Novanta f201, User Manual

Page: 55 / 105

OPTICAL SETUP PAGE | 55
f201 lasers, with their internal one-meter beam path and conditioning optics, can be mounted right at the
work area.
Figure 4-2 “Flying optics” beam path.
Important Note: Optical components in the beam path must always be aligned to the actual
beam path, not the laser faceplate. Because of slight variations in laser construction, the beam
path may not always be centered in, or perpendicular to, the aperture in the faceplate.
Expander/collimators are optical devices that reduce beam divergence while at the same time increasing
beam diameter by a selectable magnification factor. Adding an expander/collimator to the “flying optics”
setup shown above would substantially reduce beam divergence and any variance in beam diameter
caused by the changing optical path length. In fixed-length delivery systems where the laser is positioned
only one meter away from the focusing optic and a small spot size is required, an expander/collimator is
again the best solution to provide the required beam expansion before reaching the focusing optic.
Focusing optics
When selecting a focusing optic, the primary consideration should be material thickness and any vertical
tolerances that occur during final part positioning rather than selecting based only on minimum spot size.
The chosen focal length should create the smallest possible focused spot while providing the depth of
field required for the material to be processed. Optics are fragile and must be handled carefully, preferably
by the mounting ring only. Be careful to select optics that are thick enough to withstand the maximum
assist gas pressure available for the process. This is especially important in metal cutting applications using
high-pressure assist gases.
Cleanliness is another important issue affecting performance and becomes increasingly important as laser
power increases. Dirty or scratched lenses will underperform, exhibit a vastly shortened lifetime, and may
fail catastrophically.
When the application requires air (instead of nitrogen) as an assist gas, use only breathing quality air
available in cylinders from a welding supply company. Compressed shop air contains minute particles of
oil and other contaminants that will damage optical surfaces. If compressed shop air is the only choice
available, it must be filtered and dried to ISO 8573-1:2010 Class 1, 2, 1 specification shown in the table below.
Table 4-1 Assist gas purity specifications.