[Laser Guy]

I'm very interested in building a beam expander. Would you be willing to share some of the technical specifications for this project. Specifically what type of optics and the source. This just happens to be one of the projects on my list of things to do. Also, the spot size was 0.005

Thanks

[Laser Guy]

Halfnutz

There are many different methods of beam delivery, one the most common is found on a gantry style laser cutter/engraver.The unfocused, or raw beam exits the laser resonator and bounces off a series of mirrors directing it to the cutting head. Here it passes through the lens where it is focused and directed to the cutting surface . Please see the attached diagrams for more information.

[Halfnutz]

Thats kinda what I thought, it must be a lot of work to get everything adjusted correctly, but I geusse it only has to be done once.

Great drawings, very informative, thanks for the info!

[the4thseal]

Is there a problem with the momentum of the moving parts inducing alignment issuses? Vibrations and such.
This is a great thread!!!

[KTP]

Laserguy:

I have not really designed a galilean beam expander yet, rather I was deciding if one were neccesary and/or if I should leave room for it in my beam path. They are pretty simple though...a negative lens (plano/concave) followed by a positive lens (plano/convex). The distance between the two lenses is found by subtracting the focal length of the plano/concave (negative lens) from the focal length of the plano/convex (positive lens). The new divergence of the expanded beam will be the original divergence divided by the telescope power (Fpos/Fneg).

A simple example (I hope):

Negative (plano/concave) lens with a F.L. of 50mm
Positive (plano/convex) lens with a F.L. of 150mm

Distance between lenses = 100mm

Power of galilean beam expander = 150/50 = 3

Thus a 4mm beam entering the expander with a divergence of 3mrad will leave as a 12mm beam with a divergence of 1mrad.

Again, I haven't had my coffee yet, so could have screwed stuff up.

[KTP]

the4thseal:

I hope not! (vibrations) I am trying to keep the mass of my gantry low while using pretty beefy alluminum extrusions on the non-moving parts of my engraver frame. I am also driving the gantry from both sides with belts. I am definately concerned about vibrations.

[pyroplotter]

KTP ... well as promised I got a J48-1 now and bought the new UC2000 controller for a good price for a refurbished laser directly from Synrad. Then I got a good lab supply off ebay and some high velocity fans also. I am not going to be water cooling this one just yet.

Got the optics from Laser Mechs but have a question for you ... what's your experience in gas nozzle pressure flow rates and use of different gases ? For my limited application of laser engraving onto wood, rather than cutting of wood, and with all the gases that produces, would I be better off going to a bottle of Nitrogen right away rather than breathing air ?

[KTP]

Hey wtawtaw, congrats on your new laser!

Air cooling a J48-1 is perfectly fine, the heat load is only like 200 watts or something.

So do you actually have a gas nozzle or just the lens?

Don't use bottled nitrogen, that would get expensive in a hurry. I use clean dry shop air, at varying pressures up to 60PSI or so. I made a dryer comprised of (don't laugh) a long piece of 3 inch dia galvanized plumbing pipe with a hose barb tapped into each end and filled with 3 bags of descicant contained inside panty hose. It is like a $10 descicant dryer with a huge volume! Every now and then you can drive the water out of the descicant with heat, or you can just replace it (like $1 from home depot). Before this dryer I have the common water/air separator, but that doesn't remove all the water. After this dryer I use a small screen inline filter to remove any descicant dust that makes it through the panty hose, but to date there does not seem to be much dust.

So are you mounting the laser directly to the gantry? If so, I imagine you will be up and running in like a couple days...show us pictures!

[pyroplotter]

Hello KTP .... I really like your CDA dessicator design and you bet! I'll do the same thing here. I found a small compressor that only draws 2 amps and that will supply the table.

The last couple of days have been intense and I've made progress in the laser mount. The gantry moves in X only, and the laser is mounted on a stilt type of platform over top the Z axis assembly. The optics will move in Z a maximum of 3 inches in relation to the laser and I am making my own tube-in-tube slider.

I've chose this method because I have a very sensitive Z axis crash detect system and am using that for the laser optics also. The design allows me also to easily remove the optics ( a simple bolt-on bracket ) and use either an electric engraver, a pneumatic engraver, a dremel drill / engraver, or a hot point soldering iron.

I'm not totally happy yet with how all the lines run but I've attached some pix of what I've been able to complete. We'll be ging to Hawaii next week and I will not likely get the laser fired up before then. And I'll have something to look forward to when the palm trees and mai-tai's get boring .

So here's a couple of pix of the table as it now exists.

[KTP]

Very nice setup wtawtaw!

[Smertrios]

Just FYI there are 2 mirrors and a focusing lense for sale on eBay... both are listed as being made for CO2 lasers. Looked kinda like what you would need to bounce a beam a couple of times before burning just thought I would pass the info along.

http://business.search.ebay.com/co2_...sPageNameZWLRS

[KTP]

I did some work yesterday on the 2nd Synrad 50 watt CO2 laser (48-5-28W) and determined the low power in one side (dual tube design, one side is doing 33 watts, the other side 15.4 watts) was due to a bad RF driver board, not a problem with the gas mixture! This means I can fix it instead of having to send it in for a refill. The 150 watt RF mosfet is a MRF150, and I have a few coming in the mail. It is quite funny that both of these lasers appeared to be either dead or low power but both just required electronic fixes.

This 2nd laser will probably go up for sale on ebay as I really don't need two.

[zoltan]

Hi KTP,

Are you still around? I have sent you a pm, but did not get any answer. I am interested about the results of your laser build. Also, I need some advices regarding the synrad lasers as I plan to buy one from e-bay. Thank you.

Zoltan

[skip20]

don't know if this is still going on or not.
Read the whole this & it stop in 2006
Are you still making the Pixie P100 servo controller, your web site say NO.
I've been think along the same idea to build a stonger laser.
I have a Univ X25, Had a Univ 1750 but in the early 90's

Skip20

[killor]

:wee: :wee: :wee: :wee: :wee: :wee: :wee: :wee:
:banana: :banana: :banana: :banana: :banana: :banana: :banana: :banana:

My plotter just got a laser upgrade! I bought a known broken Synrad 48-5-28W 50 watt laser and spent all day today repairing several fried circuits and damaged components on one of the two control boards. Someone had evidently miswired the unit as one trace leading to the DB9 connector was vaporized!

Reinstalled the circuit, powered up the included! UC-1000 controller and switching power supply and presto 64 watts of power with a really great beam profile! I am so happy now...my engraver project was in need of a bigger laser and this should fit the bill.

I took a picture of it blasting through a piece of balsa into a brick (which took about 0.01 seconds for the unfocused beam ) but the laser melted the brick and turned it incandescent so all you really see is what looks like the worlds most impressive white light laser (chair) I took another picture with the laser off so you could actually see things. Yes, I know this laser needs water cooling. It came with the hoses and connections, but it is perfectly fine to run it for a few seconds for the testing and pictures. There is actually quite a bit of aluminum that has to get warm before the laser would start complaining.

Hello,
I read that you had to repair the laser unit.
Would a picture from inside your laser unit?
I am interested in knowing, The Duo-Lase technique.
What optics used for the two beams combined?

Thanks