A clever trick, no doubt. I've seen a project like this years ago that
detected the length of a loop of wire via time of flight of electrons.  The
trick was to cascade a bunch of gates in parallel, trigger a pulse in them
and the wire at the same time, and read the gates cascade logic state when
the pulse was detected at the far end of the wire.  There would be a
probability distribution across the parallel cascades, but by reading in
their state at the exact moment the pulse arrived back, one could estimate
a length.  Averaging repeated measures increased the accuracy and
repeatability.



On Tue, Sep 1, 2015 at 8:18 AM, Isaac Marino Bavaresco <
isaacbavaresco@yahoo.com.br> wrote:

> Wow!!! LASER Time-of-flight with resolution of millimeters???
> Are they using a clock close to 300 GHz inside or some very clever trick?
>
> Isaac
>
>
> Em 01/09/2015 01:45, Bob Blick escreveu:
> > Here's a distance sensor intended for cell phone face proximity. Uses
> > time-of-flight of a laser:
> >
> > http://www.st.com/web/catalog/mmc/FM132/CL2136/SC1934/PF260441
> >
> > In the past I might have recommended one of the Sharp rangefinding
> > modules, but the ST thing makes them seen crude:
> >
> >
> http://www.digikey.com/product-search/en?v=3D425&v=3D1149&FV=3Dfff4001e%2=
Cfff803b2&k=3Ddistance&mnonly=3D0&newproducts=3D0&ColumnSort=3D0&page=3D1&q=
uantity=3D0&ptm=3D0&fid=3D0&pageSize=3D25
> >
> > Bob
> >
> > On Mon, Aug 31, 2015, at 08:39 PM, Neil wrote:
> >> Anyone know of a non-contact distance sensor that can measure up to sa=
y
> >> 1 inch?  I built a machine for maker faire (in less than 2 weeks) that
> >> lets people draw on a touch screen an that will get printed with
> >> frosting on a cookie.  But if the cookie is not flat (rarely are they
> >> really flat), there are issue with the frosting not sticking properly =
in
> >> some corners or sharp curves.  I'm thinking if I can map the surface o=
f
> >> the cookie quickly before printing each one, I can have the Z-axis tra=
ck
> >> the cookie's "terrain".  This is a fun project so low-cost is importan=
t.
> >>
> >> Cheers,
> >> -Neil.
> >>
>
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