1. SwissCheesEx An idea to obtain over-diffraction limited imaging with a seeing limited, extremely large telescope over a wide range of wavelengths A. Richichi - Garching Science Day 2006

2. The Moon’s limb acts as a straight diffracting edge. The diffraction phenomenon occurs in “vacuum”, no turbulence effects. High-angular information is embedded in the diffraction fringes. The “resolution” is independent from telescope diameter (but depends on signal-to-noise ratio). Temporal scales (depending on wavelength and apparent limb velocity ) are ~0.1s. High temporal rates are needed, typically ~1 ms in the near-IR. Diffraction patterns of two or more components add linearly. Lunar Occultations

3. Why Lunar Occultations are good Simple, economical (also in time) High angular resolution (0.5-1 mas) Sensitive (on a large telescope) Why the are not good enough Cannot choose the source About 10% of sky covered by the Moon (in 18.5 years) One-dimensional scan only

4. Artificial Occultations using Giant Sails Choose your own targets / time Repeat observations High sensitivity (no background) Tomographic Imaging (Swiss Cheese)

5. Why an ELT? Sails should be as large as possible, but won’t be as large as the Moon  They have to be very close to Earth to have a decent angular coverage  They will have a high angular speed to remain in a stable orbit  Integration times will have to be correspondingly short  Short wavelenths (not hitherto possible) will also require short integration times Telescope area is critical to set the limiting magnitude (not its optical quality)

6. What can you do with a Swiss Cheese in Space? Assume 42m ELT, 1000km Ø sail, 0.05m/ms (P ~1 yr) K mag ~ 17, 0.5 mas (eq. to 800m). Also B, V 2º (16x Moon area) Full imaging in few hours 30m vs 42m: also OK, same angular resolution, 0.4mag loss Perfect coronograph, direct detection of exoplanets Showstoppers/Difficulties Build, deploy and control large sail?? Orbit must be low, slow, provide sky coverage Non-Fresnel diffraction requires ad-hoc analysis Financial support from Swiss Cheese Producers?