Claims
- 1. An optical system for use in a projection exposure apparatus for processing an excimer laser beam, the optical system comprising:at least one optical member made of silica glass having a chlorine concentration of about 1 ppm or less; and at least one optical member made of silica glass having a fluorine content of about 0.01 wt % to about 0.5 wt %, wherein, both optical members are located in accordance with an energy density of light that each said optical member is to process.
- 2. An optical system for use in a projection exposure apparatus for processing an excimer laser beam, the optical system comprising:at least one optical member made of silica glass having a chlorine concentration of about 1 ppm to about 200 ppm; and, at least one optical member made of silica glass having a fluorine content of about 0.01 wt % to about 0.5 wt %, wherein both optical members are located in accordance with an energy density of light that each said optical member is to process.
- 3. An optical system for use in a projection exposure apparatus for processing an excimer laser beam, the optical system comprising:at least one optical member made of silica glass having a chlorine concentration of about 1 ppm or less; and, at least one optical member made of silica glass having a chlorine concentration of about 1 ppm to about 200 ppm; and, at least one optical member made of silica glass having a fluorine content of about 0.01 wt % to about 0.5 wt % each, wherein each optical member is located in accordance with an energy density of light that each said optical member is to process.
- 4. The optical system according to any one of claims 1 through 3, wherein said silica glass having the fluorine content of about 0.01 wt % to about 0.5 wt % has a chlorine concentration of about 1 ppm or less.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-318472 |
Nov 1998 |
JP |
|
Parent Case Info
This is a divisional of U.S. application Ser. No. 09/437,780, filed Oct. 25, 1999, now U.S. Pat. No. 6,373,554, which is incorporated by reference in its entirety. This application claims the benefit of Japanese Application No. 10-318472, filed in Japan on Nov. 10, 1998, which is hereby incorporated by reference.
US Referenced Citations (10)
Foreign Referenced Citations (1)
Number |
Date |
Country |
0147029 |
Mar 1985 |
EP |