The appreciation of LED-based white light sources by Dutch and Chinese people in three application areas

The aim of this study was to evaluate differences in appreciation for LED-based white-light sources between Dutch and Chinese people, when used for the illumination of three applications: fresh food, packaging material and skin tone. Furthermore, the contribution of the CIE special and general colour rendering indices ( Ri and Ra), a colour gamut measure ( Ga), and chroma changes for specific test-colour samples to perceived attractiveness was investigated. Thirty-four Dutch and 36 Chinese people assessed the attractiveness of the object appearance, with paired comparison experiments, for seven light sources at two CCT settings, 3000 K (Dutch and Chinese) and 4000 K (Chinese only), and a range of Ra and Ga values. It was found that for illuminating fresh food and packaging material, most Dutch and Chinese participants preferred light settings with an increased colour gamut. In contrast to colour rendering indices, the chroma change for the strong red test colour sample could be used to predict object attractiveness, but the established equations were different per application and culture. There was no clear relation between objective measures and skin tone preference for the Dutch study. Finally, Chinese participants did not like an increase in red saturation at 3000 K, but they allowed an increase at 4000 K.

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A white–cyan-red LED system for low correlated colour temperature lighting

Lighting Research and Technology ◽

10.1177/1477153515608416 ◽

2015 ◽

Vol 49 (3) ◽

pp. 343-356 ◽

Cited By ~ 2

Author(s):

M Chakrabarti ◽

A Thorseth ◽

DD Corell ◽

C Dam-Hansen

Keyword(s):

White Light ◽

Colour Temperature ◽

White Leds ◽

Geometrical Modelling ◽

Red Led ◽

Colour Gamut ◽

Museum Display ◽

Colour Rendering ◽

Red Leds ◽

Planckian Locus

A white LED complemented by cyan and red LEDs is a good candidate for achieving high colour rendering at low correlated colour temperatures. This is usually very difficult with commercially available white LEDs. In addition, the system is able to replace incandescent lighting in many applications; for example, the lighting for museum display cases. To investigate and optimize the colour and light distribution properties, both spectral and geometrical modelling are used. Mapping of the possible combinations of LEDs is used to locate the optimal solutions within the colour gamut, with emphasis on chromaticity and colour rendering indices. A geometric optical model is used to design and optimize the homogeneity of the colour and light intensity distribution as a function of angle. The resulting system produces diffused homogeneous white light with a tunable correlated colour temperature from 2000 K to 2400 K. Within this range the white light is characterized by a high general colour rendering index (Ra > 90), special colour rendering indices for saturated red objects (R9 > 85), and low chromaticity distance (Duv) from the Planckian locus (Duv < 2 × 10−3).

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Green Silver Nanoparticles Embedded in Cellulosic Network for Fresh Food Packaging

Journal of Pure and Applied Microbiology ◽

10.22207/jpam.15.3.13 ◽

2021 ◽

Author(s):

S. Chaitanya Kumari ◽

P. Naga Padma ◽

K. Anuradha

Keyword(s):

Electron Microscopy ◽

Silver Nanoparticles ◽

Silver Nitrate ◽

Shelf Life ◽

Food Packaging ◽

Nitrate Solution ◽

Packaging Material ◽

Packaging Materials ◽

Coated Paper ◽

Fresh Food

The demand for increasing the shelf life of fresh food as well as the need for protecting the food against foodborne infections warrant the demand for increasing the shelf life of fresh food. The incorporation of nanoparticles into the packaging material can enhance the preservation of perishable foods. Silver nanoparticles (AgNPs), in particular, have antibacterial, anti-mold, anti-yeast, and anti-viral activities can be embedded into the biodegradable packaging materials for this purpose. This study focuses on antimicrobial packaging materials for food by mixing the extracts of different plants with silver nitrate and depositing this mixture as a layer on the blotting papers, which are thick sheets of paper made of cellulose. Because the blotting papers are highly absorbent and porous, silver nitrate solution along with the plant extracts can be easily applied and allowed for in situ synthesis of AgNPs. Subsequently, these papers were analyzed and characterized using scanning electron microscopy, transmission electron microscopy, atomic absorption spectroscopy, and energy dispersive X-ray analysis. The coated paper exhibited good antibacterial activity against Escherichia coli and Staphylococcus aureus. Furthermore, the coated paper when used as a packaging material for tomatoes and coriander leaf, the shelf life was extended to about 30 days and 15 days respectively. The prepared cost-effective silver packing material can be used in food packaging for various perishable foods.

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Influence of Peak Wavelengths on Properties of Mixed-LED White-Light Sources

Advances in OptoElectronics ◽

10.1155/2010/437564 ◽

2010 ◽

Vol 2010 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Snjezana Soltic ◽

Andrew N. Chalmers

Keyword(s):

Light Source ◽

White Light ◽

Light Sources ◽

Peak Wavelength ◽

White Light Source ◽

Luminous Efficacy ◽

Colour Temperature ◽

Colour Rendering

The purpose of this investigation is to quantify the influence of the peak wavelength shifts in commercially available LEDs on the characteristics of the mixed-LED white-light sources. For this purpose, a tetrachromatic spectrum was optimized and then subjected to deviations in the peak wavelengths. A total of 882 combinations of peak wavelength values were evaluated, and the results are reported in terms of correlated colour temperature, colour-rendering properties, and radiant luminous efficacy. The results show that there can be significant changes in the characteristics of the source under these conditions. Such changes are highly likely to present problems when dealing with applications where an effective and accurate white-light source is important.

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The effect of age on white light perception.

International Journal of Sustainable Lighting ◽

10.26607/ijsl.v20i2.83 ◽

2018 ◽

Vol 20 (2) ◽

pp. 29-43

Author(s):

Jacobus Gideon Van der Westhuyzen ◽

Frederick Wilhelm Leuschner

Keyword(s):

White Light ◽

Test Procedure ◽

Age Groups ◽

Index Number ◽

Light Sources ◽

Colour Rendering ◽

Effect Of Age ◽

Psychophysical Test ◽

Two Age Groups ◽

The Way

The way that persons from different age groups experience “white light” is investigated. Human eye lens transmission changes spectrally with age and this may influence the way that humans from different ages experiences light. Such a difference may be important in industrial and medical environments. Two different age groups, one group younger than 40 years of age and another group older than 50 years of age were subjected to the same “white” definition task. A conventional single-booth setup was used where observers were able to adjust the intensity of four coloured LED’s. Results of the psychophysical test procedure were used to generate specifications of two light sources, as selected by the two age groups. The two age groups selected two very different light sources when tasked to achieve a “perception” of white. Results show that the older group prefers a source with a colour rendering index number of 89 and the younger group prefers a source with a colour rendering index number of 74. The sources selected by the two age groups specifies correlated colour temperature values of 5150 K for the older age group and 6592 K for the younger group.

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Crystalline Silicon White Light Sources Driven by Optical Resonances

Nano Letters ◽

10.1021/acs.nanolett.0c04314 ◽

2021 ◽

Vol 21 (6) ◽

pp. 2397-2405

Author(s):

Jin Xiang ◽

Mincheng Panmai ◽

Shuwen Bai ◽

Yuhao Ren ◽

Guang-Can Li ◽

...

Keyword(s):

White Light ◽

Crystalline Silicon ◽

Light Sources ◽

Optical Resonances

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Photocatalytic Performance of ZnO: Al Films under Different Light Sources

International Journal of Photoenergy ◽

10.1155/2012/780462 ◽

2012 ◽

Vol 2012 ◽

pp. 1-7 ◽

Cited By ~ 13

Author(s):

Prashant Pradhan ◽

Juan Carlos Alonso ◽

Monserrat Bizarro

Keyword(s):

White Light ◽

Irradiation Time ◽

Zno Films ◽

Light Sources ◽

X Ray Diffraction ◽

Treatment Processes ◽

Vis Spectroscopy ◽

Doped Zno ◽

Very High ◽

High Degradation Rate

ZnO and Al doped ZnO films were produced by spray pyrolysis. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis spectroscopy, and photoluminescence. Their photocatalytic activity was evaluated by the decomposition of the methyl orange dye using different light sources: ultraviolet light, artificial white light, and direct sunlight. The films were also tested under darkness for comparison. The ZnO films were able to degrade the test pollutant under UV and sunlight in more than a 60% after 180 min of irradiation and a scarce degradation was obtained using white light. However, the Al doped ZnO films presented a very high degradation rate not only under UV and sunlight (100% degradation), but also under white light (90% degradation after the same irradiation time). An unexpected high degradation was also obtained in the dark, which indicates that a nonphotonic process is taking place parallel to the photocatalytic process. This can be due to the extra electrons—provided by the aluminum atoms—that migrate to the surface and produce radicals favoring the decomposition process even in the dark. The high activity achieved by the ZnO: Al films under natural conditions can be potentially applied to water treatment processes.

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System efficiency of laser-based white light

Advanced Optical Technologies ◽

10.1515/aot-2014-0048 ◽

2014 ◽

Vol 3 (5-6) ◽

Cited By ~ 1

Author(s):

Roland Lachmayer ◽

Alexander Wolf ◽

Gerolf Kloppenburg

Keyword(s):

Thermal Management ◽

White Light ◽

High Power ◽

Laser Diodes ◽

Light Sources ◽

System Efficiency ◽

Light Emitting ◽

Scale Down ◽

Color Rendering ◽

Product Weight

AbstractFor many lighting applications, light-emitting diodes (LEDs) are replacing traditional light sources providing the possibility for smart and efficient systems as well as a reduction in the product weight. A next step in this development is the integration of laser-based light sources to increase luminance and to further scale down the optics possibly leading to a reduction of necessary resources. This article reviews the possibilities and challenges arising from the use of laser diodes especially compared to current high-power LED systems in terms of efficiency, color-rendering properties, and thermal management.

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Towards the Optimum Light Source Spectrum

Advances in OptoElectronics ◽

10.1155/2010/596825 ◽

2010 ◽

Vol 2010 ◽

pp. 1-9 ◽

Cited By ~ 8

Author(s):

Andrew Chalmers ◽

Snjezana Soltic

Keyword(s):

Light Source ◽

Large Scale ◽

Source Spectrum ◽

Light Sources ◽

Luminous Efficacy ◽

Light Emitting ◽

Spectral Bands ◽

Good Energy ◽

Lighting Systems ◽

Colour Rendering

This paper is concerned with designing light source spectra for optimum luminous efficacy and colour rendering. We demonstrate that it is possible to design light sources that can provide both good colour rendering and high luminous efficacy by combining the outputs of a number of narrowband spectral constituents. Also, the achievable results depend on the numbers and wavelengths of the different spectral bands utilized in the mixture. Practical realization of these concepts has been demonstrated in this pilot study which combines a number of simulations with tests using real LEDs (light emitting diodes). Such sources are capable of providing highly efficient lighting systems with good energy conservation potential. Further research is underway to investigate the practicalities of our proposals in relation to large-scale light source production.

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