8955Re: [diy_3d_printing_and_fabrication] RE: RE: RE: RE: Highest DIY XY resolution ?
- Oct 14, 2013Reinis Veips wrote:
> Do you mean this one: http://wot.lv/scanning-laser-projector.html ?The original laser mechanism has a photodiode in the path to sense the
> I did it, but I didn't like the results. It was done on ARM MCU development
> board from TI- Stellaris (now Tiva) Launchpad.
> Main problem was- how to detect start of the line condition reliably. I tried to use
> ordinary LED (with peak emission wavelength a bit above what I wanted to
> detect), which generates tiny current when hit by laser. Projected pattern
> shifted back and forth- it never stayed at exactly the same place.
start of the
sweep. My guess is that thwe circuit you were using was photoelectric,
reverse bias on the photodiode. If you run it in photoconductive mode with
reverse bias, it greatly reduces the capacitance of the diode, allowing
get a much faster response to the light pulse. It is also possible you need
a different diode to be sensitive to the UV laser. LEDs can't take a lot
of reverse bias (5 V might be the max) so a diode made specifically for
light sensing applications might be better.
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