What is "critical exposure"?

From: Werdinius Christian (K92089@chestud.chalmers.se)
Date: Wed Jan 21 1998 - 18:46:00 EET


I´m going do to some experiments on stereolitografi, trying to get an
extremly small cured point, with a very focused laser. I´ve got some Ciba
Tool SL5190 to do the experiment with. According to the label on the bottle
it´s supposed to work with a Nd-YVO4 laser. Is that the standard laser in
the SLA-machines?

I´ve heard that the wavelength of the laser is 354 nm, is that correct?
I´m going to work with a pulsed dye-laser, 50Hz with a variable wavelength
of 210-750 nm - do you think there will be any problems working with that
laser, if I tune it to the right wavelength?

The "critical exposure" for the resin is 14,9 mJ/cm2 and the "penetration
depth" 4,6 mils (is mils=millimeter?). What´s the meaning of these two

I´ve heard that you get a better finish with a longer exposuretime at a
lower power than the opposite, is that true?
In which ranges can you then vary the time and power parameters?

I want to make my focused point on a flat plate , with a good adhesion
towards the polymer. Which material do you suggest?

I have another bunch of questions, but I think these will du for this time!


Christian Werdinius
Department of Polymertechnology
Chalmers University of Technology

Christian Werdinius
Fredåsgatan 12A
431 67 Mölndal
tel 031-16 04 87 el. 070-602 60 58

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