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| Paper: |
A New Technique for Solar Imaging Spectro-polarimetry using Shack-Hartmann and Fabry-Pérot |
| Volume: |
463, 2nd ATST-EAST Workshop in Solar Physics: Magnetic Fields from the Photosphere to the Corona |
| Page: |
301 |
| Authors: |
Gosain, S.; Sankarasubramanian, K.; Venkatakrishnan, P.; Raja Bayanna, A. |
| Abstract: |
A new technique for solar imaging spectro-polarimetry is
presented. Using the combination of a Shack-Hartmann (SH) and a
Fabry-Pérot (FP) interferometer, high-cadence spectroscopic
observations can be obtained at discrete wavelength positions
simultaneously, thereby avoiding errors due to non-simultaneity of the
wavelength scans. A SH mask is used to generate multiple images of the
same field-of-view (FOV). These multiple images when passed through the FP
in a collimated-beam arrangement are shifted in wavelength due to
the angular dependence of the FP filter transmission profile. Thus, by
re-imaging one obtains multiple images of the FOV which are tuned to
different wavelength points across the spectral line, in a single
exposure. The schematic of the setup and the laboratory simulation of such
a configuration is presented. The technique has an advantage of
simultaneity over conventional wavelength scanning filtergraphs and
has potential for observing highly-dynamic phenomena like solar
flares. Also, one can exploit the method to perform snapshot
spectropolarimetry by designing a special polarization modulator. The
limitation of this technique is that it downgrades the spatial
resolution due to the downsampling of the pupil into smaller
sub-apertures. However, for large aperture telescopes like 4 meter
class telescopes (ATST) this is not a major issue and one can still
work at sub-arcsec resolution, though not at the diffraction limit of
the full aperture. |
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