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405nm Laser Build Question

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lavachemist

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Jul 27, 2020
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I'm doing some experimentation with using different laser modules in the Formlabs Form1+ 3D printer and I'm curious about setting up a custom/DIY laser for it.

I have done some searching on the forum, but I don't really know where to begin. I'm hoping someone can point me in the right direction for getting this set up. What should I consider when selecting a diode and lens? Do I need special equipment for adjusting/configuring the diode, or can this be done by a DIYer with good results?

Here are some parameters that I do know:
wavelength - 405nm
focus distance - 300mm (approximately - I will verify)
spot size - goal is 100-150u
housing diameter - 15mm
power - 120-150mW (operating power is always less than 65mW)

I can't post pictures or links, unfortunately, since I'm a new member.
 





lavachemist said:
I'm doing some experimentation with using different laser modules in the Formlabs Form1+ 3D printer and I'm curious about setting up a custom/DIY laser for it.

I have done some searching on the forum, but I don't really know where to begin. I'm hoping someone can point me in the right direction for getting this set up. What should I consider when selecting a diode and lens? Do I need special equipment for adjusting/configuring the diode, or can this be done by a DIYer with good results?

Here are some parameters that I do know:
wavelength - 405nm
focus distance - 300mm (approximately - I will verify)
spot size - goal is 100-150u
housing diameter - 15mm
power - 120-150mW (operating power is always less than 65mW)

I can't post pictures or links, unfortunately, since I'm a new member.
Click to expand...
What are your planned applications? Maybe 405nm might not be the cheapest way to go
 
gazer101 said:
What are your planned applications? Maybe 405nm might not be the cheapest way to go
Click to expand...

The planned application is in a resin 3D printer (Formlabs Form1+). It must be 405nm because that is the wavelength that the resin cures at, so that is a hard requirement for sure.
 
lavachemist said:
The planned application is in a resin 3D printer (Formlabs Form1+). It must be 405nm because that is the wavelength that the resin cures at, so that is a hard requirement for sure.
Click to expand...
From my short research, a 250 mW laser with a 3-element lens should get the job done, albeit slowly
 
gazer101 said:
From my short research, a 250 mW laser with a 3-element lens should get the job done, albeit slowly
Click to expand...

Interesting. Why the need for such high power? The original laser is 120mW, I was thinking it could be more in that range. I also don't understand what you mean by "albeit slowly." I'm a noob, sorry!
 
^From my limited knowledge on resin printing, the cure is energy dependent, not power-dependent. For instance 25mW for 10 seconds is the same energy as 250mW for 1 second, and would in theory produce the same cure, all else equal.

What's wrong with the original laser though? If you're a self-reported noob, why are you attempting a custom laser and throwing out the one that the professional printer designers have included with their own product?
 
Cyparagon said:
^From my limited knowledge on resin printing, the cure is energy dependent, not power-dependent. For instance 25mW for 10 seconds is the same energy as 250mW for 1 second, and would in theory produce the same cure, all else equal.

What's wrong with the original laser though? If you're a self-reported noob, why are you attempting a custom laser and throwing out the one that the professional printer designers have included with their own product?
Click to expand...

Great questions.

Dose is what we are interested in when curing resin. I think of dose as energy over time, which is what you're describing. The galvos in this printer are happiest at about 800mm/s in X/Y maximum feedrate. In other words, you can't achieve the correct dose if your laser power is set too high, because you can't print fast enough. Too high of a dose results in over cured resin or even damage to the printer. Most resins I've calibrated end up needing roughly 30-50mw at 800mm/s for good print quality with the OEM laser and even less with a smaller spot size.

These printers stopped being produced almost 4 years ago so the Form 1+ printers are 3-6 years old and replacement parts are no longer available. The OEM laser is decent, but has a large (130u) spot size. A smaller spot size is an upgrade based on the testing I've done. So there are two main factors driving this.

I say I'm a noob because I have never assembled a laser from scratch. I currently have seven of these Form 1+ printers and I'm testing various configurations.
 
gazer101 said:
Low power lasers are pretty cheap, I don't even think this one needs a heatsink
Click to expand...

That one has the opposite problem. 10mW would not be nearly enough (I had to remove the link because I don't have a high enough post count)

My thinking is that I will need a 120-150mW single mode 405nm diode and a lens. I'm completely unsure of what to use for a lens though. I'm guessing most people in this group are looking for significantly longer focal distance, if not infinite focus right? How do I determine what lens to use?
 
gazer101 said:
This one is capable of 200mW, but you could probably run it at less by giving slightly less voltage:
Click to expand...

That one is more interesting. I wonder what the spot size is though. Is says focusable <0.3mm. I don't know if that is saying you can focus as close as 0.3mm or that the spot size is 0.3mm.

On the topic of power, I should clarify that the printer controls the amount of power going to the laser dynamically based on parameters supplied by the user. So, higher mW isn't necessarily bad unless that also means it can't fire at lower power.
 
lavachemist said:
That one is more interesting. I wonder what the spot size is though. Is says focusable <0.3mm. I don't know if that is saying you can focus as close as 0.3mm or that the spot size is 0.3mm.

On the topic of power, I should clarify that the printer controls the amount of power going to the laser dynamically based on parameters supplied by the user. So, higher mW isn't necessarily bad unless that also means it can't fire at lower power.
Click to expand...
Yeah just do some research, maybe there's a supplier closer to you that can ship it faster. For me, eBay's the go-to-place for laser diodes/modules
 
gazer101 said:
Yeah just do some research, maybe there's a supplier closer to you that can ship it faster. For me, eBay's the go-to-place for laser diodes/modules
Click to expand...
Hi,
You should check out DTR's Laser Shop. Very good US based components with proven quality and customer support. Very well organized and great prices too :)
 
You still haven't been clear on how the stock laser is sub optimal. However, you should be able to easily change the spot size of the original laser.
 
Cyparagon said:
You still haven't been clear on how the stock laser is sub optimal. However, you should be able to easily change the spot size of the original laser.
Click to expand...

I don't think I would describe the stock laser as sub optimal; I'm really not qualified to make that assessment even if it is.

The biggest problem is that even if it's the best laser for the job, you can't buy a replacement and if you have a dead laser module it doesn't matter how optimal it was when it still worked. The smaller spot size can produce finer prints since the curing radius is smaller - at a sacrifice of longer print times. So, hopefully that clears up any confusion. I would not modify the original laser because it is irreplaceable.
 
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