Optics for color mixing
For white-light illumination, the appropriate output can be achieved by combining the output of discrete color emitters and/or using static white-light LEDs. There are a large number of ways that effective color mixing can be accomplished, including:
• No optics: the LEDs are oriented such that their outputs overlap at the target; with this approach, there is no control of the illuminance distribution at the target. • Individual optics: employs separate optics for each of the LEDs. • Group optic: employs a common optic for a group of LEDs. • Combination optic: employs individual or group optics whose outputs are then coupled into a final common optic. • Dichroics: technique that employs dichroic filters to improve the mixing into a common optic.
Color-mixing systems can be simulated using optical modeling software. This enables accurate modeling of sources, optical systems, and optical properties such that a realistic color distribution is found. The system can be radically altered, and potential problems can be circumvented.
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This article was published in the November/December 2007 issue of LEDs Magazine.
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