COLOR SEPARATION OPTICAL SYSTEM AND IMAGE PICKUP APPARATUS
First Claim
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, anda 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, andthe 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.
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Accused Products
Abstract
It is disclosed that a color separation optical system improves color reproducibility by obtaining a characteristic which approximates an ideal spectral characteristic in view of influence of polarization separation caused according to the magnitude of an incidence angle. In the color separation optical system, a curve representing a characteristic of a green-reflecting dichroic film DG has a shape along the characteristic curve representing an ideal spectral characteristic corresponding to green light. Further, the characteristic of the blue-reflecting dichroic film DB is associated with that of the green-reflecting dichroic film DG. A part, in which the transmittance of the blue-reflecting dichroic film DB changes from a low transmittance to a high transmittance, in the transmittance characteristic curve representing the characteristic of the blue-reflecting dichroic film DB is included in a predetermined wavelength region associated with the characteristic of the green-reflecting dichroic film DG.
31 Citations
24 Claims
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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:
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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. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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2. 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:
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a first prism having a first dichroic film, from which a first color light component reflected by the first dichroic film is taken out; a second prism having 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 red light as the second color light component, 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 reflection characteristic curve representing a wavelength-to-reflectance characteristic of the second dichroic film has a part in which a reflectance rises from 20% to 80% within a reflectance range between the lowest reflectance and the highest reflectance, and the part, in which the reflectance rises from 20% to 80% within the reflectance range between the lowest reflectance and the highest reflectance, of the reflectance 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. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification