| 摘要 |
A DSP control circuit monitors a scan position of laser beams on the target region based on a signal from a PSD. Further, the DSP control circuit measures an amount of laser beams reflected from the target region for each scan position based on a signal from a beam receiving portion. The DSP control circuit compares an amount of reflected beams P 0 at a scan position (reference position) on the target region with an amount of reflected beams Pk at a scan position adjacent to the scan position. If Pk/P 0 is equal to or smaller than a threshold value Rs, it is determined that the scan position corresponding to the amount of reflected beams Pk is nonuniform in irradiation intensity of the laser beams. The DSP control circuit increases emission intensity plurality of times for the position that is determined to be nonuniform in irradiation intensity of the laser beams. With this, it is possible to make irradiation intensityies of the laser beams uniform over the target region.
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