Dual-focus optics

[Dan Hintz]

Anyone seen these yet?
http://www.ulooptics.com/ulo_optics/products/dualfocus.asp
http://www.ulooptics.com/images/pics/pic_df.gif
http://www.ulooptics.com/images/pics/diag_df1.gif

By distributing a calculated fraction of the laser energy into a secondary (lower) focus, the lenses provide faster, cleaner cuts, with easier initiation and the elimination of sub-surface dross.

Dual-Focus lenses also allow much thicker materials to be cut at a given laser power. Additional advantages come from the fact that assist gas requirements are significantly reduced.

The come in 127, 190, and 254mm focal lengths, though the listed sizes start at 1.1" diameter, so these won't be a direct fit for the majority of our machines.

This may increase the cutting thickness capability of some materials, such as acrylic, wood, etc. I have a message in to them and I'll let you know what they say as far as availability goes for our machines.

[Mike Null]

Dan

Good find. It'll be intersting to see if they can bring that concept to lower wattage equipment.

[Dave Johnson29]

Good find. It'll be intersting to see if they can bring that concept to lower wattage equipment.

Mike,

I think the problem with lower Wattage lasers will be the collimated beam diameter being small and getting it accurately aligned so there is an even amount of beam falling around the "dot."

I could easily make an adapter but our raw beam (under 200Watts) is probably smaller then the "dot." :)

[Tom Winters]

This same thread has actually been started in CNC zone too. I have some news about this lens. Last night I probably spent an hour plus talking with this company's representative. This lens has been designed to assist cutting results when cutting thick metal. This lens was never intended to be for our lower wattage lasers. Last night he told me a few things and one of the things was that the lens will not work because of the design. :( We talked about his other products and then the conversation was dropped.

I received a call back from him about two hours ago and I guess these threads are really getting some attention. The rep looked into it more and he thinks he MIGHT have a solution to fit our needs. He is not sure and will have to test prior to giving a definite answer due to the lens now being used for something else besides its original purpose.

The lens has two focal distances. Each focal distance is set during lens creation. The two focal distances can be manufactured according to the user's preference.

What does this mean?

(IF this works) With a $1,000 price tag, the purchasee would have to know what material they would be cutting, how thick of a material they would be cutting and where the first focal point should be. Could be worth while, it just depends.... I will keep you all posted on this, I am interested in seeing some results myself.

Happy Engraving!

[Dan Hintz]

I received a reply back. The lenses are custom made (which always screams "expensive" to me) for a particular application (read, material) based upon the thickness being cut. Not appropriate for most of us, but he mentioned some of his customers have had great success cutting 1/4" stainless (no mention of wattage, but even so, that's a good feat). For metals in general, he says they generally shoot for 60% power on the top and 40% power into the kerf. I specifically mentioned acrylic and wood in my request, as that's what the majority of us would be trying to cut in any thickness.

Is there any good news? Actually, yes. I'll have to change my definition of expensive and "custom made". He said a 0.75" diameter, 2" FL lens would cost $630 with a 9-week lead time. Considering we all pay $250-$350 for a lens in mount, that's not such a bad deal if you need it. I'm trying to imagine how thick a piece of acrylic I could cut in one pass :cool:

[Dan Hintz]

Tom,

Looks like you posted while I was penning my reply. $1k is a bit much, but certainly better then the HPDFO lens for the ULS machines, particularly if you have a specific application in mind. That said, I bet the $1k price tag was an off-the-cuff estimate given to you, whereas I was a little more specific as to the wattage and beam type, hence the more specific price in the $600 range. For those who would like to make their own awards from acrylic, this would allow for a thicker piece.

[Robert Ray]

I looked into those lenses last year, as I wanted to cut coorugated aluminum foil for model railroad uses.
At my day job, I work with some laser guys (Scientists and Phd types working on Laser Spike Anneal products) who told me those lasers were intended for the 2000+ watt cutting lasers, but it is possible to make such a lens system, if a beam expander was used first to keep the beam cylindrical while it propogates the full XY travel of our engravers.

By putting the beam expander before the Y Axis mounted mirror, the beam would stay the same diameter and shape at the top left and bottom right of travel for most of our engravers, giving suce a dual focus laser a much better chance of cutting the same across the whole table.

Then they mentioned it would probably cost $5K for such a lens to be made.

I would sure like to be a beta test guy though!

-Robert

[Dan Hintz]

Robert, the HPDFO lens system uses a collimator and costs $2,650. A DIY CNC'd collimator could easily be made under $1k, including lenses and mounts. Knowing the price of the lens itself isn't outrageous, this could very well be a viable option for those who use a significant amount of their machine's time on cutting thicker material. I know if I could put together such a system I would shoot towards more custom awards and signs.