Effect of amplitude modulation on the read-out signal in an optical disc system with a residual aberration

We conducted a numerical calculation for the point spread function and the variation of the read-out signal in optical disc systems using several apodizing filters, taking into account a spherical aberration and the variation in the bump shape. Based on calculations using the scalar diffraction theory, we are able to determine the best bump size and shape giving the maximum read-out signal for each incident beam modulated by an apodizing filter. This work facilitates the fabrication of high density optical disc systems with a spherical aberration and can then be applied to a real optical disc system like a commercial digital video disc (DVD) system.