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NOAO Newsletter - National Solar Observatory - June 1999 - Number 58


Two-Dimensional Spectrographic Spectroscopy Using a Micro-Lens Array

Simultaneous spatial spectra of extended solar structures, at a high spatial resolution and temporal cadence are important to track and understand the physics of dynamical evolutionary phenomena. Replacing the slit of a conventional spectrograph with a micro-lens array will then help to capture simultaneous spatial spectra using a large format CCD camera. Such a technique will be useful to study small structures (a few arcsec across) such as Ellerman bombs, kernels of flares, filamentary evolution, and spicules.

At the Richard B. Dunn Solar Telescope, Y. Suematsu (National Astronomy Observatory, Japan) and collaborators L.A. Smaldone (University of Naples), K.S. Balasubramaniam (AFRL/NSO), K. Yoshimura (Kyoto University), S. Hegwer (NSO), H. Ohtani (Kyoto University) have used a micro-lens array (0.6 mm pitch, 50 50 lenslets) to observe structures with a spatial sampling of 0.24" in the H spectral line. The spectral sampling is 0.93 pixel over a 10 bandwidth. The field-of-view is however limited to about 12".

The accompanying figure shows the sample 2-D spectra in H.

image
Caption: Multi-lens H array spectra of an active sunspot region, about 12" FOV. The bottom left panel shows an individual spectrum and the bottom right panels show the reconstruction of the images in the H wings and core.

There are plans to explore the possibility of extending the observations to other spectral lines such as FeI 6302.5 for variation in the line-of-sight of subarcsecond magnetic fields, HeI 10830 measurements, and CaII K 3933 for measuring dynamic variation of the multiple reversals and high spatial resolution CaII bright point spectroscopy.

Y. Suematsu, L. A. Smaldone,
K. S. Balasubramaniam, K. Yoshimura,
S. Hegwer, H. Ohtani


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