I was sitting in a meeting at work today.

When I looked up there was a projector facing the rear wall letting out a very bright white light (the projection).

When I look right at it, all I could see was white light.

But as I illustrated below when I shifted my gaze away I saw the white light split into each individual color.

I was able to reproduce this repeatedly just by shifting my gaze.

Any explanation? Gama rays? Do I have a super power?

enter image description here

  • $\begingroup$ If you squint very carefully through ever so slightly open eyes, you can sometimes see diffraction patterns with colours (different diffraction angles for different wavelengths) at the edges like tiny rainbows. The works best and night and it takes some practice. $\endgroup$ – WetSavannaAnimal Oct 4 '13 at 0:18

It's because of DLP projectors. In such projectors a 3-color wheel rotates in front of the light thus projects only one color at a time but very rapidly. Search google for DLP rainbow effect. It's common to see an be bothered by this.

Source: http://en.wikipedia.org/wiki/Digital_Light_Processing#The_color_wheel_.22rainbow_effect.22


Well it appear that you are looking at the projector beam itself. Actually it isn't a single white light beam, it is a three color red blue green probably, and is three separate beams originating from different points. They appear to form white light when they overlap on the screen, but when you move your eye you scan the three separate sources across your retina, and see each separately while moving. One other possibility, but less likely, is that you have a sequential three color time multiplexed projector, so a single source projects three pictures in rapid succession. This is less likely because ordinary head movements, watching such a device can be annoying, and the 1/3 duty cycle gives reduced screen "brightness".

  • 1
    $\begingroup$ So no super powers... $\endgroup$ – Anthony Russell Oct 3 '13 at 23:05

Another, unrelated way this can happen is, if you wear thick eyeglasses, they may exhibit chromatic aberration, which you will perceive as rainbow fringes at the edges of objects, especially light sources and dark objects against bright backgrounds. The effect is most obvious if you look at the edge of a light source through the outermost (thickest) part of the glasses.

This is a purely optical phenomenon and is unaffected by the nature of the light source, except that of course it won't happen if the only available light source is monochromatic (sodium arc streetlights, for instance).


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