My recent understanding of the mechanism by which laser beams cut, has had knock on effects that help solve other issues that I have been struggling with. In particular I have never been able to get even close to the spot sizes claimed for various focal length lenses. I have known for many years that the idea of a fixed focal point for our laser machine lenses was a myth but never understood why. It is easily proven that changing speed or power can affect the "focal point", thus proving it must be something other than a light ray focal point which is fixed when the lens is designed. With my new found knowledge of the cutting mechanism, I now understand why the spot size and other claimed lens properties are so exaggerated and impossible to achieve. A normal light beam carrying image information can be manipulated and tamed by one or more lenses, however, although a laser beam obeys the same laws of physics, the peculiar non-uniform INTENSITY within the beam exploits weaknesses inherent within the spherical lens design.
