Please note, due to essential maintenance online transactions will not be possible between 02:30 and 04:00 BST, on Tuesday 17th September 2019 (22:30-00:00 EDT, 17 Sep, 2019). We apologise for any inconvenience.
Telescopic phase retardation in connection with the polarizer behind a polarimeter's KDP-crystal strongly influences the Zeeman pattern, since the circular polarized parts of the two σ-components are strengthened and weakened respectively. This influence depends on the hour angle if the solar image rotates with respect to the polarizer (e.g. for Coudé telescopes).