An analytic framework and a complete description for the design and optimisation of on-axis
centred spatially filtering common path systems are presented. The Generalised Phase
Contrast method is derived and introduced as the common denominator for these systems
basically extending Zernike’s original phase contrast scheme into a much wider range of
operation and application. It is demonstrated that the Generalised Phase Contrast method can
be successfully applied to the interpretation and subsequent optimisation of a number of
different, commonly applied spatially filtering architectures. Optimal conditions for
visibility, peak irradiance and accuracy are derived and shown to be perfectly in line with
empirical results from the literature. New graphic methods for advanced analysis purposes
are demonstrated supporting these conclusions as well as providing new tools for innovative
filter designs and parameter settings. Finally, a number of original applications facilitated by
the parallel light-beam encoding of the Generalised Phase Contrast method are briefly
outlined. These include among others, wavefront sensing and generation, advanced usercontrolled
optical micro-manipulation, optical phase-only encryption/decryption and fully
integrated micro-optical implementations.