technical reference
37
Synrad
Series 48Series 48
Series 48Series 48
Series 48 operator’s manual
Technical overview
Duo-Lase
®
operation (48-5)
The 48-5 laser combines two laser tubes for twice the output of a standard laser. The outputs from two
25 W sealed CO
2
tubes are combined optically to provide a single diffraction-limited beam at 50 W. This
optical combining technique is based on the fact that each laser is linearly polarized, allowing the use of a
polarization sensitive beam combiner to achieve 98% efficiency in combining the two beams. The two
components of the resulting beam are spatially parallel and collinear, reducing the normal temporal and
spatial variations of a single laser. Output polarization is random and therefore superior for many cutting
applications.
The 48-5 laser uses two control boards and four RF drivers. The control boards are tied together elec-
tronically so that if a failure mode shuts down either board, both laser tubes are turned off. The control
boards are equipped with individual fuses for each RF driver PWM output. In the event of an RF driver
failure, only that fuse will open, allowing other RF drivers in the system to continue operating. Unless
both fuses are open on a given control board, no shutdown will occur, nor is there a fault output signal.
In general, the two Command inputs (CTRL1 and CTRL2) should always be driven identically with a
“Y” or “T” connector. For special applications in redundant or ultra-wide dynamic range systems, it is
permissible to drive only one Command input; however, the beam’s random polarization is compromised.
Optical setup
After selecting a CO
2
laser for your processing system, the two most important elements to consider are:
(1) 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 reliable laser-based
material processing system and each element should be approached with same careful attention to detail.
Delivery optics
Divergence, or expansion, of the laser beam is important for materials processing since a larger beam
entering the focusing optic produces a smaller focused spot. Because the laser beam diverges slowly,
increasing 4 mm in diameter over every meter, Series 48 lasers should be mounted a distance of 1.0 m to
1.5 m (40" to 60") away from the work area. Right angle turning mirrors are often used in conjunction
with the laser mounting position to obtain this distance. Figure 3-5 shows how right angle turning
mirrors in a “flying optics” setup create this longer beam path.
Figure 3-5 “Flying optics” beam path
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