Re: [CAD_CAM_EDM_DRO] Laser distance meters/ laser trackers

I looked into that a while back. It's a difficult problem, especially to get
the sub-mm accuracy we want in machining/object scanning.
http://www.repairfaq.org/sam/laserlia.htm#liarfbl

If you do figure it out, I hope you write it up, I think the community would
greatly benefit from a good set of plans for a laser range finder.

I want something like this, myself:
http://www.polhemus.com/?page=Scanning_Fastscan
Handheld or machine-mounted, I'm not picky.

Luckily, for sub-mm scanning these all you need is structured light scanning.
http://en.wikipedia.org/wiki/3D_scanner#Structured_light

Here's a guy who's working on a turntable and structured-light based scanner.
He's fairly far along, but the website doesn't show that. When he's done,
he'll be writing it up and publishing stl files for the parts of the scanner.
http://www.splinescan.co.uk/index.php

Steve Baker's scanner:
http://www.sjbaker.org/projects/scanner/

My humble efforts, done in an evening and then put on the back burner:
http://objects.reprap.org/mediawiki/index.php/RepRap_Laser_Scanning_Head

Are you sure you can't get the results you need using triangulation? Much
easier.
http://en.wikipedia.org/wiki/3D_scanner#Triangulation

Regards,
Sebastien Bailard
RepRap.org - self-replicating 3D printer project.

On Tuesday 07 November 2006 18:08, Harko Schwartz wrote:
> Look at Optodyne they do the same thing as renishaw but in the return of
> the same signal
>
> Harko
>
> On 11/7/06, Graham Stabler <eexgs@...> wrote:
> > I'm researching laser trackers at the moment with a view to building a
> > low resolution one.
> >
> > If you want to know what one is check out:
> >
> > http://www.faro.com/content.aspx?ct=uk&content=pro&item=3
> >
> > http://www.leica-geosystems.com/corporate/en/products/laser_tracker/lgs_3
> >5317.htm http://www.apisensor.com/
> >
> > Basically the head tracks a retro reflector and using the angle and
> > the distance to the reflector works out position. The returned beam
> > from the retro reflector is off-set unless the beam strikes the centre
> > and this is used for tracking control (servos try to keep zero offset).
> >
> > Distance is determined by interferometry (incremental encoding) or by
> > time-of-flight phase shift methods that provide absolute distance
> > measurement (ADM). Neither of this methods involve triangulation.
> > These methods give increadible positioning accuracy (tens of microns)
> > at 10's of meters range.
> >
> > Leica do hand held laser distance meters accurate to +/-1.5mm, I need
> > something that can hold 1mm resolution accurately. I'm looking for
> > distance measuring modules that can do that but am not having much
> > look. I thought I'd cast a line to the group and ask. I'd prefer ADM
> > but an interferometer would not be ruled out, Renishaw do them but
> > they seem to have two beams, it must be single beam.
> >
> > Cheers,
> >
> > Graham
>
> [Non-text portions of this message have been removed]
>
>
>
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