Out-of-phase mixed holographic gratings: a quantative analysis
  We show, that by performing a simultaneous analysis of the angular dependencies of the +/- first and the zeroth diffraction orders of mixed holographic gratings, each of the relevant parameters can be obtained: the strength of the phase grating and the amplitude grating, respectively, as well as a potential phase between them. Experiments on a pure lithium niobate crystal are used to demonstrate the applicability of the analysis. 
Martin Fally, Mostafa A. Ellabban, Irena Drevensek-Olenik