Abstract: The present invention aims to provide a projection optical system that projects an image displayed on an image display surface of an image display element in an enlarged manner on a projection receiving surface as a projection image, the projection optical system comprising: a refractive optical system and a refractive/reflective optical element arranged in sequence from near the image display surface toward the projection receiving surface, wherein the refractive optical system includes a plurality of lenses, wherein the refractive/reflective optical element includes an optical element unit that includes a reflection surface member including a reflection surface, and a refractive medium portion that is in tight contact with the reflection surface, the refractive medium portion includes an incidence surface and an emergence surface, and the reflection surface is a curved surface having refractive power, and wherein an image-forming light beam emerging from the refractive optical system is caused to enter the

Abstract: A stereo camera device includes a plurality of cameras, a distance sensor configured to detect a distance to an object, a holder configured to hold the plurality of cameras and the distance sensor so that the optical axis of the distance sensor and the optical axes of the plurality of cameras are in the same direction, an electronic circuit, and a case in which the plurality of cameras and the distance sensor held by the holder, and the electronic circuit are provided.

Abstract: A projection optical system includes a first refractive system, a reflective optical system, and a second refractive system, disposed in the stated order in a direction from the reduction side toward the enlargement side, to enlarge and project an image displayed on an image display element, onto a projection surface. A first lens group of the first refractive system forms a first intermediate image with a light beam from the image display element. A second lens group of the first refractive system forms a second intermediate image with a light beam from the first intermediate image. A light beam from the second intermediate image is reflected by the reflective optical system and is then refracted by the second refractive system. A condition (1): 1.5<Bf/f<25 is satisfied, in which f represents a focal length of the entire projection optical system and Bf represents a back focus obtained by air conversion.

Abstract: A stereo camera device includes a plurality of cameras, a distance sensor configured to detect a distance to an object, a holder configured to hold the plurality of cameras and the distance sensor so that the optical axis of the distance sensor and the optical axes of the plurality of cameras are in the same direction, an electronic circuit, and a case in which the plurality of cameras and the distance sensor held by the holder, and the electronic circuit are provided.

Abstract: A projection optical system includes a first refractive system, a reflective optical system, and a second refractive system, disposed in the stated order in a direction from the reduction side toward the enlargement side, to enlarge and project an image displayed on an image display element, onto a projection surface. A first lens group of the first refractive system forms a first intermediate image with a light beam from the image display element. A second lens group of the first refractive system forms a second intermediate image with a light beam from the first intermediate image. A light beam from the second intermediate image is reflected by the reflective optical system and is then refracted by the second refractive system. A condition (1): 1.5<Bf/f<25 is satisfied, in which f represents a focal length of the entire projection optical system and Bf represents a back focus obtained by air conversion.

Abstract: A projection zoom lens is configured by a first group having a negative refractive force, a second group having a positive refractive force, a third group having a positive refractive force, an aperture diaphragm, a fourth group having a positive refractive force, and a fifth group having a positive refractive force. The groups are arranged in aforementioned order from an enlarged-side to a reduced-side in the projection zoom lens, wherein the reduced-side is telecentric, wherein the first group is configured by a first sub-lens group having a positive or a negative refractive force, a second sub-lens group having a negative refractive force, and a third sub-lens group having a negative refractive force, wherein the sub-lens groups are arranged sequentially from the enlarged-side to form a focusing group, wherein the second group to the fifth group constitute a zooming group.

Abstract: A lens barrel including a space-saving position adjustment function. The lens barrel constitutes a part of a projection optical system including a catoptric system including at least one reflecting mirror and that uses a dioptric system including multiple lens groups. At least one of the multiple lens groups includes a non-circular lens. The lens barrel includes a movable part that has an inner wall surface holding the non-circular lens and that is able to move the lens group that includes the non-circular lens in an optical axis direction of the non-circular lens, a holding part that is disposed on an outer circumferential side of the movable part and that holds the movable part and a shaft part formed in the optical axis direction, and a curved part that is disposed on an outer circumferential side of the holding part.

Abstract: The present invention aims to provide a projection optical system that projects an image displayed on an image display surface of an image display element in an enlarged manner on a projection receiving surface as a projection image, the projection optical system comprising: a refractive optical system and a refractive/reflective optical element arranged in sequence from near the image display surface toward the projection receiving surface, wherein the refractive optical system includes a plurality of lenses, wherein the refractive/reflective optical element includes an optical element unit that includes a reflection surface member including a reflection surface, and a refractive medium portion that is in tight contact with the reflection surface, the refractive medium portion includes an incidence surface and an emergence surface, and the reflection surface is a curved surface having refractive power, and wherein an image-forming light beam emerging from the refractive optical system is caused to enter the

Abstract: An eyepiece lens system having a large amount of allowable eccentricity. This eyepiece system forms a magnified virtual image of an observation object, and the eyepiece system has a horizontal angle of view of 40 degrees or more. The maximum amount of eccentricity S that makes the proportion of the amount of change, ? mm, in tangential field curvature in the amount of eccentricity, S mm, between the optical axis Ax and an observer's eye satisfy Condition (1), namely, ?0.25<?/S<0, at all image heights is 3 mm or more.

Abstract: An eyepiece lens system forms a magnified virtual image of an object to be observed, the system including: a first group disposed adjacent to an image display device and having negative refractive power; and a second group disposed adjacent to the first group on a side closer to an eye and having positive refractive power; the first group including a cemented doublet lens of a biconcave lens and a biconvex lens, the second group including two or three positive lenses, being telecentric on the object side. The eyepiece lens system has satisfactory telecentricity on the object side and satisfactorily corrects aberration.