Effects of Light-Emitting Diode (LED) Red and Blue Light on the Growth and Photosynthetic Characteristics of <i>Momordica charantia</i>L.

With andromonoecious Momordica charantia L. (bitter gourd) as material, three light qualities (50 μmol·m-2·s-1) including white LED light (WL), blue monochromatic light (B, 465 nm), and red monochromatic light (R, 650 nm) were carried out to investigate their effects on seed germination, physiological and biochemical parameters, sex differentiation and photosynthetic characteristics of bitter gourd. The results showed that compared to the WL treatment, the R treatment significantly promoted seed germination, seedling height elongation and soluble sugar content, the B treatment significantly increased seedling stem diameter, reducing sugar content and soluble protein content, the R and B treatments both significantly reduced sucrose content, but their POD activity showed no significant difference. Compared with the R treatment, the B treatment significantly increased the total female flower number and female flower nod ratio in 30 nods of main stems. The study of photosynthetic characteristics found that the R and B treatments could effectively increase the stomatal conductance (GS) of leaves, significantly improved the net photosynthetic rate (Pn) compared to the WL treatment, and the effect of the B treatment was better. Compared to the R and WL treatments, the B treatment increased the maximum photosynthetic rate (Pmax), apparent quantum efficiency (AQE) and light saturation point (LSP), and reduced the dark respiration rate (Rd) and light compensation point (LCP) of the leaves. Fit light response curves showed that the adaptability and utilization of weak light in bitter gourd were middle or below, but it showed higher adaptability and utilization of strong light. Thus, it suggests that Momordica charantia is a typical sun plan with lower Rd. In summary, it is concluded that blue light has a positive effect on the seed germination, seedling growth, sex differentiation and improving the photosynthetic performance, and this will lay the foundation for artificially regulating optimum photosynthesis using specific LEDs wavelength, and help to elucidate the relationship how light quality influences the sex differentiation of plant.

Pterygium associated with light-emitting diode use:a case report

Background:Pterygium is a sun-related ocular surface disease secondary to ultraviolet(UV)radiation exposure.Outdoor occupational UV exposure is known to occur secondary to sun exposure.We present a unique case of pterygium associated with indoor occupational light-emitting diode(LED)exposure not previously described in the literature.Case Description:A mobile phone repairer presented with blurred vision and a superotemporal pterygium of his dominant left eye associated with a magnifying glass LED work lamp was diagnosed.This was excised routinely with conjunctival autografting to the defect.Histopathology confirmed benign pterygium and recovery was uncomplicated with resolution of blur.Conclusions:The development of pterygium in our patient may have arisen due to the LED lamp’s wavelengths possibly falling within the UV as well as the upper end of the visible light radiation spectrum.Given the increasing reliance on LED light sources in modern life,ocular conditions arising from exposure to these radiation sources may now need to be listed in the differential diagnoses of patients with pterygium.Appropriate UV protection counselling for these types of lights may also now need to be considered.

Effect of packing density and packing geometry on light extraction of Ⅲ-nitride light-emitting diodes with microsphere arrays

The finite-difference time-domain method was employed to calculate light extraction efficiency of thin-film flip-chip In Ga N/Ga N quantum well light-emitting diodes（LEDs） with TiO2 microsphere arrays. The extraction efficiency for LEDs with microsphere arrays was investigated by focusing on the effect of the packing density,packing configuration, and diameter-to-period ratio. The comparison studies revealed the importance of having a hexagonal and close-packed monolayer microsphere array configuration for achieving optimum extraction efficiency, which translated into a 3.6-fold enhancement in light extraction compared to that for a planar LED. This improvement is attributed to the reduced Fresnel reflection and enlarged light escape cone. The engineering of the far-field radiation patterns was also demonstrated by tuning the packing density and packing configuration of the microsphere arrays.

LED光源在现代农业的应用原理与技术进展

随着LED技术的发展和制造成本的下降,LED光源在现代农业中的应用越来越受到世界各国的广泛关注。LED不仅具有体积小、寿命长、能耗低、发光效率高、发热低等光电特性优点,而且还能根据农业生物的需要进行光谱的精确配置,促进农业生物的生长发育和光形态建成,从而提高其产量和品质。本文介绍了LED在农业照明领域的应用现状,分析了LED在农业领域的应用潜力,指出了限制农用LED推广应用的关键因素,并提出促进LED在现代农业中应用的发展思路、方向和重点以及对策。

LED的光谱分布可调光源的设计

介绍了一种光谱分布可调光源的设计,该光源由积分球和大量不同颜色的LED组成。在可见波段,这种光源能产生不同光谱曲线,可以模拟很多不同光源的光谱分布。该项设计通过仿真使光源的光谱分布模拟目标光源的光谱分布,并设计了电源控制箱精确地控制每个LED模块。光源的面非均匀性为0.53%,角度特性在±10°以内,最大偏差为0.77%。这种新型光源在光辐射测量中可以作为一种传递标准。

水冷式植物工厂LED面光源及散热系统的研制与测试

大功率LED的散热问题影响着LED的发光效率和电能消耗。该研究设计了水冷式植物工厂LED面光源及散热系统,通过水循环将LED面光源产生的热量及时置换,从而降低LED结温、延缓其光衰,同时将置换的热量根据植物工厂需热特点配置,降低控温能耗。该系统主要包括LED面光源、散热器和水循环系统三部分。水循环系统水路分为两路,在采暖季节将热量置换于植物工厂内部用于室内增温,而在非采暖季节将热量置换于室外,通过风冷散热后再进入水循环系统。性能测试试验表明:水冷式散热装置具有降低LED面光源散热器温度的作用,较无水冷散热装置的散热器温度最少低5.3℃,最高低19.3℃,不仅直接降低了散热器温度,还间接降低了LED结温,从而延长了LED面光源的使用寿命。

利用LED的投影系统光源设计

设计了利用多颗LED(Light Emitting Diode,发光二极管)阵列组成的扩展面光源.经过合理的聚光设计使之符合某些投影设备对亮度要求不是很高,但结构紧凑、性能稳定、使用寿命长的要求.结合数学建模和软件模拟的方式设计了一种小巧的反光杯,利用反光杯把LED近180°的发散光束汇聚到60°左右;然后再用一一对应的透镜阵列汇聚为平行光;最后采用柯勒照明方式把较大的面光源阵列汇集到LCD投影屏幕上,从而达到了较高亮度且具有很高均匀性的目的.

Light output improvement of GaN-based light-emitting diodes grown on Si (111) by a via-thin-film structure

This work reports the fabrication of via-thin-film light-emitting diode （via-TF-LED） to improve the light output power （LOP） of blue/white GaN-based LEDs grown on Si （111） substrates. The as-fabricated via-TF-LEDs were featured with a roughened n-GaN surface and the p-GaN surface bonded to a wafer carrier with a silver-based reflective electrode, together with an array of embedded n-type via pillar metal contact from the p-GaN surface etched through the multiple-quantum-wells （MQWs） into the n-GaN layer. When operated at 350 mA, the via-TF- LED gave an enhanced blue LOP by 7.8% and over 3.5 times as compared to the vertical thin-film LED （TF-LED） and the conventional lateral structure LED （LS-LED）. After covering with yellow phosphor that converts some blue photons into yellow light, the via-TF-LED emitted an enhanced white luminous flux by 13.5% and over 5 times, as compared with the white TF-LED and the white LS-LED, respectively. The significant LOP improve- ment of the via-TF-LED was attributed to the elimination of light absorption by the Si （111） epitaxial substrate and the finger-like n-electrodes on the roughened emitting surface.

多主色LED照明光源的相关色温调控

通过建立光电热(PET)模型,研究了发光二极管(LED)光源相关色温(CCT)的模型预测控制方法,实现了多主色LED光源的相关色温控制。首先,提出了热平衡状态稳定假设和修正的非对称高斯函数作为基函数的假设;根据软模型建模思路,用最小二乘估计求解各个模型参量的回归子模型,分析光谱敏感系数曲线随CCT变化的关系。然后,通过重力线法调试出在3 000,4 500和6 500K下3个常用色温点处所需的电流控制量。最后,在调设好的电流控制量上加以一定的无规则扰动产生一组验证数据,用于评价模型精度。实验结果表明:建立的多主色LED光源的PET数学模型能够很好地通过电流控制量和环境温度来预测LED的热沉温度和多主色合成光谱功率分布函数,进而能够预测控制色温,具有很好的模型精度。得到的色度坐标预测精度优于±0.005,CCT预测精度优于±150K。提出的基于模型的控制方法不仅适用于常用LED光源的CCT调控,还可推广到更多通道的LED光源的色度及CCT控制中。

照明用无桥LED驱动电路及其输入电流谐波分析

用大功率高亮度发光二极管取代白炽灯、荧光灯等传统照明光源已是大势所趋,本文提出了一种直接利用市电但不需整流桥的大功率LED驱动电路。分析了其工作过程、输入输出电量与电路结构参数的关系及输入交流电流的谐波分布,指出该电路使用本文介绍的控制方法可以高效率运行,完全适应LED的特性需要,并且具有很高的功率因数和很小的电流谐波失真度,电路的实验结果证实了结论。

一种基于LED的光谱可调光源

介绍了一种光谱可调光源。该光源可以用来实现各种各样的光谱功率分布。一个光谱可调光源系统的具体设计包括成千上万个高功率LED,其波段可覆盖整个可见光光谱。光谱可调光源具有极大的现实意义,它除了可以对光学遥感器进行定标之外,还可以用于光度计和辐射度计的检测校准。通过模拟不同的光照条件,可以对材料特性及物体反射率进行评估。另外,该光源也可用于展示。

Traffic light detection and recognition in intersections based on intelligent vehicle

To ensure revulsive driving of intelligent vehicles at intersections, a method is presented to detect and recognize the traffic lights. First, the stabling siding at intersections is detected by applying Hough transformation. Then, the colors of traffic lights are detected with color space transformation. Finally, self-associative memory is used to recognize the countdown characters of the traffic lights. Test results at 20 real intersections show that the ratio of correct stabling siding recognition reaches up to 90%;and the ratios of recognition of traffic lights and divided characters are 85% and 97%, respectively. The research proves that the method is efficient for the detection of stabling siding and is robust enough to recognize the characters from images with noise and broken edges.

LED光源的电视应用

论文首先论述了光源发光原理和实用发光二极管(LED)光源的结构类型;然后,重点介绍了LED光源在家电领域:如液晶电视、显示器中的应用原理及过程;最后,对比总结了液晶电视和等离子电视在应用中的不同特点。

基于LED的光谱可调光源结构研究

介绍了一个由大量LED组合而成的光谱可调光源,通过不同LED的组合产生不同光谱分布,可以模拟各种光源。该光源主要由LED屏体、光谱匹配模块以及LED控制驱动模块构成。LED屏体由2 304个窄带LED组成,通过LED数据分配卡将接收到的显示数据进行分配,并驱动屏体上的LED,以PWM的方式精确控制每一个LED的电流,实现256级及以上灰度等级显示。整个系统经初步调试,已能模拟部分光谱。该光源将具有广泛的应用前景。

LED光源作为纤支镜光源在胸科手术中COOPDECH封堵管对位中的应用

目的评价发光二极管(LED)作为纤支镜光源在胸科手术中的应用。方法选择2016年7~12月入组的60例需行左肺手术的患者,随机分成A组(传统光源,n=30)和B组(LED光源,n=30),比较两组的左侧对位时间、再次对位次数、术中肺萎陷情况及对位成功率。同时选取60例需行右肺手术的患者,随机分成C组(传统光源,n=30)和D组(LED光源,n=30),记录右侧对位时间、再次对位次数、术中肺萎陷情况及对位成功率。结果 A组和B组对位时间[(32.6±9.8)s vs(36.4±9.9)s]、C组和D组对位时间[(41.1±11.0)s vs(40.2±11.2)s]均无明显差异(P>0.05)。A组和B组单肺时间[(74.4±20.9)min vs(81.6±21.5)min]、C组和D组单肺时间[(75.0±22.1)min vs(80.1±23.6)min]均无明显差异(P>0.05)。A和B组术中再次对位次数[(1.00±0.22)次vs(0.83±0.20)次]、C组和D组术中再次对位次数[(2.37±0.61)次vs(2.97±0.82)次]均无明显差异(P>0.05)。A组和B组术中肺萎陷情况[(1.87±0.42)分vs(2.21±0.40)分]、C组和D组术中肺萎陷情况[(1.86±0.41)分vs(1.79±0.36)分]均无明显差异(P>0.05)。4组对位成功率均为100%。左肺和右肺术中封堵管再次对位次数比较[(1.02±0.21)次vs(2.67±0.58)次],差异有统计学意义(P<0.01),术中左肺用纤支镜再次对位次数要少于右肺。结论 LED作为光源可以在胸外科麻醉中广泛应用。

基于红外LED的红外成像光学系统光源设计研究

在红外成像光学系统中提出一种基于红外LED的远距离照明系统光源设计新方法。利用红外LED的特点，设计出红外LED光源系统结构。在提高光源总的输出功率的几种方法中，采用非成像光学方法设计出一个会聚透镜和抛物面反射镜的共焦结构，减小了光源的发散角。该红外LED光源系统结构工作时照射出一束稳定的窄的高亮度平行红外光，在红外成像光学系统中能实现远距离照明。随着光源小型化和多功能的发展趋势，红外LED光源会在许多场所使用，它具有较好的性能价格比，适宜于我国目前国情，有一定的推广价值。

准直LED光斑定位系统设计

针对准直激光在长期工作过程中很难克服的漂移问题,设计了一套准直发光二极管(LED)光斑定位系统。该系统将LED光源发出的光经透镜汇聚进光纤,再经过准直器准直输出,用CCD探测光斑图像,采用多圆拟合法定位光斑位置。将系统与定制的半导体激光器(LD)准直定位系统进行了长期稳定性对比实验。结果表明,所设计的准直的LED光斑定位系统光斑位置漂移量更小,稳定性更高,可以作为高精密光学测量的定位基准光源。

LED光源在博物馆文物展示环境中应用展望

博物馆文物展示过程中 ,易受光照环境的红外及紫外辐射影响 ,而造成文物的老化损坏 ,于目前展示环境广为应用的金卤灯 ,因其投资成本及耗电量大而易造成博物馆运营的负担 ,LED新光源的发展已随光源研究的进步而渐受重视 ,本文乃就LED的发展历程与特性予与说明介绍 ,并就其在博物馆文物展示环境之应用潜力作一预测与分析。

蓝光LED芯片波长对COB光源颜色一致性的影响

采用不同波长的蓝光发光二极管（LED）芯片,制作了色坐标相同和人眼视觉效果相同的板上芯片（COB）白光LED样品,并分析了人眼视觉差异性产生的原因。研究结果表明,利用不同波长蓝光LED芯片制作白光LED时,在色坐标相同的情况下,会出现人眼视觉颜色不一致的现象。通过调整荧光粉中黄绿光荧光粉和红光荧光粉的比例,可以得到人眼视觉效果一致的LED光源,这时光源的色坐标、色温存在着差异。在实际生产中,COB白光LED的分档不能把色坐标作为唯一依据,只有建立蓝光波长和色坐标结合的分档标准,才可以保证同一档位光源人眼视觉效果的一致性。

Photosynthetic Performance and Potency of <i>Cannabis sativa</i>L. Grown under LED and HPS Illumination

Light-emitting diodes (LEDs) can be used as an energy efficient alternative to high-pressure sodium (HPS), which have historically been the standard for supplemental lighting in cannabis cultivation. However, there is a lack of scientific understanding in the cannabis industry regarding plant physiology, which has resulted in the adoption of cannabis cultivation methods based on hearsay rather than scientific research. The goals of this study were to 1) compare LED lighting options that are commonly used in the cannabis industry and 2) compare the top performing LED light with an industry standard HPS light. Specifically, three LED lights were compared (California Light Works ((SolarSystem 1100), BIOS Lighting (Icarus Gi2), and Fluence Bioengineering (now Fluence by Osram) (SPYDR xPLUS)), based on light distribution, leaf temperature, and photosynthetic performance indices. The LED versus HPS comparison was based on light response curves measured at photosynthetic photon flux densities (PPFD) of (0, 100, 200, 300, 400, 500, 750, 1000, 1250, 1500, 1750 and 2000 μmol∙m−2∙s−1), carbon assimilation rates (A) μmol CO2 m−2∙s−1 using a LiCor-6800 and resulting cannabinoid potency (THCA). The SPYDR xPLUS-Fluence by Osram had the highest performing LED light used in the LED comparison. At the suggested distance from bulb to canopy in the HPS versus LED comparison (6 inches for LEDs and 4 ft for HPS), carbon assimilation rates displayed a 142% percent increase in plants grown under LED vs. HPS with average photon flux densities of 795 and 298 μmol∙m−2∙s−1 for LED and HPS, respectively. All cultivars of Cannabis sativa L. showed increased cannabinoid potency when grown under LED illumination. The results of this study provide further insight regarding the selection of supplemental light to achieve maximum productivity of Cannabis sativa L.