AN OVERVIEW OF THE IMPACT OF STRAY LIGHT FROM COMMERCIAL GREENHOUSES

2021 ◽  
Author(s):  
K. Bertin ◽  
G. Zissis ◽  
G. Salas ◽  
P.M. Raynham ◽  
A. Moutsi ◽  
...  
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Stray Light ◽  
Significant Problem ◽  
Light Sources ◽  
Spectral Power Distribution ◽  
Outdoor Work ◽  
Local Residents ◽  
The Impact ◽  
Current Standards

Stray light from commercial greenhouses is becoming a significant problem causing disruption to wildlife activity and annoyance for local residents. To quantify the amount of stray light from a typical large greenhouse the authors have modelled several lighting installations based on a range of generic horticultural light sources. The impact of the stray light is dependent on the spectral power distribution of the sources employed, the intensity and distribution. Current standards for obtrusive light from outdoor work places do not seem to be suitable when applied to greenhouses.

Circadian stimulus – A computation model with photometric and colorimetric quantities

2019 ◽  
Vol 52 (6) ◽  
pp. 751-762
Author(s):  
W Truong ◽  
V Trinh ◽  
TQ Khanh
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
External Validation ◽  
Circadian System ◽  
Model Fit ◽  
Light Sources ◽  
Computation Model ◽  
Internal Validation ◽  
Spectral Power Distribution ◽  
Chromaticity Coordinate

The circadian stimulus is an important, validated and updated metric that describes the invisible influences of light on the human circadian system explicitly and scientifically. However, an absolute spectral power distribution must be supplied for its computation, which is only measurable by an expensive and complicated spectrometer. This paper proposes an alternative circadian stimulus computation model that is identified as the function CS(z, Ev) for white light sources based on the most common and simplest parameters of illuminance Ev in lux and the chromaticity coordinate z. These parameters are well known and widely used in both colour science and lighting technology. In order to prove the accuracy and availability of the model, an internal validation was performed with the adapted method repeating split data to check the goodness of the model fit. The fitted model achieved a maximum residual of 0.058 in the circadian stimulus quantity (R2 = 0.998). An external validation with the maximum residual of 0.030 (R2 = 0.999) provided stronger evidence for the usability of the model in applications.

scholarly journals Optimising the illumination spectrum for enhancing tissue visualisation

2017 ◽  
Vol 51 (1) ◽  
pp. 99-110 ◽  
Author(s):  
J Shen ◽  
S Chang ◽  
H Wang ◽  
Z Zheng
Keyword(s):  
Biological Tissue ◽  
Power Distribution ◽  
Spectral Reflectance ◽  
Evaluation Method ◽  
Multispectral Imaging ◽  
Spectral Power ◽  
Light Sources ◽  
White Led ◽  
Spectral Power Distribution ◽  
Visual Entropy

In operations, light reflected from biological tissue can be used for disease detection. In this paper, we used a visual entropy evaluation method to design the optimal illuminant to improve colour discriminability of biological tissue. The optimal spectral power distribution of the illuminant was obtained by maximising the visual entropy value of sample tissue based on the human visual system. In the experiment, multispectral imaging was used to measure the spectral reflectance of the tissue and colour clustering was conducted to extract its colour features. To verify the effectiveness of this method, simulated tissue images under illuminations with optimised spectral power distributions were compared with those under other light sources such as the standard illuminant D65 and white LED light sources. Results show that the sample under optimised illumination has a higher visual entropy value with better perceptual visibility.

scholarly journals Spectral properties of smart LED lamps

2020 ◽  
Vol 12 (1) ◽  
pp. 16
Author(s):  
Jacek Kusznier ◽  
Wojciech Wojtkowski
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Electrical Engineering ◽  
Climatic Conditions ◽  
Intraocular Lenses ◽  
Automated System ◽  
Integrating Sphere ◽  
Light Sources ◽  
Spectral Power Distribution

Intelligent LED lamps are most often used in intelligent lighting installations. They frequently use one of two different ways to obtain white light. The first is the mixing of monochrome lights R, G and B. The second way is to mix the light of the blue diode with the yellow phosphor radiation. Adjusting the luminous flux in RGBW LED lamps causes greater changes in the position of the chromaticity point than in the case of CW WW LED lamps. In the case of big changes, this can lead to a visible change in the perceived color. Full Text: PDF References:https://re.jrc.ec.europa.eu/pvg_tools/en/tools.html [DirectLink]https://dateandtime.info/pl [DirectLink]J. Kusznier and W. Wojtkowski, "Impact of climatic conditions on PV panels operation in a photovoltaic power plant," IEEE, 2019 15th Selected Issues of Electrical Engineering and Electronics (WZEE), Zakopane, Poland, 2019, pp. 1-6 [CrossRef]J. Kusznier and W. Wojtkowski, "Impact of climatic conditions and solar exposure on the aging of PV panels," IEEE, 2019 15th Selected Issues of Electrical Engineering and Electronics (WZEE), Zakopane, Poland, 2019, pp. 1-6 [CrossRef]https://www.weatheronline.pl/weather/ [CrossRef]L.T. Sharpe, A. Jagla, W. Jägle, "A luminous efficiency function, V*(λ), for daylight adaptation", J. Vision 5(11), 948 (2012) [CrossRef]http://www.ee.co.za/article/integrating-sphere-data-sincere.html [DirectLink]Simunovic M. P., "On Seeing Yellow The Case for, and Against, Short-Wavelength Light-Absorbing Intraocular Lenses", Archives of Ophthalmology, vol. 130, no. 7, pp. 919-926, 2012 [CrossRef]I. Fryc, "Important parameters of multichannel spectroradiometer", Przeglad Elektrotechniczny R. 88(4a), pp. 230-231 (2012) [DirectLink]I. Fryc, "Measurement techniques of optical LEDs properties performed with compliance conformity with CIE 127:2007 standard", Przeglad Elektrotechniczny R. 85(11), pp. 317-319 (2009) [CrossRef]J. Kowalska, I. Fryc, "Colour rendition quality of typical fluorescent lamps determined by CIE Colour Fidelity Index and Colour Rendering Index", Przeglad Elektrotechniczny R. 95(7), pp. 94-97 (2019) [CrossRef]M. Gilewski, L. Gryko, A. Zajac, "Digital controlling system to the set of high power LEDs", Proc. of SPIE, 8902, 89021D, 2013 [CrossRef]M. Gilewski, "The ecological hazard of artificial lighting in greenhouses" Photonics Letters of Poland, vol. 11 Issue: 3 Pages: 87-89, 2019 [CrossRef]I. Fryc and T. Dimitrova-Grekow, "An automated system for evaluation of the quality of light sources," 2016 IEEE Lighting Conference of the Visegrad Countries (Lumen V4), Karpacz, 2016, pp. 1-4. [CrossRef]I. Fryc, "The spectral power distribution of LED driven by square shape pulses", Przeglad Elektrotechniczny R. 88(6), pp. 131-133 (2012) [DirectLink]I. Fryc, "LED's spectral power distribution under different condition of operating temperature and driving current", Przeglad Elektrotechniczny R. 86(10), pp. 187-189 (2010) [DirectLink]J. Kusznier, "Changes in the Spectral Power Distribution of Light Sources for Smart Lighting," IEEE, 2018 14th Selected Issues of Electrical Engineering and Electronics (WZEE), Szczecin, Poland, 2018, pp. 1-5 [CrossRef]

scholarly journals Analysis and Simulation of the Illumination Optics of Rigid Medical Endoscopes

2018 ◽  
Vol 4 (1) ◽  
pp. 169-172 ◽  
Author(s):  
Alexander Gaertner ◽  
Paola Belloni
Keyword(s):  
Simulation Model ◽  
Power Distribution ◽  
Spectral Power ◽  
Integrating Sphere ◽  
Light Sources ◽  
Optimization Approach ◽  
Medical Endoscope ◽  
Spectral Power Distribution ◽  
Light Coupling ◽  
External Light Source

AbstractOur work focuses on enhancing the illumination optics of a rigid medical endoscope using optomechanical simulation. We aim on improving the efficiency of the illumination optics to provide more light in the surgeon’s field of view (FOV) and therefore better image quality. We conducted an extensive market analysis and measured several rigid endoscopes and their external light sources in the lighting technology laboratory. Surprisingly, all endoscopes showed a degree of efficiency below 20 %. Our optimization approach is based first on a photometric and colorimetric analysis carried out with an integrating sphere and a goniophotometer. Secondly, the results obtained are implemented in a 3Doptomechanical simulation model developed with the raytracing software LightTools (Synopsis©). In the simulation model both the geometrical components as well as the critical interfaces are examined considering light coupling at boundary surfaces and light transfer within the illumination optics. Moreover, the optimization takes into account spectral power distribution (SPD) and angular light distribution (ALD) of the light provided from the fiberoptic cable connected to an external light source as well as additional interfering factors like gluing, dispersive absorption and total reflection at critical angles.

Correlated color temperature: Use and limitations

2021 ◽  
pp. 147715352110343
Author(s):  
D Durmus
Keyword(s):  
Power Distribution ◽  
Spectral Power ◽  
Ease Of Use ◽  
Chromatic Adaptation ◽  
Color Temperature ◽  
Light Sources ◽  
One Dimensional ◽  
Spectral Power Distribution ◽  
Color Quality

Correlated color temperature (CCT) is a one-dimensional metric that aims to quantify the perceived visual quality of nominal white light sources. It is often used as a proxy for the color quality of light sources due to its ease of use. However, CCT lacks the accuracy in communicating color information for research purposes. Two light sources with identical CCTs can appear perceptually different, and these differences are not estimated by CCT due to the loss of information caused by reducing spectral power distribution of light sources into a one-dimensional metric. Using supplemental metrics in addition to CCT, providing the absolute spectral power distribution of light sources in graphical and tabular form, and documenting and accounting for potential confounding factors, such as chromatic adaptation, can increase the validity of research results, improve the repeatability of studies, and help address replication concerns.

scholarly journals LED LAMP FOR APPLICATION IN MEDICAL CENTERS – DESIGN AND THERMAL MANAGEMENT

2017 ◽  
Vol 3 ◽  
pp. 207
Author(s):  
Petko Mashkov ◽  
Hristo Beloev ◽  
Berkant Gyoch ◽  
Tamara Pencheva
Keyword(s):  
Circadian Rhythm ◽  
Power Distribution ◽  
Spectral Power ◽  
Experimental Studies ◽  
Spectral Composition ◽  
Light Sources ◽  
Artificial Lighting ◽  
Spectral Power Distribution ◽  
Medical Centers ◽  
Selection Of

The goal of this work is research and development of light sources suitable for use in hospitals, nursing homes, hospices and other similar institutions. During the day spectral power distribution (SPD) of this type luminaire needs to simulate natural day light that affects the natural circadian rhythm of humans. Maintaining the natural circadian rhythm impacts positive on human health, improves mood, prevents the development of depression and helps to overcome them. In the late afternoon increase light in the red-orange part. Light of this kind of spectral composition doesn’t inhibit melatonin production and the human body naturally prepares for rest and sleep. At night artificial lighting should be in the red - orange area to enable patients to sleep and staff to fulfill their obligations. Theoretical analysis and selection of suitable LEDs for the realization of the luminaire with the desired characteristics are made. Performed experimental studies make possible achieving the desired characteristics of light and appropriate LEDs’ modes of operation.

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