View Full Version : Epilog Laser EXT100 alignment problem

Graham Symns
09-19-2010, 7:14 PM
I have just re-aligned my 75 W laser after some re-building and was able to align the laser to some degree of satisfaction.
However the earthquake on Sept 4 has curtailed my plans to install an exhaust system outside on the street side of my workshop as I have yet to be assessed by the Earthquake Commission adjusters.(my house has suffered a moderate of damage).
Anyway I thought that I would continue work on my 100W re-build by performing an alignment on it also.
So with good intentions I started on the diode pointer as I wanted to treat the machine as a just-assembled machine as it had been involved in a fire after all, and I wanted the laser beam to be under control in an orderly fashion.
I struck a significant snag in this exercise.
In brief the pointer beam wants to land on the X-beam mirror some 10mm to the right of the sweet spot ..actually not on the mirror but on the clamp screw that holds the mirror clamp.
At this stage I could see the shape of the red beam centralised on the exit point of the laser housing.
Any adjustments that I made to shift the beam by use of the pointer control adjustment screws caused the pointer beam to be so off course that the beam bounces off the wall of the exit point (inside it)of the laser and caused a dispersed beam to light up the right hand side wall of the machine and a diminished intensity spot on the mirror and subsequently on a target fixed to the downward facing lens!
It is as if the lefthand end of the laser itself needs to be packed out from the rear mounting wall to swing the beam to my left as viewed from the front of the machine.

So here is the question....can anyone advise on this?

Regards Graham Symns

paul mott
09-20-2010, 8:41 AM

Its just a personal opinion but I would ignore the diode pointer and set / adjust the CO2 beam using Kapton or similar targets (you want something that is not going to burst into flames), one at a time mounted just in front of each mirror starting at the tube and finishing at the lens. When that is correct then adjust the diode pointer to match the actual beam path.


Graham Symns
09-20-2010, 4:54 PM
Hello Paul,

After I had sent the post I went back and aligned the laser beam in the same way that I had done the 75W laser (as per your subsequent advice)
That was a breeze so I re-tried aligning the red dot pointer.
The end result was the same.
My business partner suggested that I take the 75W machine's red dot pointer and try that.
I'll do that shortly and keep you posted.
It does seem that the red dot pointer might be faulty...really odd!
BTW there is a small trim pot on the top of the diode capsule...does any one know if it this needs adjustment in this situation?

Regards Graham

Graham Symns
09-20-2010, 5:41 PM
Hi Paul,

It's me again.
My trial using the diode pointer from my 75W laser performed no better!!

Regards Graham

paul mott
09-21-2010, 2:34 AM

I think that trim pot is for adjusting the diode current. Best left alone as the diode could be damaged by adjusting this.
Do you have a beam combiner and have you tried adjusting the position of that ?


Graham Symns
09-21-2010, 3:17 AM
Hi Paul,

The laser system is as follows:
The laser beam travels left to right along the machine,it then meets a steering mirror which directs the beam to the front of the machine.
Before the beam exits the laser unit it passes under a combiner into which passes the red laser pointer diode output.
It may be that in its travel from Auckland to Christchurch by truck, a trip of about 800 miles,this combiner/steering mirror for the red laser diode has moved a little.
I'm only surmising that this is what may have happened as the main laser seems to be unaffected. and its alignment seems OK.
What I would like to know now is that if this is what has happened would I be able to strip this part and re-align it myself?
Your advice would be appreciated.
I really don't want to send it to the USA for this.

Thanks for your interest and help

Regards Graham

Graham Symns
09-21-2010, 3:24 AM
Hi Paul,

I should have mentioned that the diode pointer is adjustable by a trio of screws that steer the diode housing to align the red laser diode beam to the X-beam mirror etc via the combiner/mirror.This is perched above the combiner/mirror prior to the exit of the laser beams from the laser exit point.
Thanks for the tip regarding the trimpot..I'll leave it alone.

Regards Graham

paul mott
09-21-2010, 3:52 AM

Without exact knowledge of your laser I can only generalize.
The beam combiner is usually mounted concentrically within and at around 45 degrees to the beam path. The 10600nm CO2 wavelength, more or less, goes straight through the combiner whereas the 650nm of the diode (which is mounted at 90 degrees to the beam path) reflects off. The trick is to align the diode so it reflects off the combiner and follows the CO2 beam exactly along concentrically and finally out through the focus lens.
Without knowing your skill levels I can't say if you can do it or not but if you are able to check and adjust the CO2 beam path you sure as hell can adjust the path of the pointer. If it is not aligned at present then you cant make it any worse :)
Take it slow, one adjustment at a time and it may pay to temporarily remove the air nozzle (if you have one) as this will allow a larger diameter of exit hole to initially aim for.

Good luck with this and please excuse me if I have just repeated stuff you already know.


Graham Symns
09-23-2010, 8:18 PM
Hi Paul,

Thought that I would keep you up to date with my latest findings.
I have also got a contact on the go with Dan at Epilog.
He's out of the office until the 28th so I decided to investigate the hardware a little further.
The final part of the laser optics on my Coherent DEOS laser model GEM-100A is is an aluminium tube mounted after the diode pointer and mirror and projecting into the working space.
I removed this from the the laser housing and found what I think is the problem.
Fair in the middle is a burn mark on the filter at the beam entry to this unit
of about 1.5 to 2.0 mm in diameter which I think would certainly disperse the red diode laser pointer beam.
I should say that for a closed area there was a surprising amount of dust on all the optics excepting the laser mirror so I guess that someone has been here before me and it is the dust absorbing some of the CO2 laser energy which has done the damage.
So I will see what can be done to replace, at minimum the ,the marked piece.
Anyway there it is for the moment until I can get Dan's input and see if my diagnosis has any merit.
Your advice has been encouraging as to how the 2 beams are combined so thanks for that.

Regards Graham

Graham Symns
09-29-2010, 8:06 PM
Hi All,
Just thought that I would let you know about my latest trial with this project.
While waiting for some information from Epilog I removed from the laser carcase a Blue anodised housing,the proper title for this is that it is a collimator optics unit.
I spied on the lens nearest the laser carcase a burn mark fair in the centre.
I deduced that it was dispersing the red diode laser.
I got a price for its replacement ,through the Auckland Epilog agent, which took my breath away.
So what I would like to know from SMC guys is if anyone has a scrapped laser of the model (see pix next post)
Then I would like to know if this part could be bought for a sensible price?
The fact that this machine has had a hard time (fire) but initial testing is encouraging but does not justify the cost (which I haven't quoted.)
Hope that this finds someone who can help.
For technical reasons I'll send another post with the pix.

Regards Graham

Dan Hintz
09-29-2010, 8:15 PM

Considering you have nothing to lose at this point, try cleaning the lens... be aggressive if you need to.

Graham Symns
09-29-2010, 8:19 PM
Hi All,

Here are the pix referred to in my previous post

Regards Graham

Graham Symns
09-29-2010, 9:07 PM
Hi Dan,

I'm in agreement with your opinion and I will try to clean it up but for the moment I'll hold off until I see some more posts from SMC posters.
I really must be simple though to think that anything to do with lasers is cheap!
Thanks for your advice.

Regards Graham

Graham Symns
09-29-2010, 9:36 PM
Hi Dan,

I was frustrated with another project so I thought that I would re-inspect the lens to see if it could be cleaned.
Unfortunately the damage seems to be incorporated into the volume of the
lens itself and bearing in mind that the CO2 laser seems to be unaffected by this blemish I think I'll put off the cleaning attempt for the time being.
So thanks again for your help

Regards Graham