Narrow-band Light-emitting Diode Research Articles

Robust, Narrow-Band Nanorods LEDs with Luminous Efficacy > 200lm/W: Next-Generation of Efficient Solid-State Lighting.

Energy-efficient white light-emitting diodes (LEDs) are in high demand across the society. Despite the significant advancements in the modern lighting industry based on solid-state electronics and inorganic phosphor, solid-state lighting (SSL) continues to pursue improved efficiency, saturated color performance, and longer lifetime. Here in this article, robust, narrow emission band nanorods (NRs) are disclosed with tailored wavelengths, aiming to enhance the color rendering index (CRI) and luminous efficacy (LE). The fabricated lighting device consists of NRs of configuration CdSe/ZnxCd1-xS/ZnS, which can independently tune CRI R1-R9 values and maximize the luminous efficacy. For general lighting, NRs with quantum yield (QY) up to 96% and 99% are developed, resulting in ultra-efficient LEDs reaching a record high luminous efficacy of 214lmW-1 (certified by the National Accreditation Service). Furthermore, NRs are deployed onto mid-power (0.3 W@ 50mA) LEDs, showing significantly enhanced long-term stability (T95 = 400h @ 50mA). With these astonishing properties, the proposed NRs can pave the way for efficient lighting with desired optical spectrum.

Ocular accommodation and wavelength: The effect of longitudinal chromatic aberration on the stimulus-response curve.

The longitudinal chromatic aberration (LCA) of the eye creates a chromatic blur on the retina that is an important cue for accommodation. Although this mechanism can work optimally in broadband illuminants such as daylight, it is not clear how the system responds to the narrowband illuminants used by many modern displays. Here, we measured pupil and accommodative responses as well as visual acuity under narrowband light-emitting diode (LED) illuminants of different peak wavelengths. Observers were able to accommodate under narrowband light and compensate for the LCA of the eye, with no difference in the variability of the steady-state accommodation response between narrowband and broadband illuminants. Intriguingly, our subjects compensated more fully for LCA at nearer distances. That is, the difference in accommodation to different wavelengths became larger when the object was placed nearer the observer, causing the slope of the accommodation response curve to become shallower for shorter wavelengths and steeper for longer ones. Within the accommodative range of observers, accommodative errors were small and visual acuity normal. When comparing between illuminants, when accommodation was accurate, visual acuity was worst for blue narrowband light. This cannot be due to the sparser spacing for S-cones, as our stimuli had equal luminance and thus activated LM-cones roughly equally. It is likely because ocular LCA changes more rapidly at shorter wavelength and so the finite spectral bandwidth of LEDs corresponds to a greater dioptric range at shorter wavelengths. This effect disappears for larger accommodative errors, due to the increased depth of focus of the eye.

Highly Monochromatic Ultraviolet LED Based on the SnO2 Microwire Heterojunction Beyond Dipole-Forbidden Band-Gap Transition.

SnO2 has been extensively applied in the fields of optoelectronic devices because of its large band gap, high exciton binding energy, and outstanding optical/electrical properties. However, its applications in ultraviolet light-emitting diodes (LEDs) are still hindered by the dipole-forbidden rule. Herein, the dipole-forbidden rule can be conquered by synthesizing Sb-incorporated SnO2 microwires (SnO2:Sb MWs), which are examined by ultraviolet photoluminescence emitting at 363.2 nm and a line width of 11.3 nm. Subsequently, a highly monochromatic ultraviolet light-emitting diode (LED) based on a SnO2:Sb MW heterojunction was constructed with a p-GaN film serving as the hole supplier. In the LED, the presence of a MgO intermediate layer can modulate carrier transport and recombination path, thus achieving band-edge optical transition in the SnO2:Sb MW. As the LED is modified using Ag nanowires, electrical properties, especially for the hole injection efficiency, were dramatically boosted, contributing significantly to the device high brightness. The LED emits at 365.9 nm and a line width of 12.4 nm. Therefore, we have realized a high-brightness and narrow-band ultraviolet LED with the shortest peak wavelength never seen in previously reported SnO2 LEDs. This work will promote the potential applications of low-dimensional SnO2 optoelectronic devices and provide an effective exemplification to overcome the dipole-forbidden rule in metal-oxide materials with "forbidden" energy gaps.

Development and performance validation of a low-cost algorithms-based hyperspectral imaging system for radiodermatitis assessment.

Whilst radiotherapy (RT) is widely used for cancer treatment, radiodermatitis caused by RT is one most common severe side effect affecting 95% cancer patients. Accurate radiodermatitis assessment and classification is essential to adopt timely treatment, management and monitoring, which all depend on reliable and objective tools for radiodermatitis grading. We therefore, in this work, reported the development and grading performance validation of a low-cost (∼2318.2 CNY) algorithms-based hyperspectral imaging (aHSI) system for radiodermatitis assessment. The low-cost aHSI system was enabled through Monte Carlo (MC) simulations conducted on multi-spectra acquired from a custom built low-cost multispectral imaging (MSI) system, deriving algorithms-based hyper-spectra with spectral resolution of 1 nm. The MSI system was based on sequentially illuminated narrow-band light-emitting diodes (LEDs) and a CMOS camera. Erythema induced artificially on healthy volunteers was measured by the aHSI system developed, with algorithms-based hyper-spectra and skin layer resolved physiological parameters (i.e., the blood volume fraction (BVF) and the oxygen saturation of hemoglobin in blood, et. al.) derivation using MC simulations. The MC simulations derived BVF and the oxygen saturation of hemoglobin in blood showed significant (P < 0.001, analysis of variance: ANOVA) increase with erythema. Further 1D-convolution neural network (CNN) implemented on the algorithms-based hyper-spectra leads to an overall classification accuracy of 93.1%, suggesting the great potential of low-cost aHSI system developed for radiodermatitis assessment.

Investigation of Narrow-band NIR LED Spectral Response Towards a Non-invasive Glucose Sensor.

Spectroscopy is utilised extensively in medical sensing technology. Typically, hand-held spectroscopy equipment uses miniature narrow-band light emitting diodes (LEDs) and photodiodes to emit and detect light, respectively. Photodiodes typically absorb light across a wide spectra so measurements can be corrupted by surrounding light. LEDs in the visible spectrum have a narrower spectral response and can be used in place of a traditional photodiode. However, the absorption characteristics of near infrared (NIR) spectrum LEDs is unknown. A discrete, low-cost spectrophotometer was designed to assess spectral response for 8 narrow band NIR LEDs. The normalised and raw spectral response determined the optimum detector for 1050 nm - 1300 nm is the 1450 nm LED, and the optimum detector for 1450 nm - 1650 nm emissions is the 1650 nm LED.Clinical relevance - Understanding the spectral response of narrow-band LEDs in the NIR spectrum will aid development of NIR hand-held spectroscopy medical devices.

Key to the conservation of calligraphy and painting relics in collection: proposing a lighting damage evaluation method

As an important supporting material for calligraphy and painting relics in collections, the silk substrate is generally in acidification. And owing to an extremely high light response, it is very prone to different forms of lighting damage, including color and mechanical aspects. Considering that the Light Emitting Diode (LED) with flexible spectral compositions is widely used in the lighting environment of collections, the spectral responsivity of acidified silk substrates is the core issue concerning the long-term conservation of calligraphy and painting relics. In this study, based on the accelerated aging experiment of nine narrowband LEDs with different wavelengths (λ) in the visible range on silk samples with different acidification degrees (pH values), the infrared spectrum was measured non periodically. Processed with the Principal Component Analysis (PCA), the obtained ΔPC1 was used to evaluate the lighting damage of silk samples. Based on the damage change curve, its spectral responsivity function, that is, the mathematical relationship between lighting damage and λ and pH values, was further fitted. Combined with the previous research on the spectral responsivity of colorants, an evaluation method for lighting damage was proposed, which is the key to the conservation of calligraphy and painting relics.

The spectral composition of a white light influences its attractiveness to Culex pipiens mosquitoes.

Insect attraction to artificial light can potentially facilitate disease transmission by increasing contact between humans and vectors. Previous research has identified specific wavelength bands, such as yellow and red, that are unattractive to biting flies. However, narrow-band, non-white lights are unsuitable for home lighting use as their very poor color rendering is often considered aesthetically undesirable. The creation of a white light that is unattractive to insects has so far remained elusive. White light can be created by combining a number of narrow-band light-emitting diodes (LEDs). Through choice chamber experiments on Culex pipiens (Cx.pipiens) mosquitoes, we examine whether combining specific wavelength bands has an additive, subtractive or synergistic effect on insect attraction. We show that a white light created by combining narrow-band red, green and blue (RGB) LEDs is less attractive to Cx.pipiens than a broad-spectrum white light; and that a white light created by combining narrow-band blue and yellow LEDs is more attractive than a broad-spectrum white light. White light produced by RGB combinations could therefore serve as a safer and cheaper light in countries where phototactic vectors and vector-borne disease are endemic.

Spectral Light Fading of Inkjet Prints

(1) Background: The use of light-emitting diode (LED) lighting is increasingly replacing traditional light sources in museums. There is a need to anticipate the damage caused by LED lighting to photographic prints. The aim of this study is to quantitatively predict fading on three inkjet color patches exposed to different white light LED; (2) Method: The novel approach of this work is to measure the wavelength-dependent photochemical efficiency on color patches using a narrow band LED. First, the color patches are exposed to narrow band LED lamps in a proprietary light chamber. Sensitivity curves are obtained by plotting the density changes caused by narrow band exposure as a function of the exposure. In the second step, action spectra are derived from the slopes of the sensitivity curves. The action spectra correspond to the rates of change of a color patch to exposure with different wavelengths of light. In the third step, the narrow band light emissions are fitted to the emission spectra of the white LED of interest. The fitting factors are used to calculate the weighted sum of the density changes; (3) The method predicts the absolute density change of color patches for several white light LED exposures.

Plastic Morphological Response to Spectral Shifts during Inorganic Phototropic Growth.

Plants exhibit phototropism in which growth is directed toward sunlight and demonstrate morphological plasticity in response to changes in the spectral distribution of the incident illumination. Inorganic phototropic growth via template-free, light-directed electrochemical deposition of semiconductor material can spontaneously generate highly ordered mesostructures with anisotropic, nanoscale lamellar features that exhibit a pitch proportional to the wavelength (λ) of the stimulating illumination. In this work, Se–Te films were generated via a two-step inorganic phototropic growth process using a series of narrowband light-emitting diode sources with discrete output wavelengths (λ0 ≠ λ1). Analogous to the plasticity observed in plants, changes in illumination wavelength from λ0 to λ1 resulted in morphological changes including feature branching, termination, and/or fusion along the growth direction. The interfacial feature pitch changed with the growth duration, in some cases in a notably nonmonotonic fashion, and eventually matched that obtained for growth using only λ1. Simulated morphologies generated by modeling light–material interactions at the growth interface closely matched the evolved structures observed experimentally, indicating that the characteristics of the optical stimulation produce the observed plastic response during inorganic phototropic growth. Examination of the interfacial electric field modulation for λ1 illumination of simplified structures, representative of those generated experimentally, revealed the interfacial light scattering and concentration behavior that directed phototropic growth away from equilibrium, as well as the emergent nature of the phenomena that reestablish equilibrium.

Narrow-Band Light-Emitting Diodes (LEDs) Effects on Sunflower (Helianthus annuus) Sprouts with Remote Monitoring and Recording by Internet of Things Device.

Previous studies have demonstrated that light quality critically affects plant development and growth; however, the response depends upon the plant species. This research aims to examine the effects of different light wavelengths on sunflower (Helianthus annuus) sprouts that were stimulated during the night. Natural light and narrow-band light-emitting diodes (LEDs) were used for an analysis of sunflower sprouts grown under full light and specific light wavelengths. Sunflower seeds were germinated under different light spectra including red, blue, white, and natural light. Luminosity, temperature, and humidity sensors were installed in the plant nursery and remotely monitored and recorded by an Internet of Things (IoT) device. The experiment examined seed germination for seven days. The results showed that the red light had the most influence on sunflower seed germination, while the natural light had the most influence on the increase in the root and hypocotyl lengths.

Application of ESCO phytosystem based on narrow-band light-emitting diodes for growing cucumbers under photoculture conditions

The article deals with the study of photomorphogenesis of different cucumber varieties under light culture conditions. Studies were carried out under laboratory conditions using an experimental phytosystem ESCO based on narrow-band light-emitting diodes, which is equipped with a microcontroller. The microcontroller controls the supplementary light modes. Studies were conducted to develop recommendations for selecting and controlling the spectral composition of light optimal for the life cycle of plants. The aim of our research is to study photomorphogenesis of different cucumber varieties under light-culture conditions using an experimental ESCO phytosystem based on narrow-band light-emitting diodes equipped with a microcontroller that controls the supplementary light modes. Four cucumber hybrids were used to test the ESCO phytosystem. Phytolamps were placed at the height of 1 m in the beginning, then at the height of 1.2 m. Every day we recorded the growth of shoot length, establishment of generative organs (flowers), we recorded the date of flowering and fruit formation. Conditions of humidity, nutrient and air regimes corresponded to biological requirements of growth and development of cucumber plants. Studies have shown that laying of generative organs of cucumber with additional lighting with narrow-band light emitting diodes is good. Female flowers appeared 7-14 days earlier in BV700+RV350+ BF350+FRF350 regime than in plants grown under natural light. The RV light regime had a significant effect on the increase in plant height. Determination of chlorophyll content showed its optimal amount and depended on the varietal characteristics of plants. The best supplementary light mode was BV700+RV350+ BF350+FRF350 during the cultivation of seedlings of different cucumber hybrids. Mode change all to 500 after planting in the ground.

Case Studies on Structure-Property Relations in Perovskite Light-Emitting Diodes via Interfacial Engineering with Self-Assembled Monolayers.

Metal halide perovskites promise bright and narrow-band light-emitting diodes (LEDs). To this end, reliable understanding on structure-property relations is necessary, yet singling out one effect from others is difficult because photophysical and electronic functions of perovskite LEDs are interwoven each other. To resolve this problem, we herein employ self-assembled monolayers (SAMs) for interfacial engineering nanomaterials. Four different molecules that have the same anchor (thiol), different backbone (aryl vs alkyl) and different terminal group (amine vs pyridine vs methyl) are used to form SAMs at the interface with the thin film of a green-color perovskite, CH3NH3PbBr3. SAM-engineered perovskite films are characterized with X-ray diffraction (XRD), depth-profile X-ray photoelectron spectroscopy (XPS), Kelvin probe force microscopy (KPFM), scanning electron microscopy (SEM), time-resolved laser spectroscopy, and UV-vis absorption and emission spectroscopies. This permits access to how the chemical structure of molecule comprising SAM is related to the various chemical and physical features such as quality and grain size, cross-sectional atomic composition (Pb(0) vs Pb(II)), charge carrier lifetime, and charge mobility of perovskite films, leading to inferences of structure-property relations in the perovskite. Finally, we demonstrate that the trends observed in the model system stem from the affinity of SAM over the undercoordinated Pb ions of perovskite, and these are translated into considerably enhanced EQE (from 2.20 to 5.74%) and narrow-band performances (from 21.3 to 15.9 nm), without a noticeable wavelength shift in perovskite LEDs. Our work suggests that SAM-based interfacial engineering holds a promise for deciphering mechanisms of perovskite LEDs.

A novel multi-band plenoptic pyrometer for high-temperature applications

A snapshot, multi-band imaging pyrometer was developed for two-dimensional, high-temperature measurements. The multi-band pyrometer is composed of a plenoptic camera and a continuous wavelength filter (450 nm–850 nm), located at the aperture plane of the primary imaging lens. A microlens array forms micro-images of the color filter with a resulting spectral resolution of approximately 25 nm per pixel. A wavelength calibration method was developed to use eight narrow-band light-emitting diodes at discrete wavelengths with sub-pixel wavelength location determined using a weighted intensity centroid algorithm. Temperature calibration was conducted using a graphite block as a gray-body radiator placed in a box furnace with controlled temperatures of 600 ∘C–1100 ∘C. Temperature is estimated at each microlens location using the spectral pyrometry method, which reduces the dependency of the measurement on a priori knowledge of material emissivity. Simulated data with Gaussian noise demonstrates reduced uncertainty at higher temperatures and larger bit-depths. Experimental measurements with a heated graphite block demonstrated accuracy within the uncertainty bounds of a reference thermocouple (±0.75%). In addition, validation experiments were conducted in the more dynamic environments of a strand burner and a solidifying copper pool, which contain high-temperature, moving particles and phase dependent emissivity, respectively. The addition of alumina particles to solid fuel produced an expected increase of over 400 ∘C that was measured by both a multi-band imaging pyrometer and a thermocouple. The pyrometer demonstrated the ability to measure temperatures for liquid and solid phases of copper simultaneously with temperature accuracy better than 5%, despite larger differences in material emissivity.

An Approach for Designing Mixed Light-Emitting Diodes to Match Greenhouse Plant Absorption Spectra

We report a methodological approach for simulating luminary output radiation, which is achieved by mixing light-emitting diodes (LEDs) in order to match any plant absorption spectrum. Various recorded narrow-band LED spectra of different colors were first characterized and then fitted with a multi-Gaussian model. An optimizing procedure computed the optimal weighting of the relevant parameters so as to minimize the discrepancy between the combined spectrum and the reference target curve. The particle swarm optimization (PSO) method was applied because it is the most suitable technique for mono-objective situations. Within the useful spectral interval, the worst relative standard deviation between the optimized curve and recorded LED spectral power distribution (SPD) was 3.4%. When combining different LED types, the simulated light output showed that we could limit ourselves to selecting only five colored sources. This work will help us to design an optimized 200 W laboratory luminaire with a pulse-width switched-mode power supply.

Spectral effects of blue and red light on growth, anatomy, and physiology of lettuce.

Characterizing spectral effects of blue and red light ratios on plants could help expand our understanding of factors that regulate growth and development, which is becoming increasingly important as narrowband light-emitting diodes become common for sole-source lighting. Herein we report growth, physiological, and anatomical responses of two lettuce cultivars grown indoors under various blue and red ratios including monochromatic treatments. When used in combination with red, increasing the proportion of blue light generally reduced growth but increased chloroplast abundance and single-leaf photosynthetic efficiency. However, when used as single wavebands, both blue and red light increased leaf area and epidermal cell area, but reduced root dry mass, SPAD index, stomatal density, and leaf thickness compared to dichromatic light. In addition, chloroplast abundance and single-leaf physiological responses were higher in plants grown under monochromatic blue compared to red light, but the opposite trend was measured for shoot biomass. Our results show that spectral effects on morpho-anatomical leaf responses can largely influence plant growth and single-leaf physiological responses. However, a significant blue light reduction in radiation capture ultimately limits growth and productivity of lettuce plants when dichromatic blue and red light is used.

Narrowband Blue and Red LED Supplements Impact Key Flavor Volatiles in Hydroponically Grown Basil Across Growing Seasons.

The use of light-emitting diodes (LEDs) in commercial greenhouse production is rapidly increasing because of technological advancements, increased spectral control, and improved energy efficiency. Research is needed to determine the value and efficacy of LEDs in comparison to traditional lighting systems. The objective of this study was to establish the impact of narrowband blue (B) and red (R) LED lighting ratios on flavor volatiles in hydroponic basil (Ocimum basilicum var. “Genovese”) in comparison to a non-supplemented natural light (NL) control and traditional high-pressure sodium (HPS) lighting. “Genovese” basil was chosen because of its high market value and demand among professional chefs. Emphasis was placed on investigating concentrations of important flavor volatiles in response to specific ratios of narrowband B/R LED supplemental lighting (SL) and growing season. A total of eight treatments were used: one non-supplemented NL control, one HPS treatment, and six LED treatments (peaked at 447 nm/627 nm, ±20 nm) with progressive B/R ratios (10B/90R, 20B/80R, 30B/70R, 40B/60R, 50B/50R, and 60B/40R). Each SL treatment provided 8.64 mol ⋅ m−2 ⋅ d–1 (100 μmol ⋅ m–2 ⋅ s–1, 24 h ⋅ d–1). The daily light integral (DLI) of the NL control averaged 9.5 mol ⋅ m−2 ⋅ d–1 during the growth period (ranging from 4 to 18 mol ⋅ m−2 ⋅ d–1). Relative humidity averaged 50%, with day/night temperatures averaging 27.4°C/21.8°C, respectively. Basil plants were harvested 45 days after seeding, and volatile organic compound profiles were obtained by gas chromatography–mass spectrometry. Total terpenoid concentrations were dramatically increased during winter months under LED treatments, but still showed significant impacts during seasons with sufficient DLI and spectral quality. Many key flavor volatile concentrations varied significantly among lighting treatments and growing season. However, the concentrations of some compounds, such as methyl eugenol, were three to four times higher in the control and decreased significantly for basil grown under SL treatments. Maximum concentrations for each compound varied among lighting treatments, but most monoterpenes and diterpenes evaluated were highest under 20B/80R to 50B/50R. This study shows that supplemental narrowband light treatments from LED sources may be used to manipulate secondary metabolic resource allocation. The application of narrowband LED SL has great potential for improving overall flavor quality of basil and other high-value specialty herbs.

Circadian tuning with metameric white light: Visual and non-visual aspects

The growing awareness of the biological effects of electric light on humans has stimulated ample research. New research has been devoted to lighting solutions that dynamically change their colour to mimic spectral changes of daylight. However, in some situations, the visual properties of light must be preserved, such as when working under standardised lighting conditions to do colour correction in post-production. We have investigated the possibility to tune circadian effects using white lights that are spectrally different but nonetheless appear as a similar white tone. Our simulation results, for example, sets of light-emitting diodes, indicate that it is possible to modulate circadian light effects from 0.20 to 0.41 circadian stimulus by combining light-emitting diodes to create neutral white (4000 K) light. However, the results also show that the solutions combining single-colour light-emitting diodes leading to similar range between maximum and minimum circadian stimulus (ΔCS &gt; 0.20) have a CRI below 80. Combining narrowband light-emitting diodes with a broadband white light-emitting diode improves the colour-rendering quality, and we show how far circadian light effects can be tuned according to common theoretical models. The aim is to maintain the natural cycle of melatonin levels as much as possible with high light stimulus in the morning and low light stimulus in the evening. Therefore, we show what maximum and minimum circadian effects are possible with a given set of light-emitting diodes.

Field evaluation of light-emitting diodes to trap the cotton bollworm, Helicoverpa armigera

The cotton bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is a limiting pest of many agricultural crops worldwide. At present, in-field populations of H. armigera are routinely monitored using conventional light traps. During 2014, 2015, we conducted field assays to assess the relative attractiveness of narrow-band light-emitting diodes (LEDs) at 19 single wavelengths (375–748 nm) in H. armigera light traps. Between 2016 and 2019, LEDs with the most attractive wavelengths were then further evaluated in two different sites, i.e., Xinxiang and Anci (China). During 2014–2015, the highest H. armigera trap capture was obtained with LEDs at 395 nm, while it was not significantly different from LED wavelengths of 375 nm and 418 nm in 2015. During field trials in Xinxiang, H. armigera trap capture did not differ among (four) wavelengths (375 nm, 385 nm, 395 nm, and 405 nm) in either year. In the Anci site, most H. armigera adults were caught in traps equipped with LEDs of 385 nm during two years, but it was not significantly different from those at 405 nm in 2017. In 2019, H. armigera trap capture rate was higher for LEDs at 385 nm than for those at 395 nm, and 2.91-fold higher to that of a commercial UV blacklight (365 ± 50 nm) trap. Our work shows how LED-equipped traps constitute an efficient, energy-conserving way to monitor cotton bollworm populations, providing trap capture rates that surpass those of conventional technologies. We discuss how these innovative measures can complement the integrated pest management (IPM) toolbox for H. armigera in China and abroad.

Metabolic Reprogramming in Leaf Lettuce Grown Under Different Light Quality and Intensity Conditions Using Narrow-Band LEDs

Light-emitting diodes (LEDs) are an artificial light source used in closed-type plant factories and provide a promising solution for a year-round supply of green leafy vegetables, such as lettuce (Lactuca sativa L.). Obtaining high-quality seedlings using controlled irradiation from LEDs is critical, as the seedling health affects the growth and yield of leaf lettuce after transplantation. Because key molecular pathways underlying plant responses to a specific light quality and intensity remain poorly characterised, we used a multi-omics–based approach to evaluate the metabolic and transcriptional reprogramming of leaf lettuce seedlings grown under narrow-band LED lighting. Four types of monochromatic LEDs (one blue, two green and one red) and white fluorescent light (control) were used at low and high intensities (100 and 300 μmol·m−2·s−1, respectively). Multi-platform mass spectrometry-based metabolomics and RNA-Seq were used to determine changes in the metabolome and transcriptome of lettuce plants in response to different light qualities and intensities. Metabolic pathway analysis revealed distinct regulatory mechanisms involved in flavonoid and phenylpropanoid biosynthetic pathways under blue and green wavelengths. Taken together, these data suggest that the energy transmitted by green light is effective in creating a balance between biomass production and the production of secondary metabolites involved in plant defence.

Observer Metamerism Models and Multiprimary Display Systems

Television and cinema displays are both trending toward greater ranges and saturation of reproduced colors, which are made possible by near-monochromatic illumination technologies. Through current broadcast and digital cinema standards work, system designs employing laser light sources, narrowband light-emitting diodes, quantum dots, and others are being actively endorsed in promotion of a wide color gamut. However, spectrally selective excitations of naturally different human color response functions exacerbate variability of observer experience. Furthermore, singular “standard observer” summaries of human color vision, such as those found in the International Commission on Illumination (CIE)'s 1931 and 1964 color-matching functions and extensively used in motion picture color management, are deficient in recognizing expected human vision variability. Many researchers have confirmed the magnitude of observer metamerism in color matching, but few have shown explicit color management with an aim of minimized observer perception variability. This paper shows that not only can observer metamerism influences be quantitatively predicted and confirmed psychophysically but that intentionally engineered multiprimary displays employing more than three primaries can also offer an increased color gamut with drastically improved consistency of experience.