Lens assembly and image-taking apparatus
A lens assembly includes a barrel having an object-side opening and an image-forming-side opening. The barrel further has a positioning section that positions an image-forming-side surface of a lens by having line contact around an optical axis at a center. The positioning section is disposed at a position that is closer to an object side than the image-forming-side opening of the barrel is. The barrel also has an image-forming section that extends from the positioning section to a center of the optical axis along the image-forming-side surface of the lens and forms an edge of the image-forming-side opening of the barrel.
1. A lens assembly, comprising:
a plurality of optical members forming an image-forming optical system and including a lens to be disposed on a side closest to an image-forming-side; and
a barrel having an object-side opening, an image-forming-side opening, and a hollow part into which the plurality of optical members are inserted so that the lens is disposed on the side closest to the image-forming-side, the barrel further having:
a positioning section that positions an image-forming-side surface of the lens by having line contact around an optical axis at a center, and
an opening forming section that extends from the positioning section to a center of the optical axis along the image-forming-side surface of the lens and forms an edge of the image-forming-side opening.
2. The lens assembly according to claim 1 , wherein the positioning section is formed to have an obtuse angle in cross section including the optical axis.
3. The lens assembly according to claim 1 , wherein the positioning section is formed to be in the shape of a convex arc bulging toward the lens in cross section including the optical axis.
4. The lens assembly according to claim 1 , wherein the image-forming-side surface of the lens is convex, and the positioning section has a part with a flat surface that contacts the lens.
5. The lens assembly according to claim 1 , wherein the opening forming section forms the edge of the image-forming-side opening at a wedge-shaped tip with an obtuse angle in cross section including the optical axis.
6. The lens assembly according to claim 1 , wherein the barrel is made of ceramic.
7. The lens assembly according to claim 1 , wherein the barrel is made of porous ceramic.
8. An image-taking apparatus, comprising:
a lens assembly comprising:
a plurality of optical members forming an image-forming optical system and including a lens to be disposed on a side closest to an image-forming-side, and
a barrel having an object-side opening, an image-forming-side opening, and a hollow part into which the plurality of optical members are inserted so that the lens is disposed on the side closest to the image-forming-side, the barrel further having:
a positioning section that positions an image-forming-side surface of the lens by having line contact around an optical axis at a center, and
an opening forming section that extends from the positioning section to a center of the optical axis along the image-forming-side surface of the lens and forms an edge of the image-forming-side opening; and
an imaging device disposed at an image-forming surface of the image-forming optical system formed by the plurality of optical members of the lens assembly.