Abstract: A diffractive optical element includes first and second diffractive optical parts to generate diffracted lights two-dimensionally with respect to incident light. The diffracted lights generated by inputting the incident light to the first diffractive optical part are input to the second diffractive optical part in order to generate the diffracted lights from the second diffractive optical part, wherein ?1??2 and k1?k2 stand or, ?1??2 and k1?k2 stand among ?1 and ?2 denote diffraction angles of the first and second diffractive optical parts, and k1 and k2 denote numbers of light spots of the diffracted lights generated by the first and second diffractive optical parts.

Abstract: An optical element includes an optical member made of a material that transmits light; a high refractive index layer and a low refractive index layer that are stacked on a front surface of the optical member; and a surface protection layer that is formed on an upper most layer among the high refractive index layer and the low refractive index layer, the surface protection layer being made of a material including one of a mixed oxide of Si and Sn, a mixed oxide of Si and Zr, and a mixed oxide of Si and Al, and the refraction index of the surface protection layer being less than or equal to the refraction index of the high refractive index layer and greater than or equal to the refraction index of the low refractive index layer.

Abstract: A diffractive optical element includes: a first diffractive element in which a plurality of basic units are two-dimensionally arranged; and a second diffractive element in which a plurality of basic units are two-dimensionally arranged, wherein when a direction in which the basic units are arranged in the first diffractive element is a first direction, a direction in which the basic units are arranged in the second diffractive element is a second direction, an angle ? between the first direction and the second direction is such that ?|?1|<?<|?1|, and ??0, sin ?1=??/?x where a closest distance of zero-order light generated when the diffracted light generated by the first diffractive element is further incident on the second diffractive element is ?x and a closest distance of the diffracted light and stray light generated by the second diffractive element is ?.

Abstract: To provide a diffractive optical element and a measuring device capable of generating light spots of dispersive type. The problem is resolved by providing a diffractive optical element having concaves and convexes and diffracting incident light in two dimensions so as to generate diffracted light, wherein when the number of a part of light spots formed by the diffracted light is denoted by n, an average distance W to the nearest neighbor in the light spots normalized by an area of a region onto which the light spots are projected falls within a range of 1/(2×n1/2)<W<1/(n1/2).

Abstract: A phase difference layer 12 and a reflection layer 13 are provided. Then, adjustment is performed such that the phase difference layer 12 and the reflection layer 13 impart a predetermined phase difference to light having a particular wavelength bandwidth or plural kinds of light of different wavelengths that enter in an oblique direction relative to the normal direction of the plane of the phase difference layer 12. By virtue of this, the light 16a that goes forward and backward through the phase difference layer 12 and then exits the layer has an ellipticity ? of 0.7 or greater. Thus, in particular, when this wave plate is employed in an optical head device, the function of reflection and the function of a ¼-wave plate are integrated. Thus, stable recording and reproduction of an optical disk are achieved, and size reduction is achieved in the optical head device.

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: The present invention relates to an aberration correcting device comprising: an aberration correcting element which modulates the phase of incident light; and a position adjusting section which can move the aberration correcting element in a direction perpendicular to an optical axis of the incident light, wherein the aberration correcting element includes first and second aberration correction plates, each of which is disposed such that the phase of transmitted light beam differs with transmission position of the incident light beam with the same phase, and the aberration correcting element has a reference arrangement which is an arrangement of the first and second aberration correction plates in which the light beams transmitted through the aberration correcting element have the same phase, and assuming that a point on the first aberration correction plate crossing the optical axis is a point Oa and a point on the second aberration correction plate crossing the optical axis is a point Ob in the reference ar

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: A diffractive optical element includes first and second diffractive optical parts to generate diffracted lights two-dimensionally with respect to incident light. The diffracted lights generated by inputting the incident light to the first diffractive optical part are input to the second diffractive optical part in order to generate the diffracted lights from the second diffractive optical part, wherein ?1??2 and k1?k2 stand or, ?1??2 and k1?k2 stand among ?1 and ?2 denote diffraction angles of the first and second diffractive optical parts, and k1 and k2 denote numbers of light spots of the diffracted lights generated by the first and second diffractive optical parts.

Abstract: A phase difference layer 12 and a reflection layer 13 are provided. Then, adjustment is performed such that the phase difference layer 12 and the reflection layer 13 impart a predetermined phase difference to light having a particular wavelength bandwidth or plural kinds of light of different wavelengths that enter in an oblique direction relative to the normal direction of the plane of the phase difference layer 12. By virtue of this, the light 16a that goes forward and backward through the phase difference layer 12 and then exits the layer has an ellipticity ? of 0.7 or greater. Thus, in particular, when this wave plate is employed in an optical head device, the function of reflection and the function of a ¼-wave plate are integrated. Thus, stable recording and reproduction of an optical disk are achieved, and size reduction is achieved in the optical head device.

Abstract: A composite optical element includes: a single lens; a first resin layer formed on a surface of the single lens; a second resin layer formed on the first resin layer, wherein: the first resin layer has a diffraction grating of a Fresnel lens configuration; and a refractive index of the first resin layer and that of the second layer are substantially the same value for at least a light beam of one of a light beam of a wavelength ?1, a light beam of a wavelength ?2 and a light beam of a wavelength ?3 (?1<?2<?3), and the refractive index of the first resin layer and that of the second resin layer are different values for at least a light beam of another one of the light beam of the wavelength ?1, the light beam of the wavelength ?2 and the light beam of the wavelength ?3.

Abstract: A diffractive optical element includes: a first diffractive element in which a plurality of basic units are two-dimensionally arranged; and a second diffractive element in which a plurality of basic units are two-dimensionally arranged, wherein when a direction in which the basic units are arranged in the first diffractive element is a first direction, a direction in which the basic units are arranged in the second diffractive element is a second direction, an angle ? between the first direction and the second direction is such that ?|?1|<?<|?1|, and ??0, sin ?1=??/?x where a closest distance of zero-order light generated when the diffracted light generated by the first diffractive element is further incident on the second diffractive element is ?x and a closest distance of the diffracted light and stray light generated by the second diffractive element is ?.

Abstract: To provide a diffractive optical element and a measuring device capable of generating light spots of dispersive type. The problem is resolved by providing a diffractive optical element having concaves and convexes and diffracting incident light in two dimensions so as to generate diffracted light, wherein when the number of a part of light spots formed by the diffracted light is denoted by n, an average distance W to the nearest neighbor in the light spots normalized by an area of a region onto which the light spots are projected falls within a range of 1/(2×n1/2)<W<1/(n1/2).

Abstract: An optical rotating plate has an optical rotating material layer. A phase plate is provided on a first surface side of the optical rotating plate and has at least one birefringent material layer. The first surface side is disposed toward an emitting side of an optical path, thereby giving different phase differences to a first linearly polarized light group containing at least a linearly polarized light having a first wavelength and a second linearly polarized light group containing at least a linearly polarized light having a second wavelength which is different from the first wavelength.

Abstract: The present invention relates to an aberration correcting device comprising: an aberration correcting element which modulates the phase of incident light; and a position adjusting section which can move the aberration correcting element in a direction perpendicular to an optical axis of the incident light, wherein the aberration correcting element includes first and second aberration correction plates, each of which is disposed such that the phase of transmitted light beam differs with transmission position of the incident light beam with the same phase, and the aberration correcting element has a reference arrangement which is an arrangement of the first and second aberration correction plates in which the light beams transmitted through the aberration correcting element have the same phase, and assuming that a point on the first aberration correction plate crossing the optical axis is a point Oa and a point on the second aberration correction plate crossing the optical axis is a point Ob in the reference ar

Abstract: There is provided a diffraction grating including a convex portion and a concave portion which are used for lights having different wavelengths ?1, ?2 and ?3 and are alternately disposed on at least one surface of a substrate with a predetermined pitch. An average refractive index of the convex portion is smaller than an average refractive index of the concave portion. A phase difference in the lights having the wavelength ?1 which transmit the convex portion and the concave portion and a phase difference in the lights having the wavelength ?2 which transmit the convex portion and the concave portion are both substantially the integral multiple of 2?, and a phase difference in the lights having the wavelength ?3 which transmit the convex portion and the concave portion is substantially the non-integral multiple of 2?.

Abstract: The present invention provides a wavelength-selective diffraction element, configured such that light having a plurality of wavelengths are incident thereon as incident light, which is provided with: a transparent substrate; a concavo-convex part, formed on the transparent substrate such that concave portions and convex portions are cyclically extended in one direction, and comprised of a first material which is optically isotropic; and a filling part, filling at least the concave portions and comprised of a second material which is optically isotropic. The first material and the second material have no absorbance with respect to the wavelengths of the incident light. The first material and the second material have an identical refractive index with respect to light having a first wavelength which is at least one of the wavelengths of the incident light.

Abstract: In an optical head device that subjects light exiting from a light source to reflection on an information recording layer of an optical disk, to thus guide the light to a photodetector, an optical attenuation device is disposed in an optical path from the optical disk to the photodetector, wherein the optical attenuation device has a first region having high transmissivity, a second region having low transmissivity, and a third region having an intermediate value of transmissivity, whereby light returned from a layer differing from the information recording layer, which will be responsible for crosstalk, is reduced by mean of the photodetector.

Abstract: An optical rotating plate has an optical rotating material layer. A phase plate is provided on a first surface side of the optical rotating plate and has at least one birefringent material layer. The first surface side is disposed toward an emitting side of an optical path, thereby giving different phase differences to a first linearly polarized light group containing at least a linearly polarized light having a first wavelength and a second linearly polarized light group containing at least a linearly polarized light having a second wavelength which is different from the first wavelength.