Abstract:  Based on diffraction theory and parameters for blueray disc, this paper investigated the energy distribution on exit pupil and tracking error signal by differential push pull (DPP) method when focus spot scanning through the bluray disc. The paper also evaluated the influence of disk radial tilt on tracking error signal and the relation between amplification degree and tilt sensitive of tracking error signal. The result shows that the allowable radial tilt angle should be smaller than 0.39° to make sure that the blue disk is read correctly, and the amplification degree in DPP method only affects the amplitude of tracking error signal without influence on its tilt sensitivity.

Key words: scalar diffraction theory, differential push pull (DPP), radial tilt