| 摘要 |
PROBLEM TO BE SOLVED: To provide a lens barrel which is corrected of a change in optical characteristics by deformation of an optical element by arranging plural projecting parts supporting the optical element in such a manner the light transmission surface of the optical element is deformed symmetrically with respect to a plane inclusive of an optical axis. SOLUTION: The spherical projecting members 6 are disposed in positions equidistant from the optical axis on supporting members 4a constituting the lens barrel 4. The apexes of the two projecting members 6 existing in the positions symmetrical with respect to the X-Z plane are arranged within the same plane orthogonal with the optical axis and these apexes come into point contact with the diffraction optical element 2. The adhesion parts 5 of the element 2 with the supporting members 4a are only near the projecting members 6. The surface shape of the light incident and exit surface (light transmission surface) of the element 2 after deformation by gravity is symmetrical with respect to the X-Z plane. In addition, the surface shape of the light incident and exit surface of the element 3 after the deformation is symmetrical with respect to the Y-Z plane. The correction optical element which corrects the change in the optical characteristics induced in either of the element 2 or 3 by the deformation of another element.
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