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Laser Scanning System
#1
I read that the mod @Junker was looking to use a 'laser scanning system'. I know that in the industrial printer they use a 2 axis galvanometer system. How possible would it be to use this in a desktop machine? Do you have any idea where they can be purchased and for how much? And lastly, wondering if anyone knows how the laser stays focused to where ever it points because it seems like it would need to change its focus all the time because as the laser moves, it would change the distance from the Galvanometer to the powder bed.
Thanks, Martin
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#2
(02-05-2021, 01:50 AM)martin Wrote: I read that the mod @Junker was looking to use a 'laser scanning system'. I know that in the industrial printer they use a 2 axis galvanometer system. How possible would it be to use this in a desktop machine? Do you have any idea where they can be purchased and for how much? And lastly, wondering if anyone knows how the laser stays focused to where ever it points because it seems like it would need to change its focus all the time because as the laser moves, it would change the distance from the Galvanometer to the powder bed.
Thanks, Martin

I believe it is possible with some beam manipulation, though I don't think the NUBM31 would be the best candidate for this. Ideally you want a single coherent beam.

Here is a link to a scanner: https://www.aliexpress.com/item/40013321...web201603_

The laser stays focused by means of a F Theta lens, which maps the focal point to a flat field. These are generally quite expensive unless you stick to the industry standard of 1064nm. In that case, the laser becomes the expensive component.
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#3
I've seen a laser printer that uses a CoreXY belt system to move to mirror to get the X and Y motion, laser stays in the same location and the focal distance to the build plate is constant, but that works with a single coherent beam, the focusing of multiple beams would be challenging.
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#4
(02-07-2021, 12:35 AM)Junkers Wrote:
(02-05-2021, 01:50 AM)martin Wrote: I read that the mod @Junker was looking to use a 'laser scanning system'. I know that in the industrial printer they use a 2 axis galvanometer system. How possible would it be to use this in a desktop machine? Do you have any idea where they can be purchased and for how much? And lastly, wondering if anyone knows how the laser stays focused to where ever it points because it seems like it would need to change its focus all the time because as the laser moves, it would change the distance from the Galvanometer to the powder bed.
Thanks, Martin

I believe it is possible with some beam manipulation, though I don't think the NUBM31 would be the best candidate for this. Ideally you want a single coherent beam.

Here is a link to a scanner: https://www.aliexpress.com/item/40013321...web201603_

The laser stays focused by means of a F Theta lens, which maps the focal point to a flat field. These are generally quite expensive unless you stick to the industry standard of 1064nm. In that case, the laser becomes the expensive component.

I think these F Theta lenses are quite simple, to my understanding.. all laser leses can be quite simple. As you are only using so narrow band of light. So basically any lens works.. this is why the focusing lens can be single element.

F theta lenses seem to be simply planar lenses. They focus on a flat field.

Here are few examples:

[Image: 00050_psisdg9626_96261S_page_4_1.jpg]

Compare the simple middle design to these photo lenses. Or their front groups.

And here are old large format process lenses:

   

Here is your average modern planar lens:

[Image: optical-scheme-of-the-Planar.jpg]

It might be possible to simply use half of a process lens as a cheap F Theta lens. Or basically half of any modern planar lens. All it has to do, is to project a flat field. Basically any photo lens does that. These lenses have coating for visible spectrum, so your blue laser would work.
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#5
(07-01-2021, 11:06 PM)monkeyfist Wrote:
(02-07-2021, 12:35 AM)Junkers Wrote:
(02-05-2021, 01:50 AM)martin Wrote: I read that the mod @Junker was looking to use a 'laser scanning system'. I know that in the industrial printer they use a 2 axis galvanometer system. How possible would it be to use this in a desktop machine? Do you have any idea where they can be purchased and for how much? And lastly, wondering if anyone knows how the laser stays focused to where ever it points because it seems like it would need to change its focus all the time because as the laser moves, it would change the distance from the Galvanometer to the powder bed.
Thanks, Martin

I believe it is possible with some beam manipulation, though I don't think the NUBM31 would be the best candidate for this. Ideally you want a single coherent beam.

Here is a link to a scanner: https://www.aliexpress.com/item/40013321...web201603_

The laser stays focused by means of a F Theta lens, which maps the focal point to a flat field. These are generally quite expensive unless you stick to the industry standard of 1064nm. In that case, the laser becomes the expensive component.

I think these F Theta lenses are quite simple, to my understanding.. all laser leses can be quite simple. As you are only using so narrow band of light. So basically any lens works.. this is why the focusing lens can be single element.

F theta lenses seem to be simply planar lenses. They focus on a flat field.

Here are few examples:

[Image: 00050_psisdg9626_96261S_page_4_1.jpg]

Thanks for sharing that monkeyfist. I'm curious about b). Do you have access to the original article? I noticed it is behind a pay wall. I'm just curious to know what they are comparing/contrasting between each of those lens groups.
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