
B–70115EN/03
11. LASER OPTICAL SYSTEM
347
The internal surfaces of the output mirror and rear mirror are concave. For
laser oscillation, the curvature centers and mirror surfaces of the two
mirrors must lie on the same axis. When this axis matches the tube axis
of the discharge tubes, in other words, when the laser beam reflected by
these mirrors passes through the center of the discharge tubes, the output
level is maximized, and symmetric beam mode and a round section are
obtained.
The theory of alignment is such that while monitoring the output power
level with a tester, you adjust the angle of each mirror to obtain a
maximum output power. Once this adjustment is made, all mirrors are set
for maximum output. So, if a mirror is misaligned, the original state or
original beam mode can be restored by adjusting the misaligned mirror
only to maximize the output power. Thus, with this method, mode
adjustment is simple, and can be performed with a good reproducibility.
Section 11.2.1.1 describes the procedure for adjusting all mirrors of an
oscillator not adjusted with this method, to obtain the maximum output
state. This procedure takes a rather longer time. However, once this
adjustment is made, adjustment work required at the time of mirror
cleaning can be remarkably reduced.
Section 11.2.1.2 describes the maximum output state adjustment
procedure required to correct an optical path shift caused by a resonator
distortion during transmission or installation.
Section 11.2.1.3 describes the adjustment procedure at the time of mirror
cleaning for an oscillator adjusted to the maximum output state according
to Section 11.2.1.1 or Section 11.2.1.2.
Section 11.2.1.4 describes the method of obtaining a maximum power.
Section 11.2.1.5 describes burn pattern collection and beam mode
evaluation.
(1)Record the adjustment screw readings of the output mirror (O.C.), rear
mirror (R.M.), and folding mirrors (F.M.).
(2)Collect a burn pattern, and use it as the start state for mode adjustment.
Near (3 m): Hot mode and cold mode
Far: Hot mode and cold mode
(3)C3000C, C3000D, C6000B
1) Obtain a maximum power based on the output mirror (O.C.) by
using the rear mirror (R.M.) as the reference.
2) Obtain a maximum power based on the folding mirror (FM1) by
using the output mirror (O.C.) as the reference.
3) Obtain a maximum power based on the folding mirror (FM4) by
using the rear mirror (R.M.) as the reference.
11.2
OPTICAL AXIS
ADJUSTMENT
11.2.1
Alignment of the
Resonator (Maximum
Power Method)
11.2.1.1
Method of obtaining a
maximum power by
adjusting all mirrors