In order to achieve the high performance required for the astronomical science programs with coming Extremely Large Telescopes (ELTs), the errors due to segment misalignment must be reduced to tens of nm. Therefore the development of new co-phasing techniques is of critical importance for ground-based telescopes, and to a large extent for future space-based missions. We propose a new co-phasing method directly exploiting the scientific image delivered by the Self-Coherent Camera (SCC) by adequately combining segment misalignment estimators (piston and tip/tilt) and image processing. The Self-Coherent Camera Phasing Sensor (SCC-PS) is shown to be capable of estimating accurately and simultaneously piston and tip/tilt misalignments and to correct them in close-loop operation in a few iterations. By contrast to several phasing sensor concepts the SCC-PS does not require any a priori on the signal at the segment boundaries, or a dedicated optical path. The SCC-PS is a non-invasive concept that works directly on the scientific image of the instrument, either in a coronagrahic or a non-coronagraphic observing mode. The primary results obtained in this study are very promising and demonstrate that the SCC-PS is a serious candidate for segment co-phasing at the instrument level or at the telescope level for both ground- and space-based applications. Applications of the estimators and algorithm developed for the SCC-PS seem to be possible to other on-segment aberration measurement. Early studies are already in progress to adapt these processes.

Direct detection and characterization of exoplanets is a major scientific driver of the next decade. Direct imaging requires challenging techniques to observe faint companions around bright stars. The development of future large telescopes will increase the capability to directly image and characterize exoplanets thanks to their high resolution and photon collecting power. The E-ELT will be composed of a segmented ~40 m-diameter primary mirror. High contrast imaging techniques for E-ELT will thus need to deal with amplitude errors due to segmentation (pupil discontinuities between the segments). A promising technique is the wavefront shaping. It consists in the use of deformable(s) mirror(s) to cancel the intensity inside the focal plane region. Algorithm improvements and laboratory demonstrations have been developed since the last 20 years. The use of 2 deformable mirrors (DM) in non-conjugated planes will allow correcting not only for phase aberrations but also for the amplitude errors. Lagrange laboratory has begun in 2013 the development of an instrumental project called SPEED (Segmented Pupil Experiment for Exo-planet Detection). Its goal is to develop and test high-contrast imaging techniques optimized for segmented pupil. In this paper we present a detailed end-to-end simulation for the optimization of the SPEED experiment optical design. In particular, we pay attention to the optimal separation between the two DMs necessary for phase and amplitude correction. The trade-off between various parameters (field of correction, field of view, size constraints,...) is presented and discussed.

SPEED is a new experiment in progress at the Lagrange laboratory to study some critical aspects to succeed invery deep high-contrast imaging at close angular separations with the next generation of ELTs. The SPEEDbench will investigate optical, system, and algorithmic approaches to minimize the ELT primary mirrordiscontinuities and achieve the required contrast for targeting low mass exoplanets. The SPEED projectcombines high precision co-phasing architectures, wavefront control and shaping using two sequential high orderdeformable mirrors, and advanced coronagraphy (PIAACMC). In this paper, we describe the overall systemarchitecture and discuss some characteristics to reach 10-7 contrast at roughly 1λ/D.