SOLAR PHOTOSPHERIC AND CHROMOSPHERIC OBSERVATIONS USING A LITHIUM-NIOBATE FABRY-PEROT ETALON

We have made a narrow band tunable filter for solar observations using a Lithium Niobate Fabry-Perot etalon. The 60 mm aperture etalon with a free spectral range of 4.22 Angstrom and finesse of 26 at lambda = 6 122 Angstrom has been procured from CSIRO, Australia. The wavelength t uning is achieved by applying high voltage to the etalon substrate at the rate of 0.45 Angstrom per 1000 Volts. The filter is being used for imaging the sun in Her line and obtaining Doppler- and Magnetogram in CaI 6122 Angstrom line. In this paper, we present some initial observ ations carried out with this filter at Udaipur Solar Observatory.