I used to do this. Nothing so fancy. I still have a board with my name on it some where.
Actually I have fonder memories of using a magnifying glass and the sun to cut dead leaves into tiny little pieces. And once causing a dead leaf to burst into flames. I’d read in the Boy Scout handbook that a magnifying glass could be used to start a fire and never believed it until then.
Anyway these drawings would be impressive in any medium, but it’s amazing that Jordan Mang-osan is using this technique.
I cheat and use a laser cutter to get this effect. I can’t imagine having the patience and fortitude to hold the magnifying glass steady for that long.
Staring at that bright spot is not going to be good for his eyes.
Thought. What about a burning-grade laser diode in a pen-housing, for freeform drawing?
Sounds fine, but not for just sitting on the street. More like in an enclosed space, where everyone’s wearing goggles.
Don’t confuse “technique” with art. Technique and art aren’t the same thing.
Add a lens that shapes the beam so it is focused to a spot at a few millimeters distance from the aperture, and then becomes strongly divergent. Then you should get safe energy density even at normal viewing distance.
That will even give you the possibility of choosing between wider low-energy beam and narrower high-energy one, for e.g. shading effects.
Burning-grade laser diode! Why didn’t I think of that? The magnifier in question looks like it’s concentrating about 0.01 m^2 of sunlight, which is about 10 Watts. A similar power of IR laser would be useful. I think you can get those these days. Don’t burn a hole in yourself!
Given better focus, you may be able to get the same energy per area from even 1 or 2 watt diode.
Infrared is cheapest. I’d suggest 808 nm as the bleed to the other wavelengths may make it a little visible as dim red.
For better visibility and safety, visible may be better. Divergent beam won’t do much harm but to be sure it is better to have a wavelength that causes the eye pupil to contract and lower further the energy received by retina. The operator, who has to watch the beam impacting the substrate, should wear the appropriate colored goggles though, to avoid being dazzled.
I saw somewhere a cigarette lighter made with a blue laser diode.
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