The blue curve represents the typical emission spectrum of a white LED. The blue peak reaches its maximum value at about 435nm. It corresponds to the primary light generated by the LED semiconducting structure itself (the LED die). The secondary peak reaches a maximum value at 550nm (yellow colour) and is the secondary light emitted by luminophores excited by the blue light (fluorescence). The combination of the direct blue light and the yellow/red secondary light produces white color. The red curve is a plot of the blue light retinal phototoxicity function. It reaches a maximum value at wavelengths corresponding to the blue light peak emitted by LEDs.
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