Patent ID: 8040611
Filing Date: 2011-10-18
Classification: G02B

Abstract:
1. A color separation optical system for separating incident light into at least three color light components including green light, blue light, and red light, comprising, in order from a light incidence side: a first prism that includes a first dichroic film, from which first color light component reflected by the first dichroic film is taken out; a second prism that includes a second dichroic film, from which a second color light component transmitted by the first dichroic film and reflected by the second dichroic film is taken out; and a third prism from which a third color light component transmitted by the first and second dichroic films is taken out, wherein the first dichroic film reflects green light as the first color light component, the second dichroic film reflects blue light as the second color light component, and a reflection characteristic curve representing a reflectance-to-wavelength characteristic of the first dichroic film has a shape so that a gradient at each point of the reflection characteristic curve changes along a short-wavelength-side ideal spectral characteristic curve of green light and a long-wavelength-side ideal spectral characteristic curve of green light, a transmission characteristic curve representing a wavelength-to-transmittance characteristic of the second dichroic film has a part in which a transmittance rises from 20% to 80% within a transmittance range between the lowest transmittance and the highest transmittance, and the part, in which the transmittance rises from 20% to 80% within the transmittance range between the lowest transmittance and the highest transmittance, of a transmission characteristic curve corresponding to the second dichroic film is included in a given wavelength region interposed between wavelength points, at which a transmittance is equal to 80% between the lowest transmittance and the highest transmittance, on a transmission characteristic curve representing a wavelength-to-transmittance characteristic of the first dichroic film.