| 摘要 |
PROBLEM TO BE SOLVED: To retro-reflect light even if retro-reflecting means such as a retroreflection mirror for retro-reflecting light tilts.SOLUTION: The retroreflective device (120) is a retroreflective device for retro-reflecting incident light (LB2). The retroreflective device includes: first retro-reflecting means (121); and second retro-reflecting means (122) for retro-reflecting, toward the first retro-reflecting means, the light retro-reflected by the first retro-reflecting means. The first retro-reflecting means is a retroreflection mirror having two or less reflection surfaces, and the second retro-reflecting means is a retroreflection mirror having three or more reflection surfaces. |
