Abstract: An optical low-pass filter is arranged on an object side than an image sensor in an image pickup apparatus and has an unevenness shape. The conditions of 5.0 ?m??z?80.0 ?m and 1.0?Ps/<Pf>?20.0 are satisfied where ?z represents a distance between the optical low-pass filter and the image sensor, Ps represents a pixel pitch of the image sensor, and <Pf> represents an average pitch of the unevenness shape.

Abstract: The image capturing apparatus includes an optical low-pass filter configured to separate one incident ray into multiple rays to form multiple point images, and an image sensor configured to photoelectrically convert the multiple point images. The optical low-pass filter satisfies a condition of 0.4<2×?/P<0.9. P represents a pixel pitch of the image sensor, and ? represents a standard deviation of a distribution of the multiple point images.

Abstract: The optical element of the present invention has an anti-reflection film formed on a substrate. The anti-reflection film comprises a low refractive index layer that is formed by mutually binding hollow fine particles, each of which has a vacancy therein, using a binder, and the low refractive index layer consists of a first layer serving as an outermost layer and a second layer which is adjacent to the first layer and is located on the substrate side. Here, the filling ratio of the binder to the first layer is lower than the filling ratio of the binder to the second layer, the refractive index of the first layer is 1.1 or more but not more than 1.25 and the refractive index of the second layer is 1.26 or more but not more than 1.35.

Abstract: The anti-reflection structure includes a graded refractive index layer that is disposed on a substrate and whose refractive index decreases as a distance from the substrate increases, and a homogeneous layer that is disposed on the graded refractive index layer and whose refractive index is homogeneous. The structure satisfies a condition of nb?na>0.10 where na represents the refractive index of the homogenous layer, and nb represents a homogenous layer side effective refractive index of the graded index refractive index layer.

Abstract: The image capturing apparatus includes an optical low-pass filter configured to separate one incident ray into multiple rays to form multiple point images, and an image sensor configured to photoelectrically convert the multiple point images. The optical low-pass filter satisfies a condition of 0.4<2×?/P<0.9. P represents a pixel pitch of the image sensor, and ? represents a standard deviation of a distribution of the multiple point images.

Abstract: Provided is an anti-reflection film, which is formed on substrate, the anti-reflection film having a laminated layer structure including, in order from the substrate: a first layer to a sixth layer each formed of a dielectric thin film; and a seventh layer formed by a wet process, in which the first to the sixth layers are formed of three kinds of mediums having different refractive indices from one another, and in which, when refractive indices of the three kinds of mediums at wavelength of 550 nm are defined as nL, nM, and nH, the first layer is formed of a medium having nM, the sixth layer is formed of a medium having nH, a layer formed of a medium having nL and a layer formed of a medium having off are spaced away from each other, and nL, nM, and nH are appropriately set.

Abstract: An anti-reflection film includes first through ninth layers. Regarding light having a wavelength of 550 nm, where the refractive indexes of the first through ninth layers are n1 through n9 respectively, the optical film thicknesses d1 through d9 (nm) respectively, and the maximum value of the difference in the refractive index between adjoining layers for layers 1 through 8 is ?n, the following conditions are satisfied. 1.60?n1?1.70, 15 nm?d1?140 nm, 2.00?n2?2.40, 20 nm?d2?120 nm, 1.60?n3?1.70, 11 nm?d3?70 nm, 2.00?n4?2.40, 20 nm?d4?165 nm, 1.60?n5?1.70, 15 nm?d5?45 nm, 2.00?n6?2.40, 90 nm?d6?175 nm, 1.60?n7?1.70, 50 nm?d7?110 nm, 2.00?n8?2.40, 20 nm?d8?50 nm, 1.20?n9?1.28, 140 nm?d9?160 nm, and 0.40??n?0.67.

Abstract: An optical element includes a substrate, and an antireflection film laminated on the substrate. The antireflection film includes, in order from the substrate side, a first layer including a plurality of dielectric thin films, a second layer including hollow particles bound by a dielectric material, and a third layer laminated on the second layer and made of a homogeneous dielectric. The hollow particles have an average particle diameter of 60 nm or less. A filling rate of the hollow particles in the second layer is 65% or higher.

Abstract: An optical element includes a substrate that is transparent, and an antireflective film laminated on the substrate. The antireflective film includes, in order from the substrate, a first layer, a second layer, and a third layer. The substrate has a refractive index of 1.80 to 2.05 for the d-line. The first layer is an inorganic oxide film having a refractive index of 1.43 to 1.47 for the d-line and a physical film thickness of 29.0 to 40.0 nm and containing silica as a main component. The second layer is an inorganic oxide film having a refractive index of 2.00 to 2.20 for the d-line and a physical film thickness of 12.0 to 41.0 nm. The third layer is a film having a refractive index of 1.23 to 1.26 for the d-line and a physical film thickness of 110.0 to 130.0 nm and containing silica nanoparticles.

Abstract: Provided is an optical system with an excellent anti-reflection effect and ghost suppression effect including an aspherical lens having at least one of an incident surface and an exiting surface of an optical glass formed of an aspherical surface, in which: the aspherical surface includes an anti-reflection structure formed thereon, the anti-reflection structure having an anti-reflection function and including multiple inorganic structural parts finer than a used wavelength; and the aspherical surface has a point that satisfies the following expression: |(1/Rm?1/Rs)/Rm|>5.0×10?5, where Rm denotes a radius of curvature in a meridional direction at an arbitrary point, and Rs denotes a radius of curvature in a sagittal direction at the arbitrary point.

Abstract: The optical element of the present invention has an anti-reflection film formed on a substrate. The anti-reflection film comprises a low refractive index layer that is formed by mutually binding hollow fine particles, each of which has a vacancy therein, using a binder, and the low refractive index layer consists of a first layer serving as an outermost layer and a second layer which is adjacent to the first layer and is located on the substrate side. Here, the filling ratio of the binder to the first layer is lower than the filling ratio of the binder to the second layer, the refractive index of the first layer is 1.1 or more but not more than 1.25 and the refractive index of the second layer is 1.26 or more but not more than 1.

Abstract: An image projection apparatus includes light sources 111 to 113 emitting at least two colored lights whose wavelengths are different from each other, a polarization conversion element 2 controlling a polarization direction of the colored light, at least two light modulation elements 41 and 42 modulating incident light, a light guide optical system 31 guiding the at least two colored lights from the polarization conversion element to the at least two light modulation elements in accordance with the polarization direction, and a projection optical system 5. One of the at least two colored light and the other are emitted as lights whose polarization directions are different from each other from the polarization conversion element. A drive unit 6 turns on the light sources so that the one of the colored lights and at least one of the other enter the at least two light modulation elements at the same time.

Abstract: An image pickup apparatus includes an image pickup optical system and an image pickup unit configured to receive an image formed by the image pickup optical system. The image pickup optical system includes an optical element having optical incident and optical emergent surfaces disposed between an aperture stop and an object and a fine textured structure having a mean pitch shorter than a wavelength of visible light and formed on at least one of the optical incident and optical emergent surfaces. The conditions 3.5<RA/R0 and 60°<2? are satisfied, where RA is an effective diameter of the optical surface having the fine textured structure, R0 is a diameter determined by a height when light rays forming an image on an optical axis pass through the optical surface having the fine textured structure, and 2? is an angle of view in image taking limited by a size of the image pickup unit.

Abstract: An image pickup apparatus includes an image pickup optical system and an image pickup unit configured to receive an image formed by the image pickup optical system. The image pickup optical system includes an optical element having optical incident and optical emergent surfaces disposed between an aperture stop and an object and a fine textured structure having a mean pitch shorter than a wavelength of visible light and formed on at least one of the optical incident and optical emergent surfaces. The conditions 3.5<RA/R0 and 60° <2? are satisfied, where RA is an effective diameter of the optical surface having the fine textured structure, R0 is a diameter determined by a height when light rays forming an image on an optical axis pass through the optical surface having the fine textured structure, and 2? is an angle of view in image taking limited by a size of the image pickup unit.

Abstract: An optical system includes an optical element formed of resin. On at least one of optical surfaces on the light incidence side of the optical element formed of resin, a plurality of depressions or protrusions of a size not larger than the wavelengths of visible light is formed without a periodic structure or in a random arrangement.

Abstract: An optical element having antireflection function includes a substrate including a first relief structure on a surface, the first relief structure including at least a convex shape and a concave shape being arrayed with a pitch of at most a half of a wavelength ?, and a thin film layer including a thin film of at least one layer on the first relief structure, wherein the thin film layer has a refractive index lower than the refractive index of the substrate, and when the thin film layer includes at least two thin films more, the thin film layer are arranged in order of decreasing the refractive index from a side of the substrate toward a side of air, and the following conditional expression is satisfied: ¼?h1/h0?2??(1) ???D?2???(2)

Abstract: The anti-reflection structure includes a graded refractive index layer that is disposed on a substrate and whose refractive index decreases as a distance from the substrate increases, and a homogeneous layer that is disposed on the graded refractive index layer and whose refractive index is homogeneous. The structure satisfies a condition of nb?na>0.10 where na represents the refractive index of the homogenous layer, and nb represents a homogenous layer side effective refractive index of the graded index refractive index layer.

Abstract: A color separation/combination prism is disclosed which has an optical film arrangement capable of performing color separation, light analysis and color combination. The prism includes four prism members and at least five optical surfaces as outer surfaces thereof. Each of the prism members has at least three optical surfaces including two optical surfaces which intersect orthogonally with each other at a first side thereof. The four prism members are joined together such that the first sides of the prism members are adjacent to or contact each other. Joining portions of the four prism members are provided with wavelength-selective polarizing films.

Abstract: Provided is an optical system with an excellent anti-reflection effect and ghost suppression effect including an aspherical lens having at least one of an incident surface and an exiting surface of an optical glass formed of an aspherical surface, in which: the aspherical surface includes an anti-reflection structure formed thereon, the anti-reflection structure having an anti-reflection function and including multiple inorganic structural parts finer than a used wavelength; and the aspherical surface has a point that satisfies the following expression: |(1/Rm?1/Rs)/Rm|>5.0×10?5, where Rm denotes a radius of curvature in a meridional direction at an arbitrary point, and Rs denotes a radius of curvature in a sagittal direction at the arbitrary point.

Abstract: An image pickup apparatus includes an image pickup optical system and an image pickup unit configured to receive an image formed by the image pickup optical system. The image pickup optical system includes an optical element having optical incident and optical emergent surfaces disposed between an aperture stop and an object and a fine textured structure having a mean pitch shorter than a wavelength of visible light and formed on at least one of the optical incident and optical emergent surfaces. The conditions 3.5<RA/R0 and 60°<2? are satisfied, where RA is an effective diameter of the optical surface having the fine textured structure, R0 is a diameter determined by a height when light rays forming an image on an optical axis pass through the optical surface having the fine textured structure, and 2? is an angle of view in image taking limited by a size of the image pickup unit.