B-70265EN/02 2.INTERNAL STRUCTURE
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(30) Guide laser (red semiconductor laser)
A diode laser is overlaid on the same optical axis as a guide
beam for checking the optical axis because the CO
2
laser beam is
invisible to the unaided eye. The guide beam is emitted in
synchronization with the mechanical shutter only when the
shutter is closed. The guide laser can be used for roughly
adjusting the optical path of an external optical system and for
obtaining a guide for the machining point.
(31) Beam folding unit
This unit extends the optical path length by folding back the
laser beam output from the output coupler in the oscillator and
outputting the beam from the outlet of the oscillator. It consists
of one circular polarization mirror and one zero shift mirror or of
two zero shift mirrors. It is provided in an oscillator of short
optical path length type; it is not provided in an oscillator of long
optical path length type.