A magnetic video tape can be used to record the polarization of light from each minimum resolvable area of an extended astronomical source. The raster scan of a television camera is recorded on a video tape. The rotation index of a polarizer is recorded on the magnetic-tape audio channel. Raw data input to a computer is provided by the digitized output from the recorded magnetic tape. For each minimum resolvable area of the extended light source, the computer printout shows the intensity and the percentage and direction of polarization. The solar corona during an eclipse is one example of a suitable subject.
D. H. Menzel, W. W. Salisbury, and D. L. Fernald, "A System for Recording the Polarization of Extended Astronomical Objects," Appl. Opt. 9, 2648-2648 (1970)