MOGlabs MOA, Manual, Page: 45 / 66

7.2 Fibre alignment procedure
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13. Increase the
TA
current to operating current in at least 4 equal steps,
repeating steps 3 to 7 after each current increase. For example if the
current required for 100 mW post-isolator is 1 A and the maximum
operating current required is 3 A, increase the current by 500 mA at
each step. Very carefully (being mindful of the high power before
the fibre coupler when inserting mirrors and power sensors) measure
the net coupling efficiency after each step. The measured efficiency
should be increasing as current increases.
14. Compare the efficiency achieved to the value listed at
Full TA power
in the test report, for the same test conditions. A value within 5%
should be expected. If this is not achieved, refer to the troubleshoot-
ing section 7.4 or the advanced procedure in section 7.2.
7.2 Fibre alignment procedure
The following procedure can be used when substantial fibre coupling align-
ment optimisation is required.
1. Ensure the seed power into the
TA
is set in the range of seed power
recommended in the test report. The
TA
injection current should be
chosen to provide 10 mW before the fibre coupler.
2. Adjust
M3
(see figs. 4.1 and 5.1) so the
TA
output is incident at the
very centre of the fibre coupler input aperture. The
TA
output should
be reasonably well collimated between the isolator and the fibre
coupler, particularly in the vertical axis. If not, check with
MOGL
abs
support for how to proceed.
3. Attach the correct fibre patch cord (refer sec. 7.1, step 1) to the
output fibre coupler. Insert the opposite end into the VFL (fig. 7.2)
and switch the VFL to glint/blink mode.
4. Adjust
M4
so the VFL output is incident at the very centre of the
isolator output aperture, through to the isolator input aperture, and
if possible, all the way back to the centre of the
TA
U-chassis output