Improved APM coronagraph concept using the “geometrical” or Pancharatnam-Berry phase to provide an achromatic π phase shift between the core of the PSF and the external region. While the polarization of the core is rotated by  + π/2, the outer region polarization is rotated by −π/2 creating an achromatic Rodier & Rodier phase mask. Between the central disk electrode driving the core and the electrode driving the outer “annulus” a series of ring electrodes allows tuning the ratio of the surface areas phase-shifted respectively by  + π/2 and −π/2. This enables the adaptation of the phase mask diameter to the observation conditions. In addition, the liquid crystals are sandwiched between two crossed linear polarizers in order to modulate the outer-region wave amplitude. This enables the fine-tuning of the amplitude balance of the two phase-shifted waves and therefore the optimization of the nulling efficiency.