Tuesday, September 26, 2006

Never. The basic limit of resolution you can get is set by the Rayleigh criterion:

sin theta = 1.22 * wavelength / lens diameter

where theta is the angular diameter of the smallest detail that can be resolved.

Using a 5*10^-7 m (green light, more or less in the middle of the visible spectrum) and a 0.01 m diameter lens (which is generous for a mobile phone), this gives us a 3.5*10^-3 degree angle as the minimum amount of viewfield that can be covered by one pixel. Thus, a picture with a 20 degree viewfield* would be, at most, 5700 pixels in each dimension, or 32.5 megapixels.

*Of course, a viewfield could be wider, but getting a wider-angle picture without distortion raises a whole other batch of problems if you have to do it in such a small package.

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## Optical Limits On Miniaturization (Score:5, Informative)