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The variation of read-out signal in an optical disc system having the amplitude modulated apodizer

The most straightforward methods to increase the density of an optical disc are to use a shorter wavelength laser diode, to increase the numerical aperture of the objective lens, and to use an apodizer. Especially, the apodizer causes the diffraction image formed on the disc to be smaller and the read-out signal to increase. In the paper we investigate numerically the variation of read-out signal in an optical disc system with the amplitude modulated apodizer, using a scalar diffraction theory. The considered apodizers are the truncated Gaussian apodizers, the shaded apodizers, and the central obstruction apodizers.