Audun,
      I believe the now fairly old Compaq optical mouse that was used for our paper has only 800 dpi.
Thus, the 9000 dpi of a laser mouse should yield at least an order of magnitude improvement in the
resolution.  Since it would be relatively easy to operate with a pendulum at least 2 m long (enclosed, of
course to prevent the influence of air drafts), such a mouse should permit one to observe angular
displacement changes at the level of about 2 micro radians.  I think this would be well worth pursuing,
especially for purpose of studying long term changes in the 'figure' of the Earth. ( Even at 20
micro-radians the daily thermoelastic variation should be close to observable with the right kind of
filtering. )   I have spent a good part of my career looking at motions with periods greater than 1000 s,
a field deserving of much more study.  For example, the VolksMeter data from both Redwood City and also
here in Macon show an unmistakeable terdiurnal tide (8-h periodicity) that has never before been observed
with a simple pendulum.  I believe that an "army of amateurs" looking at diurnal variations of a simple
pendulum monitored by a mouse just might uncover some unknown secrets of our planet.  The terdiurnal tide
is best known in relationship to the atmosphere.
    Randall