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 {HEAD ~ the ratio} α between Popt and {TAIL ~ Pth}, which is set for each optical disc, to determine the optimum write power Popt 
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 { HEAD ~ the ratio } α between Popt and { TAIL ~ Pth } , which is set for each optical disc , to determine the optimum write power Popt
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