| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a light quantity adjustment device able to keep the shape of an aperture approximately circular while achieving a reduction in the number of components and a reduction in the size of the device. <P>SOLUTION: A diaphragm holder 1 is arranged orthogonal to an optical axis, and a lower diaphragm blade 2 and an upper diaphragm blade 3 move in a direction orthogonal to the optical axis. In addition, four auxiliary diaphragm blades 4a to 4d rotate around shafts 12a, 12b, 12c, and 12d so as to slide against the lower and upper diaphragm blades 2 and 3 orthogonal to the optical axis. Additionally, the lower and upper diaphragm blades 2 and 3 having approximately semicircular aperture formation parts 21 and 31, substantially equal to the diameter of a light passage hole 11, and the four auxiliary diaphragm blades 4a to 4d having an inner edge part 41 which substantially matches part of the diameter of the light passage hole 11 are driven so as to compensate for the shape of an aperture area each other. Thereby, the shape of the aperture can be kept approximately circular. <P>COPYRIGHT: (C)2013,JPO&INPIT |
