| 摘要 |
PURPOSE:To surely prevent the damage of an optical element caused by ultraviolet rays without necessitating a complicated manufacturing process such as vapor deposition or the like. CONSTITUTION:At least, one of light transmission elements 1 to 6 and 13 consists of a material having low transmissivity to ultraviolet rays in the optical system having the optical element 14 easily damaged by the ultraviolet rays and at least one of the light transmission elements 1 to 6 and 13 on the light incident side of the optical element 14. |
