Abstract: A projection lens system (G1, G2) includes a front group (G1) disposed on a projection-plane (SC) side, a rear group (G2) disposed on a display-surface (SF) side of an image display element inclined with reference to the projection plane (SC), and an aperture stop (S) disposed on the display-surface (SF) side with reference to the front group (G1). The rear-group optical axis is tilted on the shared plane at a tilt angle ? with reference to the display-surface normal. In projection lens system (G1, G2), when the amount of shift ? is zero, the tilt angle ? satisfies a conditional expression 0<?/?s<1, where ?s denotes a tilt angle when Scheimpflug principle is satisfied with reference to the display surface (SF) and the projection plane (SC).

Abstract: An infrared lens unit includes, in order from the object side, an aperture, a lens group, and a band-pass filter which passes a light beam of a prescribed wavelength band of the infrared region. The lens group further includes, in order from the object side, a first meniscus lens which has a positive power and is convex on the object side, a second meniscus lens which has a positive power and is convex on the image side, and a convex lens which has a positive power and is convex on the object side. The lens group further includes a near-telecentric state on the image side, wherein the angle of entry of the light beam into the band-pass filter is either 0° or close to 0°. Thus, it is possible to accurately pass a light beam of a prescribed wavelength band of the infrared region by the lens unit.

Abstract: An infrared lens unit includes, in order from the object side, an aperture, a lens group, and a band-pass filter which passes a light beam of a prescribed wavelength band of the infrared region. The lens group further includes, in order from the object side, a first meniscus lens which has a positive power and is convex on the object side, a second meniscus lens which has a positive power and is convex on the image side, and a convex lens which has a positive power and is convex on the object side. The lens group further includes a near-telecentric state on the image side, wherein the angle of entry of the light beam into the band-pass filter is either 0° or close to 0°. Thus, it is possible to accurately pass a light beam of a prescribed wavelength band of the infrared region by the lens unit.

Abstract: An optical module holder in which an optical transmission line attaching section for attaching an end section of a light transmission line, a photoelectric element attaching section for attaching a photoelectric element including at least one of a light-emitting element or a light-receiving element, and a wall section connecting the optical transmission line attaching section and the photoelectric element attaching section are formed integrally, and a lens for optically joining the photoelectric element and the optical transmission line is formed integrally with the wall section, so that the convex surface of the lens is on the photoelectric element side, facing the photoelectric element attached to the photoelectric attaching section, wherein one or a plurality of concave sections are formed as grooved sections on the wall section so as to surround the lens.

Abstract: An optical module holder in which an optical transmission line attaching section for attaching an end section of a light transmission line, a photoelectric element attaching section for attaching a photoelectric element including at least one of a light-emitting element or a light-receiving element, and a wall section connecting the optical transmission line attaching section and the photoelectric element attaching section are formed integrally, and a lens for optically joining the photoelectric element and the optical transmission line is formed integrally with the wall section, so that the convex surface of the lens is on the photoelectric element side, facing the photoelectric element attached to the photoelectric attaching section, wherein one or a plurality of concave sections are formed as grooved sections on the wall section so as to surround the lens.