The Phase-Shifted Zernike wave-front sensor

The next generation of Giant Fragmented Telescopes will allow the study of faint and distant objects such as exoplanets. But the structure of the telescope also brings new challenges such as pupil fragmentation or Low-Wind Effect (LWE) that needs to be corrected by the Adaptive Optics (AO) system. The Wave-Front Sensor (WFS) which is the heart of the AO system needs to be able to measure these aberrations. Because of its high sensitivity, the Zernike Wave-Front Sensor (ZWFS) appears to be a viable candidate as a 2nd stage instrument to measure telescope seeing or differential piston. However, its use is limited by its small dynamic range. We propose here a new concept of WFS based on the ZWFS with a better dynamic range : the Phase Shifted ZWFS (Phase-Shifted ZWFS).