A pair of LEDs having different wavelengths can supply the stimulus for a rudimentary spectral analysis during quality-control sorting operations. By measuring the reflectance of each LED, the circuit in Fig 1 can provide information about the spectral response of the object under test. The circuit’s operation is akin to the human eye’s using three receptors to deduce information about the entire visible spectrum.
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http://www.edn.com/archives/1994/090194/18di4.htm
This entry was posted on Tuesday, July 1st, 2008 at 7:26 am and is filed under detector, Lighting.



