| 摘要 |
PROBLEM TO BE SOLVED: To make it possible to well prevent reflection over two wavelength ranges of a UV range below a wavelength 300 nm and a range from a wavelength 600 nm to a wavelength 700 nm by specifying the constitution of an antireflection film five thin films are applied. SOLUTION: The antireflection film comprises the five-layered films on a transparent substrate (quartz) G surface; the first layer consists of AlO2 O3 of an intermediate-refractive index material or its mixture, the second layer and fourth layer consist of HfO2 of a high-refractive index material or its mixture and the third layer and fifth layer consist of SiO2 of a low-refractive index material or its mixture. The refractive indices to light of third wavelength 248 nm satisfy the condition equations 1.60<=na<=1.80, 1.95<=nh<=2.25, 2.45<=ns<=1.55 where the refractive index of the Al2 O3 or its mixture is defined as na, the refractive index of the HfO2 or its mixture as nh, the refractive index of the SiO2 or its mixture as ns. Thus, good environmental resistance, small film thickness and good productivity are resulted. |
