Making a pin-hole

I need to make the finest (smallest) possible hole in a piece of acrylic. I should be able to hold the head stationary, then “fire” the laser for a few milliseconds. Based on kerf-measurements, I can probably get a hole with a diameter less than 0.1mm.
But I cannot figure out how to fire the laser without moving the head. Any advice, leads, or work-arounds are very welcome.
Forgive me if this has been addressed before. I did search, but may have used the wrong keywords.

Unfortunately, a laser isn’t a drill. The gas & debris blowing back as the tip of the beam vaporizes the acrylic embiggens the hole around the beam diameter.

A little tinkering produced a 0.4 mm hole through 3 mm acrylic, with some surface damage around the (slightly larger) entry. It’s a somewhat irregular cylinder with smooth walls.

AFAICT, LightBurn doesn’t display a Fire! button for Ruida controllers, so the best you can do it position the head at a known coordinate, then pulse the laser manually from the control panel.

I’d lay a crosshair at the target location, Click to Move at the center to position the laser, then pulse. That might suffice for a one-off hole, but not for an array and certainly not in production.

I invented a workaround:
Create a triangle in Lightburn, with sides of exactly 100mm.
Set the layer to LINE → Advanced → Dot Mode.
Set the spacing of the dots to exactly 100mm.
Now the laser will “fire” exactly once at each vertex. Make sure the other two vertices are not on the work-piece and everything behaves as one would expect. Looks like I just “drilled” a hole about 0.1mm diameter.

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That’s clever!

Gotta drop that one on the hints-and-tips pile …

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