Resolution of digital cameras, like the ones used in video surveillance or in mobile phones has been rising year after year. More and more photosites / pixels are being jammed onto a single sensor chip. Pixel size is down to one micron. How much lower can it go?

It can’t! We have reached light diffraction limit, a hard physical barrier, beyond which making pixels smaller is simply useless.

What is light diffraction limit? A point source of light in front of the camera does not pass through the aperture unaltered -- it spreads into a spot known as Airy disk. The smallest resolvable detail cannot be smaller than that. The size of the disk is proportional to the light wavelength and the F-number of the lens. In a typical surveillance camera, the F-number is 1.8, and so the disk diameter is 2.4 microns. Pixel size in today’s image sensors is already less than half of the Airy disk diameter, so it does not matter if the pixels get even smaller -- the resolution can no longer be increased.

So, what’s next? Can image resolution transcend the physical limits? The conventional wisdom says no... True innovation is unconventional.

Stay tuned.