After experiencing some problems locking the frequency stabilisation servo yesterday.
The plan was to improve the mode matching to the pre-modecleaner.  After which the
frequency stabilisation servo still did not lock.  The cause was traced to the locking
photodiode not having it's power cord plugged in.  The power cord, located underneath
PSL Rack 1, must have been disturbed.  Once plugged in again, the frequency stabilisation
servo locked.

The power incident to the pre-modecleaner was increased to ~150 W.  The measured throughput
of the pre-modecleaner was ~124 W, with the power stabilisation off.  With the power
stabilisation the throughput was ~117 W.  The power stabilisation suffers from occasional
glitches.  It is not known where the glitches come from, they may well come from either
the pre-modecleaner or the oscillator.

The output power of the pre-modecleaner was attenuated before the IO electro-optic
modulator to 60W.  The maximum power available at the base of the IO periscope is
~60 W.  The so-called "volume" control was tested, and a maximum power of 56 W was
measured when the rotation stage MEDM screen was used to request a power or angle.  We
found that both the requested angle and requested power are consistent with the
rotation stage scale and the power meter.

A more detailed report will be submitted later.




Jason, Peter