Patent ID: 11933993
Assignee: HITACHI, LTD.
Field: Audio-visual technology (Electrical engineering)
Classification: CPC G  H | IPC G  H

Claim 2:
3. The imaging optical system according to claim 1,
wherein the optical component has a convex-concave shape made of a plurality of convex portions and concave portions that are axisymmetrically smoothly connected in a radius direction,
the convex portions and the concave portions correspond to the annular grooves,
a second-order differential value of a sag amount is almost discontinuous at a boundary between the concave portion and the convex portion,
in the concave portion, an area of an inner circumferential plane of the optical component and an area of an outer circumferential plane of the optical component are almost equal to each other at a point at which a plane of the concave portion has an extremum, and
in the convex portion, an area of an inner circumferential plane of the optical component and an area of an outer circumferential plane of the optical component are almost equal to each other at a point at which a plane of the convex portion has an extremum.