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

Claim 0:
1. An imaging optical system comprising:
an optical component having a plurality of annular grooves formed to provide a predetermined phase to optical ray propagating an effective pupil,
wherein the plurality of annular grooves are sequentially formed in an order from an inner circumferential side to an outer circumferential side,
in each of the annular grooves, a value of longitudinal aberration of the optical ray between an inner circumferential end of the annular grooves and an outer circumferential end of the annular grooves continuously changes from a first value to a second value, a sign of which is inverted from a sign of the first value,
the value of the longitudinal aberration between the plurality of annular grooves alternates between the first value and the second value plural times to zigzag,
the longitudinal aberration continues at a boundary between the annular grooves that are adjacent to each other,
in each of the annular grooves, 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 zero cross point at which the longitudinal aberration is zero.