to be published in Modern Solar Facilities - Advanced Solar Science,
  F. Kneer, K.G. Puschmann, and A.D. Wittmann (eds.), Universit\"atsverlag
  G\"ottingen, 2007, p. 321 - 337, please download pdf-file of better quality
  figures from http://www.kis.uni-freiburg.de/~steiner/goettingen.pdf