| 摘要 |
PURPOSE: To correct problems such as astigmatism, isofocal bias, and ellipticity by providing four lens which are displaced between a radiant energy beam source and a work piece. CONSTITUTION: A lens 302 has a convex to which a beam 310 is made incident, and a plane from which the beam 310 emits. Also, a lens 303 has a flat face to which the beam 310 is made incident, and a cylindrical convex from which the beam 310 emits. A third lens 304 has a flat surface to which the beam 310 is made incident, and a convex from which the beam 310 emits. A fourth lens 305 has a flat face to which the beam 310 is made incident, and a cylindrical concave from which the beam 310 emits. Then, astigmatism and ellipticity with changing amounts can be introduced to a focal point 310 by changing spaces between the lens elements 303 and 304, and the lens elements 304 and 305, and the introduced astigmatism and ellipticity is moved to the final video face of a pattern generating device. Thus, the astigmatism, isofocal bias, and ellipticity can be corrected. |
