def METHOD_NAME(self):
    """
    Initialise default values and objects
    """
    super().METHOD_NAME()
    _divergence_vertical = self.get_property("beam_divergence_vertical")
    _divergence_horizontal = self.get_property("beam_divergence_horizontal")
    self._beam_divergence = (_divergence_horizontal, _divergence_vertical)
    self._beam_position_on_screen = (0, 0)