Sophie Gillet

Imaging capabilities of hypertelescopes with a pair of micro-lens arrays

We verify the imaging performance of hypertelescopes on the sky, using a new scheme for pupil densification. To avoid seeing limitations, we used a miniature version with a 10 cm aperture containing 78 sub-apertures of 1 mm size, arrayed periodically as a square grid. The pupil densification is achieved with a pair of micro-lens arrays, where each pair of facing lenses behaves like a tiny demagnifying telescope. We have tested the direct snapshot performance with laboratory-simulated multiple stars and observed the binary star Castor (α Gem). We measured a separation of 3.8 �� and a magnitude difference of 0.85 which is in agreement with current orbital data. This verified the theoretical expectations for hypertelescopes in terms of field of view and fluxes and qualified the new optical implementation for future arrays at the scale of meters and beyond.

High Angular Resolution in 2010-2020: A comparison between possible post-VLT/VLTI instruments

The 8-m class telescopes are now in full operation, while 100-m baseline interferometers (VLTI, KeckI) are starting routine operation too. A working group from the French high angular resolution community tried to identify what could be our post-VLT/VLTI instruments after 2010. Possible future instruments, ground or space-based, can be split into three main categories: Extremely large filled aperture telescopes, diluted interferometric arrays for direct imaging, and diluted interferometric arrays for aperture synthesis imaging. These concepts are compared in terms of observing capabilities and performances (spatial resolution, field of view, imaging capability, sensitivity, photometric dynamical range, etc.), technological issues (adaptive optics, phasing, instrument mount, etc.) and R&D priorities.

Hypertelescopes for direct imaging and coronagraphy

Densified-pupil interferometers, also called hypertelescopes, can provide direct images usable for general imaging and coronagraphy. Their properties can be deduced from a comparison with blazed diffraction gratings. Ground-based versions are considered, in the form of 10 km planar telescope arrays or of 5 km spherical arrays comparable to the Arecibo radio-telescope. Steps are taken for tests at Arecibo. Space versions are proposed for detecting extra-solar planets and, in a second step, for resolving these planets and searching photosynthetic bio-markers.

Optical designs of snapshot interferometer for coronography

Following the idea developed in (Boccaletti et al. 2000), a snapshot imaging interferometer is proposed as an alternative to the NASA Origin project.