Design of an integral field unit for a solar telescope

Abstract

Generally, classic longslit spectrometers consist of an entrance slit, a collimating lens, a disperser, and a projection lens. High spectral resolution is the main quality function of spectral devices; however, there is also a possibility to achieve high spatial resolution along the slit. Many scientific tasks require high spatial resolution along with high spectral one in astronomical instrumentation. For that, the integral field spectroscopy can be applied. The possibilities of an integral field unit (IFU) optical system synthesis are investigated in this work. The IFU optical system is supposed to be connected to a Solar Telescope-Coronagraph (the main mirror diameter is equal to 3 meters), which operates in a wide spectral range (0,39 - 1,60 microns). Application of integral field units for increasing the spatial resolution of spectral astronomical devices is formulated. The integral field spectroscopy technique description is given as well as the principal concept is shown. Classification of the IFU optical systems (lenslet-, fiber-, mirror-based) is provided. For systems, operating in a wide spectral range, the allreflective design is considered. The system design where the input telescope field (6′′ x 12′′) is divided into 64 slices (0,09′′ x 12′′ each) is proposed. The research results conclude in a computer model of the optical system of the integral field unit with the paraxial optics approach. The proposed solutions may be utilized in the design of optical slicing systems for various applications.