| 摘要 |
PROBLEM TO BE SOLVED: To inexpensively and easily reduce in the relative deviation of plural beams in a main scanning direction by measuring and re-correcting the relative deviation after electrically correcting the write start timing of either beam and the other. SOLUTION: A main scanning direction relative positional deviation detection means 1 detects the relative main scanning positional deviation between plotting by a 1st laser beam and plotting by a 2nd laser beam at respective positions in the main scanning direction, that is, plural positions from starting write to finishing write. A beam detector(BD) signal correction means 2 decides how much a BD signal is delayed or advanced in order to make the absolute value of the relative deviation minimum based on the relative main scanning positional deviation at the respective positions. A corrected BD signal generation means 4 generates the BD signal corrected to be actually used based on the result obtained by the correction means 2. Thus, the relative deviation in the main scanning direction is restrained without using an expensive optical correction means.
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