3 ms·

Interesting. I wonder if this could be used to print telescope mirrors if you could get an "ink" that has high thermal stability, or if that would be in conflic

Interesting. I wonder if this could be used to print telescope mirrors if you could get an "ink" that has high thermal stability, or if that would be in conflict with the low temperature printing.

hbrav 1y ago
That seems like it would be very difficult. For a telescope mirror you want a very good surface finish, and that's one thing that 3D printing does very poorly.
- giantg2 1y ago
  The polishing process could be done differently. If you could print the specific parabolic shape, that could save a lot of time hogging out. Although slumping might work better if surface ends up smoother. Im not sure of the annealing process might go.
  - taneq 1y ago
    There's a few combined-process setups coming out these days that use 3D printing as a first pass and then machine the print in-place before sintering etc. which saves a ton of setup and fixturing time.
    - sheepscreek 1y ago
      Yes! This is exactly what I had in mind. Sintering (thanks for the term) combined with this 3D printing technique could still make the process faster and lead to more consistent results. Now that’s I think about it, one could in theory use the exact same process for plastic-polymer lenses too, albeit at lower temperatures (better).
  - bhickey 1y ago
    The parabola of a telescope mirror generally deviates from a sphere by tens of micrometers at best. Figuring happens after grinding and after polishing. Slumping is neat, but I've heard from the grognards that they can shatter if the temperature changes too quickly.
sheepscreek 1y ago
Maybe with further augmentation to the process. The 3D printing seems to leave pretty big grooves on the glass - which can distort the passage of light. For any real optical application, that will have to be removed somehow. Such as baking the glass structure in a high heat oven with a centrifuge/fast spinning base and some kind of mould to put the initial piece on. The high heat and spin action could, in theory, fuse the individual grooves for a more uniform dispersion of light, and the mould shape would further press on the glass to maintain or alter its shape to be closer to a lens. Finish that off with fine “sanding” and/or polish, and that might do the trick? Honestly, experimentation might be the only way to find out.
kragen 1y ago
You'll probably be interested in https://dercuano.github.io/notes/gradient-refractive-index.html https://dercuano.github.io/notes/gradient-refractive-index.h..., which isn't exactly what you described.

Interesting. I wonder if this could be used to print telescope mirrors if you could get an "ink" that has high thermal stability, or if that would be in conflict with the low temperature printing.

hbrav 1y ago

That seems like it would be very difficult. For a telescope mirror you want a very good surface finish, and that's one thing that 3D printing does very poorly.

giantg2 1y ago
The polishing process could be done differently. If you could print the specific parabolic shape, that could save a lot of time hogging out. Although slumping might work better if surface ends up smoother. Im not sure of the annealing process might go.
- taneq 1y ago
  There's a few combined-process setups coming out these days that use 3D printing as a first pass and then machine the print in-place before sintering etc. which saves a ton of setup and fixturing time.
  - sheepscreek 1y ago
    Yes! This is exactly what I had in mind. Sintering (thanks for the term) combined with this 3D printing technique could still make the process faster and lead to more consistent results. Now that’s I think about it, one could in theory use the exact same process for plastic-polymer lenses too, albeit at lower temperatures (better).
- bhickey 1y ago
  The parabola of a telescope mirror generally deviates from a sphere by tens of micrometers at best. Figuring happens after grinding and after polishing. Slumping is neat, but I've heard from the grognards that they can shatter if the temperature changes too quickly.

sheepscreek 1y ago

Maybe with further augmentation to the process. The 3D printing seems to leave pretty big grooves on the glass - which can distort the passage of light. For any real optical application, that will have to be removed somehow. Such as baking the glass structure in a high heat oven with a centrifuge/fast spinning base and some kind of mould to put the initial piece on. The high heat and spin action could, in theory, fuse the individual grooves for a more uniform dispersion of light, and the mould shape would further press on the glass to maintain or alter its shape to be closer to a lens. Finish that off with fine “sanding” and/or polish, and that might do the trick? Honestly, experimentation might be the only way to find out.

kragen 1y ago

You'll probably be interested in https://dercuano.github.io/notes/gradient-refractive-index.html https://dercuano.github.io/notes/gradient-refractive-index.h..., which isn't exactly what you described.