A solution to mode match the output of the 70 W power amplifier to the pre-modecleaner was found that
did not mechanically clash too badly with already installed components.  The lenses were positioned and
the initial pre-modecleaner visibility was ~60%.  After adjusting the lenses, the visibility improved to
~88%.

    Upon increasing the power incident on the pre-modecleaner the visibility dropped to ~78%.  Some
tweaking of the lens positions under full power will be required - which is not surprising.  Attached
are the two transfer functions measured at low and high power.  Both have a unity gain frequency of
~5.5 kHz.  At the moment ~56 W is transmitted through the pre-modecleaner.

    Transfer functions of the frequency servo were also taken.  We were able to push the unity gain
frequency out to ~540 kHz with a phase margin of ~60 degrees.




  Jason / Peter