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View Full Version : Anyone Using a Beam Combiner?



Mikah Barnett
10-19-2014, 12:29 PM
I know they take away some power, but most of the time I'm nowhere near 100% anyway, and this is with my 80W tube in. Looks like I'm going to be doing a lot more engraving on aluminum (a good thing!) and having an accurate, precise red dot would be a huge help. The one I have now has gotten dirty or scratched over the years and the "red dot" is more of a "red haze" which makes it nearly useless.

I could fab up a little fold-away bracket to hold the red laser and beam combiner, but just wanted to know if any of you are doing this already. Does the combiner get very hot? What's the expected life span? Is the accuracy between dot and real beam what you were hoping for?

I appreciate any insight.

Dave Sheldrake
10-19-2014, 2:08 PM
Go with a green Mikah, it's in the mid range of human vision (532nm) so you can use a lower powered diode(unit) and still have a visible spot. In the dusty / smokey atmosphere of the cabinet a green will be visible along it's path as well.

Accuracy wise beam combiners are far more accurate than any human can adjust them, it's all in the set up as to how well they work.

cheers

Dave

Mikah Barnett
10-19-2014, 2:46 PM
Go with a green Mikah, it's in the mid range of human vision (532nm) so you can use a lower powered diode(unit) and still have a visible spot. In the dusty / smokey atmosphere of the cabinet a green will be visible along it's path as well.

Accuracy wise beam combiners are far more accurate than any human can adjust them, it's all in the set up as to how well they work.

cheers

Dave

Thanks Dave, green makes sense. Any thoughts on heat/lifespan of the combiner?

Dave Sheldrake
10-19-2014, 5:49 PM
To the laser beam (10,600 nm) the combiner is basically transparent (about 98.8%), to the 532 wavelength it's reflective but as you will only be using a Green of around 5 - 10 mW there isn't any heat as such to worry about. There is no such thing as a green diode as such, they are frequency doubled IR's to produce a green beam. It does make them a little bigger (not much) but overall the benefits of green far outweigh the tiny size increase.

In effect you will be pumping maybe 5mW into the combiner, even the air around it is enough to keep that cool :) A tiny fan (25mm etc) blowing onto the Green unit will ensure a long life. The actual CO2 beam will be doing more heating than a tiny diode set. Combiners for CO2 wavelength are Zinc Selenide, much the same as most final focal lens's.

cheers

Dave

Combiners drain power when they get dirty, same for heat, if you let them get mucky they will crack due to the laser inducing heat in the surface dirt.

Mikah Barnett
10-20-2014, 12:18 PM
Thanks again, Dave. I had it in my head they were 90% transmission efficiency so was worried about the 10% turning in to heat, but 2% is much less concerning. I will post some pictures of my proposed mount soon. Been considering replacing the steel head on my unit with a custom CNC billet aluminum one anyway, this might be just the right time to look at that.

Dave Sheldrake
10-20-2014, 4:06 PM
Careful when swapping heads Mikah, the extra weight transmits a lot more force / work onto the steppers, on the beam combiners, get a good one from II-VI or RMI, the cheap chinese ones are likely nearer 90% transmission, that said heat isn't really a problem even on the cheap versions.

cheers

Dave