Abstract: A zoom lens system includes: a first lens group having positive power; a second lens group having negative power; a third lens group having positive power; a fourth lens group having negative power; and a fifth lens group having positive power. The first lens group is made up of a single lens. The second lens group is made up of four lenses. The zoom lens system is configured to zoom from a wide-angle end toward a telephoto end such that the fifth lens group does not move but the first to fourth lens groups move to change intervals between the lens groups.

Abstract: A light guide plate includes a first hologram element including a plurality of diffraction cells. At least one of edge lines of one diffraction cell among the plurality of diffraction cells included in the first hologram element is located at a position other than on extensions of all edge lines of an adjacent diffraction cell adjacent to the one diffraction cell, the adjacent diffraction cell being included in the plurality of diffraction cells.

Abstract: A zoom lens system includes: a first lens group having positive power; a second lens group having negative power; a third lens group having positive power; a fourth lens group having negative power; and a fifth lens group having positive power. The first lens group is made up of a single lens. The second lens group is made up of four lenses. While the zoom lens system is zooming from a wide-angle end toward a telephoto end during a shooting session, the fifth lens group does not move but the first to fourth lens groups move to change intervals between the lens groups.

Abstract: In a display device, an irradiation unit includes an imaging optical system. The imaging optical system scans and irradiates a front surface of a screen with light to form an image. The light passing through the screen and output from the screen in a movement direction is incident on a projection unit as incident light. The projection unit irradiates a reflective member with the incident light to allow the reflective member to reflect the incident light to form a virtual image corresponding to the image in a target space. A locus of a focal position of the imaging optical system when the irradiation unit wholly scans the front surface of the screen is within a range between the front surface of the screen at a first position and the front surface of the screen at a second position.

Abstract: An oblique viewing endoscope has an aperture through which some rays out of rays reflected from an object in an oblique viewing direction pass, an imaging element that captures an image, based on image forming of the rays passing through the aperture, and a lens that is disposed between the aperture and the imaging element, and that has a lens surface on which the image is formed by causing some rays in at least a visual field center out of the rays passing through the aperture in the oblique viewing direction to be substantially vertically incident on a center of the imaging element.

Abstract: In a display device, an irradiation unit includes an imaging optical system. The imaging optical system scans and irradiates a front surface of a screen with light to form an image. The light passing through the screen and output from the screen in a movement direction is incident on a projection unit as incident light. The projection unit irradiates a reflective member with the incident light to allow the reflective member to reflect the incident light to form a virtual image corresponding to the image in a target space. A locus of a focal position of the imaging optical system when the irradiation unit wholly scans the front surface of the screen is within a range between the front surface of the screen at a first position and the front surface of the screen at a second position.

Abstract: A head-up display projects an image on a windshield to allow a viewer to visually observe a virtual image. The head-up display includes a display device, a relay optical system, and a projection optical system. The display device displays an image. The relay optical system provides the image displayed by the display device as an intermediate image. The projection optical system reflects the intermediate image provided by the relay optical system to project the intermediate image on the windshield.

Abstract: An oblique viewing endoscope has an aperture through which some rays out of rays reflected from an object in an oblique viewing direction pass, an imaging element that captures an image, based on image forming of the rays passing through the aperture, and a lens that is disposed between the aperture and the imaging element, and that has a lens surface on which the image is formed by causing some rays in at least a visual field center out of the rays passing through the aperture in the oblique viewing direction to be substantially vertically incident on a center of the imaging element.

Abstract: A lens system, an interchangeable lens apparatus, and a camera system each include a front group including a first focus lens group that moves with respect to an image surface in focusing from an infinity in-focus condition to a close-object in-focus condition; a rear group including a second focus lens group that moves with respect to the image surface in focusing, the front group and the rear group being located in order from an object side to an image side; a fixed lens group including at least one positive power lens element, the fixed lens group being located between the front group and the rear group and fixed with respect to the image surface in focusing; and an aperture diaphragm. The positive power lens in the fixed lens group satisfies dPgF>0.015 (dPgF is an anomalous dispersibility in a g-line and an F-line of the lens element).

Abstract: Head-up display projects an image on transparent windshield to cause an observer to visually recognize a virtual image. Head-up display includes screen, optical system displays the image. Optical system projects the image displayed by screen on windshield. Driving unit moves screen. Optical system forms an intermediate image between optical systems, the intermediate image being larger than the image of screen.

Abstract: A head-up display projects an image on a windshield to allow a viewer to visually observe a virtual image. The head-up display includes a display device, a relay optical system, and a projection optical system. The display device displays an image. The relay optical system provides the image displayed by the display device as an intermediate image. The projection optical system reflects the intermediate image provided by the relay optical system to project the intermediate image on the windshield.

Abstract: A lens system according to the present disclosure includes a plurality of lens groups, each having at least one lens element, the lens system including, in order from an object side to an image side, a first lens group that is fixed with respect to an image plane in focusing from an infinity in-focus condition to a close-object in-focus condition; an aperture diaphragm; a second lens group that moves in a direction of an optical axis in the focusing; a third lens group that is fixed with respect to the image plane in the focusing; a fourth lens group that moves in the direction of the optical axis in the focusing; and a lens group closest to the image side, wherein the following conditions (1) and (2) are satisfied: 2.5<|f2/f4|<6.5 ??(1) 0.5<|f/f4|<1.5 ??(2) where f2 is a focal length of the second lens group, f4 is a focal length of the fourth lens group, and f is a focal length of the entire optical system in an infinity in-focus condition.

Abstract: Provided is a zoom lens system including, from an object side to an image side: a first lens group having positive power; a second lens group having negative power; and a subsequent lens group including at least three lens groups, wherein the subsequent lens group includes two or more positive lens groups, the first lens group includes two or less lens elements, the second lens group includes four or more lens elements, the first lens group, the second lens group and a most image side lens group which disposed closest to the image side move with respect to an image plane in zooming from a wide angle end to a telephoto end, and a lens group disposed between the third lens group and an image plane is moved along an optical axis as a focusing lens group in focusing from an infinity in-focus condition to a close-object in-focus condition.

Abstract: A lens system, an interchangeable lens apparatus, and a camera system each include a front group including a first focus lens group that moves with respect to an image surface in focusing from an infinity in-focus condition to a close-object in-focus condition; a rear group including a second focus lens group that moves with respect to the image surface in focusing, the front group and the rear group being located in order from an object side to an image side; a fixed lens group including at least one positive power lens element, the fixed lens group being located between the front group and the rear group and fixed with respect to the image surface in focusing; and an aperture diaphragm. The positive power lens in the fixed lens group satisfies dPgF>0.015 (dPgF is an anomalous dispersibility in a g-line and an F-line of the lens element).

Abstract: A zoom lens system having at least five lens units, each lens unit being composed of at least one lens element, the zoom lens system, in order from an object side to an image side, comprising: a positive first lens unit; and a negative second lens unit, and in order from the image side to the object side, comprising: a positive lens unit ?; a negative lens unit ?; and a positive lens unit ?, wherein the first lens unit is composed of only optical elements having optical power, and in zooming from a wide-angle limit to a telephoto limit, at least the positive first lens unit is fixed with respect to an image surface, the positive lens unit ? moves with respect to the image surface separately from an aperture diaphragm, and the negative lens unit ? moves to the object side.

Abstract: A zoom lens system, in order from an object side to an image side, includes a first lens unit having positive optical power; a second lens unit having negative optical power; a third lens unit having positive optical power; a fourth lens unit having negative optical power, and a subsequent lens unit. The first lens unit includes a negative lens element and a positive lens element. In the zoom lens system, the conditions: 1.47<nd2<1.57 and 60<vd2<75 (nd2: a refractive index to a d-line of the positive lens element, vd2: an Abbe number to a d-line of the positive lens element) are satisfied.

Abstract: A zoom lens system comprising a positive first lens unit, a negative second lens unit, and subsequent lens units composed of three or more lens units and an aperture diaphragm, wherein intervals between adjacent lens units vary in zooming, the first lens unit is composed of two or less lens elements and moves along an optical axis in the zooming, three or more negative lens elements are located between the first lens unit and the aperture diaphragm, and the conditions: 0.30<|BFW/YW|<1.39 and 1.10<SDT/SDW<2.00 (BFW: back focal length at wide-angle limit, YW=fW×tan (?W), fW: focal length of zoom lens system at wide-angle limit, ?W: half view angle at wide-angle limit, SDW: maximum diameter of aperture diaphragm at wide-angle limit, SDT: maximum diameter of aperture diaphragm at telephoto limit) are satisfied.

Abstract: A lens system including: a positive most-object-side lens unit; a first most-image-side lens element; and a second most-image-side lens element, wherein the most-object-side lens unit is fixed in focusing, at least one of the first and second most-image-side lens elements has negative optical power, and the conditions: 0.5<DAIR/Y and 1.5<DIM/DOB<4.0 (DAIR: maximum value of air spaces between the lens elements constituting the lens system in an infinity in-focus condition, Y=f×tan ?, f: focal length of the lens system, ?: half view angle of the lens system, DOB: optical axial thickness of the most-object-side lens unit, DIM: optical axial distance from an object side surface of a most-object-side lens element in a lens unit located immediately on the image side relative to the most-object-side lens unit, to an image side surface of the first most-image-side lens element) are satisfied.

Abstract: An inner focus lens system comprising lens units each composed of at least one lens element, wherein a most object side lens unit is provided and is fixed with respect to an image surface in focusing, and the conditions: BF/Y<1.7 and (L×FNo)/f<2.2 (BF: a distance from an image side surface apex of a most image side lens element to the image surface, Y=f ×tan ?, L: an overall length of lens system, FNo: a F-number of lens system,f: a focal length of lens system, ?: a half view angle of lens system) are simultaneously satisfied, or only the condition: (L×FNo)/f<2.0 (L: the overall length of lens system, FNo: the F-number of lens system,f: the focal length of lens system) is satisfied.

Abstract: A zoom lens system having at least five lens units, each lens unit being composed of at least one lens element, the zoom lens system, in order from an object side to an image side, comprising: a positive first lens unit; and a negative second lens unit, and in order from the image side to the object side, comprising: a positive lens unit ?; a negative lens unit ?; and a positive lens unit ?, wherein the first lens unit is composed of only optical elements having optical power, and in zooming from a wide-angle limit to a telephoto limit, at least the positive first lens unit is fixed with respect to an image surface, the positive lens unit ? moves with respect to the image surface separately from an aperture diaphragm, and the negative lens unit ? moves to the object side.