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Choosing the correct type of filter

  1. Jan 28, 2012 #1

    i bought a machine which determines led colours by measuring intensity for a product.
    the product has three leds:green,red,orange. the equipment works well for the green and red leds but fails most of the time with the orange leds. i looked up wavelength values for the colours and i found that:


    you can see that the minimum wavelength value for the red light is the same as the maximum wavelength as the orange light and this is where the problem is. the machine sometimes detects orange as 636nm or 640nm which returns a fail for the led correct colour. so i was recently reading up on different types of optical filters and i plan on adding a mechanism which will hold a filter in between the leds of the product the machine which measures wavelength of the leds. but i am not sure what type of optical filter i require. i was wondering if it was possible to add a coloured filter which would reduced orange wavelength slightly and increase red wavelength.
  2. jcsd
  3. Jan 29, 2012 #2


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    Staff Emeritus
    Science Advisor

    Are you sure the LED is putting out orange light and not a mix or red and yellow or other color combination that looks orange to our eyes?
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