| 摘要 |
PROBLEM TO BE SOLVED: To manufacture an optical system at a low cost as a whole without deteriorating the characteristics of the system, such as the durability, light transmittance, etc., even when the system emits ArF excimer laser by constituting the optical system by combining synthetic quarts glass with fluorite. SOLUTION: An optical system for exposing circuit pattern having means transmissivity of >=98.0%/cm as a whole is constituted by using a single-crystal fluorite optical body which has a hydrogen molecule concentration CH2 of 5×10<17> to 5×10<18> molecules/cm<3> , a refractive index distributionΔn of <=2×10<-6> /cm, and an amount of double refraction of <=1 nm/cm in a first synthetic glass optical body having transmissivity of >=99.5% at the wavelength 193 nm of ArF laser light and a light energy densityεof 0.1-0.4 mJ/cm<2> and a refractive index distributionΔn of <=3×10<-6> and an amount of double refraction of >=h2.0 nm/cm in a second synthetic quartz glass optical body having a light energy densityεof >=0.4 mJ/cm<2> and transmissivity of >=99.8% at the wavelength 193 nm of ArF laser light.
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