Problems with signal lighting colours’ recognition

The article presents the main eye hazards caused by excessive eye exposure on optical radiation. The human eye sensitivity spectral distribution in the context of signal colour recognition was discussed. In order to explain the effects of the mechanism of phenomena responsible for the recognition of signal lights colour, a graphical analysis of spectral distributions of signal lights emitted from traditional incandescent sources and LED sources (light emitting diode) was performed. This analysis also takes into account the conditions under which observation of signal lights may take place (daylight and night vision conditions). The conclusions also indicate the further direction of studies on the influence of colour recognition affected by vision conditions, eye sensitivity spectral distribution (including disturbance of colour recognition) and different types of signal light sources.

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Spectral ray data for optical simulations

Advanced Optical Technologies ◽

10.1515/aot-2018-0049 ◽

2019 ◽

Vol 8 (1) ◽

pp. 55-65

Author(s):

Ingo Rotscholl ◽

Klaus Trampert ◽

Franz Schmidt

Keyword(s):

Ray Tracing ◽

Optical System ◽

White Light ◽

Light Emitting Diode ◽

Angular Variable ◽

Light Sources ◽

Far Field ◽

Mathematical Concepts ◽

Light Emitting ◽

Different Types

Abstract This paper summarizes selected approaches, to generate spectral ray data for different types of spectrally varying light sources including only angular variable as well as spatial and angular variable sources. This includes a description of their general ideas and applications, the required measurements, and their mathematical concepts. Finally, achieved results for an Red/Green/Blue/White-light emitting diode (RGBW-LED) system are shown. Ray tracing simulations of a spatially and angularly spectral varying LED system combined with a spectrally sensitive optical system are qualitatively and quantitatively compared to a colorimetric far-field measurement of the same system. The results demonstrate the potential and benefits of spectral ray files in general.

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Radiometric and Spectrophotometric Analysis of Third Generation Light-Emitting Diode (LED) Light-Curing Units

The Journal of Contemporary Dental Practice ◽

10.5005/jcdp-8-2-43 ◽

2007 ◽

Vol 8 (2) ◽

pp. 43-51 ◽

Cited By ~ 5

Author(s):

Barry M. Owens ◽

Kelbin H. Rodriguez

Keyword(s):

Spectral Distribution ◽

Light Emitting Diode ◽

Spectrophotometric Analysis ◽

Battery Life ◽

Light Sources ◽

Third Generation ◽

Light Emitting ◽

Led Light ◽

Restorative Materials ◽

Light Curing

Abstract Aims Light-emitting diode (LED) polymerization of dental restorative materials has become increasingly popular. However, individual light-curing unit (LCU) functions (intensity and/or wavelength emission) may not conform to manufacturer specifications due to quality control issues. The purpose of this study was to evaluate the quality of irradiance, in terms of power density (intensity) and spectral distribution (peak wavelength), emitted from LED and quartz-tungsten halogen (QTH) LCUs in vitro. The battery expenditure of these LED units was also tested. Methods and Materials The intensity and spectral distribution from four third generation LED (Smartlite PS, Coltolux LED, radii Plus, Diopower) and one QTH (Schein Visible Cure) light sources were measured using six different dental curing light meters (Coltolux, Cure Right, Demetron 100, Demetron LED., Hilux, and Light Meter-200) and a visible-ultraviolet light spectrophotometer (Hitachi Elmer-Perkins). The battery life was also plotted for each light source following a 1500 second duration period. The data obtained from radiometric and spectrophotometric analysis was compared to manufacturer specifications. Results Radiometric evaluation revealed LED light units tested did not satisfy manufacturer claims for minimum intensities. Spectral emissions from the LED light sources did meet manufacturer requirements. No clinically appreciable battery drain was evidenced from testing all re-chargeable LED units. Conclusion Despite limitations LED technology appears to be an effective alternative for curing of lightactivated esthetic restorative materials. Additional advantages associated with LED curing lights include ergonomic handling capabilities, negative heat generation, and minimal maintenance concerns. Citation Owens BM, Rodriguez KH. Radiometric and Spectrophotometric Analysis of Third Generation Light- Emitting Diode (LED) Light-Curing Units. J Contemp Dent Pract 2007 February;(8)2:043-051.

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Electrically driven single microribbon based near-infrared exciton-polariton light-emitting diode

CrystEngComm ◽

10.1039/d1ce00419k ◽

2021 ◽

Author(s):

Mingming Jiang ◽

Fupeng Zhang ◽

Kai Tang ◽

Peng Wan ◽

Caixia Kan

Keyword(s):

High Performance ◽

Near Infrared ◽

Light Emitting Diodes ◽

Light Emitting Diode ◽

Light Sources ◽

Coherent Light ◽

Light Emitting ◽

Exciton Polaritons ◽

Laser Devices

Achieving electrically-driven exciton-polaritons has drawn substantial attention toward developing ultralow-threshold coherent light sources, containing polariton laser devices and high-performance light-emitting diodes (LEDs). In this work, we demonstrate an electrically driven...

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Reliability of High-Power Light Emitting Diode Attached With Different Thermal Interface Materials

Journal of Electronic Packaging ◽

10.1115/1.4002299 ◽

2010 ◽

Vol 132 (3) ◽

Cited By ~ 23

Author(s):

Xin Li ◽

Xu Chen ◽

Guo-Quan Lu

Keyword(s):

High Power ◽

Heat Dissipation ◽

Light Emitting Diode ◽

Temperature Cycling ◽

Fluorescent Light ◽

Light Sources ◽

Light Emitting ◽

Die Attach ◽

Nanosilver Paste ◽

Interconnection Material

As a solid electroluminescent source, white light emitting diode (LED) has entered a practical stage and become an alternative to replace incandescent and fluorescent light sources. However, due to the increasing integration and miniaturization of LED chips, heat flux inside the chip is also increasing, which puts the packaging into the position to meet higher requirements of heat dissipation. In this study, a new interconnection material—nanosilver paste is used for the LED chip packaging to pursue a better optical performance, since high thermal conductivity of this material can help improve the efficiency of heat dissipation for the LED chip. The bonding ability of this new die-attach material is evaluated by their bonding strength. Moreover, high-power LED modules connected with nanosilver paste, Sn3Ag0.5Cu solder, and silver epoxy are aged under hygrothermal aging and temperature cycling tests. The performances of these LED modules are tested at different aging time. The results show that LED modules sintered with nanosilver paste have the best performance and stability.

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Enhancing and Tuning broadband near-infrared (NIR) photoluminescence properties in Cr3+-doped Ca2YHf2Al3O12 garnet phosphors via Ce3+/Yb3+-codoping for LED applications

Journal of Materials Chemistry C ◽

10.1039/d0tc05657j ◽

2021 ◽

Author(s):

Qianqian Zhang ◽

Guogang Li ◽

Peipei Dang ◽

Dongjie Liu ◽

Dayu Huang ◽

...

Keyword(s):

Near Infrared ◽

Light Emitting Diode ◽

Food Composition ◽

Night Vision ◽

Photoluminescence Properties ◽

Light Emitting ◽

Measurement Area

Near-infrared emitting phosphor-converted light-emitting diode (NIR pc-LED) attracts much attention as the promising applications in night vision, biosensor, food composition and freshness measurement area and so on, while the discovery...

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In-Use Photostability Practice and Regulatory Evaluation for Pharmaceutical Products in an Age of Light-Emitting Diode Light Sources

Journal of Pharmaceutical Sciences ◽

10.1016/j.xphs.2018.10.003 ◽

2019 ◽

Vol 108 (3) ◽

pp. 1172-1176 ◽

Cited By ~ 3

Author(s):

Leonardo R. Allain ◽

Brittany C. Pierce ◽

W. Peter Wuelfing ◽

Allen C. Templeton ◽

Roy Helmy

Keyword(s):

Light Emitting Diode ◽

Pharmaceutical Products ◽

Light Sources ◽

Light Emitting ◽

Regulatory Evaluation

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Manufacture and Evaluation of Light Emitting Diode Package Substrate Using Flexible Printed Circuit Board

Journal of Nanoscience and Nanotechnology ◽

10.1166/jnn.2015.11153 ◽

2015 ◽

Vol 15 (10) ◽

pp. 7578-7581

Author(s):

Jung-Kab Park ◽

Jin-Ha Shin ◽

Mun-Gi Jung ◽

Tomabechi Shigehisa ◽

Hwa-Sun Park ◽

...

Keyword(s):

Thermal Resistance ◽

Light Emitting Diode ◽

Thermal Conductance ◽

Polyimide Film ◽

Luminous Efficiency ◽

Circuit Board ◽

Light Sources ◽

Thermal Shock Test ◽

Light Emitting ◽

Au Electrode

Unlike other light sources such as fluorescent lamps and incandescent bulbs, light-emitting diodes (LED) convert 70∼80% of energy into heat. If the heat produced an LED chip is not effectively released, its luminous efficiency and lifespan are reduced. Therefore, as a method effectively release heat, an LED PKG substrate containing a heat-releasing material with excellent thermal conductance was fabricated, and its thermal resistance and luminous efficiency were analyzed. In this experiment, a thin polyimide film with excellent ductility was used to fabricate the LED PKG substrate. A 35-μm-thick Cu foil with excellent thermal conductance was subjected to high temperature and pressure and attached to both sides of the polyimide film. By electroplating Ag or Au, which has excellent thermal conductance, for us as the electrode and heat-releasing material, LED PKG substrate was fabricated with a thickness of approximately 170 μm. (−40 °C → RT → 120 °C). The results revealed that the LED PKG substrate having a Ag electrode with excellent thermal conductance had an excellent thermal resistance of approximately 4.2 °C/W (Au electrode: 5.6 °C/W). The luminous flux after 100 cycles in the thermal shock test was reduced by approximately 0.09% (Au electrode: 2.77%), indicating that the LED PKG substrate had excellent thermal resistance without any mechanical and material defects in a rapid-temperature-changing environment. The advantages and excellent thermal resistance can be exploited in cellular phones and LCD panels, and heat-releasing problems in thin panels be solved.

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