| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a method for protecting an optical element and removing particles easily upon deposition. <P>SOLUTION: In place of avoiding deposition of particles, the particles are deposited intentionally on removable optical elements 50, 51, 53, 54 thus protecting the optical elements. A material containing one or more elements selected from B, C, Si, Ge and/or Sn is prepared, and at least a part of that material is made to fly to a radioactive source SO during use thus producing a material capable of being deposited. That material is arranged to be deposited at leat partially on the optical element. That material can be removed relatively easily with atom hydrogen and/or halide gas. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
