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Video-projector for scanning small objects?

Questions, problems, comments and tips regarding the 3d scanning process.

Video-projector for scanning small objects?

Postby MagWeb » Wed Apr 23, 2008 9:53 pm

Hy Davidians,

today I borrowed a LCD-projector to see its use for DAVID. My idea:

A laserlight's upper and lower edgeplanes are allmost parallel. The video projector`s beam gets wider in XZ AND Y the farther the distance.

So, the other way round, it is very narrow near to the projector. In theory one line is a 1/480 of the picture´s height at VGA.... So if the picture is only 100mm....at SVGA...

Unfortunatly videoprojectors/beamers are made to produce rather big pictures.... My projector of today lost his focus nearer than about 50 cm. The light-line at ths distance was about as thick as the one produced by my Picotronic focusable red one.

But another optics .... I know, here are some guys rebuilding their cams - so why not rebuild a projector (by the way: a diascope might do the same job, if you move it to move the beam... logo)

That´s just an idea I'm not able to follow... but maybe someone else?

bye

Gunter
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Postby WalterMo » Thu Apr 24, 2008 10:53 am

Hi Gunter,
You should simply try to get the lens a few mm away from the LCD display.
But I have never opened a LCD-projector and think that a problem could occur regarding the motor drive for remote focussing.
For photo camera lenses there are special extension adapters available. E.g. for C-mount here:

http://www.theimagingsource.com/en/prod ... ics/tubes/

Good luck!

Walter
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Postby florin.topala » Thu Apr 24, 2008 11:18 am

Hi Gunter
try to extract the objectiv
and ... do not use a big hammer :|

or you can put another lenses in front of objective I think
Good luck

Florin Topala
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Postby MagWeb » Thu Apr 24, 2008 11:33 am

Hi Walter and Florin,

thanks for your tips!
the problem is: it is not my projector and I gave it back today, so I can´t check it out....

I posted the idea hoping someone picks it up...for it should work...

Gunter
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Postby florin.topala » Thu Apr 24, 2008 1:35 pm

:twisted:

oki I will try with one of my friends
could you tell me what is the distance between projector and you object

1 m , 0.5m?

Thak you,
Florin
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Postby MagWeb » Thu Apr 24, 2008 3:27 pm

Hey Florin

:wink: No risk - no fun

I could focus that projector at a minimal distance of 50cm - At that distance the picture was about 30cm high. And a one pixel line appeared about 0,8mm. The max resolution of that projector was 1024x768 so I made a *.mov on that res with Keynote (similiar to Powerpoint). If you need it, I may post ithe *.mov - but it´s a simply thing to do.

Now it`s up to me to wish

good luck!
Gunter
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