The determined PthO and the PcO are used to determine the write power threshold Pth that satisfies the equation Pth=PthO+PcO. The determined Pth value is, for instance, multiplied by the ratio α between Popt and Pth, which is set for {HEAD ~ each optical disc}, to determine {TAIL ~ the optimum write power} Popt 
to determine
The determined PthO and the PcO are used to determine the write power threshold Pth that satisfies the equation Pth = PthO+PcO. The determined Pth value is , for instance , multiplied by the ratio α between Popt and Pth , which is set for { HEAD ~ each optical disc } , to determine { TAIL ~ the optimum write power } Popt
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