of the sample allow us to conclude that application of such light sources is approved in special conditions. Absence of electronic components in the distant radiation source of white light allows increasing the light source reliability substantially. Therefore, the laser spotlights are acceptable for application in the hard-to-reach places for installation of the lighting equipment, for example, on high places where the equipment demount used for repairing works is too difficult. It is actually to use also the developed light sources at the explosive industrial facilities having the current-transmitting elements of construction, especially having the open contacts. That allows reducing the safety of facility operation significantly.

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11. Prytkov, S.V., Kapitonov, S.S., Kolyadin, M.V. Generalization and Research of the Keitz Equation Inaccuracy when Radiation Flux of Linear Low Pressure UV Lamps is Measuring // Light & Engineering, 2022, Vol. 30, # 1, pp. 12–23.

The high-intensity discharge (HID) lamp, mainly the high-pressure sodium vapor lamp and the MH lamp are the most common lamps used in public lighting purposes in Indian context, despite of the fact that uses of light emitting diodes are becoming common nowadays. The aim of this paper is to study the harmonic content in these high-power lighting networks. These light sources have been chosen because of their high power and another component, known as the igniter, which is connected to the circuit and whose effect can be studied. The study presented in this paper is completely based on measurements, including the harmonic analysis. Different combinations of ballasts and lamps have been chosen to perform the experiment. The main results show that high-pressure sodium vapour (SON) lamps have a much higher harmonic content in the lamp voltage and supply current waveforms as compared to the metal halide (MH) lamps. Results also indicate that lamp voltage harmonic contains significant amount of higher order harmonics, and its waveform is much distorted than the supply current or the ballast waveform. Furthermore, the percent of total harmonic distortion (THD) content is higher. These results will guide the future designer to select a light source from the point of view of the harmonic content in the lamp voltage, ballast voltage, and the supply current.

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The device for quality analysis of solar cells with different sensitive surface areas using radiation from a non-mechanical planar system is described. Current solutions for quality analysis of solar cells have disadvantages: work with analogy data, large dimensions of mechanical focusing system, interaction with small areas active zone of solar cells without possibility of identifying point pattern efficiency. Accordingly, a method is proposed for measuring the efficiency of solar cells at the production stage and during the operational period, which makes it possible to identify places of its insensitivity with the possibility of obtaining quantitative data on efficiency for the purpose of their mathematical processing. The developed photo scanning control device can be suitable for solar cells diagnostics with a sensitive zone area from 9 mm2 to A5 sheet size. The method makes it possible to measure local photocurrent and to find places of solar cell shunting.
Process of diagnostics is controlled by one personal computer, which performs functions of controlling illumination of a monitor, setting diagnostic modes, obtaining data on the efficiency of the solar cells, storing and processing them. The device can be based on a laptop and is considered as mobile. Special software is used to manage, visualize and process the output data in a form of a rectangular matrix. An experiment was carried out on artificial darkening of the working areas of solar cells of different sensitivity. This confirmed effect of data changes and a visual display of obscuring zone on the output results. Tests were carried out on solar cells based on polycrystalline silicon. The results showed a high level of visibility and repeatability of the darkened area, and the quality of the data obtained made it possible to identify a small measurement error associated with external “noise”.

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The digital world and energy world will form deeply integrated development in future under the trend of low carbonization, electrification, digitalization and intelligence. China’s energy industry enters into the new era of digital energy. To discuss development characteristics of China’s photovoltaic industry, influencing factors of China’s photovoltaic industrial development were analysed by using the multiple linear regression (MLR) method based on data about China’s photovoltaic industry from 2013 to 2022. Results show that, except for the installed power generation capacity, conversion efficiency of photovoltaic enterprises, investment amount to photovoltaic industry, employment quantity of photovoltaic industry, solar module output and photovoltaic power generation capacity – all have positive effects on photovoltaic industrial output. Specifically, conversion efficiency of photovoltaic enterprises and investment amount to photovoltaic industry are the most critical influencing factors with a coefficient of 1062.32 and 225.51, respectively. On this basis, some development countermeasures were proposed for China’s photovoltaic industrial development from perspectives of policies, technologies and talents. Research conclusions provide some references to China’s photovoltaic industrial development in the digital economic era.

1. Naizhu, P., Yongheng, Z., Yintao, M. China’s policy analysis and perfection strategy of photovoltaic industry // Science and Technology Management Research, 2016, Vol. 36, # 7, pp. 150–153.
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8. Qi, Z., Ningbin, W., Xiaojie, C. Research on investment estimation model of photovoltaic energy project in the background of “carbon neutrality”: Investment analysis based on SMX distributed photovoltaic project // China’s Collective Economy, 2023, Vol. 742, # 14, pp. 24–27.
9. Chao, W., Huizhi, T., Zihao, Z. Household photovoltaic business and risk control from the perspective of lease finance company: A case study based on H lease finance company // Green Finance and Accounting, 2023, Vol. 429, # 3, pp. 43–46.
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The article describes the most important component of gemstones: their colour. The subject of the article is determination of the colour of diamonds with the most frequently encountered yellow tones of different saturation, fancy-colour diamonds as well as emeralds, rubies, and sapphires. For non-ambiguous determination of the colour of gemstones and elimination of human factor, the comparison method known in photometry, i.e., comparison of the colour of a given diamond with the colour of a reference sample is used. The article describes methods of determination of the colour of yellow-hue diamonds when assessing them visually, using reference colours: a set of diamonds. Information on colour groups of diamonds of different cuts used in Russia and the system of Gemological Institute of America (GIA) is provided.
Fancy colours of diamonds are very variable and, therefore, they have no references such as the ones for yellow-hue diamonds. For evaluation of fancy colours, the Munsell Book of Colour is used. It includes 1600 colour samples on 40 maps each having its own colour hue. The samples are arranged in rows and columns: samples of the same row have the same brightness; samples of the same column have the same saturation. As the samples for determination of fancy colours of diamonds as well as emeralds, rubies, and sapphires plastic plates of different colours are used. The colours of the examined gems are compared to them. The article describes the methods of assessment of fancy colours of diamonds adopted in Russia.
Nowadays, a software colour evaluation system is proposed by GIA to be used as an alternative to colour samples. Gemewizard software proposed by Izrael may identify 31 main colour tones. It reproduces each tone in six colour hues. Each hue is divided by six brightness levels. In general, this system allows us to determine 1116 colours of gemstones. The software approach had been already proposed previously but computer screens have different colour rendering, which is still the main hindrance for determination of gem colour by means of software.

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The aspects of measurement and presentation of radiation parameters of germicidal lamps, including radiant flux within the set spectral range, are under consideration. Radiant flux is currently used as their main parameter. There are the following methods of measurement of this parameter: indirect, by means of irradiance from the lamps, goniometric, and the integrating sphere method. The goal of the work was to compare the results of measurement of germicidal lamps using different methods and to analyse the practice of presentation of germicidal lamp parameters. TUV, HNS, LTC, DB, DKB and DKBU germicidal lamps and irradiators with different power capacity and peak radiation in the mercury line 253.7 nm were selected as the measurement objects and such parameters as radiant flux, germicidal flux, and radiant flux stabilisation time were selected as assessed parameters. The measurements were made and the values of radiant flux and germicidal flux, using the indirect and goniometric methods, were obtained. The graphs of radiant flux stabilisation of different lamps are presented. The analysis of the measurements demonstrated necessity of modification of the approaches to measurement and presentation of the germicidal lamp parameters.

1. Kovalenko, O. Yu., Pilshchikova, Yu.A., Guseva, E.D. Increasing Efficiency and Monitoring of Parameters of Radiation Sources of Agricultural Irradiating Installations [Povysheniye effektivnosti i kontrol’ parametrov istochnikov izlucheniya obluchatel’nykh ustanovok v sel’skom khozyaystve] // Fotonika, 2017, Vol. 8 (68), pp. 68–73.
2. Kovalenko, O. Yu., Kozyreva, V.V. On Possibility of Application of Prospective Radiation Sources in Lighting and Irradiating Installations [O vozmozhnosti primeneniya perspektivnykh istochnikov izlucheniya v osvetitel’nykh i obluchatel’nykh ustanovkakh] // Vestnik FGOU VPO MGAU, 2008, Vol. 4 (29), pp. 9–13.
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Interests are vastly growing on optical wireless communication (OWC) technology in recent times. This technology is mostly used where fibber-optic or wired communication technology cannot be used. However, the main constraints of this OWC technology are the attenuation of the laser power due to different atmospheric effects. This paper investigates the effects on the 1550 nm laser link in the various simulated atmospheric conditions, such as rain, fog, and heat in terms of signal to noise ratio (SNR), bit error rate (BER), optical power attenuation with the help of some pre-established models etc. For analysing the previously mentioned parameters in different simulated atmospheric conditions, a 10 MHz, NRZ-OOK, OWC communication channel has been established using fibber coupled acousto-optic modulator (FCAOM), and all the parameters are measured for 18 m link range. The peculiarity of this article is that the calculations and results have been made with keeping in mind the Indian atmospheric conditions. Indian weather report data has been used to do so.

1. Jabeena, L.S.A., Jayabarathi, T., Aggarwal, R. Review on optimization of wireless optical communication system // Trends Opto-Electro Optical Communication, 2019, Vol. 4, pp. 9–19.
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This article discusses the issues of modelling the human centric lighting environment using computer graphics methods. Modern computer graphics programs allow for the calculation of spatial-angular distribution of luminance, a fundamental characteristic that shapes the visual perception of a scene. Richard Kelly, the founder of lighting design, states in his works that the main aspect of the comfortable visual luminous environment creating is the distribution of luminance in space. Analysing the spatial-angular distribution of luminance allows for a new stage in the evolution of assessing the quality of lighting in a simulated or real environment.
By solving the task of forming a set of photometric parameters for human centric lighting (HCL) within this research, the possibility of designing a lighting installation for a specified lighting quality using computer graphics methods is demonstrated.
The term human centric lighting refers to lighting that considers both the visual and non-visual effects of light on humans, starting from the visual representation of the environment and visual comfort, and extending to the impact on sleep quality, wakefulness, mood, and human behaviour.
This article presents a lighting quality criterion based on spatial-angular distribution of luminance and a developed psychophysical scale, which together allow for the assessment of lighting quality using computer graphics methods.

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Design an urban public landscape lighting control system based on DMX512 protocol to improve the lighting effect of urban public landscapes. The system uses the upper computer urban public landscape scene transformation software to edit the colour change data of urban public landscape lamps, set a reasonable number of sub-controllers according to the actual needs of urban public landscape scenes, and store relevant data in the SD card of the data storage layer. The Ethernet transmits the data in the SD card to the lighting control module, the main controller transmits the data in the SD card to the sub-controller, and the ARM of the sub-controller decodes the urban public landscape scene data, and uses the fireworks algorithm-fuzzy adaptive PID. The control algorithm solves the control data of urban public landscape lighting lamps, and the data that meets the DMX512 protocol is edited by FPGA and transmitted to the DMX512 controller. Through the DMX512 controller, the control data of urban public landscape lighting lamps is transmitted to the equipment module realize the control of LED lamps for urban public landscape lighting. The experimental results show that the response speed of the system is fast, at 0.60s it can quickly reach the illuminance value of the park landscape lighting LED light 7.5 lx set in the experiment, and its control ability is strong. At the same time, the system has high software and hardware compatibility and system stability. Better, in multiple operating systems, there will be no problems such as flashback, blue screen, crash, etc., ensuring the safe operation of the PC and improving the effect of park landscape lighting control.

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In this paper, an automatic, fault-adaptive, and dimmable LED driver circuit and LED lamp module is designed and simulated. The designed LED driver can automatically operate and dim (18–72) W LED modules assembled with unknown series-parallel combination of 3 W LED chips on universal AC input (Vrms=(90–265) V, 50/60 Hz). The unique feature of the modelled LED driver circuit is its ability to monitor and detect failure of any connected LED chip and then adapt to provide optimised light output from the LED modules under faulty conditions. The proposed LED driver circuit and LED lamp module are simulated in MATLAB Simulink environment to evaluate the electrical performance. The operation of the simulated LED driver circuit from 100 % to 30 % of rated light output and during occurrence of fault is satisfactory and in compliance with IEC61000–3–2:2014 and IEEE Standard P1789. Input power factor of the simulated LED driver ranges from 0.74 to 0.99, THD from 3.33 % to 30.63 %, and output current ripple from 4.6 % to 20 % under operation of all connected LED modules.

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Modern light sources (light emitting diodes, organic light emitting diodes) have considerable flexibility in creating a wide range of colours and brightness of lighting devices and monitors in which they are used. Evaluation of the homogeneity of the chromaticity of radiation is carried out using the colour thresholds obtained in the McAdam experiment and named after their shape McAdam ellipses. This experiment was carried out under the same observation conditions. Their application in practice is limited and requires research in a wide range of observation conditions. To date, in colorimetry, there is a colour perception model CIECAM02, which is approved by the CIE (International Commission on Illumination). This model allows you to recalculate the chromaticity coordinates for observation conditions that are different from the initial conditions. In this work, a model of the CIECAM02 algorithm is implemented and a study is made of the transformation of McAdam ellipses under changing observation conditions. The result of the study demonstrates the change in the position of the ellipses on the CIE 1931 colour chart, as well as their shape. The data obtained allow us to speak about the relevance of further research on the perception of white colour radiation in a wide range of chromaticity and brightness in order to improve the algorithms of the colour perception model.

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1. Agafonov, D.R., Sapritsky, V.I., Stolyarevskaya, R.I., Tolstykh, G.N. Working standard of luminous intensity based on LEDs [Rabochiy etalon sily sveta na osnove svetodiodov] // Svetotekhnika, 2000, # 3, pp. 9–12.
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Metal halide (MH) lamps comes under the category of high intensity discharge (HID) lamps, which involves high intensity thermal plasma discharge phenomenon. In this paper we have considered ceramic MH lamps. The plasma discharge in MH lamps is different from other plasma discharge by the velocity of all the discharge obeys Maxwellian distribution, the excited energy states are occupied by Boltzmann distribution, and composition of the plasma can be derived from local chemical equilibrium. This paper explores the temperature distribution and the immediate effects towards the life of MH lamp.
The temperature profile for the MH lamp is numerically investigated using WELSIM 2.0, considering the lamp plasma model mathematical equations. Since electrode plays a significant role, influencing MH lamp life, it becomes imperative to understand the electrodes. In this context, the energy balance equation is taken into consideration. The equations are solved using finite element method. The necessary boundary condition for solution of the equation is the plasma boundary layer for the cathode heat conduction. The analysis provides the temperature distribution inside the lamp for different electrode geometry. The solutions to the equations have been pictorially investigated for the lamp starting phenomena and E/N ratio. For HID lamps in general, the improvements in HID technology are all linked to the performance of the arc tube, and within that tube, the chemical reaction, the pressure, and the temperature of the reaction. Another feature in the case of MH lamps that is worth mentioning in the determination of lamp life is the ratio between electric field to gas number density.
From the above, we can draw the following conclusion that the radiation transport mechanism of the HID lamps plays a pivotal role apart from other parameters influencing the lifetime of HID lamps. The paper envisages all these aspects using PDEs, the solutions of which provide an insightful understanding of the phenomena substantially.

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Tatyana V. Smirnova (Meshkova), George V. Boos, Vladimir P. Budak, and Ekaterina A. Ilyina
Evaluation of Lighting Quality Based On Visibility мVladimir P. Budak and Ruzana A. Delyan
Changing MacAdam Ellipses with Adaptation

Shibabrata Mukherjee, Sujoy Paul, and Saswati Mazumdar
Experimental Studies and Analysis of 1550 nm Laser as Optical Wireless Communication Link in Simulated Rainy, Foggy, and Heating Conditions According to Indian Atmosphere

Pallavi Malik and Kalpna Sharma
Analysis of the Plasma Discharge Phenomena for Ceramic Metal Halide Lamps Using Finite Element Method

Vishwanath Gupta, Biswarup Basak, and Biswanath Roy
Design and Performance Evaluation of an Automatic Dimmable Fault-Adaptive LED Driver Circuit

Suddhasatwa Chakraborty, Gaurav Chakraborty, Aiswarya Dev Goswami, and Jyotipriya Roy
Study of the Harmonic Analysis of the High-Intensity Discharge Lamps

Tatyana V. Smirnova (Meshkova), George V. Boos, Vladimir P. Budak, and Ekaterina A. Ilyina
Evaluation of Lighting Quality Based On Visibility мVladimir P. Budak and Ruzana A. Delyan
Changing MacAdam Ellipses with Adaptation

Shibabrata Mukherjee, Sujoy Paul, and Saswati Mazumdar
Experimental Studies and Analysis of 1550 nm Laser as Optical Wireless Communication Link in Simulated Rainy, Foggy, and Heating Conditions According to Indian Atmosphere

Pallavi Malik and Kalpna Sharma
Analysis of the Plasma Discharge Phenomena for Ceramic Metal Halide Lamps Using Finite Element Method

Vishwanath Gupta, Biswarup Basak, and Biswanath Roy
Design and Performance Evaluation of an Automatic Dimmable Fault-Adaptive LED Driver Circuit

Suddhasatwa Chakraborty, Gaurav Chakraborty, Aiswarya Dev Goswami, and Jyotipriya Roy
Study of the Harmonic Analysis of the High-Intensity Discharge Lamps