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For example... If I had a 2W green laser, a 2W red laser, and a 2W blue laser, could I combine them using crystals to form a 6W white laser? Or is that now how it works? If not what would be the output in watts of such a laser?

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Red and blue make purple, not white. – Jerry Schirmer Aug 26 '12 at 21:43
Does RGB not make white? I also included green. – Digital Brent Aug 26 '12 at 21:48
Oh, didn't see the green. Disregard. – Jerry Schirmer Aug 26 '12 at 22:04
up vote 3 down vote accepted

You would have 6 watts of total power, and the color may appear white to a human; but "white" is not a wavelength. Nothing special would happen to the light where the beams overlap, and the fact that your light sources are lasers wouldn't matter.

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Thanks for the answer and info! Good to know! – Digital Brent Aug 26 '12 at 22:20
Now wait a second - what about destructive interference? – Schilcote Jan 18 '15 at 22:16
What about it? I'm not sure what relevance that has here. – Colin K Jan 19 '15 at 0:15

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