Re: [CAD_CAM_EDM_DRO] PIC DRO _now_ i've made it a stupid question

Eric Keller wrote:

> Jon wrote:
> Really, if someone can come up with accurate grating patterns on film
> or
> glass, it is fairly easy to make your own linear encoder. Does anyone
> have
> any ideas on
> where to get such grating patterns?
>
> Jon
>
> It seems that they can print the strips, so the question is will they
> do it?
> the Heds module i'm looking at is a rotary, so it has two sets of
> grates to
> look at
> It has a small stainless steel grating with ~6 holes apiece,
> apparently
> photoetched.
> The thought i'm having is what is stopping you from using a piece of
> the
> linear strip as your grating. might need a larger pair of holes to
> keep the
> light in the right place.

Yes, precisely! You could either take the sensors and logic out of an
HP encoder, and
just use the finer grating, or make an entire assembly and PC board.
You put the
'analyzer' grating on a slant with respect to the long one, and adjust
it until you get the
right quadrature relationship on the two signals. Without exotic
collimating optics, the
higher the frequency of the grating, the closer the gratings have to be
to each other.

Jon