A color filter, often used for making color separations and generating laser light, that will only allow light of certain specified wavelengths through, causing all other wavelengths to be reflected. In contrast, a conventional filter absorbs all the light it doesn't transmit. A dichroic filter accomplishes this by means of several thin layers of coating that, for certain wavelengths, create interference reflections. The coatings can be so formulated to allow only light of a very narrow range of wavelengths to pass through, and as a result are widely used in scientific analysis. See Filter.
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