| 摘要 |
PROBLEM TO BE SOLVED: To provide such a dichroic mirror for color separation and synthesis of a projection-type color liquid crystal display device that even when a glass substrate is very thin, the mirror has little change in warpage due to environmental changes. SOLUTION: An optical multilayered film produced by alternately depositing low refractive index films and high reflective index films of dielectric materials is formed on a glass substrate having 30 to 50×10<-7> /C coefft. of thermal expansion. It is preferable that the low refractive index films consist of one kind of Al2 O3 or SiO2 single films or mixture films of these and that the high refractive index films consist of one kind of TiO2 , ZrO2 , HfO2 or Ta2 O5 single films or mixture films of these.
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