Laser focus question (and others...)

[Jukurpa]

Hello all,

First, congratulations for the innovative concept for this printer.
(Second, sorry for my maybe poor English, I'll do my best)

Curious about this project, I'm experimenting with some concepts and parts used here.
So, I bought a Laser module 405nm 50mW.
(And yes, I know you're planning to use a different solution with your own circuit, but for the lens, I suppose you'll use something similar to the ones used on the commercial modules)
Then, here's my question: after some quick tests, the spot's size, if focused at one level, increase quickly as you increase/decrease the distance from the level where you focused the laser.
So, in the Peachy, the laser being "static", and the distance with the resin level decreasing as you print, do you have the same problem with the spot's size? And how do you solve this problem to keep a focused dot and, I suppose, an optimal effect on the resin?

For moving the mirrors, did you tried to use some galvanometer where you could add a mirror?
I bought some to try to fix mirrors on it, miniature galvanometers with central zero.
Here is what I "dismantled" to make my tests:

galvanometre-miniature-a-zero-centrala.jpg


Concerning the sound card, if we want to use a cheap USB sound card as those we can find it easily on the web, to have a better analogic signal to drive the X and Y mirrors, could it be possible to add an USB port on your card so the USB sound card take benefit of your improved power supply, which is, I suppose, less noisy than the original USB which leads to better ouput analogic signals?
So, the power signal for the USB could come from your power supply and the data signals pass through directly to the sound card.

[rylangrayston]

....do you have the same problem with the spot's size? And how do you solve this problem to keep a focused dot and, I suppose, an optimal effect on the resin?....
.

We typicaly focus the laser at infinity so that the beam spot size dosent change much over the course of a print.
Some people are working on motorized focus that will allow for a much smaller spot size, but this will have to be an add on to the 100 dollar printer kit.