Power from columnation and expansion

[Terk]

Good day laser fans,
Today we are going to discuss the easiest way to increase your feed rate without upgrading the tube. As mentioned in other posts in this forum air assist is crucial and clean optics a must for a starting point. Next you may want to consider a beam expander. The way the expander I use works is as follows : adjust the optic; when the beam passes through the optics of the expander it will be expanded by the multiplication factor of the expander you purchased, ( I use a 2.5x ) , pick 3 places past the optic ( 4" , 36" and 72" ) and make a quick burn and measure the patterns. When the unit is adjusted properly the burn should measure the same at all three locations. This adjustment gives you a columnated beam, in other words you have just overcome the lasers tendency to produce a beam with an angle of degradation. My output size without expansion is 5mm, so my expanded value will be 12.5mm. How does this help you ? The way your focusing optic is designed it will work at its best when the beam is in column form. The optic also will produce a better quality kerf ( cut line ) at higher point of impact power levels when the power transmitted covers more of the input surface of the optic. I hope this helps. The results will please you.
I cut 1/4" ABS plastic at 15mm per sec unexpanded, after expansion I cut at 34mm per sec. and because the angle of degradation has been eliminated my machine cuts consistently over the entire work surface. To explain this I give the following example : pre expansion my cut was finer and more powerful at the furthest distance from the output of the laser. This was caused by the beam growing larger as it got further from output of laser. The reason for the better output at longer distance goes back to the focusing optic design, bigger surface coverage of focusing optic produces a finer and more powerful point of impact.
Enjoy the info !
http://www.beamexpander.com/BEX-10-6-2-5Z1.pdf this is my model, http://www.beamexpander.com/ is home
ps link to the site I use for expanders, The guy there is super and I feel smarter just from talking to him !

[Tech_Marco]

What made of the lens? I could find some for almost half price but it's K9 lens. Not sure if it can sustain the high temperature beam from the laser.