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Tom Bull
01-03-2008, 9:25 PM
Has anyone seen something like this work? If it is like they say, what would happen with the beam after it passed through your work? I am refering to the using 2 lens system they show.
I don't know if this ebay link will show, so the item # on ebay is: 150199294961

Thanks, a happy and prosperous new year to all.

Rob Bosworth
01-04-2008, 12:36 PM
Tom, the auction is for a coated focusing optic for CO2 or similar wavelength lasers. The explanation shows how this could be used in a collimator type of assy. Collimators are used in laser systems to try to minimize the effect of divergent or convergent beams coming out of a laser. A laser beam usually expands as it comes out of a laser. The further away from the laser output, the larger the diameter of the beam. If you try to focus that beam at different lengths away from the laser, you will see different focused spot sizes. (You might also see different other beam characteristics, but let's stick with the focus spot.) The larger the beam diameter, the smaller the spot size you can achieve. So if you have a laser system that has 10 ft. of travel from near to far, you might have a 1/4" diameter beam at 0,0, and a 3/8" diameter beam at 5', 5'. The beam focused at the 0,0 spot with a 2" fl. lens might be .006" dia. and maybe .0045" diameter at the 5,5 spot.

If you wanted to just buy the 2.5" fl. GaAs coated lens to use in your system, you could. It is a fairly small diameter lens (.431" dia.) and is convex on one side and concave on the other. The lens you now have in your system should be Plano Convex which means it is convex on one side and flat on the other. The optic in the auction is also a little thin at .072" thick.

Larry Bratton
01-04-2008, 6:00 PM
Now that's what I call a technical answer!

Tom Bull
01-04-2008, 11:43 PM
You are so right, that is technical, but helpful. The part I was intrigued by was having 2 lens set-up to have a beam that was focused over a wide distance. Not something I want, but could see how it would be useful for cutting and keeping a truly perpendicular side.