| 摘要 |
PURPOSE:To attain the correction of high degree without incurring substantially the performance even if the scanning line length is made longer by measuring the amount of shift of a beam spot from the scanning reference and correcting the frequency of an input modulating signal to an optical modulator accordingly. CONSTITUTION:A modulating signal input 8 reaching the optical modulator 2 is amplified 9 for a correcting signal from a luminous amount detecting sensor 6 at first, becomes a luminous amount correcting signal via a signal processing 10 and is mixed 11. On the other hand, a correcting signal from an uneven pinch position detecting sensor 5 is amplified 12, processed 13 and further, an output 14 of start synchronizing signal and a correcting signal from a start position detecting sensor 7 are processed 17 together so as to form an uneven pitch correcting signal due to face run-out of a polygon and eccentric rotation of motor shaft, the signal is frequency-converting 18 and mixed 19 and amplified 20 with a modulating signal corrected in luminous amount as before and the result is applied to the optical modulator 2. |
