2-DIMENSIONAL POLARIMETER WITH A CHARGE-COUPLED-DEVICE IMAGE SENSOR AND A PIEZOELASTIC MODULATOR

We present the first measurements and scientific observations of the s olar photosPhere obtained with a new two-dimensional polarimeter based on piezoelastic modulators and synchronous demodulation in a CCD imag er. This instrument, which is developed for precision solar-vector pol arimetry, contains a specially masked CCD that has every second row co vered with an opaque mask. During exposure the charges are shifted bac k and forth between covered and light-sensitive rows synchronized with the modulation. In this way Stokes I and one of the other Stokes para meters can be recorded. Since the charge shifting is performed at freq uencies well above the seeing frequencies and both polarization states are measured with the same pixel, highly sensitive and accurate polar imetry is achieved. We have tested the instrument in laboratory condit ions as well as at three solar telescopes.