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 includes a first periodic structure portion being formed on a base portion and having a one-dimensional periodic structure in which a first medium and a second medium with a smaller refractive index than that of the first medium are alternately disposed in a first direction, and a second periodic structure portion being formed on the first periodic structure portion and having a periodic structure in which a third medium and a fourth medium with a smaller refractive index than that of the third medium are alternately disposed in the first direction. At an interface between the first and second periodic structure portions, a ratio of the first medium in the first periodic structure portion and a ratio of the third medium in the second periodic structure portion are different from each other. The element has a good form birefringence effect and a high reflection-suppressing effect.

Abstract: Provided is an optical element having a high performance anti-reflection structure without increasing the height of the grating, including: a transparent substrate on which an anti-reflection structure having a plurality of gratings having one of a convex shape and a concave shape are arranged is formed, the plurality of gratings being arranged with an average interval of a wavelength equal to or smaller than a predetermined wavelength falling within a working wavelength range, the anti-reflection structure including a structure wherein a first layer and a second layer having different filling factors of gratings in the arrangement surface of the gratings are laminated, and the first layer and the second layer satisfying a conditional expression of 0.36?FF1?FF2?0.56 when the first layer has a filling factor FF1 of the gratings therein and the second layer has a filling factor FF2 of the gratings therein.

Abstract: An optical system includes a first lens with a functional film having film hardness of equal to or less than H formed on at least on one surface thereof, and a second lens located opposite the surface with the functional film of the first lens and having a diameter larger than that of the surface with the functional film, wherein the first lens and the second lens are in marginal contact with each other.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.

Abstract: An optical system includes a first lens with a functional film having film hardness of equal to or less than H formed on at least on one surface thereof, and a second lens located opposite the surface with the functional film of the first lens and having a diameter larger than that of the surface with the functional film, wherein the first lens and the second lens are in marginal contact with each other.

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 includes a first periodic structure portion being formed on a base portion and having a one-dimensional periodic structure in which a first medium and a second medium with a smaller refractive index than that of the first medium are alternately disposed in a first direction, and a second periodic structure portion being formed on the first periodic structure portion and having a periodic structure in which a third medium and a fourth medium with a smaller refractive index than that of the third medium are alternately disposed in the first direction. At an interface between the first and second periodic structure portions, a ratio of the first medium in the first periodic structure portion and a ratio of the third medium in the second periodic structure portion are different from each other. The element has a good form birefringence effect and a high reflection-suppressing effect.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.

Abstract: In a diffraction optical element in which a plurality of diffraction gratings are laminated and the maximum difference of length among optical paths of light passing through the plurality of diffraction gratins is integer multiples of a plurality of wavelengths, diffraction efficiency is further improved and even when an environmental condition changes, a deviation of the diffraction efficiency is reduced. More specifically, a diffraction optical element is disclosed which includes, as the plurality of diffraction gratings, a first diffraction grating made of a resin material, in which inorganic fine particles are dispersed, and a second diffraction grating made of a material whose organic matter composition is substantially same as that of the resin material.

Abstract: In a diffractive optical element and a polarization separation element using this diffractive optical element, incident light can be effectively separated for the respective polarization directions over the entire used wavelength range. The diffractive optical element is arranged such that the diffractive optical element has a grating structure in which at least two blazed type grating portions are successively arranged along a light traveling direction. Additionally, in at least one grating portion of the two blazed type grating portions, structures smaller than a used wavelength are arranged in a periodic manner.

Abstract: In a diffraction optical element in which a plurality of diffraction gratings are laminated and the maximum difference of length among optical paths of light passing through the plurality of diffraction gratins is integer multiples of a plurality of wavelengths, diffraction efficiency is further improved and even when an environmental condition changes, a deviation of the diffraction efficiency is reduced. More specifically, a diffraction optical element is disclosed which includes, as the plurality of diffraction gratings, a first diffraction grating made of a resin material, in which inorganic fine particles are dispersed, and a second diffraction grating made of a material whose organic matter composition is substantially same as that of the resin material.

Abstract: A diffractive optical element includes a plurality of diffraction gratings. A diffraction grating within the plurality of diffraction gratings includes a plurality of grating parts having a curved grating surface and grating tips which connect to define a curved envelope face. The grating surface has a radius of curvature larger than a radius of curvature of the envelope face. In addition, two diffraction gratings within the plurality of diffraction gratings are composed of different materials having different dispersions. Therefore, even when the radius of curvature of the envelope face is small, the degradation of the diffraction efficiency is suppressed.

Abstract: A layered diffractive optical element is disclosed, with which a high diffraction efficiency is attained over a broad region of used wavelengths, and with which diffraction light of unnecessary diffraction orders can be suppressed. A diffractive optical element of the present invention includes a plurality of diffraction gratings made of materials with different Abbe numbers, the plurality of diffraction gratings being layered with each other. Moreover, the partial dispersion ratio with respect to a g-line and a F-line of the material constituting at least one of the plurality of diffraction gratings satisfies the condition represented by a specified expression.

Abstract: A diffractive optical element of the blazed-binary grating type is disclosed, with which a high diffraction efficiency can be achieved over substantially the entire used wavelength region. The diffractive optical element has a periodic structure taking a grating unit including a plurality of grating portions with different grating width and grating interval as one period. The diffraction element further includes a plurality of first grating portions made of a first material and a plurality of second grating portions made of a second material having a different refractive index than the first material that are arranged between the first grating portion.

Abstract: Disclosed is a diffractive optical element which is made of at least two materials of different dispersions and which includes at least two diffraction gratings being accumulated one upon another, wherein each diffraction grating is formed on a curved surface of a substrate, and wherein a diffraction grating, of the at least two diffraction gratings, in which a curvature radius of the curved surface and a curvature radius of a grating surface in a portion where a grating pitch is largest, have different signs, is one of the at least two diffraction gratings which has a smallest grating thickness.

Abstract: A diffraction optical element wherein a plurality of diffraction gratings formed of at least two kinds of materials differing in dispersion are laminated, at least two of the plurality of diffraction gratings are formed on a curved surface and adjacent to each other, and these two adjacent diffraction gratings are equal to each other in the shape of a curved tip plane in which the tips of respective grating portions are ranged.