Abstract: A display apparatus of the present technique includes for use with a light transmissive display member and is configured to project an image onto the light transmissive display member to forms a virtual image of the image, on an opposite side of the display member from a user. The display apparatus includes a display device housed in a housing and configured to display an image, and a projection optical system housed in the housing and configured to project the image displayed on the display device onto the display member. The housing has an opening through which projection light is emitted. The projection optical system includes, on an optical path from the display device to the opening, a first reflection member disposed on a display device side, and a second reflection member disposed on the opening side.

Abstract: A head-up display is mounted to a vehicle having a windshield, and includes a display element configured to display an image, a first optical system configured to reflect the image displayed by the display element and project the image onto the windshield; and a second optical system configured to reflect the image displayed by the display element and project the image onto the windshield. The image projected with the first optical system is projected onto the windshield at a position below a position of the image projected with the second optical system.

Abstract: A head-up display includes a first display device having a first display element and a combiner; a second display device including a second display element and a second optical system having a first mirror and a second mirror; and a housing having an opening. The first display element is disposed at a back of a vehicle relative to the opening, and the second mirror is disposed at a front of the vehicle relative to the opening.

Abstract: A display apparatus includes a display unit that projects an image to a light transmissive display member. The display apparatus forms a virtual image of the image projected by the display unit. The display unit includes a display device including a display region and a non-display region formed around the display region, a display controller that inputs an image signal to the display device in order to display a predetermined image in the display region, and a projection optical system that projects the image displayed on the display device to the display member. The projection optical system includes a first reflecting member disposed on a display device side and a second reflecting member disposed on a display member side in an optical path extending from the display device to the display member. The display controller is able to change a display position of the image in the display region.

Abstract: A head-up display according to the present disclosure is mounted to a vehicle having a windshield and allows an observer to visually recognize a virtual image. The head-up display includes a display element configured to display an image, a reflection optical system configured to reflect the image displayed by the display element and project the image onto the windshield, and a refraction optical system disposed between the reflection optical system and the windshield and having optical power. The reflection optical system reflects the image toward the refraction optical system. The head-up display is configured such that a position where a center optical path of the image emitted from the display element is incident on the refraction optical system is located at a side of the windshield of the vehicle relative to a center axis of the refraction optical system.

Abstract: A zoom lens system, in order from an object side to an image side, comprising: a first lens unit having negative optical power; a second lens unit having positive optical power; a third lens unit having negative optical power; and a fourth lens unit having positive optical power, wherein the third lens unit is composed of two or less lens elements, the fourth lens unit is composed of two or less lens elements, the first lens unit has at least one air space between lens elements constituting the first lens unit, and the condition: Dair/fW>0.75 (Dair: an air space located on the most object side in the first lens unit, fW: a focal length of the entire system at a wide-angle limit) is satisfied; an imaging device; and a camera are provided.

Abstract: An inner focus lens system, in order from an object side, comprising: a first lens unit including a most-object-side negative first lens element; a positive second lens unit; and a negative third lens unit, wherein an aperture diaphragm is included, the first lens unit, the third lens unit, and the aperture diaphragm are fixed relative to an image surface in focusing, the second lens unit moves relative to the image surface in the focusing, and the conditions: BF/Y<1.7 and TH/f>1.6 (BF: distance from an apex of an image-side surface of a most-image-side lens element to the image surface; Y: maximum image height; TH: distance from an apex of an object-side surface of a most-object-side lens element to the apex of the image-side surface of the most-image-side lens element; f: focal length of the lens system) are satisfied.

Abstract: A zoom lens system comprising a positive first lens unit; a negative second lens unit; and subsequent five or six lens units, wherein an aperture diaphragm is provided, intervals between the adjacent lens units vary in zooming, the first lens unit moves in zooming and is fixed in focusing, and the conditions: BF/fW<0.66, DA/LW>0.42, and DAIR/Y<2.00 (BF: distance from an image-side surface apex of a most-image-side lens element to an image surface, fW: focal length of system at wide-angle limit, DA: sum of optical axial thicknesses of the lens units in system, LW: overall length of system at wide-angle limit, DAIR: maximum of air spaces between the lens elements constituting system at wide-angle limit, Y=fT×tan(?T), fT: focal length of system at telephoto limit, ?T: half view angle at telephoto limit) are satisfied.

Abstract: An inner focus lens system, in order from an object side, comprising: a first lens unit including a most-object-side negative first lens element; a positive second lens unit; and a negative third lens unit, wherein an aperture diaphragm is included, the first lens unit, the third lens unit, and the aperture diaphragm are fixed relative to an image surface in focusing, the second lens unit moves relative to the image surface in the focusing, and the conditions: BF/Y<1.7 and TH/f>1.6 (BF: distance from an apex of an image-side surface of a most-image-side lens element to the image surface; Y: maximum image height; TH: distance from an apex of an object-side surface of a most-object-side lens element to the apex of the image-side surface of the most-image-side lens element; f: focal length of the lens system) 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: A zoom lens system comprising a positive first lens unit composed of three or four lens elements, a negative second lens unit, and subsequent lens units, wherein the subsequent lens units include an aperture diaphragm, an image blur compensating lens unit, and a focusing lens unit, which are provided on the image side relative to the aperture diaphragm, and the conditions: 1.8<|(YW/fW)×FNOT×(fT/fW)|<4.5 and 0.001<(D1W+D2T)/fW<0.200 (YW=fW×tan(?W), fW, fT: focal length of the zoom lens system at wide-angle limit, telephoto limit, ?W: half view angle at wide-angle limit, FNOT: F-number at telephoto limit, D1W: inter-apex distance between the first and second lens units at wide-angle limit, D2T: inter-apex distance between the second lens unit and a most object side lens unit among the subsequent lens units at telephoto limit) are satisfied.

Abstract: An inner focus lens system, in order from an object side, comprising: a first lens unit including a most-object-side negative first lens element; a positive second lens unit; and a negative third lens unit, wherein an aperture diaphragm is included, the first lens unit, the third lens unit, and the aperture diaphragm are fixed relative to an image surface in focusing, the second lens unit moves relative to the image surface in the focusing, and the conditions: BF/Y<1.7 and TH/f>1.6 (BF: a distance from an apex of an image-side surface of a most-image-side lens element to the image surface, Y: a maximum image height, TH: a distance from an apex of an object-side surface of a most-object-side lens element to the apex of the image-side surface of the most-image-side lens element, f: a focal length of the lens system) are satisfied.

Abstract: A zoom lens system comprising: a first lens unit having negative optical power; a second lens unit having positive optical power; and a third lens unit having positive optical power, wherein the first to third lens units are individually moved along an optical axis to vary magnification in zooming, each lens unit includes at least one lens element that satisfies the conditions: nd?1.67, vd<59 and 0.000<PgF+0.002×vd?0.664 (nd, vd and PgF: a refractive index to the d-line, an Abbe number to the d-line and a partial dispersion ratio, of the lens element), and the condition: 0.31<Ir/?(|fG1×fG2|) (Ir=fT×tan(?T), fT and ?T: a focal length of the entire system and a half value of maximum view angle, at a telephoto limit, fG1 and fG2: a focal length of each of the first lens unit and the second lens unit) is satisfied; an imaging device; and a camera are provided.

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 terahertz light generation device 1 comprises a resonator structure 12 for intensifying incident light and outputting the intensified light and laser oscillation units 10, 11 for feeding the incident light into the resonator structure 12. The incident light comprises first and second incident light components having polarization states different from each other and frequencies different from each other. The laser oscillation units 10, 11 feed the resonator structure 12 with the first and second incident light components at an angle inclined from a principal surface in the resonator structure 12. The resonator structure 12 outputs light having a frequency corresponding to the difference between the respective frequencies of the first and second incident light components.

Abstract: An inner focus lens system comprising a first lens unit and subsequent lens units, wherein an aperture diaphragm is provided, the first lens unit is: fixed with respect to an image surface in focusing; and composed of five or more lens elements including a first positive lens element located closest to the object side and a second positive lens element, the subsequent lens units include at least a first focusing lens unit located closest to the object side and a second focusing lens unit, at least one of the first focusing lens unit and the second focusing lens unit is composed of two or less lens elements, at least one lens element is provided on the image side relative to the aperture diaphragm, and the condition: NF1?NF2 (NF1, NF2: the number of lens elements constituting the first, second focusing lens unit) is satisfied.

Abstract: A zoom lens system comprising: a negative first lens unit; a positive second lens unit; and a positive third lens unit, wherein the first to third lens units are individually moved along an optical axis to vary magnification in zooming, the first lens unit is composed of two lens elements and includes a positive lens element having at least one aspheric surface, the third lens unit is composed of one lens element, and the condition: 1.74<Ir/?{square root over ((|DL1×fG1|))} (DL1: an optical axial thickness of an object side first lens element in the first lens unit, fG1: a focal length of the first lens unit, Ir=fT×tan(?T), fT and ?T: a focal length of the entire system and a half value of maximum view angle at a telephoto limit) is satisfied; an imaging device; and a camera are provided.

Abstract: A zoom lens system comprising a positive first lens unit composed of three or four lens elements, a negative second lens unit, and subsequent lens units, wherein the subsequent lens units include an aperture diaphragm, an image blur compensating lens unit, and a focusing lens unit, which are provided on the image side relative to the aperture diaphragm, and the conditions: 1.8<|(YW/fW)×FNOT×(fT/fW)|<4.5 and 0.001<(D1W+D2T)/fW<0.200 (YW=fW×tan(?W), fW, fT: focal length of the zoom lens system at wide-angle limit, telephoto limit, ?W: half view angle at wide-angle limit, FNOT: F-number at telephoto limit, D1W: inter-apex distance between the first and second lens units at wide-angle limit, D2T: inter-apex distance between the second lens unit and a most object side lens unit among the subsequent lens units at telephoto limit) are satisfied.

Abstract: An inner focus lens system, in order from an object side, comprising: a first lens unit including a most-object-side negative first lens element; a positive second lens unit; and a negative third lens unit, wherein an aperture diaphragm is included, the first lens unit, the third lens unit, and the aperture diaphragm are fixed relative to an image surface in focusing, the second lens unit moves relative to the image surface in the focusing, and the conditions: BF/Y<1.7 and TH/f>1.6 (BF: a distance from an apex of an image-side surface of a most-image-side lens element to the image surface, Y: a maximum image height, TH: a distance from an apex of an object-side surface of a most-object-side lens element to the apex of the image-side surface of the most-image-side lens element, f: a focal length of the lens system) 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.