| 摘要 |
PROBLEM TO BE SOLVED: To compensate the deterioration of image-forming performance caused by the deformation of a reflection type diffraction optical device and to keep optical performance excellent by changing the shape of the reflection type diffraction optical device by a shape changing means. SOLUTION: This diffraction optical device 91 is held by eight holding members 921 to 928 installed at the periphery part, and the holding member 92i is coupled with a lens barrel through a piezoelectric element (elastic member) 93i and a lens barrel connection member 94i. The length of the element 93i is elongated/contracted according to voltage applied from a curve controller (shape changing means) so as to finely move the member 92i. By pressing the member 92i to the center side of the device 91, the device 91 is finely curved. By pulling the device 91 to the outside as shown by an arrow, the flatness of the device 91 is increased and gravity deformation caused by gravity is corrected. Thus, the optical characteristic of the device 91 is changed and the optical characteristic of an optical system including the device 91 is controlled.
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