Abstract: Provided is a magnified-projection optical system, which can retain a considerably long back focus although a focal length is short and which has a small chromatic aberration. The optical system comprises a projecting optical system, a relay optical system and a display element, which are sequentially arrayed from a screen side along the optical axis. The projecting optical system enlarges and projects the image, which has been linearly focused by the relay optical system, on the screen, and includes a negative group and a positive group arrayed sequentially from the screen side and having a negative optical power and a positive optical power, respectively. The optical system satisfies the following conditional relations of |Fb/F|>10 and 0.5<|F/Fp|<2.

Abstract: Provided is a magnified-projection optical system, which can retain a considerably long back focus although a focal length is short and which has a small chromatic aberration. The optical system comprises a projecting optical system, a relay optical system and a display element, which are sequentially arrayed from a screen side along the optical axis. The projecting optical system enlarges and projects the image, which has been linearly focused by the relay optical system, on the screen, and includes a negative group and a positive group arrayed sequentially from the screen side and having a negative optical power and a positive optical power, respectively. The optical system satisfies the following conditional relations of |Fb/F|>10 and 0.5<|F/Fp|<2.

Abstract: An optical system has a plurality of optical surfaces and an aperture stop, and has an eccentric reflective surface as at least one of the plurality of optical surfaces. For different conjugate distances, focusing for keeping a position of an entire image surface substantially constant while keeping substantially constant an axial imaging position and an angle of incidence of an axial principal ray on an image surface is performed by parallel and rotational movement of a group provided as a focusing group having at least one surface as the eccentric reflective surface.

Abstract: A taking optical system for forming an optical image of an object on the light-receiving surface of an image sensor has at least one optical prism that has an entrance surface, at least three reflective surfaces each curved, and an exit surface, and that receives rays from the object side through the entrance surface, then reflects the rays on the at least three reflective surfaces, and then lets out the rays through the exit surface. The optical prism is formed of a medium having a refractive index of 1.2 or more. An optical aperture is disposed on or near one of the at least three reflective surfaces. At least one of the at least three reflective surfaces is an eccentrically disposed rotation-asymmetric surface.

Abstract: An optical system has a plurality of optical surfaces and an aperture stop, and has an eccentric reflective surface as at least one of the plurality of optical surfaces. For different conjugate distances, focusing for keeping a position of an entire image surface substantially constant while keeping substantially constant an axial imaging position and an angle of incidence of an axial principal ray on an image surface is performed by parallel and rotational movement of a group provided as a focusing group having at least one surface as the eccentric reflective surface.

Abstract: An image-taking optical system for forming an optical image of an object on the light-receiving surface of an image sensor includes a plurality of optical blocks. The optical blocks each have a prism unit provided with a curved surface and an optical unit composed of a member different from a member composing the prism unit. The prism unit uses the curved surface as a total reflection surface and also as a transmission surface. The optical unit has near the curved surface a curved surface identically or substantially identically shaped therewith.

Abstract: To provide an imaging optical system which is compact (thin) and can provide high performance (high resolution, high aberration correcting ability or the like). In the imaging optical system OS of the present invention, at least three or more prism elements (for example, prisms PR1 to PR3) have a positive power, and an emission surface of one of the prism elements and an incident surface of at least one of the residual prism elements are arranged so as to be opposed to each other. The imaging optical system OS prevents a light ray which passes through the prisms from being intermediately imaged. Further, since an asymmetrical optical surface (for example, reflection surface) is provided, an optical path can be bent, so that the system can be made to be compact. Further, an asymmetrical optical surface or the like is adopted, so that asymmetry-specific aberration is corrected.

Abstract: A taking optical system for forming an optical image of an object on the light-receiving surface of an image sensor has at least one optical prism that has an entrance surface, at least three reflective surfaces each curved, and an exit surface, and that receives rays from the object side through the entrance surface, then reflects the rays on the at least three reflective surfaces, and then lets out the rays through the exit surface. The optical prism is formed of a medium having a refractive index of 1.2 or more. An optical aperture is disposed on or near one of the at least three reflective surfaces. At least one of the at least three reflective surfaces is an eccentrically disposed rotation-asymmetric surface.

Abstract: An image-taking optical system for forming an optical image of an object on the light-receiving surface of an image sensor includes at least one optical prism in which light from the object side enters through an entrance surface, is then reflected by at least three reflection surfaces each formed with a curved surface, and subsequently exits from an exit surface. At least one of the reflection surfaces is provided with an optical aperture stop. At least one of the reflection surfaces is a rotationally asymmetrical surface so arranged as to be off-centered.

Abstract: An image-taking optical system for forming an optical image of an object on the light-receiving surface of an image sensor includes a plurality of optical blocks. The optical blocks each have a prism unit provided with a curved surface and an optical unit composed of a member different from a member composing the prism unit. The prism unit uses the curved surface as a total reflection surface and also as a transmission surface. The optical unit has near the curved surface a curved surface identically or substantially identically shaped therewith.

Abstract: An imaging optical system 100 has an imaging side prism 102 for bending incident light at about 90 degrees for reflection, and an image sensor 105 having a light receiving surface opposing to an exit surface 102b of the imaging side prism 102. At least one of an incident surface 101a of an incident side prism 101 and an incident surface 101a of the imaging side prism 102, or at least one of an exit surface 101b of the incident side prism 101 and the exit surface 102b of the imaging side prism 102 has an optical power. An arrangement relation between the exit surface 102b of the imaging side prism 102 and the image sensor 105 is established to satisfy the conditional formula (1): 0.0?d/a<0.8 ??(1) where d represents a distance between the exit surface 102b and the light receiving surface of the image sensor 105, and a represents a height of the light receiving surface of the image sensor 105 on a plane where an optical path of the imaging optical system 100 is folded, e.g.

Abstract: A zoom lens system comprises, from the object side, a first lens unit having a positive refractive power, a second lens unit having a positive refractive power and a third lens unit having a negative refractive power. During zooming, the sizes of the first area of empty space between the first lens unit and the second lens unit and the second area of empty space between the second lens unit and the third lens unit change.