Digital BW, The Print

Hi Paul,

> I've seen diagrams that imply that they deposit dyes right on the
> chips...

I haven't seen any of those, but that certainly is possible.  My guess is
that those are probably interline sensors.

> but
> I suppose it's possible that some chips are made differently from others.

As I said, I KNOW the Bayer filter is removable on the sensors I've used...

> The datasheet for the Sony ICX282AQ, which is the chip used in my Minolta
> DiMage 7, clearly says "R, G, B primary color mosaic filters on
> chip".

Two things strike me about that...one, that the go out of their way to
mention "on chip", which to me implies that others aren't "on chip"...what
ever "on chip" means...it could simply mean cemented onto the package.  The
sensors are made up of quite a few components.  They contain the actual chip
die, the carrier (typically ceramic simply due to stability of the
material), plus the wires that bond the die to the carrier.  Then, there is
a cover over the open side of the chip...so that's four physically separate
components for a rather simple imaging sensor.  So, on-chip, may simply mean
it's glued to the carrier...

> When
> you're dealing with the 7 micron sensors of the 10D (or the 3.4u
> sensors in
> the DiMage 7), I don't see how they could align a mechanical assembly
> accurately enough across the whole chip.

I never asked...but I'd simply have targets (typically called fiducials) on
the die, and optically place the filter aligning it with the targets.  I've
seen this done with many other types of technologies that require precision
alignment.  Think about how the die is made coplanar with the "film
plane"...with a device that's glued into a carrier, and a carrier that is
typically simply soldered onto a PCB...which is how a typical CCD/CMOS full
frame image sensor is mounted into the camera.

> As to removing the filters, it
> wouldn't surprise me if that guy has come up with a way of
> removing the dyes
> chemically, since the underlying chip probably has glass passivation over
> it.

We don't know if the sensors used in the cameras he claims he "modifies" are
die or he can actually remove the filter.  If you find out, please let me
know.  He says his process is "patented", but many people say that as a
simply false claim...but I could hardly see how popping a Bayer pattern
filter off would be patented, unless he developed a special "tool/procedure"
to do it...but personally, I've just used an Xacto knife, but I've only done
it to large sensors.

Regards,

Austin