Reflecting back to 1989 when I entered into this career eager to apply my degree in Laser Technology, mainstream fabrication lasers were typical low powered 800 and 1200 watts. With today’s lasers now at 5000 and 6000 watts, I find there are still common areas of maintenance and problems between them. However, some of these issues are exponentially magnified with the higher wattage.

We will cover routine maintenance items that the majority of operators or maintenance personal can comfortably handle. However, until you have been properly trained, or even when in doubt you should always have a trained technician complete or assist you with the tasks.

Meniscus Lenses
Meniscus lenses have one concave surface and one convex surface.
A meniscus lens creates a smaller beam diameter thus reducing the spherical aberration and beam waste when precision cutting or marking.

Plano-Convex Lenses
Plano-Convex lenses have one flat surface and one outward curving surface.
These lenses are more suitable for high turnover cutting applications and when cutting and welding certain materials (metals, wood, ceramics, plastics and composites) - when the cost is more important than the level of accuracy.

The focusing lens is the last optic in the laser path, before it hits the workpiece. Its main role is to focus the laser beam to a specific focal length (FL) - depending on the application. Therefore, the focal length - that is dictated by the radiuses and curvatures of the lens - is its most important feature.
The focusing lens is normally made of Zinc Selenide (ZnSe) using an anti-reflective coating. Focusing lenses are either Plano-Convex or Meniscus.

Focal length and mounting distance

In general, there are two types of focusing lenses: planoconvex lenses which have one convex surface (convex = dome-like curvature) and one flat surface, and meniscus lenses which have one convex surface and one concave surface (concave = hollow curvature). In most laser cutting machines, meniscus lenses are used because they produce a smaller focus diameter (see next section). In some machines, plano-convex lenses are used because their production costs are a little bit lower.