| 摘要 |
A machining device for illuminating a periodic pattern of a mask with coherent light emitted from a light source and projecting the image of the pattern onto a workpiece through an optical system. The optical system includes first and second optical members. The second optical member, which is positioned at an area where diffracted light rays of different orders out of the diffracted light rays generated by the mask are superimposed, employs an optical material having a smaller variation in an optical path length arising from light absorption than an optical material of the first optical member, which is positioned at an area where diffracted light rays of different orders are not superimposed. |
