Abstract: An anti-reflection coating having an three-layer structure comprising first to third layers formed in this order on a substrate, the substrate having a refractive index of 1.6-1.9, the first layer having a refractive index of 1.37-1.57, the second layer having a refractive index of 1.75-2.5, and the third layer having a refractive index of 1.18-1.32, to light in a wavelength range of 550 nm; the third layer being formed by silica aerogel; and the first and second layers containing no Al2O3.

Abstract: An anti-reflection coating having an three-layer structure comprising first to third layers formed in this order on a substrate, the substrate having a refractive index of 1.6-1.9, the first layer having a refractive index of 1.37-1.57, the second layer having a refractive index of 1.75-2.5, and the third layer having a refractive index of 1.18-1.32, to light in a wavelength range of 550 nm; the third layer being formed by silica aerogel; and the first and second layers containing no Al2O3.

Abstract: An anti-reflection coating having an three-layer structure comprising first to third layers formed in this order on a substrate, the substrate having a refractive index of 1.6-1.9, the first layer having a refractive index of 1.37-1.57, the second layer having a refractive index of 1.75-2.5, and the third layer having a refractive index of 1.18-1.32, to light in a wavelength range of 550 nm; the third layer being formed by silica aerogel; and the first and second layers containing no Al2O3.

Abstract: An optical device for forming an image of an object, comprising: a semitransparent mirror surface disposed on an optical path of the image of the object; and a light projection unit configured to project light to the semitransparent mirror surface and thereby to combine, on the optical path, the projected light transmitting through the semitransparent mirror surface with the image of the object reflecting from the semitransparent mirror surface, wherein: a first wavelength region is defined in a visible light region to include a wavelength of the projected light; the semitransparent mirror surface has a substantially flat reflectance property within a second wavelength region which is defined in the visible light region not to include the first wavelength region; and transmissivity of the semitransparent mirror surface at the wavelength of the projected light is higher by 10% to 50% than transmissivity in the second wavelength region.

Abstract: An anti-reflection coating having an three-layer structure comprising first to third layers formed in this order on a substrate, the substrate having a refractive index of 1.6-1.9, the first layer having a refractive index of 1.37-1.57, the second layer having a refractive index of 1.75-2.5, and the third layer having a refractive index of 1.18-1.32, to light in a wavelength range of 550 nm; the third layer being formed by silica aerogel; and the first and second layers containing no Al2O3.

Abstract: An optical device for forming an image of an object, comprising: a semitransparent mirror surface disposed on an optical path of the image of the object; and a light projection unit configured to project light to the semitransparent mirror surface and thereby to combine, on the optical path, the projected light transmitting through the semitransparent mirror surface with the image of the object reflecting from the semitransparent mirror surface, wherein: a first wavelength region is defined in a visible light region to include a wavelength of the projected light; the semitransparent mirror surface has a substantially flat reflectance property within a second wavelength region which is defined in the visible light region not to include the first wavelength region; and transmissivity of the semitransparent mirror surface at the wavelength of the projected light is higher by 10% to 50% than transmissivity in the second wavelength region.

Abstract: An imaging apparatus comprising an optical member in an optical path from a lens to an imaging device, said optical member comprising a water-repellent or water/oil-repellent coating, a first antireflection coating, an infrared-cutting glass, a lowpass filter, and an infrared-cutting coating in this order from the side of said lens.

Abstract: A method for manufacturing a dust-proofing and light-transmitting member comprising the steps of forming a deposited coating and forming a dust-proofing coating is provided. The dust-proofing and light-transmitting member is arranged on a side of a light-receiving surface of an imaging device. The deposited coating is formed on a light-incident surface of a light-transmitting substrate. The deposited coating comprises aluminum, alumina, or a mixture of aluminum and alumina. The dust-proofing coating having fine roughness is formed on a surface by carrying out a hot water process for the deposited coating. Water warmed to between 40 and 100 degrees Celsius or a mixture of water and organic solvent is used in the hot water process.

Abstract: An imaging apparatus comprising an optical member in an optical path from a lens to an imaging device, said optical member comprising a water-repellent or water/oil-repellent coating, a first antireflection coating, an infrared-cutting glass, a lowpass filter, and an infrared-cutting coating in this order from the side of said lens.

Abstract: An objective lens on which a beam having parallel light fluxes is incident includes a single element lens and a reflection suppressing coating formed on at least one surface of the single element lens. The reflection suppressing coating is formed such that the reflectivity across a radius of the objective lens exhibits a local maximal value, and the reflection suppressing coating is formed to achieve the following condition: 0.6<h1/hmax<0.95, wherein h1 denotes a distance between an optical axis and a position at which the reflectivity exhibits the local maximal value, and hmax denotes a distance between the optical axis and an outermost position of the effective diameter of the objective lens.

Abstract: An objective lens on which a beam having parallel light fluxes is incident includes a single element lens and a reflection suppressing coating formed on at least one surface of the single element lens. The reflection suppressing coating is formed such that the reflectivity across a radius of the objective lens exhibits a local maximal value, and the reflection suppressing coating is formed to achieve the following condition: 0.6<h1/hmax<0.95, wherein h1 denotes a distance between an optical axis and a position at which the reflectivity exhibits the local maximal value, and hmax denotes a distance between the optical axis and an outermost position of the effective diameter of the objective lens.