Abstract: An optical element transmits incident light having a particular polarization direction mainly by 0-order transmission and diffracts incident light having a perpendicular polarization direction. The optical element includes a periodic structure having a period equal to or greater than the wavelength of the incident light. The periodic structure includes first and second subwavelength concave-convex structures formed perpendicularly adjacent to each other in each period of the periodic structure. The first and the second subwavelength concave-convex structures have a period less than the wavelength of the incident light. A filling factor and a groove depth of the first and the second subwavelength concave-convex structures are determined such that they have the same effective refraction index with respect to the incident light having the particular polarization direction and a phase difference ? with respect to the incident light having the particular polarization direction.

Abstract: A disclosed optical pickup includes an aberration correction unit with a phase shifter surface. On the phase shifter surface, rectangular or staircase-like steps are formed in a concentric manner around an optical axial center, in certain regions where a light beam passes through. The steps have different heights in the optical axial direction. A light beam having a wavelength of 405 nm is directly transmitted through the steps so that a phase difference is applied for correcting spherical aberration that occurs on a first optical recording medium. A light beam that passes through an annular region without any steps is focused on a second optical recording medium. A light beam that passes through an outside region is focused by an object lens on the second optical recording medium, and is not focused on the first optical recording medium.

Abstract: An optical device having a sub-wavelength grating formed in a specified region is disclosed that is able to prevent wave front degradation accompanying a phase difference of a polarized light beam passing through the optical device. The optical device includes a circular-belt-like region where the sub-wavelength diffraction grating is formed, and a center portion where the sub-wavelength diffraction grating is not formed. A vertically polarized light beam used for operations on a blue-light optical recording medium A has a phase difference in the sub-wavelength diffraction grating to be an integral multiple of 2? and hence is transmitted through the sub-wavelength diffraction grating. A horizontally polarized light beam used for operations on a blue-light optical recording medium is diffracted by the sub-wavelength diffraction grating.

Abstract: Disclosed is a reflecting wavelength plate that deflects and reflects a light path and adds a phase difference with respect to plural incident light having different wavelengths. The reflecting wavelength plate includes a substrate; a reflecting film laminated on the substrate; and a sub-wavelength concavo-convex structure that is laminated on the reflecting film and has a pitch less than or equal to the shortest wavelength of the plural incident light. The filling factor and the groove depth of the sub-wavelength concavo-convex structure are determined so as to add the phase difference obtained by (k?)/8, where k is an integer, to the plural incident light having the different wavelengths.

Abstract: Disclosed is a reflecting wavelength plate that deflects and reflects a light path and adds a phase difference with respect to plural incident light having different wavelengths. The reflecting wavelength plate includes a substrate; a reflecting film laminated on the substrate; and a sub-wavelength concavo-convex structure that is laminated on the reflecting film and has a pitch less than or equal to the shortest wavelength of the plural incident light. The filling factor and the groove depth of the sub-wavelength concavo-convex structure are determined so as to add the phase difference obtained by (k?)/8, where k is an integer, to the plural incident light having the different wavelengths.

Abstract: An optical element transmits incident light having a particular polarization direction mainly by 0-order transmission and diffracts incident light having a perpendicular polarization direction. The optical element includes a periodic structure having a period equal to or greater than the wavelength of the incident light. The periodic structure includes first and second subwavelength concave-convex structures formed perpendicularly adjacent to each other in each period of the periodic structure. The first and the second subwavelength concave-convex structures have a period less than the wavelength of the incident light. A filling factor and a groove depth of the first and the second subwavelength concave-convex structures are determined such that they have the same effective refraction index with respect to the incident light having the particular polarization direction and a phase difference ? with respect to the incident light having the particular polarization direction.

Abstract: A disclosed optical element includes: a transparent substrate; a subwavelength structure layer disposed on the transparent substrate, the subwavelength structure layer having a refractive index different from a refractive index of the transparent substrate; a minute concave and convex structure of one-dimensional grating formed on the subwavelength structure layer with a subwavelength period smaller than a wavelength to be used, where a concave portion reaches a boundary surface between the transparent substrate and the subwavelength structure layer; and an open hole portion formed on a subwavelength structure layer side of the transparent substrate so as to communicate with the concave portion of the minute structure and to be arranged with the same period as in the minute structure of one-dimensional grating. At least at the open hole portion, a refractive index relative to an incident light is changed in a direction orthogonal to the boundary surface.

Abstract: Disclosed is a reflecting wavelength plate that deflects and reflects a light path and adds a phase difference with respect to plural incident light having different wavelengths. The reflecting wavelength plate includes a substrate; a reflecting film laminated on the substrate; and a sub-wavelength concavo-convex structure that is laminated on the reflecting film and has a pitch less than or equal to the shortest wavelength of the plural incident light. The filling factor and the groove depth of the sub-wavelength concavo-convex structure are determined so as to add the phase difference obtained by (k?)/8, where k is an integer, to the plural incident light having the different wavelengths.

Abstract: An optical device having a sub-wavelength grating formed in a specified region is disclosed that is able to prevent wave front degradation accompanying a phase difference of a polarized light beam passing through the optical device. The optical device includes a circular-belt-like region where the sub-wavelength diffraction grating is formed, and a center portion where the sub-wavelength diffraction grating is not formed. A vertically polarized light beam used for operations on a blue-light optical recording medium A has a phase difference in the sub-wavelength diffraction grating to be an integral multiple of 2? and hence is transmitted through the sub-wavelength diffraction grating. A horizontally polarized light beam used for operations on a blue-light optical recording medium is diffracted by the sub-wavelength diffraction grating.

Abstract: A disclosed optical pickup includes an aberration correction unit with a phase shifter surface. On the phase shifter surface, rectangular or staircase-like steps are formed in a concentric manner around an optical axial center, in certain regions where a light beam passes through. The steps have different heights in the optical axial direction. A light beam having a wavelength of 405 nm is directly transmitted through the steps so that a phase difference is applied for correcting spherical aberration that occurs on a first optical recording medium. A light beam that passes through an annular region without any steps is focused on a second optical recording medium. A light beam that passes through an outside region is focused by an object lens on the second optical recording medium, and is not focused on the first optical recording medium.

Abstract: An optical device having a sub-wavelength grating formed in a specified region is disclosed that is able to prevent wave front degradation accompanying a phase difference of a polarized light beam passing through the optical device. The optical device includes a circular-belt-like region where the sub-wavelength diffraction grating is formed, and a center portion where the sub-wavelength diffraction grating is not formed. A vertically polarized light beam used for operations on a blue-light optical recording medium A has a phase difference in the sub-wavelength diffraction grating to be an integral multiple of 2? and hence is transmitted through the sub-wavelength diffraction grating. A horizontally polarized light beam used for operations on a blue-light optical recording medium is diffracted by the sub-wavelength diffraction grating.

Abstract: Disclosed is a reflecting wavelength plate that deflects and reflects a light path and adds a phase difference with respect to plural incident light having different wavelengths. The reflecting wavelength plate includes a substrate; a reflecting film laminated on the substrate; and a sub-wavelength concavo-convex structure that is laminated on the reflecting film and has a pitch less than or equal to the shortest wavelength of the plural incident light. The filling factor and the groove depth of the sub-wavelength concavo-convex structure are determined so as to add the phase difference obtained by (k?)/8, where k is an integer, to the plural incident light having the different wavelengths.

Abstract: An optical pickup is disclosed that includes a simplified phase correction element enabling sufficient correction of spherical aberration and realization of compatibility with blue-light, DVD-type and CD-type optical recording media with a two-stage numerical aperture switching operation. The phase correction element includes a phase shifting part and a diffraction part superposed on the phase shifting part. The phase shifting part has stepwise concentric circular regions including more than two stages. The diffraction part includes periodically arranged projecting and depressed portions formed on the phase shifting part. The phase shifting part suppresses spherical aberration related to red light used for a DVD-type optical recording medium when the object lens is optimized relative to blue light used for a blue-light optical recording medium. The diffraction part sets a most appropriate NA to each of the blue-light, DVD-type and the CD-type optical recording media by switching the numerical aperture.

Abstract: A disclosed optical element includes: a transparent substrate; a subwavelength structure layer disposed on the transparent substrate, the subwavelength structure layer having a refractive index different from a refractive index of the transparent substrate; a minute concave and convex structure of one-dimensional grating formed on the subwavelength structure layer with a subwavelength period smaller than a wavelength to be used, where a concave portion reaches a boundary surface between the transparent substrate and the subwavelength structure layer; and an open hole portion formed on a subwavelength structure layer side of the transparent substrate so as to communicate with the concave portion of the minute structure and to be arranged with the same period as in the minute structure of one-dimensional grating. At least at the open hole portion, a refractive index relative to an incident light is changed in a direction orthogonal to the boundary surface.

Abstract: A method of fabricating a mold and a method of fabricating an article with the mold is disclosed that is capable of fabricating a high three-dimensional surface structure and extending the service life of the mold. A mold having a fine surface shape of a height less than an object height is fabricated, then the fine surface shape of the mold is transferred to an intermediate mold by dry-etching, and then the fine surface shape of the intermediate mold is further transferred to a final article material by dry-etching. In each transfer step by dry-etching, the etching selection ratio is appropriately adjusted to increase the height of the fine surface structure step by step, so that the fine surface shape of the final article material has the object height. On the surface of the final article material, a preliminary pattern of the object surface shape may be formed beforehand to reduce the required thickness of the curable resin.

Abstract: An optical device having a sub-wavelength grating formed in a specified region is disclosed that is able to prevent wave front degradation accompanying a phase difference of a polarized light beam passing through the optical device. The optical device includes a circular-belt-like region where the sub-wavelength diffraction grating is formed, and a center portion where the sub-wavelength diffraction grating is not formed. A vertically polarized light beam used for operations on a blue-light optical recording medium A has a phase difference in the sub-wavelength diffraction grating to be an integral multiple of 2? and hence is transmitted through the sub-wavelength diffraction grating. A horizontally polarized light beam used for operations on a blue-light optical recording medium is diffracted by the sub-wavelength diffraction grating.

Abstract: An optical pickup is disclosed that includes a simplified phase correction element enabling sufficient correction of spherical aberration and realization of compatibility with blue-light, DVD-type and CD-type optical recording media with a two-stage numerical aperture switching operation. The phase correction element includes a phase shifting part and a diffraction part superposed on the phase shifting part. The phase shifting part has stepwise concentric circular regions including more than two stages. The diffraction part includes periodically arranged projecting and depressed portions formed on the phase shifting part. The phase shifting part suppresses spherical aberration related to red light used for a DVD-type optical recording medium when the object lens is optimized relative to blue light used for a blue-light optical recording medium. The diffraction part sets a most appropriate NA to each of the blue-light, DVD-type and the CD-type optical recording media by switching the numerical aperture.

Abstract: A polarization optical device is disclosed that includes: an inorganic dielectric substrate transparent with respect to incident light having a flat surface; and an array of strips of conductive elements embedded from the flat surface of the inorganic dielectric substrate to a uniform depth, with an equal width, and with an equal separation in a pitch shorter than the wavelength of the incident light in a manner such that the surfaces of the strips of conductive elements are flush with the surface of the substrate.

Abstract: A method of fabricating a mold and a method of fabricating an article with the mold is disclosed that is capable of fabricating a high three-dimensional surface structure and extending the service life of the mold. A mold having a fine surface shape of a height less than an object height is fabricated, then the fine surface shape of the mold is transferred to an intermediate mold by dry-etching, and then the fine surface shape of the intermediate mold is further transferred to a final article material by dry-etching. In each transfer step by dry-etching, the etching selection ratio is appropriately adjusted to increase the height of the fine surface structure step by step, so that the fine surface shape of the final article material has the object height. On the surface of the final article material, a preliminary pattern of the object surface shape may be formed beforehand to reduce the required thickness of the curable resin.

Abstract: To provide a gradation mask which can easily assure distribution of desired exposure intensity.?Means to accomplish the object!A metal and/or metallic compound film 2 (FIG. 1) is uniformly formed on a transparent substrate 1 such that they have a transmittance of 10% or less. An etching mask having a desired pattern is formed on the metal and/or metallic compound film 2. The metal and/or metallic compound film 2 is dry- or wet-etched. The metal and/or metallic compound film 2 is repeatedly subject to patterning and etching steps by using etching masks with different patterns, so that the obtained layers have a thickness Z(X, Y) varying in three or more steps in accordance with desired transmittance.