Optimization of information pit shape and read-out system in read-only and write-once optical storage systems

Vector diffraction analysis of optical disk readout

The optical disk readout signals from ROM disks are presented by use of a rigorous three-dimensional vector diffraction method. The optical disk is modeled as a crossed metal grating without restriction on the form of the information marks, and the permittivity of the metal is taken into account. The diffracted field from the disk is obtained by means of decomposing the focused incident beam into a spectrum of plane waves and then calculating the diffracted plane waves for each respective incident component. The readout signal is obtained by integration of the energy-flux density of the diffracted field according to the detection scheme of the optical disk system. A typical digital versatile disk (DVD) system is applied with this theory, and the result is far from that of scalar diffraction theory.

Direct modeling of the output parameters of an optical recording

The relationship between the recorded bit size and write beam characteristics has been analyzed and calculated. A unified formulation for the reflectivity after recording is introduced, and a new analytical description of reflection contrast is established. The effects of read/write beam characteristics on the recording contrast are discussed. The theoretical analysis results are well supported by experiment results.