Temporarily installed a 2 in. diameter, 45 degree thin film polariser in the output of the pre-modecleaner.
Measured 0.342 W reflected from the polariser with the 10A-V2-SH power meter.  Measured 92.5 W transmitted
through the pre-modecleaner with the polariser removed, and with the L300W-LP power meter.  The power
stabilisation was on for both measurements.

    The output polarisation is calculated to be (1 - 0.342/92.5)*100 =  99.6% linearly polarised.

    Using the same thin film polariser in the input beam to the pre-modecleaner, 15.0 mW was measured in
reflection.  1.51 W was measured in transmission.  The power stabilisation was off for this measurement.
The input polarisation is calculated to be (1 - 0.015/1.51)*100 = 99%.  It's not obvious why it would be
this low.  Other than perhaps the angle of incidence alignment is off a little - a degree of freedom we
do not have - because typically thin film polarisers are somewhat sensitive to input angle.

    Another high power attenuator was installed in the beam between the two Picomotor equipped mounts.
We confirmed that we could re-lock the pre-modecleaner prior to turning off the high power oscillator to
allow for modifications to the field box(es) by Daniel and Keita.




Jason/Peter