White LEDs as broad spectrum light sources for spectrophotometry: Demonstration in the visible spectrum range in a diode-array spectrophotometric detector

2010 ◽  
Vol 31 (22) ◽  
pp. 3737-3744 ◽  
Author(s):  
Tomasz Piasecki ◽  
Michael C. Breadmore ◽  
Mirek Macka
Keyword(s):  
Broad Spectrum ◽  
Visible Spectrum ◽  
Diode Array ◽  
Light Sources ◽  
White Leds ◽  
Spectrum Range

scholarly journals Effect of Supplementary Light Source on Quality of Grafted Tomato Seedlings and Expression of Two Photosynthetic Genes

Agronomy ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 207 ◽  
Author(s):  
Hao Wei ◽  
Jiangtao Hu ◽  
Chen Liu ◽  
Mengzhao Wang ◽  
Jin Zhao ◽  
...  
Keyword(s):  
Light Source ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Light Sources ◽  
Seedling Production ◽  
White Leds ◽  
Tomato Seedlings ◽  
Photosynthetic Genes ◽  
Supplementary Lighting

Supplementary lighting is commonly used in high-quality seedling production. In this study, grafted tomato seedlings were grown for 10 days in a glasshouse with 16-h daily supplementary lighting at 100 μmol·m−2·s−1 PPFD (Photosynthetic photon flux density) from either high-pressure sodium (HPS), metal halide (MH), far-red (FR), white LEDs (Light emitting diodes) (W), or mixed LEDs (W1R2B1, where the subscript numbers indicate the ratio of the LED chips) to determine which light sources improve the seedling quality. The control seedlings did not receive any supplementary light. Physiological parameters and the expression of genes related to photosynthesis were analyzed. The results showed that root length, biomass, number of leaves, chlorophyll (SPAD), scion dry weight to height ratio (WHR), and specific leaf weight (SLW) were the greatest for grafted seedlings grown in W1R2B1. The level of root ball formation was the greatest for seedlings grown in W1R2B1, followed by those grown in W, HPS, and MH. Seedlings grown in FR did not fare well, as they were very thin and weak. Moreover, the expression of two photosynthetic genes (PsaA and PsbA) was significantly increased by W1R2B1 and W, which suggests that the plastid or nuclear genes might be regulated. The overall results suggest that W1R2B1 was the most suitable light source to enhance the quality of grafted tomato seedlings. The results of this study could be used as a reference for seedling production in glasshouses, and may provide new insights in the research on lights affecting the development of plants.

scholarly journals Response of Polycrystalline Solar Cell Outputs to Visible Spectrum and other Light Sources-a Case Study

2018 ◽  
Vol 8 (6) ◽  
pp. 4096
Author(s):  
Ayman Y. Al-Rawashdeh ◽  
Omar Albarbarawi ◽  
Ghazi Qaryouti
Keyword(s):  
Solar Cells ◽  
Visible Spectrum ◽  
Artificial Light ◽  
Light Sources ◽  
Variable Response ◽  
Artificial Illumination ◽  
Different Color ◽  
Color Filters ◽  
Sunlight Radiation

<p>In this case study, two polycrystalline solar modules were installed outdoors (irradiated by sunlight) and indoors (irradiated by artificial lights). The solar cells in both cases were installed using different color filters that allowed the passage of certain light frequencies. The amount of energy produced by each module were measured and compared to a reference module with no filter. The results indicated the variable response of polycrystalline solar cells to natural and artificial light sources, being more responsive in both cases to red band color as could be deduced from their % current outputs (72.5% sunlight radiation; 84.38% artificial light sources). Other colors, including yellow, green, orange and violet afforded acceptable outputs. The results indicated that electrical outputs of indoor solar cells decreased when colored filters were used, but red filter in general afforded the maximum outputs, for both the artificially radiated indoor and naturally radiated outdoor solar cells. The case study suggests the possible complementary advantage of using indoor mounted solar cells for the production of electricity during artificial illumination period of the day.</p>

scholarly journals Assessing the Stability of Surface Lights for use in Retrievals of Nocturnal Atmospheric Parameters

2019 ◽  
Author(s):  
Jeremy E. Solbrig ◽  
Steven D. Miller ◽  
Jianglong Zhang ◽  
Lewis Grasso ◽  
Anton Kliewer
Keyword(s):  
Near Infrared ◽  
Correlation Coefficients ◽  
Visible Spectrum ◽  
Light Sources ◽  
Infrared Observations ◽  
Spatially Resolved ◽  
Relative Standard ◽  
Geometric Variables ◽  
The Stability

Abstract. Detection and characterization of aerosols is inherently limited at night due to a lack of sensitivity—information typically provided by visible spectrum observations. The VIIRS Day/Night Band (DNB) onboard the Suomi-NPP satellite is a first-of-its-kind calibrated sensor capable of collecting visible/near-infrared observations during both day and night. Multiple studies have suggested that anthropogenic light emissions such as those from cities and gas flares may be useable as light sources for retrieval of atmospheric properties including cloud and aerosol optical depth. However, their use in this capacity requires proper characterization of their intrinsic variation, which represents a source of retrieval uncertainty. In this study we use 18 months of cloud-cleared VIIRS data collected over five selected geographic domains to assess the stability of anthropogenic light emissions and their response to varied satellite and lunar geometries. Timeseries are developed for each location in each domain for DNB radiance, four infrared channels, and satellite and lunar geometric variables, and spatially-resolved correlation coefficients are computed between DNB radiance and each of the other variables. This analysis finds that while many emissive light sources are too unstable to be used reliably for atmospheric retrievals, some sources exhibit a sufficient stability (relative standard deviation

Energy-Efficient Lighting System for Greenhouse Plants

2018 ◽  
pp. 204-229 ◽  
Author(s):  
Leonid Yuferev ◽  
Alexander Sokolov
Keyword(s):  
Power Supply ◽  
Energy Efficient ◽  
Power Supply System ◽  
Radiation Power ◽  
Gas Discharge ◽  
Supply System ◽  
Light Sources ◽  
Lighting System ◽  
Spectrum Range ◽  
Frequency Changes

This chapter describes how with the artificial cultivation of plants lamps are required with a certain spectrum of radiation. For lighting plants have developed a special lamp. Industry produces special gas discharge lamp. In these lamps a fixed range of radiation. Recently, there were light sources for plants on LEDs. LEDs can create light with any spectrum range from 360 to 800 nm. The authors of the article give a technique for modeling the spectrum of luminaires and calculating LED lamps for plants. The tests of the developed lamps for plants in dark chambers are given. A description of a resonant regulated power supply system for LED luminaires is given. In the proposed system when the frequency changes radiation power.

scholarly journals 200 Comparison of Spinach Growth and Development Under Broad- and Narrow-spectrum Lighting Sources

HortScience ◽  
2000 ◽  
Vol 35 (3) ◽  
pp. 425D-425
Author(s):  
Gregory D. Goins ◽  
Neil C. Yorio ◽  
Lynn V. Lewis
Keyword(s):  
Broad Spectrum ◽  
Growth And Development ◽  
Light Emitting Diodes ◽  
Leaf Growth ◽  
Light Sources ◽  
Light Emitting ◽  
Narrow Spectrum ◽  
Controlled Environments ◽  
Photosynthetic Responses ◽  
Light Spectral Quality

Various electric lamp sources have been proposed for growing plants in controlled environments. Although it is desirable for any light source to provide as much photosynthetically active radiation (PAR) as possible, light spectral quality is critical in regard to plant development and morphology. Light-emitting diodes (LEDs) and microwave lamps are promising light sources that have appealing features for applications in controlled environments. Light-emitting diodes can illuminate a narrow spectrum of light, which corresponds with absorption regions of chlorophyll. The sulfur-microwave lamp uses microwave energy to excite sulfur and argon, which produces a bright, continuous broad-spectrum white light. Compared to conventional broad-spectrum sources, the microwave lamp has higher electrical efficiency, and produces limited ultraviolet and infrared radiation. Experiments were conducted with spinach to test the feasibility of using LEDs and microwave lamps for spinach production in controlled environments. Growth and development comparisons were made during 28-day growth cycles with spinach grown under LED (at various red wavelengths), microwave, cool-white fluorescent, or high-pressure sodium lamps. Plant harvests were conducted at 14, 21, and 28 days after planting. At each harvest under all broad-spectrum light sources, spinach leaf growth and photosynthetic responses were similar. Major differences were observed in terms of specific leaf area and weight between spinach plants grown under 700 and 725 nm LEDs as compared to plants grown under shorter red wavelengths.

Full‐visible spectrum emitting Zn–In–S:Cu/ZnS nanocrystals based on varying Cu concentrations and its application in white LEDs

2018 ◽  
Vol 101 (12) ◽  
pp. 5586-5595
Author(s):  
Mengmeng Cao ◽  
Caiyan Yu ◽  
Jinfeng Xia ◽  
Danyu Jiang ◽  
Shiwei Wang ◽  
...  
Keyword(s):  
Visible Spectrum ◽  
White Leds ◽  
Zns Nanocrystals
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