| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that it is difficult to effectively bring the shape of a diaphram opening close to that of a perfect circle over the entire region of an NA (numerical aperture) set from the maximum NA to minimum NA. SOLUTION: An NA diaphram mechanism comprises a plurality of diaphram blades each including a pin member as a rotation center and a pin member for setting a rotation angle both implanted thereon, moving means for moving the pin member of each diaphram blade as a rotation center in a direction in a plane perpendicular to an optical axis, a diaphram blade container including a groove engaging the pin member of each diaphram blade as a rotation center, and a cam member including a cam groove engaging the pin member for setting a rotation angle of each diaphram blade provided therein. In the NA diaphram mechanism, the pin member as a rotation center of the diaphram blade is moved and the pin member for setting the rotation angle is moved by permitting the cam member and the diaphram blade container to relatively rotate around the optical axis, whereby the position and rotation angle of the diaphram blade are changed, and the diaphram opening is constructed by making use of the overlapping of the plurality of the diaphram blades. COPYRIGHT: (C)2005,JPO&NCIPI
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