| 摘要 |
PURPOSE:To prevent a reflection of light which has been made incident on an attenuation filter, by forming the first layer, the third layer and the fifth layer from the surface of an optical lens, by a layer consisting of MgF2, and forming the second layer and the fourth layer by a layer consisting of Cr. CONSTITUTION:In a small area part of the surface containing an optical axis of an optical lens 1, an attenuation filter in which the first layer 12, the third layer 13 and the fifth layer 14 counted in order from the surface of the optical lens 1 are formed by a dielectric thin film layer consisting of MgF2, and the second layer 15 and the fourth layer 16 are formed by a thin metallic film layer consisting of Cr is formed. |
