Abstract Details
| Name: Athira B S Affiliation: IISER KOLKATA Conference ID: ASI2017_1158 Title : Development of a novel Spectral Imaging Polarimeter for Application in Coronal Magnetometry Authors and Co-Authors : 1.Dr.Nirmalya Ghosh, DPS, IISER Kolkata 2.Dr.Dibyendu Nandy, DPS,CESSI, IISER Kolkata Abstract Type : Poster Abstract Category : Instrumentation and Techniques Abstract : Magnetic instabilities in sunspot structures and reconnection mediated restructuring of fields produce violent solar eruptions such as flares and coronal mass ejections (CMEs) which have severe space weather consequences. Measurement and analysis of the components of the vector magnetic field in the solar corona can potentially yield quantitative information on coronal magnetic structures, dynamics and heating. Among the various experimental techniques explored for coronal magnetometry, optical polarimetry (on selected spectral lines of radiation emitted by ions) has been found particularly promising. An instrument that can perform simultaneous imaging, spectroscopic diagnostics and polarimetric imaging of corona is highly desirable for astronomical observations. Such an instrument should be capable of recording full stokes vector elements over a broad wavelength region with simultaneous imaging capability. Here we describe the development of a hyper spectral imaging instrument for this purpose, which is being developed at CESSI. We demonstrate two specific experimental concepts, both of which uses a combination of birefringent medium and a polarizer in polarization analyzing unit (PSA) to determine the stokes vector. In one such system we uses a rotating waveplate with a polarizer and in the other a liquid crystal variable retarder (LCVR) in combination with a fixed polarizer. Simultaneous measurement of polarization states, spectroscopy and imaging is done by using a combination of liquid crystal tunable filter (LCTF-which selects the desired wavelength range) and the PSA unit with a CCD. The PSA unit is calibrated using the so-called eigen value calibration method which ensures high accuracy and sensitivity in measuring the full stokes vector elements. The specification of the experimental scheme, instrument development and eigen value calibration method with the system is discussed. |