F2 laser-induced damage on transparent fluoride crystals

Yoshizo Kawaguchi, Aiko Narazaki, Tadatake Sato, Ryozo Kurosaki, Hiroyuki Niino, Hiroki Sato, Tomohiko Satonaga, Tsuguo Fukuda

Research output: Contribution to journalConference articlepeer-review


For the application of F2 lasers to micro- / nano-fabrication including photolithography, one of the important research subjects is to eliminate the chromatic aberration, and combination of lenses made of two optical materials with different refractive indices is the effective way. However, only CaF2 is widely applied to lenses for a vacuum ultraviolet (VUV) beam, and a "second material" to be paired with CaF2 is strongly requested. Here, we examined two fluoride crystals which are transparent in the VUV region, BaF2 and LiCaAIF6 grown by the Czochralski technique, as candidates for VUV optics. We investigated the change of the VUV transmittance and the onset of optical damage of these fluoride crystals against F2 laser irradiation. These crystals showed good optical tolerance against cumulative F2 laser irradiation, and the damage threshold of LiCaAIF6 was similar to mat of VUV grade CaF2 while that of BaF2 was about half of the other two fluoride crystals.

Original languageEnglish
Article number71
Pages (from-to)438-443
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2004
EventFifth International Symposium on Laser Precision Microfabrication - Nara, Japan
Duration: 2004 May 112004 May 14


  • BaF
  • Damage threshold
  • F laser lithography
  • F laser processing
  • LiCaAIF
  • Optical damage
  • Optical material
  • Transmittance
  • Vacuum ultraviolet light


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