Ayone else remember the 'Optic RaM', a poor-man's image sensor. the package (it's been suggested you could take a cerdip 4116 or 4164, knock off the top and replkce it with a window). The idea was you focussed an image onto the chip. Stored 1's in all locations, waited a bit and read out the contents. Those cells which had been exposed to enough light would read out as 0's. Do it again with different waiting times (note, once you've read out a pattern, you've lost the charge stored in the cells, you have to start again, you can't read the chip repeatedly without filling it with 1's), combine the resulting bit patterns to get a sort-of grey scale image.