Three-dimensional analysis of light-beam scattering from pit and emboss marks of optical disk models

Scattering problems of beam waves from various shapes of objects have been analyzed by many research workers. From a practical point of view, the scattering of an optical beam from pit and emboss marks of optical disk models has attracted much attention for achieving a higher-density version of conventional CD-ROM type of optical disks. This paper treats two different shapes of pit and emboss as the marks of the recorded signal, i.e. cylinder type and conical trapezoid type. The readout characteristics of the sum and differential signals are calculated by solving the three-dimensional integral equation. Moreover, the dependence of those signals on the size of the pit and emboss marks is examined.