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Showing posts from November, 2015

Li-Fi LEDs for Internet of Things

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Li-Fi   is a   bidirectional , high speed and fully networked   wireless communication   technology similar to   Wi-Fi . Coined by Prof. Harald Haas, Li-Fi is a subset of   optical wireless communications   (OWC) and can be a complement to   RF communication   ( Wi-Fi   or   Cellular network ), or a replacement in contexts of   data broadcasting . It is wireless and uses   visible light communication   or infra-red and near ultraviolet (instead of radio frequency waves) spectrum, part of optical wireless communications technology, which carries much more information, and has been proposed as a solution to the   RF-bandwidth limitations .   A complete solution includes an industry led standardization process. Technology details This OWC technology uses light from  light-emitting diodes  (LEDs) as a medium to deliver networked, mobile, high-speed communication in a similar manner to  W...

Light Color and Color Rendering

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True Colors do not exist. People tend to judge colors under what they consider to be natural or true lighting conditions, often  mistakenly using daylight for this purpose. but the colors seen under daylight on a Sunny day can be widely different to those seen on a day with overcast sky. For the spectral distribution of daylight is not constant, but is continually changing from hour to hour and from season to season. The correct thing to do, of course , is to assess the colors under the same type of lighting as that existing in the area where they will be finally seen. For example, an evening dress would be chosen under incandescent lighting, for this is the sort of lighting most likely to be employed at the evening function where it will be worn. Similarly, the color scheme for an office should be preferably be chosen under lighting identical to that which will later be installed there. Image Courtesy Philips Spectral Distribution The spectral distribution of the light de...