Total laser newb here, but I have been doing some initial research to possibly build a diode laser capable of cutting 5mm ply. I've built CNC and 3D print machines, so I am familiar with the mechanics of an xyz machine.
One limitation I keep reading about diode lasers is that the point of focus is quite shallow. If you cut in multiple passes, the deeper you go the less in focus the beam will be. So, a simple question: Why not lower the toolhead for each pass? For example, if your focus length is 22mm and you are cutting 8mm in 8 passes, why not lower the head 1mm per pass? It seems like you would have plenty of travel before the laser itself interferes with the work piece.
There must be an obvious reason. People with a lot of experience and training have spent more time than I can imagine trying to squeeze better performance out of inexpensive lasers. I'm just wondering what it is so I can finalize my build design.
Thanks!