| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide an optical member which exhibits high transmittance at a short wavelength, especially, at 193 nm or shorter and has other desired characteristics. <P>SOLUTION: The optical member has an optical incident axis and is comprised of OD-doped silica glass having an absorption limitλ(limit) at 165 nm or shorter. In a certain embodiment, the OD-doped silica glass further contains fluorine. In another embodiment, the OD-doped silica glass contains fluorine of less than about 5,000 mass ppm. Furthermore, in another embodiment, the OD-doped silica glass contains Na of less than about 50 mass ppb. In an embodiment, the optical member is a photomask substrate to be used at a wavelength of shorter than 190 nm. <P>COPYRIGHT: (C)2008,JPO&INPIT</p> |
