| 摘要 |
A dichroic film formed on a prism base member contains 10% by volume or more of a high-thermal-conductivity substance having a thermal conductivity of 20 W/mK or more at a temperature of 300 K. Preferably, the dichroic film is composed of high- and low-refractive-index layers laid alternately on one another, and the low-refractive-index layers contain 20% by volume or more of the high-thermal-conductivity substance. For lower angle-of-incidence dependence and higher light use efficiency, preferably, the following conditions: N<SUB>L </SUB>>=1.58 and N<SUB>H</SUB>/N<SUB>L</SUB>>=1.33, where N<SUB>L </SUB>represents the refractive index of the low-refractive-index layers, and N<SUB>H </SUB>represents the refractive index of the high-refractive-index layers.
|
