A red dot is very useful for alignment of the work origin and has been a common request. Our 60W professional units already have it built in but many users of the 40w hobby lasers also want it.
A beam combiner is a round piece of glass that is reflective on one side and anti reflective on the other side. This window is usually put at 45 degrees and allows the invisible CO2 laser light to pass through the back and reflects a red laser dot from a laser pointer off the front.
Here is a photo of the idea. The red laser pointer on the right puts out a laser beam that hits the beam combiner at 45 degrees and gets reflected on the Y axis mirror then to the laser head.
Both the beam combiner and the red laser pointer are stationary so once it is aligned nothing should need to change.
The invisible CO2 laser beam just passes straight through the beam combiner down the the Y axis mirror.
You can make your own mount or just stick the optic in some silly putty to hold it up as shown in the picture.
Another possible position is to put the beam combiner closer to the lens with some silly putty and drill a hole on the left side of the laser case to mount the red laser pointer out the left side.
The beam combiner can be purchased from an optics store for around $150-200 or you can use a cheaper ZeSn window (not coated reflective on one side but enough reflection takes place at 45 degrees that you can still see the dot). ZeSn windows can be purchased on ebay for $10-20 (not available from us). Diameter doesn't really matter as long but bigger is easier to mount. Regular glass absorbs the Co2 laser light so cannot be used.
nice kiah, i have contacted a ompany in india about the mirrors. i believe they cost 150 dollar. would like to build also something myself because the red pointer is kinda useless if you ask me when you change hight
vincenttor, it is still useful. when you are the focal distance, it is pointing to the right spot.
My issue is that the laser point is SO HUGE compared to the actual CO2 laser point. My feeling is that going to the system mentioned above with combining optic, it will also focus the RED laser to a much finer point that will be way more accurate for locating where the work will be. Can anyone confirm my thought?
(That would be the beginner that grins really big and often)
Great idea on masking the existing targeting laser with tape that has a pin hole. Your cross hairs look cool and effective, but I'm not worried about multiple focal lengths. I only have the one focal length lense. Why do you need the different distances? What kind of things are you cutting? Bigrinner
The standard laser will only be in focus at one height. For example, if you align the red laser with the surface of a part you're engraving, then you want to cut something, you will have to put the focal point midway through the piece you're cutting. When you do this, the angle of the laser causes the dot to shift, making alignment of a piece for cutting difficult.
Easiest way I have found for repeatable alignment is a sheet of paper, always have an outline in another color and zap the outline on it's own at low power, it shows you exactly where it's going to cut. then leave or remove the paper depending on what you are lasering. I laser can lids alot so I just leave the paper there, hit the go button and repeat.