| 摘要 |
A polarization conversion element capable of converting, with a limited light quantity loss, a linearly polarized incident light having a polarization direction in an almost single direction into a circumferentially polarized light having a polarization direction in an almost circumferential direction. A polarization conversion element (10) for converting the polarization state of an incident light into a specified polarization state. It is formed of an optical material having optical rotation, for example, quartz, and has a thickness distribution changing in a circumferential direction. The thickness distribution is so set that a linearly polarized light having a polarization direction in an almost single direction is converted into a circumferentially polarized light having a polarization direction in an almost circumferential direction. It has a plurality of circumferentially divided areas (10A-10D), and two arbitrary adjacent areas in the plurality of areas are different in thickness from each other. Also, two arbitrary facing areas in the plurality of areas have optical rotation angles almost equal to each other. |
