Quote:
Originally Posted by NullNix
Hm. The rainbow effect on sapphire is a diffraction effect (as is the varying colouration on beetle cases and the heads of mallards, as it happens). I would expect any such effect to be caused by the diffraction grating, not the glass. Glass *can* diffract, but the effect should be minimal, particularly with small thicknesses of glass as in the Kindle. (But perhaps the 'gorilla' part of gorilla glass has additives which increase diffraction? You'd think Amazon would have taken a lot of care with that, with a diffraction grating already in the mix...). If this was the case, i'd also expect you to see *strong* rainbowing when the frontlight was off and the Kindle was lit only by the Sun (which is, after all, passing through a double-thickness of the same thing before it reaches your eyes).
I'm wondering if anyone knows how monochromatic the light from the LEDs is? It can't be completely monochromatic, surely, since the diffraction grating has to send the light in divergent directions at each point, and AIUI this requires multiple wavelengths so the waveguide can split them off one by one out of the screen. I'm not sure if it's optically possible for the wavelength to be completely invariant across the screen whle retaining a waveguide, though they could probably apply yet another variable coating to absorb the varying light and re-emit it at a constant wavelength -- but this would likely also scatter the light, which would be disastrous for clarity.
Can anyone who actually understands optics answer this?
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My impression is that the LEDs are white (approximately). White light is a mixture of colors. There is no wavelength that is white. There is no wavelength that is black. Black is when all light is absorbed. White is when "all colors" are reflected. I don't know what colors would need to be combined to reflect white light. However, if diffraction is possible, then it can happen with white light. I say this even though I don't have this problem. I am happy with my Voyage (as I have said before and before and…)
