| 摘要 |
PURPOSE:To obtain the laser beam scanning method characterized by a uniform scanning speed and high accuracy, by selecting a parabolic mirror or a spherical mirror which is used as a concave mirror in correspondence with a slant angle or a scanning angle. CONSTITUTION:For example, in an off axis method, a scanner 7 is arranged on two axes, with the center of the concave mirror 6' as an original point 0. Then, a value XP of an x coordinate of a scanning point P at the scanning angle theta by the laser beam 10 is determined by whether the concave mirror 6' is the spherical mirror or the parabolic mirror based on the slant angle OMEGA and the scanning angle theta. The coordinate XP in the case for the axial center at the slant angle OMEGA/2 is likewise determined. Then a distortion rate TAU corresponding to the deviation in the scanning speed is computed based on the equation I. When the method which satisfies conditions I-IV is selected so that said distortion rate becomes small, the laser beam scanning method characterized by the uniform scanning speed and the high accuracy is obtained. Note: XP (1); the value of the coordinate XP for the scanning angle of l deg.. |
