| 摘要 |
PROBLEM TO BE SOLVED: To provide an illumination optical device which can form an annular pupil distribution in circumferential polarization state, while suppressing light quantity loss well.SOLUTION: The illumination optical device includes a light flux conversion element 50 for forming an annular light intensity distribution on a predetermined surface on the basis of an incident light flux. The light flux conversion element consists of a first basic element 50A formed of an optical material having optical rotation, and forming a first arcuate region distribution out of annular light intensity distributions on the basis of the incident light flux, a second basic element 50B for forming a second arcuate region distribution, a third basic element 50C for forming a third arcuate region distribution, and a fourth basic element 50D for forming a fourth arcuate region distribution. Each basic element has a different thickness in the transmission direction of light. |
