PREPARATION OF THIN OPTICAL DIELECTRIC FILM

摘要

PURPOSE:To suppress change with lapse of time by forming thin dielectric films each consisting of single dielectric material or alternately laminated layers of a low-refractive index material and high-refractive index material by a vacuum deposition method, then subjecting the films to a treatment to impart a hydrophobicity thereto. CONSTITUTION:This film is a single half wave type interference filter (interference filter) consisting of 10 layers of lambda/4 films constituted of the alternate layers of SiO2 which is the low-refractive index material and TiO2 which is the high- refractive index material. The thin dielectric films are formed on a glass substrate in an atmosphere of 300 deg.C substrate temp. and 2X10<-6>Torr oxygen partial pressure by using an electron beam vapor deposition device. The interference filter is subjected 1hr of a deaeration treatment in <=1X10<3>Torr vacuum prior to execution of the treatment to impart the hydrophobicity in this case. The interference filter subjected to the deaeration treatment is then immersed in a trimethyl chlorosilane/chloroform soln., by which the treatment to impart the hydrophobicity to the interference filter is executed. The thin dielectric film which changes less with lapse of time is thereby obtd.