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Let's say an array of rays of light is given.
Each ray has a specific wavelength (in the range of visible light).

Example:

ray1 = 470 nm
ray2 = 640 nm
ray3 = 510 nm

Can these rays be merged into a single ray of "white light" which preserve the information of it's components?

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1 Answer 1

up vote 2 down vote accepted

Short answer: No.

Long answer: What is the 'information' you wish to preserve? The phase? In that case, if you manage to make the rays collinear, you will have three monochromatic rays that each have a separate phase, so yes, the information will be preserved, but it will not be white light - it will be three monochromatic rays of 470, 510, and 640 nm. What is generally referred to as 'white light' has a broad spectrum and is not monochromatic (or trichromatic) at all.

What's more, when you are dealing with real 'rays', they will never be perfectly collinear, so they will separate after some distance. If they are travelling through a medium, like air, they will also have slightly different indices of refraction, so their relative phases will not be preserved either.

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The util information is the wavelength. So this merged ray in that case where all rays are collinear put through a triangular prism will be dispersed as follows: 470, 510, 640, in this order? Thank you! –  iuliux May 8 '11 at 14:04
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@iuliux Maybe one should stress that frequencies of light and perception of colour do not have a one to one correspondence. For paintings one can use three colours of paint and get all the palette, but it is a perception by the way the receptors in our eyes and the programming in our brains work. I think the inventor of polaroid, E.Land, found he could produce fully coloured pictures with just two frequencies: en.wikipedia.org/wiki/Two-color_system –  anna v May 8 '11 at 19:55
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@ptomato "but it will not be white light - it will be three monochromatic rays of 470, 510, and 640 nm" - but your eye may see it as white light, given the intensity ratio of the three component waves are proper. –  Leos Ondra Apr 25 '12 at 15:28

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