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In the paper is described the concept and architecture of the multi-channel control system for set of high-power LEDs. The broadband source of radiation for prototype illuminator is dedicated to the investigation of Low Level Laser Therapy procedures. The general scheme of the system, detailed schemes, control algorithm and its implementation description in FPGA structure is presented. The temperature conditions and the opportunity to work with a microcomputer are characterized. MOTIVATION TO INVESTIGATIONTo irradiation in vitro cell lines and in vivo human organs in procedures of Low Level Laser Therapy (LLLT) are used almost exclusively semiconductor radiation sources emitting in the spectral range 600-1000nm -laser diodes and LEDs [1] -and HILT systems (High Intensity Laser Therapy). HILT produces relatively high energy/power pulse with pulse duration of about 100-200 µs and wavelength 1064 nm. Individual sources are used or their matrixes. The radiation power emitted by the individual emitter is from several mW to 500 mW, whereby the total optical power of the system is usually not higher than 2 W. Constant power density of the radiation does not exceed 100 mW/cm 2 on the surface of the object. Exposure takes place in order to stimulate tissue for positive reaction and eventually induce therapeutic effect [2][3][4]. This effect is related to the absorption of low-energy (low-power) radiation that initiates the processes in the tissue at the cellular and molecular level [5-10] without damage and without significant thermal effect (increase of body temperature is less than 1 K). The narrow spectrum of radiation allows selective excitation of specific chemical tissue substances to stimulate certain chemical processes. The cellular response is dependent on the wavelength of the radiation, the surface power density and surface energy density, exposure time and agenda, as well as the tissues type and the functional state of cells [11][12][13][14][15]. These factors determine what changes are induced in irradiated tissues.In available publications in the field of LLLT many authors show positive effects of laser radiation in variety of different diseases, some investigators found no positive effects of laser stimulation or observed negative results [16]. Lack of clear guidelines on the methodology and dosing of laser treatments may be the cause of the absence of positive therapeutic effects -delivered energy dose may be too low or too high, radiation parameters of the source selected for the treatment ineffective. Investigators state that mechanisms of interaction of laser light with the tissue, which had been not fully understood yet, do not allow to consider in reliable and irrefutable manner that biostimulation is an effective therapeutic instrument [16]. However, the vast number of reports about unambiguous therapeutic effects obligates to undertake research into their explanation and settlement the selection of procedure parameters. Without scientific verification of LLLT influence on lived cell lines and clinic...

In the paper the authors present the developed optoelectronic system for controlled, repetitive exposure by electromagnetic radiation of biological structures in the Low Level Laser (LED) Therapy procedures. The set allows for objective selection and control of the irradiation parameters by light from spectral range of the tissues transmission window. Measurements of optical parameters of thin biological medium -spectral absorption coefficient and the amount of absorbed energy -can be implemented in the measuring chamber during irradiation treatment. The radiation source is the broadband illuminator consists of set of selected high power LEDs. The maximum optical power of single source is from 80 mW to 800 mW. Illuminator is controlled and powered by the multi-channel prototype control system, which allows independently control a current of each emitter. This control allows shaping spectral emission characteristic of broadband source in range 600-1000 nm. Illuminator allows providing in the working area of 700 cm 2 a uniform distribution of optical power density, of 10 mW/cm 2 for maximum. Set ensure uniform distribution of the spectral power density of up to 40 mW/nm.

This article describes the differences in how people and plants perceive light. This is important in some artificial light applications. In particular, it concerns the horticulture area, in which LED lighting is increasingly used. There is a misunderstanding of the specifics of the environment in this area. As a result, even experienced lighting professionals design greenhouse lamps in the same way as for people. This article describes the negative consequences of this approach. Full Text: PDF ReferencesA. R. Young, J. Claveau, and A.B. Rossi, Ultraviolet radiation and the skin: Photobiology and sunscreen photoprotection, Jurnal of the American Academy of Dermatology, vol. 76, p. 100-109, Mar. 2017. CrossRef S. Pashiardis, S.A. Kalogirou, and A. Pelengaris, Characteristics of Photosynthetic Active Radiation (PAR) Through Statistical Analysis at Larnaca, SM Journal of Biometrics & Biostatistics, p. 1-16, Jun. 2017. CrossRef W. Bommel, Interior Lighting: Visual Mechanism. Springer Nature Switzerland AG., p. 3-23, 2019. CrossRef L.T. Sharpe, A. Jagla, and W. Jägle, A luminous efficiency function, V*(λ), for daylight adaptation, Journal of Vision, vol. 5, no. 11, p. 948-968, Apr. 2012. CrossRef I. Fryc, and E. Czech, Application of optical fibers and CCD array for measurement of luminance distribution, Proceedings of SPIE, vol. 5064, p. 18-21, Apr. 2003. CrossRef I. Fryc, Design issue of novel type of an illuminance meter photometric head, Jurnal of Modern Optics, vol. 56, no. 33, p. 1504-1508, Jul. 2009. CrossRef I. Fryc, and P. Tabaka, The influence of different photometric observers on luxmeter accuracy for LEDs and FLs lamps measurements, Optica Applicata, vol. 49(2), p. 345-354, Jul. 2019. CrossRef M. Liu, Y. Yan, Q. Xue, and L. Gong, The research and analysis of factors affecting Critical Flicker Frequency, 6th Int. Conference on Applied Human Factors and Ergonomics, Las Vegas, 2015. CrossRef W. Wojtkowski, SEPIC converter for high power LED lighting, Przeglad Elektrotechniczny, vol. 86, no. 10, p. 260-263, 2010. DirectLink W. Wojtkowski, Step-up converters for power LED power supply, Przeglad Elektrotechniczny, vol. 87, no. 4, p. 71-72, 2011. DirectLink Y. Berkovich, and all, LED crop illumination inside space greenhouses, in Reach, vol. 6, Elsevier, p. 11-24, 2017. CrossRef C.M. Campillo, R. Fortes and M.H. Prieto, Solar Radiation Effect on Crop Production, Mar. 2012 CrossRef I. Ashdown, Photometry and Photosynthesis: From Photometry to PPFD., Nov. 2015 DirectLink K.J. McCree, The Action Spectrum, Abasorptance and Quantum Yield of Photosynthesis in Crop Plants, Agricultural Meteorology, vol. 9, 191-216, Oct. 1970. CrossRef OSRAM Opto Semiconductors, Horticulture Lighting with LEDs, Nov. 2016 CrossRef Standard DIN 5031-10 Optical radiation physics and illuminating engineering. CrossRef EconoLux Indastries Ltd., What Light do Plants Need, Hong Kong, 2016. CrossRef M.B. Ali, L. Khandaker, and S. Oba, Comparative study on functional components, antioxidant activity and color parameters of selected leafy vegetables as affected by photoperiods, J Food Agric Environ, vol. 7, p. 392-398, 2009. CrossRef A. Szmidt-Jaworska, K. Jaworski, A. Tretyn, and J. Kopcewicz, The involvement of cyclic GMP in the photoperiodic flower induction of Pharbitis nil, Jurnal of Plant Physiology, vol. 161, p. 277-284, 2004. CrossRef A. Szmidt-Jaworska, K. Jaworski, and J. Kopcewicz, The Involvement of Cyclic ADPR in Photoperiodic Flower Induction of Pharbitis nil, Jurnal of Plant Growth Regulation, vol. 25, p. 233-244, Sep. 2006. CrossRef A. Szmidt-Jaworska, K. Jaworski, A. Zienkiewicz, M. Lenartowska, and J. Kopcewicz, Guanylyl cyclase activity during photoperiodic flower induction in Pharbitis nil, Jurnal of Plant Growth Regulation, vol. 57, p. 173-184, 2009. CrossRef Light Laboratory Inc., Goniophotometer Test Report HLG ELITE lamps. CrossRef U.J. Błaszczak, D.A. Aziz, L. Gryko, Influence of the spectral composition of LED lighting system on plants cultivation in a darkroom, Proceedings of SPIE, vol. 10445, p. 1-9, 2017. CrossRef

The article presents an overview of currently used greenhouse lighting systems. It does not apply to traditional sodium lighting systems, but only to the most modern LEDs. The publication presents descriptions of lamp designs, both foreign and Polish. The aim of the work is not only to review solutions, but also to identify the reasons for the low transfer of scientific and technical solutions to business. There are several barriers to overcome, mainly subjective ones, so that new solutions can be implemented and developed. Full Text: PDF ReferencesS. Ki-Ho, J. Yu-Min, O. Myung-Min, "Application of supplementary white and pulsed light-emitting diodes to lettuce grown in a plant factory with artificial lighting", Springer 57(6), 561 (2016). CrossRef M. Gilewski, "The role of light in the plants world", Phot. Lett. Poland 11, 4 (2019). CrossRef K.J. McCree, Agricultural Meteorology (Elsevier Publishing Company 1972). CrossRef G. Trouwborst, J. Oosterkamp, S. Hogewoning, V. Ieperen, "The application of LEDs as assimilation light source in greenhouse horticulture: A simulation study", the 6th Int. Symposium on Light in Horticulture. Tsukuba. Japan, Nov. 2009. CrossRef K. Jaworski, A. Szmidt-Jaworska, J. Kopcewicz, " Two calcium dependent protein kinases are differently regulated by light and have different activity patterns during seedling growth in Pharbitis nil", Springerlink.com, Journal: 10725, Article: 9609, 2011. CrossRef Philips Lighting, Horticultural LED lighting applications, 2020: https://www.lighting.philips.com/main/products/horticulture. DirectLink E. de Beer, P.H. van Baar, 3 reasons why intercanopy lighting is effective for high-wire vegetables, 2020: www.lighting.philips.com. DirectLink HLG, Refurbished HLG 550, 2020, https://horticulture-lightinggroup.com/collections/lamps/products/refurbished-hlg-550-v1 DirectLink Neonica Polska, 2020, www.growy.eu CrossRef I. Fryc, T. Dimitrova-Grekow, "An automated system for evaluation of the quality of light sources", 6th IEEE Lighting Conference of the Visegrad Countries : LUMEN V4, Sept. 2016. CrossRef EconoLux Ind. Ltd., "What Light do Plants Need", Hong Kong, 2016, http://econoluxindustries.com/light-plants-need.html. DirectLink Heliospectra AB, heliospectra DYNA, 2020, https://www.heliospectra.com/led-grow-lights/dyna. DirectLink Plantlux, Horticulture LED SMD lamp Plantalux XX640W, 2020, https://plantalux.pl/en/plantalux-xx640w-en/. DirectLink M. Gilewski, "An Adaptive and Monoculture Oriented LEDs Lamp", 978-1-5386-7924-1/18/$31.00 ©2018 IEEE, 2018. CrossRef