We present a method to calculate the readout signals from optical disks and
their applications. Our method is based on a convolution operation of mark
s recorded on a disk and an extended point spread function (EPSF). Our meth
od can be applied to the case where the marks are recorded in a groove and
the photodetector has an arbitrary shape. Four analyses examples are report
ed: analysis of the tracking error detection method termed the differential
phase detection (DPD), focus shift dependency of readout signal jitter whe
n the marks are recorded in a groove, EPSF for land and groove readout, and
a compatible readout method for digital versatile disks and compact disks.