Patent ID: 8472293

Claim:
An evaluation method, comprising the steps of: fitting a relation between write powers Pw[m] (m being an integer) of a plurality of kinds, and a modulation M[m] obtained from a reproduction signal amplitude of a signal subjected to trial writing, by a modulation characteristic formula M=Masy×(1−Pint−Pasy)/(Pw−Pasy)) having an asymptotic modulation (Masy), a write power intercept (Pint), and an asymptotic write power (Pasy) as parameters to obtain an optimal value of the asymptotic modulation (Masy_opt), an optimal value of the write power intercept (Pint_opt), and an optimal value of the asymptotic write power (Pasy_opt); calculating a square of a correlation coefficient r between M (Pw[m]) obtained by substituting the Pw[m] into the modulation characteristic formula using the Masy_opt, the Pint_opt, and the Pasy_opt and the modulation M[m] obtained from the trial writing; and evaluating whether or not the relationship between the write powers Pw[m] and the modulation M[m] is appropriate for write power adjustment with use of the square of a correlation coefficient r and a predetermined value.