Image Slicer Integral Field Unit for Solar Telescope

Abstract

Integral Field Spectroscopy (IFS) can provide two-dimensional spatial and one spectral information for spectroscopic observation simultaneously. This is important for solar observatory because of the nature of the extended object of the solar observatory. Integrated Field Unit (IFU) is the key and basic tool for IFS. An innovative IFU was designed at National Solar Observatory which will deliver good image quality at visible (0.39 - 1.0 mm) and near infrared (1.0-1.6 mm) wavelength ranges simultaneously. The IFU is realized by using image slicer and will take the full advantage of the excellent corrected image of a high order Adaptive Optics (AO) and provide powerful image spectroscopic ability for a spectrograph/ polarimeter. This may be the first time that advanced IFU will achieve at visible and near infrared simultaneously and be used for solar observatory. A unique design is a key importance to ensure that the IFU image slicer can work at visible and near infrared wavelengths with excellent optical performance. The IFU design is discussed in detail in this paper. It is demonstrated that the IFU image slicer technique is suitable for both visible and near infrared solar observatories and will be particularly useful for 4 or 8-meter telescopes.