Abstract: An optical element includes an incidence surface, one or more reflecting surfaces reflecting light from the incident surface, an emergence surface, and off-axial curved surfaces causing the light to emerge from the emergence surface. At least one of the incidence surface, the emergence surface and the one or more reflecting surfaces is a surface having diffracting action. The surface having the diffracting action is a curved surface.

Abstract: An optical apparatus includes an optical unit including a light entrance surface, light reflecting surfaces and a light exit surface all of which are integrally formed of transparent material, and the optical unit has in its interior an internal refracting surface for refracting light. Since a light beam passes through the optical unit from the light entrance surface to the light exit surface via the internal refracting surface and the light reflecting surfaces along a bent optical path, the optical apparatus is reduced in size and improved in optical performance, particularly, well corrected in chromatic aberration. Another disclosed optical apparatus is arranged to achieve zooming by using a plurality of optical units each of which is similar to the aforesaid optical unit.

Abstract: A zoom lens comprises a plurality of optical elements each of which includes a transparent body having two refracting surfaces and a plurality of reflecting surfaces and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from front surface mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: In an optical element for reflecting light from an incidence surface of the optical element by one or more reflecting surfaces comprising off-axial curved surfaces, and causing the light to emerge from an emergence surface, at least one of the incidence surface, the emergence surface and the reflecting surface diffracting the light.

Abstract: A reflecting-type optical system according to the invention includes an optical element composed of a transparent body having an entrance surface, an exit surface and at least three curved reflecting surfaces of internal reflection. A light beam coming from an object and entering at the entrance surface is reflected from at least one of the reflecting surfaces to form a primary image within the optical element and is, then, made to exit from the exit surface through the remaining reflecting surfaces to form an object image on a predetermined plane, In the optical system, 70% or more of the length of a reference axis in the optical element lies in one plane.

Abstract: A zoom optical system and an image pickup apparatus using the same are disclosed. The zoom optical system comprises a first optical unit having a refractive power, the first optical unit having a reflecting surface, a second optical unit having a refractive power, and a driving portion for moving a light receiving surface which receives light from an object through the first optical unit and the second optical unit. The zoom optical system performs variation of magnification by moving at least one of the first optical unit and the second optical unit, and a deviation of a focus position due to the variation of magnification is corrected by the light receiving surface being moved by the driving portion.

Abstract: A zoom lens comprises a plurality of optical elements each of which includes a transparent body having two refracting surfaces and a plurality of reflecting surfaces and is arranged so that a light beam enters the transparent body from one of the two refracting surfaces, repeatedly undergoes reflection, and exits from the other of the two refracting surfaces, and/or a plurality of optical elements on each of which a plurality of reflecting surfaces made from front surface mirrors are integrally formed, and each of which is arranged so that an entering light beam repeatedly undergoes reflection by the plurality of reflecting surfaces and exits from the optical element.

Abstract: A photographing apparatus includes optical means for forming an object image, converting means for converting the object image into an image signal, displaying means for displaying an image on the basis of the image signal, designating means for designating an area in the displaying means, and recognizing means for extracting and recognizing a character in the image of the area.

Abstract: An image sensing apparatus has a cut-off characteristic which is changed by a mechanism for rotating a simple optical low-pass filter having a tightly sealed structure about the periphery of the photographic optical path. Light from a lens representing a subject is received and converted by an image sensing unit upon having its high-frequency components attenuated by a suitable cut-off characteristic, which is for obtaining a color natural image, of a stacked member including an optical low-pass filter or birefringence plates constructing an optical low-pass filter. In a case where a monochromatic image is obtained, some or all of the birefringence plates are rotated through a predetermined angle by changeover means such as a transmission member without sacrificing the seal about the periphery of the optical path, thereby changing over the cut-off characteristic of the optical low-pass filter to a cut-off characteristic suitable for obtaining a monochromatic image.