technical reference
34
Synrad Firestar f-Series operator’s manual
Technical overview
Optical setup
After selecting a laser for a CO
2
laser processing system, the two most important elements to consider are:
(1) beam delivery optics to transmit the beam to the work area; and (2) focusing optics to focus the beam
onto the part or material to be processed. Each element is crucial in the development of a laser-based ma-
terial processing system and each element should be approached with the same careful attention to detail.
Delivery optics
Divergence, or expansion, of the laser beam is important in materials processing since a larger beam enter-
ing the focusing optic produces a smaller focused spot. Because the laser beam diverges slowly, increasing
by two or three diameters over several meters, Firestar f100/f200 lasers should be mounted a distance of
1.3–1.8 meters (50–70 inches) away from the work area and no closer than one meter (40 inches) for
optimum performance. Right angle turning mirrors are often used in conjunction with the laser mounting
position to obtain this distance. Figure 3-2 shows how right angle turning mirrors in a “ying optics” setup
help create this longer beam path.
Firestar f201 and f400 lasers, with their internal one-meter beam path and conditioning optics, can be
mounted right at the work area.
Figure 3-2 “Flying optics” beam path
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 magnication factor. Adding an expander/collimator to the “ying optics”
setup shown above would substantially reduce beam divergence and any variance in beam diameter caused
by the changing optical path length. In xed-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.
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