Patent ID: 7120100

Claim:
A method of detecting defects during a write operation for an optical disk recording device, comprising: a. in a short period of time immediately after writing begins: i. comparing a sub-beam added (SBAD) signal and a reference signal output by a low pass filter having a second threshold frequency, and ii. identifying a defect when a difference between the SBAD signal and the reference signal exceeds either a second upper limit or a second lower limit; and b. after the short period of time: i. comparing the SBAD signal and a reference signal output by the low pass filter having a first threshold frequency, and ii. identifying a defect when a difference between the SBAD signal and the reference signal exceeds either a first upper limit or a first lower limit; wherein the second threshold frequency is higher than the first threshold frequency, the second upper limit is greater than the first upper limit, and the second lower limit is less than the first lower limit.