| 摘要 |
PROBLEM TO BE SOLVED: To provide a reflecting mirror for laser use which has higher than 95% of a reflectivity in a wide high-reflection band width, and in a wavelength shorter than 200 nm which has little incident light angle dependence. SOLUTION: In a reflecting mirror for laser use formed using a film material selected from among Al2 O3 , NdF3 , LaF3 , GdF3 and HoF3 as one of a group of high-refractive index film materials and a film material selected from among SiO2 , MgF2 and AlF3 as one of a group of low-refractive index film materials, when a laser center wavelength and an optical film thickness are respectively assumed asλ0 and dn *λ0 , the optical film thickness of a high-refractive index film is shown by dn *Hn (An optical film thickness ofλ0 /4 is 0.25 Hn .), the optical film thickness of a low-refractive index film is shown by dn *Ln (An optical film thickness ofλ0 /4 id 0.25 Ln .) and when the constitution of a multilayer film formed by laminating alternately (n) times is shown by an * (dn *Ln , dn *Hn ) as one stack, a multilayer film is the stacks of a1 * (d1 *L1 , d1 *H1 ). a2 * (d2 *L2 , d2 *H2 )< an * (dn *Ln , dn *Hn ), the optical film thicknesses of a high-refractive index film and a low-refractive index film of each stack are same and the (n) is set into a constitution consisting of more than three films. |
