Abstract: A diffractive optical element comprises a substrate, a first resin layer arranged on the substrate and a second resin layer arranged on the first resin layer. Each of the first resin layer and the second resin layer includes a grating section, or a layer portion, for forming a diffraction grating and a base section, or another layer portion, held in contact with the grating section. Either the first resin layer or the second resin layer has a lower transmittance portion in the base section thereof that shows an internal transmittance relative to a wavelength of 400 nm which is lower than that of the grating section of the resin layer by not less than 2% and not more than 6%.

Abstract: A resin layer is formed by filling a polymerizable composition between a substrate and a mold and polymerizing and curing the composition, wherein the polymerizable composition comprises a fluorene compound and a thiol compound comprising 2 to 4 thiol groups, a ratio of the number of sulfur atoms the thiol compound to the number of polymerizable functional groups of the fluorene compound is 0.02 or more and 0.25 or less.

Abstract: A cured product contains a dispersant, inorganic particles, and a resin that is a product of polymerization or copolymerization of a curable resin. The dispersant contains a compound represented by a formula R—X, wherein R represents a group having an acryloyloxy group or a methacryloyloxy group at an end of the molecule thereof, and X represents a carboxy group. The dispersant content is 10 parts by volume to 20 parts by volume relative to 100 parts by volume of the cured product. The curable resin contains at least one monomer having an N number of polymerizable reactive group, wherein N represents an integer of 2 or more. The proportion of the at least one monomer is 25 parts by volume to 76 parts by volume relative to 100 parts by volume of the cured product.

Abstract: In a diffractive optical element including a base material, a first resin layer having a diffraction grating shape including plural concentric ring bands, and a second resin layer containing an inorganic particle, the inorganic particle is adjusted to have a number mean particle diameter of 10 nm or less, a first peak in a region in which particle diameters are 2 nm or more and 7.9 nm or less, and a second peak in a region in which particle diameters are larger than those of the first peak in a grain size distribution on a volumetric basis, with the ratio of the maximum intensity of the second peak to the maximum intensity of the first peak being 0.3 or more and 0.8 or less in a grain size distribution.

Abstract: A diffractive optical element comprises a substrate, a first resin layer arranged on the substrate and a second resin layer arranged on the first resin layer. Each of the first resin layer and the second resin layer includes a grating section, or a layer portion, for forming a diffraction grating and a base section, or another layer portion, held in contact with the grating section. Either the first resin layer or the second resin layer has a lower transmittance portion in the base section thereof that shows an internal transmittance relative to a wavelength of 400 nm which is lower than that of the grating section of the resin layer by not less than 2% and not more than 6%.

Abstract: In a diffractive optical element including a base material, a first resin layer having a diffraction grating shape including plural concentric ring bands, and a second resin layer containing an inorganic particle, the inorganic particle is adjusted to have a number mean particle diameter of 10 nm or less, a first peak in a region in which particle diameters are 2 nm or more and 7.9 nm or less, and a second peak in a region in which particle diameters are larger than those of the first peak in a grain size distribution on a volumetric basis, with the ratio of the maximum intensity of the second peak to the maximum intensity of the first peak being 0.3 or more and 0.8 or less in a grain size distribution.

Abstract: A cured product contains a dispersant, inorganic particles, and a resin that is a product of polymerization or copolymerization of a curable resin. The dispersant contains a compound represented by a formula R—X, wherein R represents a group having an acryloyloxy group or a methacryloyloxy group at an end of the molecule thereof, and X represents a carboxy group. The dispersant content is 10 parts by volume to 20 parts by volume relative to 100 parts by volume of the cured product. The curable resin contains at least one monomer having an N number of polymerizable reactive group, wherein N represents an integer of 2 or more. The proportion of the at least one monomer is 25 parts by volume to 76 parts by volume relative to 100 parts by volume of the cured product.