the invention relates to a new class of schemes for simultaneously compensating readout channel distortions in optical storage systems , such as defocus , spherical aberrations , optical data carrier tangential tilt , and radial tilt . the use of cascaded adaptive filtering steps applied to the readout data signal is proposed . a first adaptive phase - filtering step , dedicated to the compensation of the non - linear phase distortion caused by the tangential tilt , is made adaptive to a measure of the tangential tilt . a second adaptive amplitude - filtering step , dedicated to the compensation of amplitude channel frequency response distortions caused by tangential tilt as well as other channel distortions such as the defocus and the spherical aberration or other types of distortions which influence mainly only the amplitude frequency response of the channel , is made adaptive to an adaptation signal generated by an adaptation step defining a set of coefficients defining a filter used in this second filtering step , in minimizing an error between the output data signal and a target data signal , such as a least mean squares error - based algorithm or zero - forcing adaptation algorithm . use : optical reader / writer