A novel dual focus objective lens for DVD/CD pick-up head

Abstract

A new dual focus objective lens of combinig aspherical surfaces of DVD and CD for DVD/CD pick-up head was designed. Numerical analysis based on the diffraction model were studied to trade off the spot size, side lobe, and energy ratio of DVD and CD, The hybrid aspherical surfaces of DVD and CD are optimized for low aberration. The spot size of full wave half maximum (FWHM) are 0.553 and 0.88 mu m for DVD and CD, respectively, measured from thus constructed double rings lens.