Phase-modulated pupil for achromatic imaging of faint companions

Planets outside our solar system may harbour life but their faint images are lost in the bright diffraction haloes of their parent stars. Here we show with a simple example that it is possible to suppress the star haloes without substantially weakening the planet signal if starlight, entering a telescope pupil, is phase-modulated in a prescribed pattern. The modulation remains effective throughout the entire visible light band and for a wide range of view angles. Furthermore, 'phase only' modulation over the pupil suggests an attractive possibility of using a single optical element (deformable mirror) for simultaneously removing diffraction haloes and correcting phase errors