Couple questions about lasers

[Jamie Barber]

I am thinking of buying a laser engraver & I have seen some machines have different settings & was wondering if someone could explain what they do when you change them.

Dpi - I would assume would be the quality ( this would be for engraving?)
ppi - pulse per inch? ( for cutting?)
frequency- no clue?

could someone explain what it does when you change them?

[Larry Bratton]

Jamie:
FYI.
http://www.epiloglaser.com/tl_resolution.htm
http://www.epiloglaser.com/tl_resizing.htm
Depending on the material different frequency settings are applied to achieve the depth required.

[Mike Mackenzie]

Hi Jamie,

DPI = Resolution this is a little mis-leading if you are comparing this to a laser printer considering that you have a fixed spot size on the laser 1.5" lens = 0.003 spot size, 2.0" Lens = 0.005 and so on.

So in reality 333 DPI with a 1.5" lens is equal to the same output on a laser system. What I mean by this is the spots that are created when the laser fires are right next to each other as you increase DPI you overlap the laser dots and in a sense remove more material and the engraving process takes longer. You also have to look at material reaction some reacts differently than others and will effect the dpi and what should be used.

PPI = Pulses per inch this allows the laser to turn on and off at a set rate higher ppi the faster the pulses and the closer together they are. Lower PPI means slower pulses and less heat or farther apart pulses. Lower PPI settings are typically used for cutting and temperature sensitive materials.

Frequency = similar to PPI just done in a different manner on different systems.