Asahi Glass Company, Limited

Toshimasa Kakiuchi

Makoto Hasegawa

Koichi Murata

Masahiro Mori

Yoshiharu Ooi

Takuji Nomura

Yuzuru Tanabe

Mitsuo Oosawa

There are provided an infrared transmission filter, which is inexpensive, is capable of being sufficiently made lighter and thinner, has no incident angle dependency, and is excellent in permselectivity for infrared light, and an imaging device, which employs such an infrared transmission filter. An infrared transmission filterincludes an infrared transmission base materialselectively transmitting light in an infrared wavelength range; and a short wavelength side infrared absorbing filmformed on one side of the infrared transmission base materialand containing a near-infrared absorbent having an optical absorption edge on a short wavelength side of a transmission wavelength band of the infrared transmission base material. An imaging device includes the infrared transmission filter

Infrared transmission filter and imaging device

A phase plate and an optical head device are provided, which are capable of suppressing changes of the amount of light incident on a light-receiving unit even if the phase difference caused by transmission through a protective layer of an optical recording medium differs depending on the type of optical recording medium. The phase plate includes a birefringent medium and produces a phase difference in linearly polarized light incident on the phase plate between a polarization component having a polarization direction parallel to the optic axis of the birefringent medium and a polarization component having a polarization direction perpendicular to the optic axis. In the phase plate, the birefringent medium includes a plurality of types of phase areas disposed adjacently; at least two types of adjacent phase areas are different from each other in phase differences, optic axes, or both phase differences and optic axes; and each of the plurality of types of phase areas is disposed so as to have two-fold rotational symmetry with respect to the optical axis of the phase plate.

Phase plate and optical head device

A liquid crystal lens element is provided, which does not produce change of transmission wavefront regardless of polarization state of incident light when it is off-state at a time of no voltage application, and which exhibits concave lens function for extraordinarily polarized incident light when it is on-state at a time of voltage application. In a liquid crystal lens elementcomprising a pair of transparent substratesandand a liquid crystal layersandwiched between the transparent substrates, which is configured to change convergent point of light transmitted through the element according to the magnitude of voltage applied to the liquid crystal layerthe liquid crystal lens elementfurther comprises a Fresnel lenshaving a concave-convex-shaped cross section formed on the transparent substrate, a first transparent electrodeformed on a flat surface of the transparent substrateon which the Fresnel lensis formed, and a second transparent electrodeformed on a flat surface of the other transparent substrate

Liquid crystal lens element optical head device

Growing community of inventors

Koriyama, Japan

Toshimasa Kakiuchi