The Planet Finder instrument for ESO's VLT telescope, scheduled for first light in 2010, aims to detect giant extra-solar planets in the vicinity of bright stars and to characterise the objects found through spectroscopic and polarimetric observations. The observations will be done both within the Y, J, H and Ks atmospheric windows (~0.95 - 2.32μm) by the aid of a dual imaging camera (IRDIS) and an integral field spectrograph (IFS), and in the visible using a fast-modulation polarization camera (ZIMPOL). The instrument employs an extreme-AO turbulence compensation system, focal plane tip-tilt correction, and interferential coronagraphs. We describe briefly the science goals of the instrument and deduce the top-level requirements. The system architecture is presented, including brief descriptions of each of the main sub-systems. Expected performance is described in terms of end-to-end simulations, and a semi-analytic performance-estimation tool for system-level sensitivity analysis is presented.
Observations of extrasolar planets using Integral Field Spectroscopy (IFS), if coupled with an extreme Adaptive
Optics system and analyzed with a Simultaneous Differential Imaging technique (SDI), are a powerful tool to
detect and characterize extrasolar planets directly; they enhance the signal of the planet and, at the same
time, reduces the impact of stellar light and consequently important noise sources like speckles. We developed a
simulation code able to test the capabilities of this IFS-SDI technique for different kinds of planets and telescopes,
modeling the atmospheric and instrumental noise sources, and the main results of this code have been presented
in Ref.1. This code, although it takes into account many parameters and sources of noise, can still be improved,
and in order to do it we studied in detail two aspects that have been neglected in the first version of the code:
the not uniform illumination of the microlenses and the speckle undersampling. The results of these studies are
presented here.
A new IDL code for simulations of observation made with an Integral Field Spectrograph attached to an adaptive optics system is here presented in detail. It is conceived to support CHEOPS, a high contrast imaging instrument for exo-planets detection. The aim of this sofware is to achieve simulated images and spectra considering realistic values of speckle noise, Adaptive Optics corrections and the specific instrumental features. This code can help us in particular to simulate close binary systems or exo-planetary system, in order to find the limit of detectability of faint objects using simultaneous differential imaging.
For applications like direct imaging detections of Exo-Planets from the ground e.g. in the CHEOPS project, extreme adaptive optics (XAO) systems using DMs with > 1000 actuators and correction frequencies of ~2kHz are proposed to be used in combination with coronographic devices. If the XAO and science channel work at the same wavelength it is a natural idea to combine the coronograph with the XAO's beam splitter (BS) to make use of the light that would otherwise just be lost. However, the location of the BS in the focal plane and the severe field limitation of the AO by a small (~0.3'') aperture in the focal plane imposes a spatial filtering on the wavefront sensor signal. In this paper, we examine the effect of the spatial filter on the "AO control radius" and the Strehl ratio provided by the system in a semi-analytical way, numerical simulations for various wavefront sensor types and a laboratory verification experiment.
A dedicated code designed to simulate observations made with a high contrast imaging instrument using an integral field spectrograph and an extreme adaptive optics system (CHEOPS) is in progress. High contrast and high angular resolution are required in order to detect close faint companions and exo-planets using the differential technique. In this paper we present a comparison, made in order to validate the code, between simulations and observations recently obtained with the Simultaneous Differential Technique (SDI)\cite{len03}, an up-graded version of NACO (AO facility at the ESO-VLT 8m telescope "Yepun").
CHEOPS is a 2nd generation VLT instrument for the direct detection of extrasolar planets. The project is currently in its Phase A. It consists of an high order adaptive optics system which provides the necessary Strehl ratio for the differential polarimetric imager (ZIMPOL) and an Integral Field Spectrograph (IFS). The IFS is a very low resolution spectrograph (R~15) which works in the near IR (0.95-1.7 μm), an ideal wavelength range for the ground based detection of planetary features. In our baseline design, the Integral Field Unit (IFU) is a microlens array of about 250x250 elements which will cover a field of view of about 3.5x3.5 arcsecs2 in proximity of the target star. In this paper we describe the instrument, its preliminary optical design and the basic requirements about detectors. In a separate contribution to this conference, we present the very low resolution disperser.
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