Integral Field Spectroscopy of the Sun with Microlens Array and Liquid Crystal Retarders

Simultaneous spectrographic observations over extended solar structures, at a high spatial resolution and temporal cadence, are important to track and understand the physics of transient phenomena such as Ellerman bombs, flare kernels, prominences/filaments and spicules. With two-dimensional (2-D) field spectral data, we can make monochromatic images at a given wavelength in a designed passband and line profile analysis to derive 2-D distribution of atmospheric parameters. One technique to produce a spectrum of each spatial elements in an extended two-dimensional field is to use a micro-lens array. Replacing a slit of a conventional spectrograph with a micro-lens array then helps to capture two-dimensionally distributed short spectra from 2-D field using additional optics inserted, a bandpass filter and a large format detector. For observations of magnetic field, we can add polarization modulator made of liquid crystal retarders which give a sequence of alternative orthogonal polarization states with time. We describe a design concept and limitations for observations with the micro-lens array spectrograph and an initial result applied for a few existing solar telescopes at NAOJ and Hida Observatory, Kyoto University.