from the building-very-tiny-crystal-palaces dept.
Researchers at the University of California, Berkeley have developed a new way to 3D-print glass microstructures that is faster and produces objects with higher optical quality, design flexibility, and strength, according to a new study published in the journal Science.
The CAL [computed axial lithography] process is fundamentally different from today's industrial 3D-printing manufacturing processes, which build up objects from thin layers of material. This technique can be time-intensive and result in rough surface texture. CAL, however, 3D-prints the entire object simultaneously. Researchers use a laser to project patterns of light into a rotating volume of light-sensitive material, building up a 3D light dose that then solidifies in the desired shape. The layer-less nature of the CAL process enables smooth surfaces and complex geometries.
The researchers have achieved a resolution of 20μm.
(Score: 3, Informative) by Anonymous Coward on Saturday May 28 2022, @05:41AM (1 child)
They’re using a polymer that hardens after it receives a certain minimum amount of light exposure, but the problem is if you shine light through it, the light passes through all of it, so how do you concentrate it in some spots to go over that threshold but not others? One way is to use a pulsed focused laser, and you can build something up dot-by-dot by moving in space where the laser spot gets put, and we’ve got one of those kind of printers where I work.
Here, they’re taking an approach where you project in the light so that it puts the concentrated light where it needs to go all at once. They’re doing it in the same way that a CAT scan works. There you are shining radiation through your body and you see what it looks like after it passes through you, where the parts of you with more density absorbs the radiation better than where it is less dense, and you get out a picture out that is sort of a shadow image like an X-ray. It turns out that if you make a bunch of these shadow projections from all different angles going around a full 360 degrees, with that info you can back out the 3D structure of what’s inside.
Here they want to work the problem backwards. They know what they want it to look like inside, so they calculate what all those shadow images would look like if they were doing a CAT scan (probably calculating the radon transform [wikipedia.org]) and then make the light they shine into it look like the inverse of that, so if they expected to see a dark shadow, they make that part of the light bright, and they use a regular projector for that. So all they have to do is rotate the light around and project in all of the appropriate inverse shadow images. Really cool, and something I could see myself throwing together if I was clever enough to have thought of the approach first. Ah well, another fortune never realized. Story of my life.
(Score: 2) by janrinok on Sunday May 29 2022, @07:10AM