IBIS: A NEW POST-FOCUS INSTRUMENT FOR SOLAR IMAGING SPECTROSCOPY

Abstract

Abstract. A new instrument for solar bi-dimensional spectroscopy, the Interferometric BIdimen-sional Spectrometer (IBIS), has been successfully installed at the Dunn Solar Telescope of the National Solar Observatory (USA-NM) in June 2003. This instrument is essentially composed of a series of two Fabry-Perot interferometers and a set of narrow-band interference filters, used in a classic mount and in axial-mode. It has been designed to take monochromatic images of the solar surface with high spectral (R ≥ 200 000), spatial ( 0.2′′), and temporal resolution (several frames s−1). IBIS has a circular field of view, 80′ ′ in diameter and, with suitable interference filters, it can be used in the wavelength range 580 – 860 nm. The wavelength stability of the instrumental profile is very high, the maximum drift in 10 hours amounting to 10 m s−1. In this paper the criteria used in the design and the expected instrumental characteristics are described. 1