Re: CCD

For the ones that have not seen it:

I used to think that I had to have a narrow slit on the photo transistor or photo cell to get good encoder resolution. There is
a much better way:

Have a regular photo transistor and light source but set up a second stationary grating next to the moving one with the same
pitch. The light has to shine through both gratings. The detector sees either many slots of light or the light is blocked. It
just average all the slots and counts light and dark cycles, not individual slots!

Try it using two regular combs with the same teeth spacing and you see what I mean.
Bertho Boman
================================

> "Ian Wright" <Ian@...> wrote:
>
> I suggested this a while ago and the opinion then was that the resolution
> would not be fine enough - however, I still think it would work and could
> even give enough resolution using phototransistors with slit apertures.
>
> Ian
> --
> Ian W. Wright
> Sheffield UK