Turning CFHT into a high resolution and high dynamic range imager in the visible
G. Perrin, S. Lacour, D. Rouan, T. Kotani, P. Fedou, O. Lai, J. Woillez

Abstract: We propose a novel technique to achieve high angular resolution imaging at high dynamic range in the visible at CFHT. The fundamental idea is to apply techniques developed for long baseline interferometry to the case of a single-aperture telescope. The pupil of the telescope is broken down into coherent sub-apertures each feeding a single-mode fiber. A remapping of the exit pupil allows interfering all sub-apertures non-redundantly. A diffraction-limited image with very high dynamic range is reconstructed from the fringe pattern analysis with aperture synthesis techniques, free of speckle noise. Raw dynamic ranges of a million can be obtained in only a few tens of seconds of integration time for bright objects and can be improved with off-line processing techniques. PUEO' can be used to correct part of the input turbulent wavefront to increase the sensitivity of the instrument. A coronograph can also be coupled to the pupil remapper to further increase the dynamic range for planet detection applications. The field of view of the instrument is given by the diffraction limit of each sub-pupil in the visible. The instrument can serve many astrophysical purposes. It provides a 1.5 better diffraction limit than HST. For example, its high dynamic range capability is well suited to image giant planets close to their central star and to study the structure of disks.