Ricoh Company, Ltd.

Toshimichi Nasukawa

Hideaki Hirai

Kazuhiro Umeki

Yuji Yamanaka

Hiroaki Takahashi

Akira Takahashi

Nobuhiro Morita

Yukiko Hamano

Toshiyuki Iseki

Shinichi Kosuga

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 &#x3c0; with respect to the incident light having the particular polarization direction.

Optical element, polarization filter, optical isolator, and optical apparatus

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.

Optical pickup and optical information processing device

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&#x3c0;)/8, where k is an integer, to the plural incident light having the different wavelengths.

Reflecting wavelength plate and optical pickup using reflecting wavelength plate

An image input apparatus that inputs an image of an object residing within a living body is disclosed. The image input apparatus includes a light source that irradiates near infrared light on the living body, a lens array arranged at a position facing the living body and including plural lenses each having a face with zero or negative power arranged at a side facing the living body and a face with positive power arranged at a side facing an image surface, an imaging unit arranged at the image surface side of the lens array that forms a compound-eye image corresponding to a collection of ommatidium images formed by the lenses of the lens array, and a reconstruction unit that reconstructs a single image from the compound-eye image using a parallax between the ommatidium images. The reconstructed single image is input as the image of the object.

Image input apparatus, image input method, personal authentication apparatus, and electronic apparatus

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.

Growing community of inventors

Iwate, Japan

Toshimichi Nasukawa