Re: [rp-ml] Laser Power in the SLA

From: Markus Hitter <>
Date: Tue Jan 22 2008 - 10:55:59 EET

Am 22.01.2008 um 05:51 schrieb Vincent Chan:

> Does the laser power in the SLA stay constant or does it vary from
> layer to layer, part to part, etc.?

Ideally, laser power at the resin surface would be constant. In real
world, the laser wears, optics get dirty and the mood of the
machine's parts changes.

> How do you measure the power in a laser power meter?

The SLA does it before drawing each layer. It's a sensor with a tiny
measurement-hole in it and the laser scans over this area not only to
measure power, but also to adjust optics ("Where do I have to move
the mirrors to get the laser beam exactly to X, Y at the resin
surface level"). For better accuracy, there are two such sensors,
diagonally across the bath.

These quick power meters have to be adjusted from time to time with a
reference power meter as well.

> Do you need a large area sensor to capture an image that the laser
> rasters or do you find a way to keep the laser still?

With handcrafted build files it's possible to stick the laser at any
position over the bath. Another option is to put the power meter to
the resting position of the laser (where the laser points while the
sweeper is running).


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Dipl. Ing. Markus Hitter
Received on Tue Jan 22 09:25:58 2008

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