The second loop power stabilisation photodetector array was installed in HAM2.  Unfortunately the beam
used for the alignment of the photodetector, the reflected beam from MC3, had the wrong polarisation.  One
consequence of which is that the expected signals levels on the quadrant photodiode were a lot lower.  This
will not be the case when the real beam into the interferometer is restored.

    The beam into the array was aligned through through the input alignment aperture such that the output
of the eight individual photodiodes was peaked.  In the end the output of one of the eight diodes was 
somewhat lower than the others.  This is not because of a problem with the photodiode but because the
input beam alignment was not optimised.  The parameter space of one end of the input beam alignment can
be explored by using the Picomotor driven mirror - the last mirror in the optical path to the photodetector
array.

    More details to follow in a later entry.

J. Gleason, P. King, R. McCarthy, O. Puncken, R. Savage