A project log for open hardware fast high resolution LASER

bringing additive manufacturing to the next level

HexastormHexastorm 08/27/2019 at 21:120 Comments

The new box works quite well.

At the moment, there is one key issue. The jitter is too large; as you can see below.
I am also not happy about the glow to the right but that's a simple alignment issue due to reflections in the prism. I changed the offset and height of the diode. As long as the spot passes the diode in the middle, the pattern remains the same. My current algorithm of simply setting the counter to zero if the photo diode is passed might be too easy. The spot changes speed while scanning. This might alter measurements. In the coming days, I will try if i can detect different facet times for each facet. I could then label facets and fix it with a timing table.

The cross scan error is low and comparable to earlier versions.
The photo diode cap is no longer needed. This seems to be due to the op-amp, Schmitt trigger circuit.

In the picture below a pixel is 4.8 micron.

Earlier results were much nicer, see earlier blog jitter removed, but you can learn a lot from the “bad” ones too.