Neje A40640II laser lens focus

[MikeyH (Mike Hembrey)]

@Bobchaos

not sure how it will impact the length of the “knife” for cutting operations

If by this you mean the Depth of Focus, It should not affect that. You are juse moving the focal point up and down.

Lightburn has a Focus Test tool you might find useful. @jkwilborn has provided some good images showing both focus and DOF.

Focus for different Materials

You need a quick review of how lenses work. There are a ton of videos, but I’ll try to simplify it to how I use lenses. Most of the time we see the diagram of a lens with there being a finite focal point. [point-focus-graphic] This is clear but pretty simplistic. Lenses don’t focus to infinitely small. There is an area called the depth of focus (dof). Within the dof, the beam is the same size. [depth-of-focus] Many of the on-line spot size calculators, like this one, will give you an …