| 摘要 |
PURPOSE:To perform highly accurate matching color, by correcting the color blurring of a scanning beam caused on an image forming plane due to a difference in color by deflecting a laser beam by a minute angle by means of a chromatic aberration correcting means. CONSTITUTION:An He-Ne laser 1, Ar laser 2, and He-Cd laser 3 are respectively used for red, green, and blue. The optical beams emitted from these lasers 1, 2, and 3 are sent to a rotating polygon mirror 7 after they are synthesized to one optical beam by means of a synthesizing optical system using dichroic mirrors 4-6. The polygon mirror 7 scan the inputted optical beam and causes the optical beam to form an image on an image forming plane 9 through an ftheta lens 8. In this case, the color blurring quantity DELTAftheta an ideal image forming location is proportional to the deflecting angle of the reflecting surface of the polygon mirror 7. Therefore, the color blurring quantity DELTAftheta is corrected by regarding the reflecting surface of the mirror 7 and deflecting surface of a chromatic aberration correcting means 11 as equivalent to each other by using the means 11 and convex lenses 12 and 13. The means 11 is constituted in such a way that the laser beam can be deflected by a minute angle so that the refractive index of the medium can be changed and the color shifting can be corrected.
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