[null and void]

There is no such thing as a colour CCD sensor. They are all basically just electronic photon counters, even the "colour" ones in eg. consumer digital cameras actually have an RGB colour filter matrix laid over the top of the pixels.

Carver Mead's Foveon chip is an actual color image sensor. He does it by stacking sensors with different peak wavelength sensitivities.

But then again he's always been a clever fellow, he and Lynn Conway changed the basic rules of IC design - design the chip to the baseline process, rather than tweak the process for every new design - and THAT played a large part in the IC revolution.

[alnitak]

Thanks for the info guys.

[Don Joe]

Carver Mead's Foveon chip is an actual color image sensor. He does it by stacking sensors with different peak wavelength sensitivities.

It is remarkable, but there's something even more remarkable, that lead (via circuitous path, no pun intended) to both holography and the Foveon. Do some googling on Gabriel Lippmann's invention of color photography back in the 1800s. His was the only "true" color photography. (Everything else used either "tripack" cameras with beam splitters, sequential RGB images (like the beautiful pictures in the Library of Congress's "The Empire That Was Russia" exhibition), RGB matrix (everything from Lumiere Autochrome to Polaroid's "Polachrome" -- and, color CRT and LCD displays), or, layered subtractive color emulsions (all curren color films).

In a nutshell, what Lippmann did was to take a sheet of metal, coat it with mercury, an place a B&W photographic plate emulsion-down against the mercury. He then exposed it through the back (glass) side.

When displayed after developing (and returned to the mercury), the result was a full color image. Not a color image composed of "synthesized" colors via mixture of additive (RGB) or subtractive (CMY) primaries, but an actual color image, with all colors actually present in the image.

What he discovered was that the mercury would reflect light back into the emulsion, and each wavelength would penetrate to a different depth. The interference patterns created by the transmitted and reflected light resulted in each color's portion of the image being present at a specific depth in the emulsion.

It was sort of like a flat ("2D") full-color hologram, invented over a hundred years ago. Very impressive! And, in a very real sense, the great-grandfather of the Foveon sensor, which also relies on different parts of the color spectrum penetrating to different depths in the sensor.