A reflector includes a low refractive index layer and a high refractive index layer. The low refractive index layer has a first average refractive index and has a laminated structure in which an AlN layer and a GaN layer are alternately laminated. The high refractive index layer has a second average refractive index higher than the first average refractive index and includes an InGaN layer.

A bandpass filter may include a set of layers. The set of layers may include a first subset of layers. The first subset of layers may include hydrogenated germanium (Ge:H) with a first refractive index. The set of layers may include a second subset of layers. The second subset of layers may include a material with a second refractive index. The second refractive index may be less than the first refractive index.

The information display apparatus has a housing with an opening and a transparent cover formed on the opening, the housing includes image-light generating means configured to generate image light that displays the image information and an optical system configured to allow a driver of the vehicle to recognize image information based on the image light from the image-light generating means as a virtual image in front of the windshield. When S-polarized light on the windshield is assumed to be a first polarized wave while polarized light that orthogonally crosses the S-polarized light in a polarizing direction is assumed to be a second polarized wave, the image-light generating means is configured to generate the image light made of the first polarized wave, and a transmittance/reflectance control means blocks a part of the first polarized wave and the second polarized wave of incident external light entering the housing from the opening.

A method of reducing surface roughness of DUV reflectance coatings for a DUV mirror to improve the reflectance of the DUV mirror includes: forming the reflectance coating on a substrate, the reflectance coating including a film stack comprising multiple dielectric layers, including an uppermost layer. The method also includes adding to the uppermost layer a cap layer comprising SiO.sub.2 and having an upper surface with an initial RMS amount of surface roughness. The method further includes adding a sacrificial layer to the upper surface of the cap layer, wherein the sacrificial layer comprises SiO.sub.2. The method also includes etching the sacrificial layer down to the cap layer so that the upper surface of the cap layer has a final RMS amount of surface roughness that is less than the initial amount of surface roughness.

A Fabry-Perot interference filter includes a substrate that has a first surface, a first laminate that has a first mirror portion, a second laminate that has a second mirror portion facing the first mirror portion via a gap, an intermediate layer that defines the gap between the first laminate and the second laminate, and a first terminal. The intermediate layer has a first inner surface surrounding the first terminal. The first inner surface is curved such that an edge portion of the intermediate layer on the substrate side is positioned on the first terminal side relative to an edge portion of the intermediate layer on a side opposite to the substrate.

A Coating, a system of coatings and a method to produce thin film coating, deposited by a stream of particles, produced by thermal evaporation or magnetron/ion-beam sputtering, wherein the thin film coating comprises at least 3 distinct refractive index layers, out of a single target (10) material. In the process of the coating, vapor flux or particle stream is pointed obliquely to the uncovered surface of the substrate (1), which can be rotated about an axis (12), parallel to the surface of the substrate. The substrates can also be rotated about an axis (16), co-aligned with the normal vector of the substrate, to obtain an evenly deposited coating with the desired amorphous structure. The structure of the coating is selected in a pattern, which allows the porosity in-between adjacent layers to be varied. As a consequence, achieving a reflectance of the coating of at least 90% for at least one frequency radiation or polarization component.

An optical element for an imaging optical system includes a substrate including a curved surface, and a multilayer film formed on the curved surface. The multilayer film includes a plurality of first films made of a first material and a plurality of second films made of a second material, each of the plurality of first films and each of the plurality of second films are alternately laminated. A predetermined inequality is satisfied.

The optical product includes an optical multilayer film which is disposed on one surface or both surfaces of a base directly or via an intermediate film. The optical multilayer film is obtained by alternately disposing an SiO.sub.2 layer and a ZrO.sub.2 layer, forming nine layers in total, such that a first layer counting from the base is the SiO.sub.2 layer. The optical thickness of the SiO.sub.2 layer as the first layer is not greater than 0.120/4 when a design wavelength is (500 nm), the optical thickness of the ZrO.sub.2 layer as a second layer is not less than 0.400/4, the optical thickness of the SiO.sub.2 layer as a third layer is not less than 0.230/4, and the optical thickness of the SiO.sub.2 layer as a seventh layer is not less than 0.450/4.

Provided are electromagnetic wave reflectors and optical devices including the same. An electromagnetic wave reflector may include a plurality of layers which have an aperiodic structure and/or thickness. The plurality of layers may satisfy a condition of spatial coherence with respect to electromagnetic waves. The electromagnetic wave reflector may include a plurality of first material layers including a first material having a first refractive index and a plurality of second material layers including a second material having a second refractive index different from the first refractive index. At least two of the plurality of first material layers may have different thicknesses. At least two of the plurality of second material layers may have different thicknesses. At least one of the plurality of first material layers and at least one of the plurality of second material layers may have different thicknesses.

Provided is a light shielding plate that, even if an infrared transmitting region is provided next to a visible/infrared opaque region, makes the infrared transmitting region less distinguishable with the naked eye. A light shielding plate 1 includes: a glass plate 2 having a first principal surface 2a and a second principal surface 2b opposed to the first principal surface 2a; a visible/infrared opaque film 3 provided on or over the second principal surface 2b; an infrared transmitting film 4 provided on or over the first principal surface 2a or the second principal surface 2b to suppress transmission of visible light; and a light absorption film 10 provided on or over the first principal surface 2a or the second principal surface 2b, the light shielding plate 1 includes: a visible/infrared opaque region B formed of the visible/infrared opaque film 3 to shield visible light and infrared light; and an infrared transmitting region C that transmits infrared light, the infrared transmitting region C is located next to the visible/infrared opaque region B, the light absorption film 10 is provided in the visible/infrared opaque region B and the infrared transmitting region C, and the infrared transmitting film 4 is provided at least in the infrared transmitting region C.