Advanced Optics and Direct Metal Marking

[fullspeceng]

Universal laser offers their HPDFO optics which claim to be able to mark metals directly by making a tighter focus.

Here is a good reference https://www.engraversjournal.com/articl ... index.html

Here is a good reference of spot size vs lens: http://www.engraversnetwork.com/uls/lens_details.html

I can make a beam expander from say 8mm beam to 12mm then use a 1" (25.4mm) focus lens to get a spot size around .0011". This is 5x smaller than the traditional 55mm lens which gives 25x more power density. So your 40W laser will be the equivalent of 1000W laser in power density.

Both the beam expander and 1" FL lens I can get reasonably inexpensive if there is sufficient interest. Direct metal marking would be interesting. Anyone want to machine the holder for it or at least make the cad drawings? The precision doesn't need to be that high.

I am not sure why the Universal laser system has a beam expander + 3 mirrors + focus lens instead of 1 beam expander + 1 mirror + 1 lens.

It also costs $2650 but I can get all the optics for a fraction of that price.

[Tweakie]

Excellent idea.
Sounds really good FSE look forward to seeing your progress on this one.

Tweakie.

[lasersafe1]

I am not sure why the Universal laser system has a beam expander + 3 mirrors + focus lens instead of 1 beam expander + 1 mirror + 1 lens.

You need to give the beam sufficient path length to expand before hitting the final focusing lens. Their design needed to fit in the same footprint as their normal 90 degree bend, so they needed three mirrors for more path lenth. The better question is why not enlarge the beam to a 1/2 to 3/4" collimated beam right at the output of the laser? This would have lower power density on all mirrors and still give the ability for a very tight focus after the final lens.

[macona]

Heres their patent for it:

http://www.google.com/patents?id=BMx3AA ... &q&f=false

I have no clue why they were given a patent like this. Lots of prior art here. Nothing new and exciting here optically speaking.

I think the reason for the folded beam path is they can use a cheaper concave-concave or plano/concave optic. My guess the more you have to grind one of these optics the more expensive they get so by lengthening the path from the spreader to the final objective you get more for less.

[lasersafe1]

A patent is only as good as the lawyers who might defend it. I also have a patent from my work for DOE, but I know it's pretty much worthless in court if the company simply alters one aspect of the claim. If you want to get a patent passed, you simply write your claims with a narrow scope. "A vehicle with 2 wheels and a harmonica mounted on the handlebars painted yellow and blue." The difficult thing to do is write a good patent with broad scope claims. "A vehicle with 2 wheels".

[fullspeceng]

I suspected the same to increase path length but 3 mirrors seems overkill. You could just have something stick out the side an inch or two and it wouldn't be that bad. Maybe there is some symmetry to preserve the wavefront that I need to think about it more.

Epilog uses exactly the scheme you proposed with beam expander +collimator at the output : http://www.epiloglaser.com/tl_radiance_optics.htm

A 1" diameter, 1" short focus lens costs a LOT more than a .5" diameter 1" short focus lens which costs a LOT more than a standard 55mm znse lens.

[sandro]

Did anything ever come of this. I'd love to be able to do direct metal marking on stainless.

[J45on]

Thunder laser have a video of their high resolution attachment marking iron sheet

[twehr]

This is the same people who posted info about the DSP (identical to LightObject). They web site does not exist so be careful?

[steves]

http://www.thunderlaser.com/ is up for me.

According to their website, they manufacture a range of laser cutters/engravers. They're located in Shenzen, China.

Steve