| 摘要 |
An optical element has a first surface, a second surface on the opposite side of the first surface, an optical surface, and a protruding part. The protruding part is held in a prescribed position by being in contact with a holding member. The protruding part comprises a first protruding part and a second protruding part. The first protruding part comprises a first contact part that is a convex circular arc shape on at least one longitudinal plane and partly comes into contact with the holding member. The second protruding part comprises a second contact part that is a convex circular arc shape on at least one longitudinal plane and partly comes into contact with the holding member. A circular arc constitutes the first contact part and a circular arc that constitutes the second contact part are present in at least one cross-section that passes through a contact point between the first contact part and the holding member as well as a contact point between the second contact part and the holding member, and the center of the circular arc that constitutes the first contact part is aligned with the center of the circular arc that constitutes the second protruding part. |
