29 Jan
2006
29 Jan
'06
11:43 a.m.
At 06:08 AM 1/29/2006 -0600, you wrote:
Ayone else remember the 'Optic RaM', a
poor-man's image sensor.
I designed some instant-display chip-fail display systems years ago. We
were probing
full wafers of chips. First thing I saw, first image that worked, was a
image of the
probes reaching in from all sides, to the chip. We forgot to turn off the
microscope illuminator, which was BRIGHT!
Guys got into scratching their initials on a chip, and saving the bitmap...
Regards, Terry King ...On The Mediterranean in Carthage, Tunisia
terry at terryking.us
From what I remember they were a normal DRAM chip
with a quartz lid to
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.