HR: 16:30h
AN: SP34A-05    [Abstracts]
TI: Triple Fabry-P‚rot Imaging Interferometer for High Resolution Solar Spectroscopy using the ATST
AU: * Robinson, B M
EM: robinsob@email.uah.edu
AF: Center for Applied Optics, University of Alabama in Huntsville 301 Sparkman Dr., Huntsville, AL 35899 United States
AU: Gary, G A
EM: allen.gary@nasa.gov
AF: National Space Science and Technology Center, Marshall Space Flight Center / NASA, Huntsville, AL 35812 United States
AU: Balasubramaniam, K S
EM: bala@nso.edu
AF: National Solar Observatory/Sacramento Peak, P.O. Box 62, Sunspot, NM 88349-0062 United States
AB: We present a telecenrically mounted triple Fabry-P‚rot imaging interferometer for the NSOs Advanced Technology Solar Telescope (ATST). It consists of three Fabry-P‚rot etalons and the feed and imaging optics. This system provides high throughput, flexibility and breadth of operation when compared to other spectroscopic imaging systems. It can operate in four distinct modes: as a spectro-polarimeter, a filter-vector magnetograph, an intermediate-band imager, and broadband high-resolution imager. In the proposed telecentric mount configuration, the transmittance of the etalon system is not a function of position in the field, so that instantaneous spectroscopic measurements can be performed across the entire field of view; however, the transmission peak of the interferometer is broadened. Mitigation of this broadening requires a low F&35; image at the etalons. Together with the requirement that the field of view be large enough to observe large-scale processes in the solar atmosphere, this limitation dictates that the diameter of the etalons have a large aperture. Specifically, for a spectrographic passband full-width at half-maximum (FWHM) of around 2 pm, and entrance pupil diameter of 4 m, and a field of view of 35", the required etalon diameter is around 200 mm. This is beyond the size of current Fabry-P‚rot etalons and near the current projected limit of manufacturability. The development of this instrument will bring these large etalons to realization and take Fabry-P‚rot imaging interferometry to the next level of operational capability within telescopes of large aperture. This instrument will provide spectral, spatial, and temporal resolution which is not currently available to large aperture solar astronomy, but which is necessary, in conjunction with the new class telescopes, to the continuing discovery of laws that govern the dynamics of the sun and the earth-sun connection. The resolution afforded by higher aperture telescopes and instrumentation will give scientists new insight into the magnetohydrodynamic processes occurring on the Sun via simultaneous spectral and spatial measurements across the entire field of view. We will describe the optical train supporting the filter system and the expected imaging performance. We will analyze the effects of spectral resolution of the instrument due etalon spacing parameters, optical configuration, and the plate defect finesse. We present calculations of the pupil apodization for three modes of operation and the consequences for the imaging and spectroscopic performance of the system; and a treatment of noise contributions from the parasitic off-band spectral orders and ghost images arising from multiple reflections within the etalon system.
DE: 0649 Optics
DE: 7500 SOLAR PHYSICS, ASTROPHYSICS, AND ASTRONOMY
DE: 7594 Instruments and techniques
SC: Solar Physics Division - AAS [SP]
MN: 2005 Joint Assembly