def METHOD_NAME(self):
    """
    Description: called if aperture, slits or focusing has been changed
    Returns: dictionary, {size_x: 0.1, size_y: 0.1, shape: "rectangular"}
    """
    size_x = min(
        self.beam_size_aperture[0],
        self.beam_size_slits[0],
        self.beam_size_definer[0],
    )
    size_y = min(
        self.beam_size_aperture[1],
        self.beam_size_slits[1],
        self.beam_size_definer[1],
    )
    self.beam_info_dict["size_x"] = size_x
    self.beam_info_dict["size_y"] = size_y
    if self.beam_size_aperture < self.beam_size_slits:
        self.beam_info_dict["shape"] = "ellipse"
    else:
        self.beam_info_dict["shape"] = "rectangular"
    return self.beam_info_dict