An optical pickup using the combination of an objective lens and a diffractive optical element for a high-density optical disk is proposed in this paper. The new system will enhance the resolution and extend the depth of focus as required in high-density compact disc (CD) pickup systems. Optimisation algorithms are used to synthesise the diffractive optical element (DOE) to meet a detailed specification of the point spread function (PSF) of the system. The theoretical simulation and experimental results show that the system produces good resolution enhancement, extended depth of focus, high diffraction efficiency and moderate sidelobe level.
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