| 摘要 |
PURPOSE:To facilitate the alignment adjustment of an optical system and to simplify the device constitution by detecting the incidence position of monitor light by an optical position detector as the scanning position of a laser beam for plotting, and aligning the optical axes of the laser beam for plotting and monitor light with each other. CONSTITUTION:The monitor light which differs in wavelength is made incident on a scanning mirror 3 along the same optical axis with the laser beam for plotting and brought under the same scanning control with the laser beam for plotting, so the position of this monitor light is detected by a beam splitter 9 and the optical position detector 11 to detect the position of the laser beam for plotting indirectly. At this time, the monitor light is not brought under the ON/OFF control of the optical modulator 2, so the signal level does not vary and the optical axes of the laser beam for plotting and monitor light area aligned with each other. Consequently, the alignment adjustment of the optical system is facilitated and the device constitution can be simplified. |
