| 摘要 |
In spectroscopy or color measurement applications which characterize the transmission, absorption, emission or reflection of a target material (such as ink on paper, paint on metal, dyes on cloth, etc.), an illumination source must be present, as well as an apparatus to measure the reflected, transmitted or emitted light. One method for providing the illumination is using light emitted from light emitting diodes (LEDs). To adequately characterize the material properties of the target that would be seen by a human observer, illumination over the entire visible wavelength range from 400nm to 700nm is desirable. Individual white or chromatic LEDs and even multiple-LED assemblies, however, often do not provide adequate intensity at all wavelengths in this range. One known solution for tailoring the emission spectra of a LED to cover the desired illumination range is to use an interference filter in combination with the LED to filter out the unwanted wavelengths. Such an arrangement, however, is not practical where the source (e.g., the LED) does not emit sufficient energy at the desired wavelength. Also, such arrangements can be inefficient for certain applications where much of the energy emissions from the source may be filter out and therefore wasted.
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