🚀 go-pugleaf

"Cory Seligman" <coryms+google@azazel.eng.monash.edu.au> wrote in message news:a64581c0.0310052014.27d17e70@posting.google.com...
> "Frank Bemelman" <bemelmanx@euronet.nl.invalid> wrote in message news:<3f747ee2$0$28885$1b62eedf@news.euronet.nl>...
> > "Cory Seligman" <coryms+google@azazel.eng.monash.edu.au> schreef in bericht
> > news:a64581c0.0309242126.7a4fe4ee@posting.google.com...
>
> > > So I got some Agilent HEDR-8100 detector chips. they have the lenses
> > > built in and do all the hard work for you. The only problem is that
> > > they're 150 lines per inch, which is more than I can do reliably on a
> > > laser printer. So I'm looking for alternatives.
>
> > If you place a transparent filter on top, also printed with 1mm stripes,
> > you don't need a very well adjusted sensor. When the rod with the stripes
> > move behind the filter, even you can clearly see that it moves. Most
> > optical encoders work like that, makes them get away with pretty coarse leds
> > and fotodiodes.
>
> > Place two filters with the stripes 90 degrees apart for A & B signals.
> > The effect is named after Moire, it's inventor, I think.
>
> Thanks for the ideas. I have a suspicion that the optical devices I'm
> using already exploit the Moire effect, since they appear to only work
> at 150 lpi. This would indicate that they already have a 150lpi screen
> internally.

> The optical mouse sensor idea is something I already thought
> of, but the specs for some of the modules they use show
> fairly lousy repeatability, which I guess amkes sense.

Makes no sense at all, you dont see any problem like that using a good one.

> I need pretty good (0.5 mm or so) repeatability.

Should be completely trivial with a decent optical mouse
and the most you might want to do is make sure that what
you are running it on isnt dead smooth like glass etc.

> I have yet to have any success with ink jet printer on transparencies.
> The ink is either too think, blobbing up and obscuring the gaps, or
> not dark enough to block the reflection. Perhaps I need better
> stationary.

Yeah, thats completely trivial to do properly too. Basically
just the right combination of transparent film and ink.

> In any case, I've ordered the lower resolution (75 lpi) encoders. I've
> printed out some 75 lpi stripes, and checked them under a microscope.
> They look clear and distinct, so I'm just going to go with that.
>
> thanks for the responses though.
>
>                    Cory