Abstract: The method for designing a diffractive lens to be formed on a refractive lens is disclosed. According to the method, a function of the diffractive lens is expressed as a polynomial optical path difference function using a height from an optical axis as a variable, a boundary of each zone to be formed is determined based on the optical path difference function, an angle of incidence of a ray on a macroscopic shape of the diffractive lens is determined, a shift, in a direction along the optical axis, corresponding to a unit wavelength of the optical path difference for each zone is determined based on the angle of incidence, an optical path difference to be given by each zone is determined based on the optical path difference function, and then a microscopic shape of each zone is determined.

Abstract: A chromatic aberration correcting element that is a simple lens having at least one aspheric surface, the radius of curvature of which increases from the optical axis toward the periphery. At least one of the surfaces is formed as a diffraction lens surface that consists of annular segments that shift discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also disclosed is a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both. The annular segments are composed of planes perpendicular to and concentric with the optical axis.

Abstract: A diffusion plate includes a plurality of superimposed basic patterns, each having a large number of microstructures, wherein the microstructures are located in two dimensional periodic arrangements, and wherein lattice vectors, corresponding to the periodic arrangement of the microstructures, vary in accordance with the pattern. The invention also discloses a method for manufacturing a master die for such a diffusion plate, and a focusing screen using the diffusion plate.

Abstract: A UV image forming optical system includes a collimating lens which collimates light emitted from a UV light source, and an imaging lens which forms an image of the collimated UV light transmitted through the collimating lens. A rear focal point of the collimating lens adjacent to the imaging lens is located closer to the imaging lens than a last lens surface of the collimating lens on the light emission side. A front focal point of the imaging lens adjacent to the collimating lens is located within the imaging lens. A lens system for UV radiation is also provided, which can be used as an imaging lens for the UV image forming optical system.

Abstract: A chromatic aberration correcting element that is a simple lens having at least one aspheric surface the radius of curvature of which increases from the optical axis toward the periphery, at least either one of the surfaces being formed as a diffraction lens surface that consists of annular segments in steps that are shifted discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also, a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both, the annular segments being composed of planes perpendicular to and concentric with the optical axis.

Abstract: A chromatic aberration correcting element that is a simple lens having at least one aspheric surface, the radius of curvature of which increases from the optical axis toward the periphery. At least one of the surfaces is formed as a diffraction lens surface that consists of annular segments that shift discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also disclosed is a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both. The annular segments are composed of planes perpendicular to and concentric with the optical axis.

Abstract: A chromatic aberration correcting element that is a simple lens having at least one aspheric surface, the radius of curvature of which increases from the optical axis toward the periphery. At least one of the surfaces is formed as a diffraction lens surface that consists of annular segments that shift discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also disclosed is a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both. The annular segments are composed of planes perpendicular to and concentric with the optical axis.

Abstract: A diffractive multi-focal objective lens formed, macroscopically, as a double convex lens having convex aspherical surfaces of which radii of curvatures are larger as a function of distance from the optical axis. One lens surface is provided with a microscopic diffractive lens construction that is formed as ring zones concentric about the optical axis. The diffractive lens construction is designed so that the higher the diffractive order, the shorter the focal length. For example, a first order diffractive light beam forms a first focal point F1 on the optical axis, and a second order diffractive light beam forms a second focal point F2 on the optical axis that is nearer to the lens than the first focal point F1.

Abstract: A beam projecting apparatus has a light source and a reflecting device for reflecting and rotating a bundle of light emitted from the light source for forming a reference plane. A shape converting optical system is provided in an optical path from the light source to the reflecting device for converting the bundle of light from an elliptical sectional shape to a circular sectional shape.

Abstract: A chromatic aberration correcting element that is a simple lens having at least one aspheric surface the radius of curvature of which increases from the optical axis toward the periphery, at least either one of the surfaces being formed as a diffraction lens surface that consists of annular segments in steps that are shifted discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also, a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both, the annular segments being composed of planes perpendicular to and concentric with the optical axis.

Abstract: A device including a polarizing beam splitter by which an incident luminous flux is split into a first luminous flux radiated onto a first photo sensor and a second luminous flux radiated onto a second photo sensor, and an adjusting mechanism provided for rotatably adjusting a position of one of the first and second luminous fluxes. The optical axis of the first luminous flux is coincident with that of the incident luminous flux. The optical axis of the second luminous flux is not parallel to the first luminous flux. By rotating the beam splitter about the optical axis of the first luminous flux, the beam receiving position of the second photo sensor, onto which the second luminous flux is radiated, is changed.

Abstract: Lens arrangements for a multibeam recording device include a first lens group that forms collimated beams paired with a second lens group, allowing the second lens group to be moved for focusing. A first lens group forms non-collimated beams is paired with a second lens group, allowing one lens group to be moved for magnification change. A first lens group forms non-collimated beams between internal portions and collimated beams leading to a second lens group, allowing magnification change by moving the two portions and focus change by moving the second lens group. A first lens group having two movable portions is paired with a second lens group, both movable portions being shiftable and tiltable to correct for decentering errors. Three concrete reduction lens system examples applicable in each of the embodiments use positive anomalous dispersion glass, allowing low dispersion and the use of blue LEDs to increase the imaging resolution.

Abstract: A diffusion plate includes a plurality of superimposed basic patterns, each having a large number of microstructures. The microstructures are located in two dimensional periodic arrangements, and lattice vectors, corresponding to the periodic arrangement of the microstructures, vary in accordance with the pattern. The invention also discloses a method for manufacturing a master die for such a diffusion plate, and a focusing screen using the diffusion plate.

Abstract: A shiftable lens system having front and rear lens groups, wherein a part or the whole of the rear lens group is shiftable in a direction perpendicular to the principal optical axis thereof.

Abstract: For an aperture plate to be used to form dot images of a two dimensional aperture pattern by projection through an imaging optical system in a normal direction, a pattern of markings in ideal positions is projected through an imaging optical system in the reverse direction to normal imaging operations. The image of the pattern is recorded at the position of the aperture plate, and the recorded image is used as a guide to form corrected apertures in the aperture plate. Accordingly, locational errors of the dot images in the normal direction are corrected when the corrected aperture plate is used.

Abstract: An optical system of an optical information recording/reproducing apparatus including a light source, an objective lens, and a chromatic aberration correcting element is provided and also includes a mechanism for independently actuating the objective lens. A beam splitter for splitting the luminous flux reflected by a medium can also be provided. The chromatic aberration correcting element is formed of a positive lens and a negative lens cemented together and satisfies the relation .vertline.n.sub.p -n.sub.n .vertline..times.10.sup.-5 <300, wherein the refractive index in a central wavelength in use of the positive lens is represented by n.sub.p and the refractive index of the negative lens is represented by n.sub.n.

Abstract: An optical system of an optical information recording/reproducing apparatus includes a light source for emitting a generally parallel luminous flux. An objective optical system for converging the luminous flux emitted from the light source portion onto a medium is provided. The objective optical system can comprise a hologram lens or can have both surfaces formed as convex aspherical surfaces. A chromatic aberration correcting element having almost no power is adapted to correct chromatic aberration of the objective lens. A mechanism for independently actuating the objective lens at least in an optical axis direction is provided. Further, a beam splitter for splitting the luminous flux reflected by the medium from a light path directed to the light source portion and guiding the luminous flux to a light receiving system can be provided.

Abstract: An optical system of an optical information recording/reproducing apparatus includes an objective lens for converging a generally parallel luminous flux. A chromatic aberration correction element for correcting chromatic aberration of the objective lens is provided and has substantially no power. The chromatic aberration correcting element comprises a positive lens and a negative lens positioned in the generally parallel luminous flux. The positive and negative lenses of the chromatic aberration correcting element have substantially the same refractive index and different Abbe's number.

Abstract: A tilting lens system including a plurality of lens groups in which at least one lens group subsequent to a first lens group can be tilted about a predetermined point on a principal ray axis thereof.

Abstract: An objective optical system of an optical information recording/reproducing apparatus includes a light source for emitting a generally parallel luminous flux, an objective optical system for converging the luminous flux emitted from the light source portion onto a medium and a chromatic aberration correcting element for correcting a chromatic aberration of the objective lens. The chromatic aberration correcting element is formed of three lens cemented together. A first lens and a third lens of the chromatic aberration correcting element have a same polarity power while a second lens has a different power from that of the first and third lenses. Incident and outgoing end faces of the chromatic aberration correcting element are formed as generally plane surfaces. A mechanism for independently actuating the objective lens at least in an optical axis direction is provided.