Abstract: The present disclosure is directed to an optical system internally having an intermediate imaging position that is conjugate with both of a magnification conjugate point on a magnification side and a reduction conjugate point on reduction side, including: a magnification optical system including a plurality of lens elements and positioned on the magnification side with respect to the intermediate imaging position; and a relay optical system including a plurality of lens elements and positioned on the reduction side with respect to the intermediate imaging position, wherein the relay optical system includes a plurality of moving lens groups which are independently movable in an optical axis direction during zooming, and wherein the reduction side-closest moving lens group that is positioned closest to the reduction side among the plurality of moving lens groups has a negative refractive power.

Abstract: The optical system includes a first sub-optical system including an aperture stop and a second sub-optical system including a prism. The prism has a first transmission surface located on a reduction side, a second transmission surface located on a magnification side, and at least one reflection surface between the first transmission surface and the second transmission surface. The first sub-optical system includes a plurality of rotationally symmetric lens elements.

Abstract: The present disclosure is directed to an optical system internally having an intermediate imaging position that is conjugated to a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side, respectively, the optical system comprising: a magnification optical system positioned on the magnification side with respect to the intermediate imaging position; and a relay optical system positioned on the reduction side with respect to the intermediate imaging position; the relay optical system including: a first lens group positioned closest to the magnification side; two lens groups positioned on the reduction side with respect to the first lens group; and a negative lens group interposed between the two lens groups, wherein during zooming the negative lens is fixed, while the two lens groups are displaced.

Abstract: A projection lens system projects an image of a reduction side into a magnification side in an image projection device, a back glass being disposed on the reduction side. In the projection lens system, all of one or more negative lenses that satisfy, in a surface on the reduction side or a surface on the magnification side, condition |h/H|<2.0 defined by height h of a most off-axis principal ray and height H of an axial ray passing through a highest pupil position satisfy conditions Tn?98.5% and Dn/Db?0.05 defined by transmittance Tn, thickness Dn of the negative lens on an optical axis, and total thickness Db of the back glass.

Abstract: A projection lens system that projects an image of a reduction side into a magnification side includes a diaphragm, a plurality of positive lenses, and a plurality of negative lenses. The plurality of positive lenses include a first positive lens closer to the magnification side than the diaphragm is and closest to the diaphragm, a second positive lens second closest to the diaphragm after the first positive lens on the magnification side, a third positive lens closer to the reduction side than the diaphragm is and closest to the diaphragm. The plurality of negative lenses include a first negative lens closer to the magnification side than the diaphragm is and closest to the diaphragm, and a second negative lens closer to the reduction side than the diaphragm is and closest to the diaphragm. The lenses have transmittances larger than threshold values, respectively.

Abstract: The present disclosure is directed to an optical system internally having an intermediate imaging position that is conjugate to a magnification conjugate point on a magnification side and a reduction conjugate point on a reduction side, respectively, the optical system including: a magnification optical system having a plurality of lens elements, positioned on the magnification side with respect to the intermediate imaging position; and a relay optical system having a plurality of lens elements, positioned on the reduction side with respect to the intermediate imaging position, wherein a first lens element located closest to the magnification side among the plurality of lens elements in magnification optical system is an aspherical lens having a negative power, the optical system satisfies the conditions (1) to (3).

Abstract: The present disclosure is directed to an optical system internally having an intermediate imaging position that is conjugate to magnification and reduction conjugate points, respectively, the optical system including: a magnification optical system having a plurality of lens elements, positioned on the magnification side with respect to the intermediate imaging position; and a relay optical system having a plurality of lens elements, positioned on the reduction side with respect to the intermediate imaging position, wherein there are a plurality of air distances among the lens elements, the magnification optical system includes a magnification optical system front group positioned on the magnification side with respect to the longest air distance in the magnification optical system and a magnification optical system rear group positioned on the reduction side with respect to the longest air distance, and the optical system satisfies the conditions (1) and (2).

Abstract: An optical system according to the present disclosure includes a first sub-optical system including an aperture stop and a second sub-optical system including a prism. The prism has a first transmission surface located on the reduction side, a second transmission surface located on the magnification side, and at least one reflection surface located on the optical path between the first transmission surface and the second transmission surface. A first reflection surface closest to the intermediate imaging position has a shape with a concave surface facing a direction into which a light ray incident on first the reflection surface is reflected. A curvature shape of the first reflection surface is set such that some of multiple principal rays passing through the reduction conjugate point intersect on the optical path between the first reflection surface and the second transmission surface.

Abstract: An image projection device includes an image display element that forms a projection image, a transmissive optical system that is disposed on an emission surface side of the image display element and includes a diaphragm and a plurality of lenses, and a reflection optical system that includes a first mirror reflecting light emitted from the transmissive optical system and having positive power and a second mirror that is a plane mirror for reflecting light reflected by the first mirror on a projection surface. The first mirror is disposed between the second mirror and the projection surface in a direction along an optical axis of the transmissive optical system. An intermediate image is formed between the transmissive optical system and the first mirror.

Abstract: A projection optical system is a projection optical system for projecting an image in an image display element on a projection target surface in an enlarged manner, and includes a transmissive optical system and a reflection optical system. The transmissive optical system includes a plurality of lenses and an aperture diaphragm. The reflection optical system includes a first reflecting surface that reflects light emitted from the transmissive optical system and a second reflecting surface that reflects light emitted from the first reflecting surface. A principal ray of the reference rays is a ray passing through a center of the aperture diaphragm among the reference rays. Local power of the first reflecting surface at a position where the principal ray enters the first reflecting surface is larger than local power of the second reflecting surface at a position where the principal ray enters the second reflecting surface.

Abstract: A projection lens system projects an image of a reduction side into a magnification side in an image projection device, a back glass being disposed on the reduction side. In the projection lens system, all of one or more negative lenses that satisfy, in a surface on the reduction side or a surface on the magnification side, condition |h/H|<2.0 defined by height h of a most off-axis principal ray and height H of an axial ray passing through a highest pupil position satisfy conditions Tn?98.5% and Dn/Db?0.05 defined by transmittance Tn, thickness Dn of the negative lens on an optical axis, and total thickness Db of the back glass.

Abstract: A projection lens system that projects an image of a reduction side into a magnification side includes a diaphragm, a plurality of positive lenses, and a plurality of negative lenses. The plurality of positive lenses include a first positive lens closer to the magnification side than the diaphragm is and closest to the diaphragm, a second positive lens second closest to the diaphragm after the first positive lens on the magnification side, a third positive lens closer to the reduction side than the diaphragm is and closest to the diaphragm. The plurality of negative lenses include a first negative lens closer to the magnification side than the diaphragm is and closest to the diaphragm, and a second negative lens closer to the reduction side than the diaphragm is and closest to the diaphragm. The lenses have transmittances larger than the respective lower limit values.

Abstract: An image projection device includes an image display element that forms a projection image, a transmissive optical system that is disposed on an emission surface side of the image display element and includes a diaphragm and a plurality of lenses, and a reflection optical system that includes a first mirror reflecting light emitted from the transmissive optical system and having positive power and a second mirror that is a plane mirror for reflecting light reflected by the first mirror on a projection surface. The first mirror is disposed between the second mirror and the projection surface in a direction along an optical axis of the transmissive optical system. An intermediate image is formed between the transmissive optical system and the first mirror.

Abstract: A projection optical system is a projection optical system for projecting an image in an image display element on a projection target surface in an enlarged manner, and includes a transmissive optical system and a reflection optical system. The transmissive optical system includes a plurality of lenses and an aperture diaphragm. The reflection optical system includes a first reflecting surface that reflects light emitted from the transmissive optical system and a second reflecting surface that reflects light emitted from the first reflecting surface. A principal ray of the reference rays is a ray passing through a center of the aperture diaphragm among the reference rays. Local power of the first reflecting surface at a position where the principal ray of the reference rays enters the first reflecting surface is larger than local power of the second reflecting surface at a position where the principal ray of the reference rays enters the second reflecting surface.

Abstract: A projection optical system is an optical system for projecting an image light flux formed in an image display element onto a projection surface, and includes a transmission optical system and a reflection optical system. The transmission optical system is located on an emission surface side of the image display element and includes a stop and a plurality of lenses. The reflection optical system includes a positive-power first mirror and a second mirror. Conditional Expression (1) is satisfied 0<TL/ft<10??(1) where ft is a focal length of the transmission optical system, and TL is a distance parallel to an optical axis of the transmission optical system from a position where the first mirror reflects a principal ray of the image light flux, to the image display element.

Abstract: A projection optical system is an optical system that magnifies and projects an image onto a projection surface from an oblique position defined by a Y-axis and a Z-axis. The image is displayed on an image display element, is defined by a positive direction of an X-axis and a positive direction of the Y-axis, and includes a long side parallel to the X-axis and a short side parallel to the Y-axis when a positional relationship is expressed using an XYZ coordinate. The projection optical system includes a transmission optical system and a transmission element. An incident angle of a light beam of the image incident on a reference vertical intersecting line with respect to one of surfaces of the transmission element is zero only at one point on the reference vertical intersecting line.

Abstract: A projection optical system is an optical system for projecting an image light flux formed in an image display element onto a projection surface, and includes a transmission optical system and a reflection optical system. The transmission optical system is located on an emission surface side of the image display element and includes a stop and a plurality of lenses. The reflection optical system includes a positive-power first mirror and a second mirror. Conditional Expression (1) is satisfied 0<TL/ft<10 ??(1) where ft is a focal length of the transmission optical system, and TL is a distance parallel to an optical axis of the transmission optical system from a position where the first mirror reflects a principal ray of the image light flux, to the image display element.

Abstract: A projection optical system projects onto a projection surface an image ray bundle formed on an image display element, and includes a transmissive optical system positioned on a side of an emission surface of the image display element and having positive power, and a reflective optical system including at least one mirror for reflecting, toward the projection surface, light rays emitted from the transmissive optical system. The transmissive optical system includes at least one positive lens disposed closer to the image display element than an aperture stop, along with first and second positive lenses having a meniscus shape, and a negative lens disposed therebetween, which are closer to the projection surface than the aperture stop is. During focusing, spacing between the first positive lens and the negative lens and spacing between the second positive lens and the negative lens remain unchanged.

Abstract: A projection optical system of the present disclosure projects onto a projection surface (screen) an image ray bundle formed on an image display element, and includes a transmissive optical system that is positioned on a side of an emission surface of the image display element and has positive power, and a reflective optical system including at least one mirror for reflecting, toward the projection surface, light rays emitted from the transmissive optical system. The transmissive optical system includes an aperture stop, at least one positive lens disposed closer to the image display element than the aperture stop is, a first positive meniscus-shaped lens, a negative lens, and a second positive meniscus-shaped lens with the first and second positive lenses and the negative lens being closer to the projection surface than the aperture stop is. The first and second positive lenses are disposed with the negative lens being disposed therebetween so that their respective concave surfaces face each other.

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.