This paper presents the results of studying four samples of phosphor for white LED manufacture, including the results of spectrum analysis of the phosphors and colorimetric analysis data for light emission values of LEDs containing these phosphors. The paper also presents the results of analyzing colorimetric and brightness characteristics of phosphor-coated LED compound 1 .

Five types of phosphors for LED ribbon beam elements in white LED lamps have been studied. The phosphor composition and colorimetric parameters have been researched during the experiment. It is found that the larger and more uniform the grains of the phosphor, the higher the emission efficiency. The most similar in color to the white color coordinates of the sample No. 5 phosphor having also higher brightness compared with samples No. 1 – No. 4.

Modern light sources, such as LEDs, make it possible to create highly efficient lighting devices with a high color rendering index (at least 85), and a luminous efficiency of up to 250 lm/W. Insufficient lighting can cause visual discomfort. A long stay in conditions of visual discomfort and tension leads to a lack of concentration, visual and general fatigue. The main challenge facing lighting manufacturers is to minimize color differences between individual lighting fixtures or between production batches. In this work, it was necessary to evaluate the spatial distribution of the spectrocolorimetric characteristics of LED lamps in MacAdam steps. To do this, at the beginning, such concepts as a comfortable light environment, correlated color temperature and MacAdam ellipses were considered. Further, it was necessary to measure 10 samples of the LED emitting element. The measurements were carried out using such instruments as a goniophotometer and a spectrocolorimeter. As a result, the main colorimetric characteristics, such as color coordinates, were obtained. Based on the chromaticity coordinates, the color deviation in MacAdam steps was calculated for each sample. Also, a regression analysis was carried out and an approximating expression for the chromaticity coordinates was obtained. On the basis of the approximating expression for the chromaticity coordinates, the average color deviation in MacAdam steps was calculated. The value made up 5 steps. The deviation for the values –40 and 40 was also calculated. In order to reduce the color deviation (reduce the number of McAdam steps), it is necessary to make changes in the technological process of manufacturing the phosphor composition. For example, to reduce the thickness of the phosphor coating or reduce the concentration of phosphor. The results of these studies can be used by the developers of LED lamps based on LED emitting elements in order to improve the uniformity of the spatial distribution of color.

Modern LED light sources make it possible to create the necessary values of photosynthetic irradiance both for growing seedlings and for growing vegetable crops in greenhouse conditions. It is LED light sources that in the near future will replace sodium lamps, which are used in most greenhouses, The area of these greenhouses in the Russian Federation is more than three thousand hectares, with electricity consumption for lighting one hectare of the greenhouse being at least 1 MW per hour. The paper presents the results of experimental studies of the photonic characteristics of LED lamps. Lighting characteristics of LED lamps were measured; light values were recalculated into energy values in accordance with GOST R 58461-2019. Research tests of LED lamps were carried under normal climatic conditions for 10,000 hours, with an intermediate test running time of 5,000 hours. It was found that the arithmetic mean value of photosynthetic irradiance decreased by 1.9 times. In the process of operation, a spectral component in the blue region of the optical spectrum grows from 0.35 to 0.6 relative units, while the spectral component in the yellow-red region of the optical spectrum decreases with time of operation. The decrease in photosynthetic irradiance is caused with the degradation of the phosphor composition over time. The results of these studies can be used by developers of LED light sources in order to improve the preservation of photonic characteristics over time, and in particular, to improve the phosphor composition that provides photosynthetic irradiation of the light source over time.