If you have all the constraints I listed met and both galvos are at 45 degree angles, the path from the laser should hit the centers of everything.
@RocusHalbasch I did start out making those changes to the model - but then SW barfed, I just canāt get it to handle lots of chained mates, and I have a lot to do before my 50cm focal length UV lens arrives tomorrow.
After my beam profile images from post 226 above Iām starting to feel more enthused about a solution ā¦
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@KevinHolmes & @JoshK Good work. Thank you for contributing. I think I understand this more.
@RocusHalbasch I know from talking directly to people at FL that the original problem was because of some bogus epoxy the vendor was using to bond the laser die to the case. The epoxy was boiling off and condensing on inside of the laserās lens. I was shocked that they were just buying lasers from China with out doing accelerated age testing. I not know about optics but I do know about semiconductors. The more we talked the more I felt like they were shining me about doing this testing now but I am sure they are not going to ever ship faulty lasers again. I think they have someone acting as an in between doing testing and etc.
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@EvanFoss very interesting history on the original F1 - thanks.
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@EvanFoss thanks for the added insight on the form1 lasers, I really like knowing what happened. As for them not ever shiping faulty lasers again. I think they might currently be doing just that. The problem here may not be degradation over time. But if the spot profile is bad enough to case some of the problems we are seeing, Iād call the lasers faulty.
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Hah. Actually, that is also due to the angle of incidence changing depending on the spot at which the beam hits the main mirror. Iāll try and illustrate itā¦
Awesome work! But i think thatās perfectly fine for the distances involved.
I doubt the beam path length changes by more than a cm or so.
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Agreed - the problem is itās impact on an aperture/iris solution to laser flare. Iām working on an extra-mirror+extra-lens+aperture approach now though ā¦
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Re: geometryā¦
You can greatly simplify the problem by treating the galvo assembly as a point source.
The changes in beam length contributed by the galvos are negligible.
Youāre then left with something like this:
Of course, without knowing the angle of the main mirror, the numbers are just one big guess 
This is what iāve meant by the angle of incidence changing the flare (shape and size):
Edit: obviously, the āshadowsā or rather projections should be cast at the point where the beam crosses the print surface - but thatās irrelevant for the purposes of the illustration.
Rightā¦I pretty much said the same thing without the fancy diagrams 
āFancyā, huh? 
Iām pretty sure the printer achieves idealā¦ With the mirror at 45Ā°, and the distance from itās center to the other centers being equal.
Depends on space constraints and internal component arrangement.
Sometimes product design and compactness take precedence over ideal component placement.
Should be easy to figure out even without measuring the angle directly - assuming the mirror-to-print coverage is 100%, measuring the longer side of the mirror should be enough.
I have a good digital inclinometer at home Iāll do some measurements tonight, get the main mirror angle and size, distance to small mirror etc.
@RocusHalbasch This is not a failure of the laser but a failure of formlabs to understand how to use tolerances in respect to lasers. It took decades from the first laser print to the first home desktop one. That was years of working out how to go from having optics that look like formlabs stuff with fasteners and custom machined metal blocks to having an epoxy fiberglass box that had all the fittings for the optics just built in. Your desktop laser printer has resolution on a par with the form 1+ and it uses crappy lasers too I bet. The difference is that the people who print on paper did the math to work out what all but the worst say 5% of lasers would be like and designed the device to accommodate that. Knowing how to do that math is what we studied in engineering school. Just doing what they did and building a device that works as a prototype and then doing a production run of them and simply retrofitting them all later is what a poor hobbiest would do. (That is being to harsh on electronics hobbiests, i was one for decades before i got my degree)
In medical device design we have to do worst case tolerance for somethings. What was done on this printer is so far from that I can not even tell what name to put on it.
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@KevinHolmes Not to drag the thread off topic but would it not have been nice if they had explained to the public how that original laser thing had gone wrong. Knowing does not make me more sympathetic but it does make me less frustrated at the lack of transparency. There is a subtle feeling in the way a lot of customers are dealt with here of āWe built the printer you just get to use it.ā that bothers me. Perhaps I am too used to working in the open source domain.
It was the same story with the galvos. Any EE worth his/her salt would have looked at those original driver boards and instantly gone āThat is too many trim pots to ever have low enough drift to ship.ā Some how they just figured that it was ok. I think because the first few prototypes worked. I wonder if they do thermal testing? I have to question what corner cases they check.
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To anyone at formlabs who reads my two above posts please keep in mind this is not meant as some kind of offense or statement of āi know more than youā. I am not by nature a competitive person. The thing is these errors in judgement are something I have no humor for any more. Look up at this I was for a long time sympathetic.
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Wow. I wish I could extra like your last few posts. The refusal to discuss or comment on anything with the community is, in my opinion, both insulting, and foolish. As for the decades from first 2D laser print to the first home desktop one stereolithography turns 30 next year:). As for their engineering judgement Iāve run into my own fair share of doubts, and realization of incredibly poor decisions.
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Actually on the laser printer thing. Arguably the first laser printer like technology was when Gary Starkweather modified a Xerox machine in 1971 to use a laser to draw lines on the drum for printing. This was adapted to have a controller and some character handling in 1972 making it more like what we think of as a printer. The first desktop version was the HP LaserJet in 1984 wrapping up a lot of what had been learned since the first machine, a mere 13 years after the proof of concept. The HP LaserJet despite being the first desktop version had excellent print quality, and dependable manufacturing quality, and a solid dependable design.
In contrast Chuck Hull patented the stereolithography process in 1986, and proceeded to start 3D Systems Inc. Over the next 28 years 3D Systems and others have improved and fine tuned the process dramatically making it extremely precise and fast. Then we got the first Form1ā¦ Not quite the same thing as the HP LaserJet but you get what you get.
@RocusHalbasch Time line aside look at the ratio of posts on this thread from users vs formlabs. We are at something like 260:3?! It is not the timeline of the printing technologies that interests me. It is how the other one got to be a mature commodity. Look at the post here see how they did that. A minimum of screws, mostly spring clips. All the alignment is consolidated into one module. This is how they got cheep and it is also how they cut the number of units destroyed in shipping. There is a lot more I could say here but I am dragging us off topic.
I know there are people working there to make a quality product. I met them and they were and sincerity I did not question. Except for one guy who was the one EE I met. He took my comments as a pissing contest and asked me to leave.
Way back I had started to design my own 3D stereolythographic printer. Then FL did their kickstarter and I saw bunnieās teardown here. I figured well it is a prototype not a mature product but they will fix that quickly. It seems that I was over optimistic. I do not need to design a better printer and beet them or prove I know some obscure thing they donāt. I just want a better printer to be available. Oh yea and for the one I got at work to perform as promised.