| 摘要 |
PURPOSE:To improve the heat resistance of an optical body consisting of the laminated films of a highly thermally expansible film and low thermally expansible films provided on a base body by interposing a Ti film or Cr film at the boundary between both expansible films. CONSTITUTION:The low expansible films 11, 12 which consist of an oxide such as ZrO2, TiO2, Al2O3, SiO2, Y2O3 or Ta2O5 or the mixture composed thereof are formed on the base body 10 consisting of floating glass, etc. by a vacuum deposition method with electron beam heating, etc. The Ti film or Cr film 13 having >=10Angstrom film thickness is formed thereon and thereafter the highly expansible film 14 which consists of a fluoride such as MgF2, CeF3, Na3AlF6 or LaF3 or the mixture composed thereof and has >=10X10<-6>deg<-1> difference in the coefft. of thermal expansion from the films 11, 12 is formed thereon to provide the intended optical body. The optical body which lessens the deterioration in the mechanical strength during the heat treatment is thus obtd. |
