| 摘要 |
PURPOSE:To easily center an aspherical lens by forming a spherical surface which has its center of curvature on the axis of rotation of the spherical surface of a lens at part of the aspherical beyond the effective diameter or over the entire surface. CONSTITUTION:The spherical part 4 is formed beyond the effective diameter of the aspherical surface 2, the axis 7 of rotation of the aspherical surface 2 runs in the center 5 of curvature of the spherical surface 3, and the spherical part 4 provided beyond the effective diameter of the aspherical surface 2 has its center 6 of curvature on the axis 7 of rotation. When the aspherical surface 2 is worked, the spherical surface part 4 is worked while the axis 7 of rotation is rotated to the axis, and consequently the center of curvature of the spherical part 4 is easily positioned on the axis 7 of rotation. Centering by a bell clamp is performed sufficiently on condition that part of the effective diameter is spherical even if the entire surface of the lens is spherical. Thus, the spherical part 4 having the center 6 of curvature on the axis 7 of rotation is provided beyond the effective diameter of the aspherical surface 2, and consequently the lens is chucked by a bell clamping method and the edge is ground to perform the centering.
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