Design and construction of a multiple integral-field unit for 8-m telescopes

Abstract

Integral Field Spectroscopy (IFS) is a powerful tool for astronomy, of particular importance to large aperture telescopes. We have designed and constructed a prototype integral field unit (IFU) for multiple-IFS which may be deployed to any desired position in a 30' diameter field of view and will deliver a good image quality simultaneously at visible (0.45 - 1.0 μm) and near infrared (1.0 - 1.8 μm) wavelength ranges. The design and construction of the multiple-IFU for the prime focus of an 8-meter telescope is discussed in this paper. The IFU uses optical fibers whose flexibility is an important advantage for a multiple-IFU. Simple and compact optics is essential for the design of the IFU. Key design issues, such as the fore-optics, microlens array and fiber bundle, are described in detail. Finally the achievable performance of the IFU is estimated.