3D printed optics

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Agro
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3D printed optics

I noticed that there are some companies that 3D print lenses.
https://sinoptix.fr/plastic-optics-showroom/plastic-injected-lens/ lists that among prototyping options.
http://www.luximprint.com seems to specialise in that.

My thinking is:

  • record chasers find it expensive to get 150+mm lenses. If quality is good enough, this should be competitive.
  • small flashlight makers can’t afford having their own optics because a mold is upfront cost of $10K. Could 3D printing work for them?

Now that I look at luximprint design guidelines – they are very restrictive. They seem to have some uses but not many. Maybe the tech is just not there yet. But it sure looks to have potential. Smile

Edited by: Agro on 02/18/2019 - 06:45
LouieAtienza
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The biggest obstacle is that any 3D printing is done in layers, and as such there will be stair-stepping that has to be dealt with by post-processing. And because with lights we’re talking about pretty shallow angles for optics, making the stair-stepping more pronounced. This can be mitigated somewhat by printing the lens vertically, but then you’re also at the mercy of the resolution of the particular printer anyway. One systems cures the resin using a laser beam guided by mirrors on galvos, and another relies on projected UV light using a hi-res LCD screen to “mask” off areas not to be cured. SLA parts have to be cured as well, which causes the part to shrink somewhat and that has to also be taken into account. Possibly some post-processing technique would yield an acceptable result, but it’s probably just as cost-effective to CNC machine and polish a solid billet of PMMA.

Agro
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http://www.luximprint.com/tag/additive-optics-fabrication/

"luximprint" wrote:
The idea of ‘printing optics’ is simple, and the approach was attempted many times in the past, especially with ‘conventional’ 3D printing processes, but products made using these processes need a lot of postprocessing. 3D printing filaments or resins might be ‘clear’ and ‘transparent’, but do not offer the optical quality and performance as needed in challenging lighting applications. From a process perspective, the layer-wise printing is not able to achieve the smooth surfaces necessary for functional parts and may have high haze values (‘inside rubbish’) that can’t be compensated from the outside of the lens.

Yes, they address that and they say their process doesn’t require post-processing.

joechina
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Luxecel got approval for medical use, so I think you don’t see layers.
https://www.luxexcel.com

Here is a one method to print lenses in ABS on a normal home 3D printer
http://fenneclabs.net/index.php/2018/12/09/3d-printing-transparent-parts...

And there a few companies which print continually, e.g. Carbon 3D, but I don’t know if they have an optical resin

Agro
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Just a note, luximprint was spun off luxexcel so they use the same tech.

joechina
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Agro wrote:
Just a note, luximprint was spun off luxexcel so they use the same tech.

Ah, I initially thought of this because of the similar names. But Luxexcel seems to expand to US by its own.
Agro
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Luxexcel is interested in optophalmics exclusively. I actually asked them a question and they redirected that question to their colleagues at Luximprint.

joechina
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Agro wrote:
Luxexcel is interested in optophalmics exclusively. I actually asked them a question and they redirected that question to their colleagues at Luximprint.

Is a starter kit still $200 200£?
http://budgetlightforum.com/node/48953
Agro
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I don’t know, that was not my question and they didn’t offer me a sample kit.

DavidEF
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It will be interesting to see if someone will use this technology in a flashlight. I want to see what the price-performance rate is.

The Cycle of Goodness: “No one prospers without rendering benefit to others”
- The YKK Philosophy

Enderman
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Lens surface accuracy for a good lens is to a fraction of a wavelength of light.
This 3d printing will get nowhere close to that.

LouieAtienza
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Enderman wrote:
Lens surface accuracy for a good lens is to a fraction of a wavelength of light. This 3d printing will get nowhere close to that.

Plus, our eyes are not outputting 20-100W+ of light…

It would be interesting, however, if someone could obtain a 3D printed lens and did a good scientific comparison to an otherwise similar ground or cast lens. My guess is that they rely on the “flow” and “self-leveling” of deposited drops to create a smooth surface. It is unclear to me as to how one layer bonds to the previous without slight changes in density, and how this scales up to larger, thicker optics. And they mention a final coating on the optic, which is essentially a post-process operation.

joechina
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The trick with 3D printing is often you print a first sample, then put it under a profile measurement device, then culate the bad stuff out.

That is the same principle when you cast things. For a cast lens you must also consider shrinking.

The samples I saw from Luxexcel a few years ago were impressive.

We should get djozz on a factory tour for a first hand report. Smile

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joechina wrote:
The trick with 3D printing is often you print a first sample, then put it under a profile measurement device, then culate the bad stuff out.

That is the same principle when you cast things. For a cast lens you must also consider shrinking.

The samples I saw from Luxexcel a few years ago were impressive.

We should get djozz on a factory tour for a first hand report. Smile


Most 3d printing is on the order of microns, not nanometers.
LouieAtienza
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joechina wrote:
Here is a one method to print lenses in ABS on a normal home 3D printer http://fenneclabs.net/index.php/2018/12/09/3d-printing-transparent-parts...

Considering the smallest claimed layer resolution I know of for 3D printing – 10 microns. that’s about 4 ten-thousandths of an inch. You would need a C2 grade precision-ground ballscrew to achieve that. Unless you buy one surplus and retrofit it into your 3D printer, virtually no home 3D printer has such a ballscrew – it would cost more than the entire printer. The typical rolled ACME screw and anti-backlash Delrin nut used for the Z axis has a lead error 10 times worse than a C2 ballscrew. So you’d need some form of closed-loop feedback like a linear scale, also non-existent on most every single home 3D printer (and most commercial printers.) But even then you’re at the mercy of the stepper motor, which has a positional accuracy of 5% of 1.8deg. on either direction. And micro-stepping is not exactly the most reliable way to gain accuracy. Resolution and accuracy are two different things. Next, the roundness of the part is totally dependent on the resolution of the system – and in most all 3D printers, they use belts which lowers the actual mechanical resolution of the system. Finally, the 3D printer is not working off any geometry – it’s creating point-to-point moves based on a point cloud, so basically a 3D printed curve consists of many straight lines, which end up as facets in a finished part.

That said, the parts look really good for home 3D printing, but I question the accuracy of the optics especially if post-processing involves manual sanding which would invariably change the shape of the optic. There are amateur telescope enthusiasts that grind far more accurate optics entirely by hand.

joechina
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You can print smaller, but the printer isn’t cheap.
Nanoscripe with 2PP
https://www.nanoscribe.de/de/anwendungen/zellgerueste/
looks like 300 or 500 nm

Agro
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Here’s another player, they claim that printing is more precise than molding:
https://www.nanoptiqs.com/en/default.aspx

Agro
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Thinking about it some more….3D printing might be an interesting way of doing complex gradient index optics. That’s pretty much another degree of freedom for optics designers. And therefore – another chance to improve performance.

Jdiddy
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Hey Agro,
Did you find any other services that offer 3d printing of optics? Great mentions here, the luximprint and nanoptiks.
Im wondering if there is 3d microprinting of liquid transparent glass available to the public yet. I read a few articles on it, but it still seems like very new tech.
I feel like this would be the ultimate, for optics at least.
Cheers,

J

Agro
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I haven’t looked into the topic since then, I don’t have any new information I could put in this thread.

Jdiddy
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I had found: http://glassomer.com/index.php/technology.html
Thought I’d share.

Jdiddy
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I’ll mention as well optical liquid silicone rubber/optical grade silicone. But it can’t be 3d printed….yet, as far as I can see