Novel inertial reference sensors for space applications using optical readout of a Spherical
proof mass (SPM), which enable full drag-free operations, are being studied for future
space programs such as Laser Interferometer Space Antenna (LISA) and Big Bang Observer.
Using this concept results in the reduction of residual acceleration noise by the
proof mass, but with the SPM under rotation the surface topography induces errors in
the center of mass position determination due to factors like surface finish, that changes
the optical path length on a nanometer scale, and the reflection angle.
To determine successfully the center of mass position with picometer accuracy, a
surface map of the proof mass is necessary in order to correct the measurement data, thus
improving the precision of the position determination.
An experimental setup using double heterodyne interferometer in opposing configuration
developed by Airbus, Friedrichshafen, is used to map one single surface circumference
of a continuously rotating proof mass. In this thesis, enhancements were done
to allow a complete surface map of the SPM with picometer accuracy at relevant angular
frequencies. Enhancements made were: The inertial-mass degrees of freedom were
increased by adding a second rotational stage. Overall software performance has been
improved by implementing fast angle read-out by the encoders. Code in LabVIEW and
MATLAB has been developed, capable of making a full 2D surface map of the SPM for
calibration of errors in the determination of the position of the center of mass. Data
acquisition has been sped up to enable low-noise full 2D surface maps
