Abstract
In order to achieve a high linear density in optical recording, undesirable asymmetry in readout waveforms due to teardrop-shaped recorded marks is analyzed and suppressed by a new readout waveform equalization technique. A polygonal approximation method is used in the analysis. This considerably reduces the calculation time, compared with the conventional method, without loss in accuracy. The readout waveform equalization not only sharpens the rise/fall time, but also effectively suppresses the asymmetry by using a nonlinear component. In the case of allowance below 10% phase shift, the available linear density is improved by 1.3 times.