[Noisebridge-discuss] Two-way optical interface?

[Sai]

On Fri, Aug 24, 2012 at 1:06 PM, Ari Lacenski <alacenski at gmail.com> wrote:
> Most go sets that I've seen have matte black stones and polished vitreous
> white ones. It would be worth getting a few cheap photodiodes, placing one
> next to an LED with a very focused view angle, and seeing if you get
> measurably different output from [no cover; reflectance from black stone;
> reflectance from white stone].

Could any of y'all help me with that? I have no experience at all with
photodiodes; I mainly do web apps, not hardware, so I don't even know
where to begin there.

Also, any thought as to whether it'd be possible to run this through a
single Thingy? I'm picturing eg little plastic stubs touching the
actual board surface; those stubs underneath are connected to fiber
optic, which has a splitter - one end taking input from individual
LEDs, the other end going to a photodiode array for reading. But I
have no idea if this kind of simultaneous i/o split is even possible.

> Daylight might ruin this whole plan; choosing a photodiode responsive to
> only a certain spectrum would help. I recommend NOT choosing the IR spectrum
> to play with.

*nod* Ideally I'd like it to work in a reasonably wide range of
lighting conditions; the display part might need to be pretty bright
to be seen though, especially when diffused as a halo.

On the up side, if the stone is covering the Thingy/photodiode, then
that blocks most outside light. Worst case scenario, it shouldn't be
too hard to distinguish 'stone' from 'no stone'. I don't know if my
"shoot light at it and read the reflectance through the same Thingy"
idea is viable, but at least the presence of the stone creates a
relatively controlled situation.

Though hm, it wouldn't necessarily be *directly* covering the Thingy
('cause go stones have a relatively small contact surface, and move
around a bit).

This is also potentially a method for playing chess or the like, with
the same board. You'd need to cover the pieces' bases with something,
but then you get to control what that something is for optimal
distinctiveness.

> It might not work at all, but little cones of light spilling from the edges
> of stones sounds like a lovely game.

*nod* I imagine one could make all sorts of neat variants if this
works. First getting it to work, though...

> Or you could hack up a two-color monome with the buttons at crosses.

That looks pretty neat equipment. Though expensive and sold out, and
not available in 19x19. ;-)

- Sai