As part of the prep work for firing up the high power oscillator, the optical surfaces were
inspected.  Some time back in 2014 there was a water leak over head 3 resulting in some of
the surfaces getting wet.

    The high power oscillator was opened.  A fragment of lens tissue was found - presumably
from the last wipe down of the laser that was done to accommodate a request from LLO - near
the lid switch close to head 4.  Some metal shards were in the location.  Small blue coloured
metal shards were also found near the Faraday rotator.  These we know to be from the blue
anodising of the lid of the oscillator.  There were signs of possible galvanic corrosion after
removing the side of the laser, and at the base of an internal support member.

    Signs of water drops on all four 4f lenses.  These were drag wiped off successfully:
Drag wiped 4f lens #1.  Mostly clean, small spot around 2 and 4 near the edge of the optic.
Drag wiped 4f lens #2.  Clean.
Drag wipes 4f lens #3, mostly clean, small spot around 2-2:30 near the edge of the optic.
Drag wiped 4f lens #4.  Possible dust spot between 11 and 12 o'clock, ~two-thirds from centre
to edge.

    After performing the drag wipe, the inside of the oscillator was wiped down again so as
to not kick up any dust during the remaining dust removal steps.

  The two quartz rotators looked fine.  All the laser rod surfaces appeared okay.  The dust
on the 45 degree dichroic mirrors was successfully blown off.

  There was a possible dust spot on output coupler at 3 o'clock as looking towards exit port.
This was blown off.

The pump light lenses looked okay with the possible exception of head 3, which looks like it
has some scratches.  The scratches were there before drag wiping, and it would see that the
laser operated previously with them.  O. Puncken was consulted.


Jason, Peter