Abstract Details

Name: Alok Ranjan Tiwary
Affiliation: Udaipur Solar Observatory, Physical Research Laboratory
Conference ID: ASI2017_592
Title : Imaging Spectro-polarimeter for Multi Application Solar Telescope (MAST): Preliminary Results Obtained in the Fe I 617.3 nm and Ca II 854.2 nm.
Authors and Co-Authors : Shibu K. Mathew, (Udaipur Solar Observatory) A. Raja Bayanna (Udaipur Solar Observatory) Rahul Yadav (Udaipur Solar Observatory)
Abstract Type : Oral
Abstract Category : Sun and the Solar System
Abstract : Multi-Application Solar Telescope (MAST) is an off-axis Gregorian telescope of 50 cm clear aperture situated on an island in the Fateh Sagar lake at Udaipur Solar Observatory (USO). An Imaging Spectro-polarimeter has been developed at USO as a back-end instrument of MAST for measuring the magnetic field in the photosphere and chromospheres at two different heights. The system consists of a narrow-band imager and a polarimeter. Narrow-band imager uses two lithium niobate Fabry-Perot etalons in tandem with a blocking filter for spectral analysis. Polarimeter yields quasi simultaneously the polarization state of light in two magnetically sensitive spectral ranges at 617.3 nm and 854.2 nm. The measurement is performed with two Liquid Crystal Variable retarders (LCVRs), which modulates the incoming polarization. Then the modulated light is transformed into a varying intensity by using a Glan-Thompson polarizers. These intensities can be demodulated to obtain full Stokes vector using an efficient modulation scheme. The instruments has been calibrated for the solar spectral lines Fe I 617.3 nm and Ca II 854.2 nm. In this work, preliminary results obtained in both the above wavelengths will be presented.