Patents Examined by Sephone B. Allen
  • Optical element having antireflection film, and exposure apparatus
    Patent number: 7492510
    Abstract: An optical element includes a substrate that transmits a light having a central wavelength in a wave range between 150 nm and 250 nm, and an n-layer antireflection film that is formed on the substrate, and includes, from the substrate, an n?2-th layer made of a high refractive index material, an n?1-th layer made of an amorphous material containing AlF3, and an n-th layer made of a low refractive index material, each of the high and low refractive index materials containing a crystalline material.
    Type: Grant
    Filed: November 8, 2006
    Date of Patent: February 17, 2009
    Assignee: Canon Kabushiki Kaisha
    Inventor: Seiji Kuwabara