Abstract: A substrate holding board includes a first layer and a second layer forming an interfacial surface with the first layer. The first layer and the second layer contain diamond-like carbon. A refractive index of the first layer in a wavelength is higher than a refractive index of the second layer in the wavelength. A distance from the second layer to a topmost surface of the substrate holding board is smaller than a thickness of the first layer.

Abstract: An optical member that has excellent antireflection properties and that can maintain antifogging properties over a long term, and a method for manufacturing an optical member are provided. The optical member includes, in sequence, a substrate, a porous layer, and a multilayered antireflection layer. The ratio n/n0 is 0.85 or more and 0.95 or less, where n represents a refractive index of a layer having the highest refractive index among layers included in the antireflection layer and n0 represents a refractive index of a compound constituting the layer having the highest refractive index at a theoretical density.

Abstract: An optical member that has excellent antireflection properties and that can maintain antifogging properties over a long term, and a method for manufacturing an optical member are provided. The optical member includes, in sequence, a substrate, a porous layer, and a multilayered antireflection layer. The ratio n/n0 is 0.85 or more and 0.95 or less, where n represents a refractive index of a layer having the highest refractive index among layers included in the antireflection layer and n0 represents a refractive index of a compound constituting the layer having the highest refractive index at a theoretical density.

Abstract: Provided are a member that reduces a change in refractive index at high humidity (60% RH or more and less than 90% RH) and a method of manufacturing the member. The member comprises a base material and a porous layer formed on at least any one of surfaces of the base material, wherein the porous layer has dN2 of 5 nm or more and 20 nm or less and dH2O of 25 nm or more and 75 nm or less, and has a contact angle with respect to water of less than 60°, in which dN2 is defined as a diameter of a pore at a time when a differential pore volume becomes maximum in the differential pore distribution in nitrogen adsorption and dH2O is defined as a diameter of a pore at a time when a differential pore volume becomes maximum in the differential pore distribution in water vapor adsorption.