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Laser Optics

(Last Updated 4/17/2016)
 
Laser Head and Mirror Mounts
 

Laser Head Operation


Laser Alignment
 
Picture:  How not to align the laser head
 This seemed like a good idea at the time....Align the head....Hit the center of the hole with the laser...all done.   Well, not quite.
https://sites.google.com/a/timsmachines.com/www/home/co2-laser/IMG_0636.JPG 
  
Course Machine Build Laser Beam Alignment
 
https://sites.google.com/a/timsmachines.com/www/home/co2-laser/laser-optics/Top%20Down%20Laser%20Alignment.png

 1)  Start with the laser
      a)  Align the laser parallel to the X-Axis
      b)  Set the height of the center line of the laser to approximately center of the laser head hole
      c)  Ensure that the laser is parallel to cutting table. (Easier just to make everything level)
2)  1st Mirror (closest to the laser tube)
      a)  Adjust mirror height such that the alignment hole is centered at the same height as the laser output
      b)  Adjust the 1st mirror alignment hole perpendicular to the laser and parallel to the Y-Axis
      c)  Ensure that the center line of the 1st mirror is parallel to the Y-Axis
      d)  Ensure that the center line of the 1st mirror  and will line up with the center line of 2nd mirror.
3)  2nd Mirror (closest to the laser head)
      a)  Ensure that the 2nd mirror height is set where the center of the mirror is centered on the laser beam and the center of the Laser Head mirror opening.
      b)  Ensure that the 2nd mirror is positioned along the X-Axis such that a line connecting the Y-Axis center of the 2nd mirror to the Y-Axis center of the 1st mirror is parallel to the Y-Axis movement.
      c)  Ensure that the 2nd mirror is positioned along the Y-Axis such that a line connecting the X-Axis center of the 2nd mirror to the X-Axis center of the Laser Head is parallel to the X-Axis movement.

https://sites.google.com/a/timsmachines.com/www/home/co2-laser/laser-optics/Front%20View%20Laser%20Alignment.png
4)  Laser Head

      a)  Ensure that the Laser Head mirror opening height is set where the center of the mirror opening is centered on the laser beam and the center of the 2nd mirror.
      b)  Ensure that the Laser Head mirror opening is positioned along the Y-Axis such that a line connecting the X-Axis center of the 2nd mirror to the X-Axis center of the Laser Head is parallel to the X-Axis movement. 

5)  Beam Expander
      a)  Adjust Beam Expander height such that the input to the lens is centered at the same height as the laser output
      b)  Adjust the lens opening perpendicular to the laser and parallel to the Y-Axis
      c)  Ensure that the center line of the lens is parallel to the X-Axis and centered on the laser beam

Fine Laser Beam Alignment
***Under Construction***
For fine laser construction I create the following alignment tools...

The one on the right is a single beam laser pointer and the one on the left is a "cross hair" laser pointer.

I use BRC 18650 4200mAH batteries, $3 laser pointers from www.AliExpress.com.  The batteries supply at 3mW these laser pointers will stay lit for a long time.  Purchase a 2000+ LM flashlight with a charger and a couple of extra batteries and a 18650 battery holder and you will have inexhaustible power.

***Under Construction  Soon to come....How to perform fine laser alignment***


Cut Beam Adjustments
The focused laser beam (what I am calling the cut beam) out of the Laser Head may have an slant/angle to it depending on how close to the center of the lens the beam was aligned.  This Cut Beam Angle may not be corrected using only the laser head thumb screws (only very fine adjustments dependant upon the size of your laser head nozzle).  Adjusting all three Thumbscrews in/out will move the Cut Beam end Left/Right.  You may have to move the laser beam height up/down by moving the Laser Tube/Laser Head to move that Cut Beam Left/Right or you may have to move the 2nd mirror along the Y-Axis to move the end of the Cut Beam forward or backward toward the tube.  See below... (Updated 4/17/2016)


To test for errors in the cut beam angle cut a 1 inch circle out of thick stock (e.g. 3/4 wood).  If the cut beam angles are correct you will have a 3/4 inch cylinder.  If  not, you will have what looks like a slant stack of quarters.  If you look close, there is still some error there.  Note some of the angle is caused by the burning through of such thick stock (ei.  More burn at the top then the bottom when cutting speed is slow).




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