Re: CCD

I have seen that done commercially. One problem to watch is any vertical movement of the strips will be translated to
horizontal movement.
Bertho
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> Paul Corner <Paul.Corner@...> wrote:
>
> Hi Arnie & Jon
>
> I've played around with some ideas on encoders - I was trying to resolve
> angular position, but the idea will apply equally to linear sensors. If you
> take two films, both with lines at the same pitch and at a slight angle, one
> film fixed and the other free to move with the slide. If the lines are arranged
> at equal and opposite angles, you will get ' moire fringes ' set up, as the
> films move relative to each other so do the moire fringes. All that is needed,
> is to count the fringes as they pass a fixed sensor. The resultant number of
> pulse are greater than the number of lines on each film, and by using a simple
> 64 bit CCD ( TI no. TSL214 ) it should be possible to resolve the position to a
> few microns. But as the sensor ihas a serial output, the speed would be rather
> slow.
>
> Regards, Paul.