Research On Key Application Technologies Of Optical Storage

The thesis includes two key application technologies of optical storage, one is the design of three-focus single objective lens used in DVD pick-up head, and the other is the research of DMD parallel storage.Optical pick-up is an important component in the optical storage system, by which the write-in and read-out of information are achieved, and in optical pick-up the optical objective lens is an important factor which influences the size of focal spot. The development-tendency of optical pick-up is integrated and multi-functional. In this thesis, based on the analysis of the theoretics and fundamental structure of the optical imaging system as well as the working mechanism, a single objective lens which can meet the compatibility between HD-DVD, DVD and CD is presented. The main contents are listed as follows:First, referred literature and material, systemic research has been done about the principle of optical storage as well as the theoretical working mechanism. The components of optical system and the design principle have been done. Objective lens with NA 0.65 for 405nm, NA 0.60 for 650nm and 0.45 for 780nm has been designed. Here the objective eliminates element aberrations of the system and each evaluation criteria of it satisfies the practical use.Second, by using the software ZEMAX, the three-wavelength optical system which is compatible to HD-DVD, DVD and CD disc has been designed. By repeating the procedures of computer optimization, system analysis, fine changing parameters, changing parametric variable, and optimization again, we designed aspheric objective lens which eliminated aberrations of the system perfectly and made the imaging spot reach diffraction limit. Through analyzing and evaluating the spot diagrams, optical path aberration, wavefront aberration and modulation transfer function, the simulation results show that OPDrms and wavefrontrms are less than 0.07λ, 0.035λ, respectively, spatial cutoff frequency is greater than 1200cycle/mm, radial of curvature tolerance and thickness tolerance are 300nm. It can satisfy practical requirement.Finally, using Digital Micromirror Device as reflecting spatial light modulator, we design parallel storage experiment preliminary, and analyze the problems in the experiment.