| 摘要 |
PROBLEM TO BE SOLVED: To restrain reflection of the incident light by a reflection preventive film, and to improve utilization efficiency of the light by forming a film having a light reflection preventive effect on a surface of a solid immersion lens. SOLUTION: A film 2 having a light reflection preventive effect is formed on a surface (a semispherical surface and a plane) of a solid immersion lens 1. As the simplest constitution of the film 2 having such a reflection preventive effect, a required process is only to arrange a film having a thickness (d) for satisfying an expression (nd=λ/4) to a wave length λ of a light beam LB by using a material of a refractive index (n) smaller than a refractive index of the solid immersion lens 1. Or a multilayer film structure by properly combining a material having a refractive index higher than the solid immersion lens 1 and a material having a low refractive index may also be acceptable. By using a conductive material on the outermost surface of the reflection preventive film 2, that is, in the case of a single layer structure, a material of the film itself is made conductive, and in the case of a multilayer structure, the outermost layer is made conductive to be put in earth electric potential to avoid electrification of the solid immersion lens 1 to prevent adhesion of dust and dirt. |
