Patent ID: 7839571

Claim:
A color-separation optical system for separating incident light into at least three color light components of blue light, red light, and green light, the color-separation optical system comprising, in order from a light-incident side: a first prism that has a first dichroic film and extracts a first color light component reflected by the first dichroic film; a second prism that has a second dichroic film and extracts a second color light component which passes through the first dichroic film and which is reflected by the second dichroic film; and a third prism that extracts a third color light component which passes through the first and second dichroic films, wherein the first dichroic film has a film configuration for reflecting the blue light as the first color light component, the second dichroic film has a film configuration for reflecting the red or green light as the second color light component, a transmission characteristic curve of wavelength versus transmissivity of the first dichroic film has a shape that tracks a short-wavelength side of an ideal spectral characteristic of green, a transmission characteristic curve of wavelength versus transmissivity of the second dichroic film has a shape that tracks a long-wavelength side of the ideal spectral characteristic of green when the second dichroic film reflects the red light, and a reflection characteristic curve of wavelength versus reflectivity of the second dichroic film has a shape that tracks the long-wavelength side of the ideal spectral characteristic of green when the second dichroic film reflects the green light.