Dr. Xi Mou Profile

Dr. Xi Mou

at Sensing Instrument

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Publications (7)

Proceedings Article | 1 April 2019 Paper

A theoretical model for predicting LED product lifetime based on solder joint failure

Nadarajah Narendran, Dinusha Thotagamuwa, Yi-wei Liu, Xi Mou

Proceedings Volume 10940, 109401Q (2019) https://doi.org/10.1117/12.2508001

KEYWORDS: Light emitting diodes, Lamps, Switching, LED lighting, Light sources and illumination, Electronics, Standards development

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Proceedings Article | 6 September 2017 Paper

Opportunities and challenges for 3D printing of solid-state lighting systems

Nadarajah Narendran, Indika Perera, Xi Mou, Dinusha Thotagamuwa

Proceedings Volume 10378, 1037802 (2017) https://doi.org/10.1117/12.2281045

KEYWORDS: 3D printing, Printing, Light emitting diodes, Light sources and illumination, Solid state lighting, Additive manufacturing, Manufacturing, LED lighting, Optical components, Solid state electronics

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SPIE Journal Paper | 12 May 2017 Open Access

Preliminary evaluation of discomfort glare from organic light-emitting diode and edge-lit light-emitting diode lighting panels

Xi Mou, Jean Paul Freyssinier, Nadarajah Narendran, John Bullough

JBO, Vol. 22, Issue 05, 055004, (May 2017) https://doi.org/10.1117/12.10.1117/1.JBO.22.5.055004

KEYWORDS: Organic light emitting diodes, Light emitting diodes, Light sources and illumination, Light sources

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Proceedings Article | 14 September 2016 Paper

Projecting LED product life based on application

Nadarajah Narendran, Yi-wei Liu, Xi Mou, Dinusha Thotagamuwa, Oshadhi V. Madihe Eshwarage

Proceedings Volume 9954, 99540G (2016) https://doi.org/10.1117/12.2240464

KEYWORDS: Light emitting diodes, LED lighting, Light sources and illumination, Failure analysis, Light sources, Lamps, Solid state lighting, Switching, Temperature metrology, Combustion

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LED products have started to displace traditional light sources in many lighting applications. One of the commonly claimed benefits for LED lighting products is their long useful lifetime in applications. Today there are many replacement lamp products using LEDs in the marketplace. Typically, lifetime claims of these replacement lamps are in the 25,000-hour range. According to current industry practice, the time for the LED light output to reach the 70% value is estimated according to IESNA LM-80 and TM-21 procedures and the resulting value is reported as the whole system life. LED products generally experience different thermal environments and switching (on-off cycling) patterns when used in applications. Current industry test methods often do not produce accurate lifetime estimates for LED systems because only one component of the system, namely the LED, is tested under a continuous-on burning condition without switching on and off, and because they estimate for only one failure type, lumen depreciation. The objective of the study presented in this manuscript was to develop a test method that could help predict LED system life in any application by testing the whole LED system, including on-off power cycling with sufficient dwell time, and considering both failure types, catastrophic and parametric. The study results showed for the LED A-lamps tested in this study, both failure types, catastrophic and parametric, exist. The on-off cycling encourages catastrophic failure, and maximum operating temperature influences the lumen depreciation rate and parametric failure time. It was also clear that LED system life is negatively affected by on-off switching, contrary to commonly held belief. In addition, the study results showed that most of the LED systems failed catastrophically much ahead of the LED light output reaching the 70% value. This emphasizes the fact that life testing of LED systems must consider catastrophic failure in addition to lumen depreciation, and the shorter of the two failure modes must be selected as the system life. The results of this study show a shorter time test procedure can be developed to accurately predict LED system life in any application by knowing the LED temperature and the switching cycle.

Proceedings Article | 7 September 2016 Paper

Evaluation of OLED and edge-lit LED lighting panels

Nadarajah Narendran, Xi Mou, Yiting Zhu, Jean Paul Freyssinier

Proceedings Volume 9954, 995403 (2016) https://doi.org/10.1117/12.2240465

KEYWORDS: Organic light emitting diodes, Light emitting diodes, Light sources, Light sources and illumination, LED lighting, Solid state lighting, Light, Eye, Visualization

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Proceedings Article | 25 September 2014 Paper

An imaging-based photometric and colorimetric measurement method for characterizing OLED panels for lighting applications

Nadarajah Narendran, Yiting Zhu, Jianchuan Tan, Xi Mou

Proceedings Volume 9190, 91900E (2014) https://doi.org/10.1117/12.2062262

KEYWORDS: Organic light emitting diodes, Light sources and illumination, Light emitting diodes, Standards development, Manufacturing, Temperature metrology, OLED lighting, Imaging systems, Infrared cameras, Luminous efficacy

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Proceedings Article | 18 September 2014 Paper

Optical and thermal performance of a remote phosphor plate

Nadarajah Narendran, Xi Mou, Yiting Zhu, Indika Perera

Proceedings Volume 9190, 91900Q (2014) https://doi.org/10.1117/12.2063045

KEYWORDS: Light emitting diodes, Thermography, Geometrical optics, Temperature metrology, Magnesium, Infrared cameras, Epoxies, Reflectors, Ray tracing, Near field optics

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