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Victor's Project Page - CAMP Summer 2007 |
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Intern: Victor Crampton, Electrical Engineering
Mentor: Hisashi Masui
Faculty Supervisor: Steven Denbaars
Department: Electrical Engineering |
FABRICATION OF WHITE LED LIGHT BULBS
Energy saving appliances provides one avenue for more sustainable resource use. Light Emitting Diodes (LEDs) are perfect for energy saving devices because they produce more light per unit power (watt) than incandescent bulbs. The Solid State Lighting Display Center (SSLDC) at UCSB has been working with single LEDs in conjunction with phosphorous layers in the creation of white light. This summer, SSLDC has had an interest in creating test systems for phosphorus layers on arrays of LEDs. These test systems will be use for light bulb fixtures and will have blue LEDs built into them. Layers of silicone and a phosphor mixture of cerenium doped yittium aluminum garnet (YAG) will be placed on top of the blue LEDs to emit white light. The goal of the test system is to focus on the optimal of phosphor concentration to maximize luminous flux. From measurements and calculations it is estimated that the maximum theoretical luminous flux that our blue LED bulb could have is 48lm. This will be at .3 in the x-coordinate of the chromatic chart. A 1.75mm layer of silicone and phosphor was fabricated with a 4% phosphor concentration. The light emitted measured to have an x-coordinate of .302 in the chromatic chart, and had a total luminous flux of 27lm, resulting in 44% loss in luminous flux. Further research is being done, in order to understand what the major factors that are causing the 21lm loss in the phosphor test system.
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