Full Version: Muscle
From: Harvey only (HARVEY-ONLY) [#4]
10 Oct 2005
To: Bob (ALLSPORT) [#3] 10 Oct 2005
The laser in a CD player is a laser diode, when they get them out of the tiny milliwatt range and into the 25 watt range we will be there.
While the physics of lasers is quite well known, the practical manufacturing is not as good as it could be. The idea of just below the next step is one great possibility.
There are laser power meters available. They are used way out of focus so will give the average beam power. How perfectly it is focused, not only hot spot size but how much is focused and how much power is left at the edges makes a big difference in cutting. [The following numbers are for example only, I have no idea of real world figures.] If the focused spot has 50% of the power and the area around it has 50% of the power it will not cut as well as if that tiny spot had 75% of the power and the expanded circle only 25%.
In theory a good laser beam should be not only coherent, but even powered within the beam and parallel focused. In practice this is not the case. Until there is a truly point source for the light, (impossible because it would laser burn that point), it cannot be focused into perfectly parallel light. The collimation is the first step.
From: Boz (CHEDDARHEAD) [#5]
19 Jan 2006
To: ALL
Your laser might not be a higher powered system than what you bought. The laser beam might just be a very good or high order mode. If the profile of the laser beam has the highest density of energy in the center and less energy towards the outside, you might be getting the great results you are seeing. Think of the profile of the laser beam as looking like a V. (If you take a piece of acrylic, set it in the unfocused beam path, and turn the laser on, you will see the profile of the beam burned. Look at the profile from the side of the piece, and you will probably see a V burned in the acrylic.) This high order beam mode will give you great results when marking or engraving on materials that need the most energy in the middle like using a metal marking spray.
On the other hand, if you have a really high order beam mode from your laser, engraving on some materials will have lines in the bottom of the engraving. Like engraving on acrylic. If your beam profile looks like a "donut" mode, your engraving on acrylic will have a much smoother bottom, but you might not get great engraving using metal marking sprays at faster speeds. Energy density can be more of a determining factor than just raw laser power, to a point.
A tip for those who get a lot of "lines" in the bottom of their engraving on materials like acrylic. Move your table and material down ~ .050" out of focus and try the engraving. The defocused beam will give you a smoother bottom to your engraving. But you might have to slow your speeds down a bit, because you have less energy density due to a larger spot size of the beam.
A tip for those who feel they aren't getting the best results with their system using metal marking sprays. Try a shorter focal length lens on your system. Instead of using a focused beam of say .006" dia., you might be using a focused beam of .004" dia. Same amount of power in both laser beams, but more energy density in the smaller diameter beam. If you go to a shorter focal length lens, you have make sure you are working on flat material because you have a shorter depth of field.
Yadda Yadda Yadda
From: Boz (CHEDDARHEAD) [#6]
19 Jan 2006
To: ALL
From: Stunt Engraver (DGL) [#7]
19 Jan 2006
To: Boz (CHEDDARHEAD) [#6] 19 Jan 2006
It made perfect sense to me and I don't even own a laser. :-)
From: Hale [#8]
27 Jun 2006
To: Bob (ALLSPORT) [#7] 28 Jun 2006
Another possibility is that the new Laserpro has a colliminator or another lense that focuses the beam tighter. That would help if cut better. The beam on my 60 watt Epilog is a lot smaller than the beam was on the 45 watt machine it replaced. I can see the difference and it cuts a lot cleaner, especailly on wood. I just cut out a couple of the epilog bird homes from 1/4" poplar I got at Lowe's and no smoke residue even without taping.
Hale Reider
To Be Cherished