Abstract: An optical system includes: a light guide to guide image light; a partial reflector; and a reflector. The partial reflector transmits a first image light guided in a first direction from a first side of the partial reflector in a light guide; and reflects second image light to exit outside from a light emission surface of the light guide, the second image light being guided in the light guide in a second direction opposite to the first direction from a second side of the partial reflector. The reflector at the second side of the partial reflector reflects the first image light back to the partial reflector as the second image light in the second direction. A dimension of the light guide in a thickness direction is longer than a beam diameter of the image light guided in the light guide. The light emission surface has a negative power.

Abstract: An optical system for a virtual display device includes: a light guide; a partial reflector to: transmit first image light guided in a first direction from a first side of the partial reflector through the light guide; and reflect second image light to exit outside the light guide, the second image light guided in a second direction, different from the first direction, from a second side different from the first side through the light guide; a reflector at the second side of the partial; and a polarizer. The polarizer rotates a polarization of the first image light polarized in a first polarization direction; and rotates a polarization of the second image light to polarize the second image light in a second polarization direction. The partial reflector has a lower reflectance for light polarized in the first polarization direction than for light polarized in the second polarization direction.

Abstract: An optical system includes: a first optical portion, on which image light from an image display element is incident; a light guide configured to guide the image light incident from the first optical portion; and a second optical portion configured to direct the image light guided in the light guide to an object. The first optical portion has an anamorphic surface having: a first shape in a first direction; and a second shape in a second direction different from the first direction, the first shape being different from the second shape. The first optical portion forms an intermediate image of the image light.

Abstract: A light guide member (300) includes a boundary surface (304) configured to reflect image light guided to the boundary surface (304) and emit the image light outside the light guide member (300), an opposing surface (306) parallel to the boundary surface (304), the opposing surface (306) facing the boundary surface (304), a first inclined surface (305) having an inclination in which a distance between the first inclined surface (305) and the boundary surface (304) decreases in a guiding direction of the image light, and a second inclined surface (307) between the opposing surface (306) and the first inclined surface (305), the second inclined surface (307) inclined at a different angle with the first inclined surface (305) in the guiding direction.

Abstract: An optical system for a virtual image display device includes a light guide, a reflector, and an intermediate image forming portion. The light guide is configured to guide image light emitted from an image display element that displays an image, to proceed in the light guide. The light guide includes a partial reflector, a first portion on one side of the partial reflector, and a second portion on another side of the partial reflector. The partial reflector transmits the image light incident from the first portion and reflects the image light incident from the second portion to guide the image light to exit the light guide. The reflector reflects the image light transmitted through the partial reflector and the second portion back to the partial reflector. The intermediate image forming portion forms an intermediate image with the image light in the light guide.

Abstract: A head-mounted display device includes a display element to display an image; a light guide member to emit the image displayed on the display element to an eye of a wearer; a housing including an optical system to guide image light of the image displayed on the display element to the light guide member; and an adjustment member provided on a side of the light guide member opposite to the optical system, and to bend the housing on a side opposite to a face of the wearer.

Abstract: In a propagation optical system to propagate light from an image display element to a light guide element, the propagation optical system includes: a prism having a first surface having negative power to which light emitted from the image display element enters; and a lens group having positive power. The prism and the lens group are arranged between the image display element and the light guide element along an optical axis, and the prism is closer to the image display element than to the light guide element.

Abstract: A light guide includes: a light guide board configured to allow light incident on an optical entrance to propagate through the light guide board, the light guide board including: the optical entrance; a first face; and at least one partial reflection layer within the light guide board and tilted to the first face. The at least one partial reflection layer is configured to reflect a part of light incident on the at least one partial reflection layer at an incident angle of greater than or equal to a critical angle ?r to allow the reflected light to exit the light guide board through the first surface while transmitting therethrough a remainder of the light incident on the at least one partial reflection layer. Formula below is satisfied: ?r=sin?1(n2/n1) where ?r is the critical angle; n1 is a refractive index of the light guide board; and n2 is a refractive index of the at least one partial reflection layer.

Abstract: A light guide includes light guiding members including first and second light guiding members, an optical entrance having a plane on which the light is incident, a light guiding unit to guide the light incident on the optical entrance with repeated reflection, a light beam ejection unit to eject the light to an outside of the light guide, and an extraction unit to reflect the light guided by the light guiding unit toward the light beam ejection unit. The light guiding members guide and eject a light, and the second light guiding member is bonded to, at least, the light guiding unit of the first light guiding member.

Abstract: A lens unit includes: a lens group including: an object-side lens closest to an object side in the lens group; an image-side lens closest to an image side in the lens group; and an intermediate lens between the object-side lens and the image-side lens, the object-side lens, the image-side lens, and the intermediate lens being arranged along an optical axis; a first holder holding an edge surface of the object-side lens and an edge surface of the intermediate lens; and a second holder separate from the first holder, the second holder holding the edge surface of the intermediate lens and an edge surface of the image-side lens.

Abstract: A virtual image display device includes: an image display element that displays an image to be displayed as a virtual image; a propagation optical system that propagates light from the image display element; and a light guide member that guides the light propagated by the propagation optical system. The light guide member includes: a light beam incident part that introduces light including image information from the propagation optical system into the light guide member; an image extractor that extracts the light including image information from an inside of the light guide member; and an image emitter that emits the light including image information to an outside of the light guide member. The propagation optical system includes one or more optical members each having a curved surface shape that is non-rotationally symmetric with respect to an optical axis.

Abstract: A zoom lens system includes a first lens group having positive refractive power; a second lens group having negative refractive power; and a rear group, the first lens group, arranged in that order from an object side. The second lens group includes a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side. During a change in a focus from a short focal length end to a long focal length end to change a magnification power, a distance between the first lens group and the second lens group-a increases, a distance between the second lens group-a and the second lens group-b is changeable or stationary, and a distance between the second lens group-b and the rear lens group decreases.

Abstract: A propagation optical system includes: a first optical system; an intermediate optical element; and a second optical system. The first optical system, the intermediate optical element, and the second optical system being sequentially arranged in a direction from the image display element toward the light guide member along an optical axis. The intermediate optical element has a non-rotationally symmetric curved surface, of which shape is non-rotationally symmetric about the optical axis. A cross-sectional shape, of the non-rotationally symmetric curved surface, in a first plane including the optical axis is non-arc shape. The first plane is a plane in which the non-rotationally symmetric surface has a strongest positive power among planes including the optical axis. The propagation optical system is configured to form, between the first optical system and the second optical system, an intermediate image corresponding to an image displayed on the image display element.

Abstract: A head-mounted display device includes a display element to display an image; a light guide member to emit the image displayed on the display element to an eye of a wearer; a housing including an optical system to guide image light of the image displayed on the display element to the light guide member; and an adjustment member provided on a side of the light guide member opposite to the optical system, and to bend the housing on a side opposite to a face of the wearer.

Abstract: An image forming lens includes a first lens group and a second lens group. The first lens group has positive refractive power moved toward the object side when focusing from a long distance to a short distance. The second lens group has positive refractive power arranged closer to the image side than the first lens group. The second lens group includes, in order from the object side to the image side, a negative lens having a concave surface on the image side, a negative meniscus lens having a concave surface on the object side, and a positive lens. The focal length f21 of the negative lens and the focal length f22 of the negative meniscus lens satisfy the following conditional expression: (1) 0.1<f21/f22<0.5.

Abstract: A zoom lens system includes a first lens group having positive refractive power; a second lens group having negative refractive power; and a rear group, the first lens group, arranged in that order from an object side. The second lens group includes a second lens group-a having negative refractive power and a second lens group-b having negative refractive power arranged in that order from the object side. During a change in a focus from a short focal length end to a long focal length end to change a magnification power, a distance between the first lens group and the second lens group-a increases, a distance between the second lens group-a and the second lens group-b is changeable or stationary, and a distance between the second lens group-b and the rear lens group decreases.

Abstract: An image forming lens includes a first lens group and a second lens group. The first lens group has positive refractive power moved toward the object side when focusing from a long distance to a short distance. The second lens group has positive refractive power arranged closer to the image side than the first lens group. The second lens group includes, in order from the object side to the image side, a negative lens having a concave surface on the image side, a negative meniscus lens having a concave surface on the object side, and a positive lens. The focal length f21 of the negative lens and the focal length f22 of the negative meniscus lens satisfy the following conditional expression: (1) 0.1<f21/f22<0.5.

Abstract: An image forming lens is formed by sequentially arranging, from an object side to an image side, a first lens group having positive refractive power, an aperture stop, a second lens group having positive refractive power, and a third lens group having positive or negative refractive power. When focusing is performed from a long distance to a short distance, the third lens group is fixed relative to an image surface, and the first lens group, the aperture stop, and the second lens group are moved integrally to the object side. In the image forming lens, the third lens group is formed by sequentially arranging, from the object side to the image side, two lenses in order of a negative lens and a positive lens, and a conditional expression is satisfied: 0.20<D/L3F-I<0.60, where D is an air space between the negative lens and the positive lens which form the third lens group, and L3F-I is a distance from an object-side surface of the negative lens of the third lens group to the image surface.

Abstract: An image forming lens is formed by sequentially arranging, from an object side to an image side, a first lens group having positive refractive power, an aperture stop, and a second lens group having positive or negative refractive power. The image forming lens satisfies a conditional expression: 0.15<D1a/D1<0.50, where D1a is an air space between the first positive lens and the second positive lens in the first lens group, and D1 is a distance on an optical axis from an object-side lens surface of the first positive lens to an image-side lens surface of the third positive lens in the first lens group.

Abstract: An image forming lens is formed by sequentially arranging, from an object side to an image side, a first lens group having positive power, an aperture stop, a second lens group having positive power, and a third lens group having positive power. The image forming lens satisfies following conditional expressions: 0.95<f12/f<1.2, 0.0<f/f3<0.2, ?0.5<(R142+R211)/(R142?R211)<?0.2, where f is a focal length of an entire system, f12 is a composite focal length of the first lens group and the second lens group, f3 is a focal length of the third lens group, R142 is a curvature radius of an image-side surface of the negative lens closest to the image side in the first lens group, and R211 is a curvature radius of object-side surface of the negative lens closest to the object side in the second lens group.