| 摘要 |
PROBLEM TO BE SOLVED: To compensate axial coma aberration or a difference between longitudinal and lateral magnifications by providing an optical device capable of turning around an optical axis and tilting and having a cylindrical surface and/or a toric surface. SOLUTION: An optical system 13 consisting of an anamorphic optical device capable of rotating around the optical axis and tilting with an axis orthogonal to the optical axis as a rotary shaft is arranged between a lens 11 nearest to the image surface side of a projection lens 17 and an image-formation surface 12. By providing the optical system with the optical device 13 whose refractive power is different in the directions orthogonal to each other and constituting the optical device 13 so that it can be turned centering the optical axis and tilted centering the axis orthogonal to the optical axis, the difference between the longitudinal and lateral magnifications of a projection system is adjusted. The cylindrical surface or the diffraction surface of a binary optics element is used as a means for giving the refractive power only in one direction to the optical device. It is conceivable to give the refractive power only to one surface on the image side or the object side of the optical device or provide the refractive power to both surfaces but in the same direction. |
