Context. In the context of direct imaging of exoplanets, coronagraphs arecommonly proposed to reach the required very high contrast levels. However,wavefront aberrations induce speckles in their focal plane and limit theirperformance. Aims. An active correction of these wavefront aberrations using adeformable mirror upstream of the coronagraph is mandatory. These aberrationsneed to be calibrated and focal-plane wavefront-sensing techniques in thescience channel are being developed. One of these, the self-coherent camera, ofwhich we present the latest laboratory results. Methods. We present here anenhancement of the method: we directly minimized the complex amplitude of thespeckle field in the focal plane. Laboratory tests using a four-quadrantphase-mask coronagraph and a 32x32 actuator deformable mirror were conducted inmonochromatic light and in polychromatic light for different bandwidths.Results. We obtain contrast levels in the focal plane in monochromatic lightbetter than 3.10^-8 (RMS) in the 5 - 12 {\lambda}/D region for a correction ofboth phase and amplitude aberrations. In narrow bands (10 nm) the contrastlevel is 4.10^-8 (RMS) in the same region. Conclusions. The contrast level iscurrently limited by the amplitude aberrations on the bench. We identifiedseveral improvements that can be implemented to enhance the performance of ouroptical bench in monochromatic as well as in polychromatic light.
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