Abstract:
The measurement of the instrumental polarization for any obliquely
reflecting telescope is necessary to measure the polarization state of the
input beam precisely. To find out the instrumental polarization of the
reflecting mirror(s), the complex refractive index of the reflecting
coating has to be measured with fairly good accuracy. Here we present the
complex refractive index measurements for the aluminium-coated mirrors of
the Kodaikanal tower tunnel telescope using an ellipsometer. The design of
the ellipsometer using a Babinet Compensator and the results of the
experiment will be discussed. These results will be used to remove the
instrumental polarization contribution from the observed Stokes profile of
magnetic regions on the sun
