| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a color separation optical system which is capable of suppressing ghost due to surfaces constituting a gap while maintaining three-color separation characteristics. <P>SOLUTION: The color separation optical system includes: a first prism which has a second surface for separating an incident luminous flux into a reflected luminous flux and a transmitted luminous flux and separates the reflected luminous flux; and a second prism which has a third surface disposed with a gap between the second surface and the third surface and has a fourth surface for separating a luminous flux impinging from the third surface into a reflected luminous flux and a transmitted luminous flux and separates a luminous flux reflected by the fourth surface and then reflected by the third surface. A multilayer film is formed on a surface of at least one of the second surface and the third surface, and the color separation optical system satisfies 0.70<nd×cosθ2A/(λ/4)<1.2 and θ2A=sin<SP POS="POST">-1</SP>ä(Ng/Nm)sin(θ2)} where λ is a center wavelength (nm) of a wavelength range of the luminous flux to be separated by the second prism, nd is an optical film thickness (nm) of a multilayer film outer most layer, Nm is a refractive index for the center wavelength of the multilayer film outermost layer, Ng is a refractive index for the center wavelength of a wavelength range of color light to be separated, of a glass material of the second prism, and θ2 is an apex angle of the second prism. <P>COPYRIGHT: (C)2013,JPO&INPIT |
