We propose a method to transform a Cherenkov telescope, primarily designed for gamma-ray astronomy, into an imaging telescope at the diffraction limit of an equivalent astronomical telescope. The method can be applied onto existing and planned Cherenkov telescopes, both taken as a single dish or a set of such telescopes configured for aperture synthesis operating as intensity interferometers. We examine the sensitivity of our method by performing extensive numerical simulations including two and three point correlations, for amplitude and closure phase quantities permitting image reconstruction of stellar surfaces with subtle structures in the range of milli-arc-second resolutions. As a case of study we apply our method to a single 20m class Cherenkov telescope with the perspective of its generalization to the diluted Cherenkov Telescope Array (CTA) under construction in North and South hemispheres.
A special case of optical aperture synthesis, homothetic mapping, is the topic of this paper. It allows for a wide field of view for interferometric instruments. This paper describes a testbed constructed and tested in TNO-TPD in Delft (the Netherlands). This testbed is intended as a tool to investigate the ins and outs of homothetic mapping. The homothetic mapping approach is explained, the whole setup is specified and results are shown.
We propose a new high dynamic imaging concept for the detection and characterization of extra-solar planets. DIFFRACT standing for DIFFerential Remapped Aperture Coronagraphic Telescope, uses a Wollaston prism to split the entrance pupil into two exit pupils. These exit pupils are then remapped with 2 apertures lenses of different diameters resulting in two separate rescaled focal images of the same star. Since the angular separation of a putative exoplanet orbiting around the star is independent of the angular resolution of the remapped output pupils they appear at the same linear location in the resulting images that differ in resolution proportional to the exit pupil sizes.
Exoplanet detection is obtained by numerically rescaling the images at the same angular resolution and substracting them, so that, under aberration and photon noise free conditions the planet twin images appear as two positive and negative Airy patterns. In real conditions however and depending on the exoplanet separation normalized to the angular resolution of the input telescope detection performances depend strongly on the adaptive optics performances and the collecting surface of the telescope. In this study we present the formal expression of DIFFRACT optics concept with a complet set of numerical experiments to
estimate the performances of the concept under real observing conditions including instrument and adaptive optics corrections.
A special case of optical aperture synthesis, homothetic mapping, is the topic of this paper. It allows for a wide field of view for interferometric instruments, interesting for astrometric measurments of wide objects. This paper describes a testbed constructed and tested in TNO-TPD in Delft (the Netherlands). This testbed is intended as a tool to investigate the ins and outs of homothetic mapping. The homothetic mapping approach is explained, the whole setup is specified and results are shown.
The Delft Testbed Interferometer (DTI) will be presented. The
basics of homothetic mapping will be explained together with the
method of fulfilling the requirements as chosen in the DTI setup.
The optical layout incorporates a novel tracking concept enabling
the use of homothetic mapping in real telescope systems for
observations on the sky. The requirements for homothetic mapping
and the choices made in the DTI setup will be discussed. Finally
the first results and the planned experiments will be presented.
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