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[filmscanners] Re: Foveon patent details

I didn't read the patents yet, but here is my take on what I did see and
read and comprehend.

I used the words "filters" and "color separates" in an earlier post, but
that's probably not the best use of terms.

The way the Foveon chip works is via the use a natural phenomenon
regarding the way photons go through some types of silicon.

So, it isn't about filters, although it is about sensors.  Unlike silver
based film which needs to have a color separation filter to direct the
photons so they activate the correct layers of the photosensitive silver
grains, silicon does this all by itself. Depending upon the "color" of
the photon, it penetrates the silicon to a different depth.  This is
"picked up" by the sensors, which I believe are imbedded at different
depths, and are probably otherwise transparent to photons which need to
travel through the sensor to go deeper.  As I understand it, there is no
need for a "filter" as such.  The silicon they use naturally isolates
different photons based upon, I assume, the wavelength, which creates
different energy levels in the photon, and causes it to penetrate to
different levels within the silicon crystalline material.  All you would
need to do is measure the depth the photon passes through and you know
its color.  In fact, you don't need to even do that.  All you need to do
is to have sensors at different levels say one on the surface, one in
the middle and one toward the bottom.  If the photon was recorded at the
top sensor, but no further, it is one color,  If it was recorded at the
top sensor AND the middle it is another, and if it is recorded at all
three sites it is still another (in a tricolor system).  Of course the
positioning of the depth of these sensors would determine which colors
one was "measuring", and I suppose if one wanted to get fancy, one could
use even more levels and layers of sensors and use a hex or other
system, although I'm not sure there would be any point for photographic
white light based images (although I could see several applications for
other purposes, like computer "eyes" which could make discrimination of
very subtle color differences for manufacturing use.  Of getting rid of
those pigeons on the pill lines. ;-)

  From the way I read it, the diagrams are just showing a sensor, and
they have been colored them to simplify the explanation.  They aren't

DISCLAIMER: Of course, I don't know anything, and am just a "parrot". So
I'm probably making all of this up.  Ask "the engineer".


markthomasz@ozemail.com.au wrote:

 > Now that I've started reading the patent details, it is obvious those
drawings don't exactly paint the full picture :-).
 > I didn't notice this before (did they just change the site?) but
there is a link to the patent from that site
 > (http://www.dpreview.com/news/0202/02021102foveonx3tech.asp)
 > and it makes *very* interesting reading - they use the depth of the
'wells' to create a filter based on the absorption characteristics of
doped silicon to the diff wavelengths. (phew!)
 > There is a further link to supporting drawings but it's not working
for me.
 > Anywa, we'll wait and see, but this is certainly pushing the
technology in the right direction.
 > Austin said:
 >>...but magically, in their
 >>sensor diagram below that, they show a blue filter, that passes both
red and
 >>green...right through, as well as a green filter that passes red.
I'm not
 >>clear on how this works...
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