Day-time local phasing of neighbouring segments of the E-ELT primary mirror, based simultaneous multi-λ shearing interferometry

In the context of the segmented primary mirror of the E-ELT, the ability to measure the phasing state of neighbouring segments during day-time represents a way to mitigate the risk of potentially time consuming on-sky phasing after segment replacement. This paper presents the concept of a local phasing sensor based on simultaneous multi-wavelength shearing interferometry, as well as experimental results obtained on the ESO M1 test facility.