Abstract: An aspherical objective lens and its manufacturing method are disclosed which allows for forming an optical spot with fewer side lobes on optical discs having a continuous lens plane and substrates different in thickness. The aspherical objective lens is characterized by converging first and second beams of light of first and second wavelengths individually on a first optical disc having a first substrate thickness and on a second optical disc having a second substrate thickness greater than the first substrate thickness at approximately a valid first numerical aperture and a second numerical aperture smaller than the first numerical aperture, respectively. A difference between average values of variations in wavefront aberration corresponding to an inner circumference portion and outer circumference portion, when the first beam of light converges on the first optical disk of the first substrate thickness, is approximately equal to one wavelength of a beam of light of the first wavelength.

Abstract: An optical wavelength demultiplexer includes an optical lens, a first-side waveguide and a plurality of second-side waveguide. The lens has a wave number distribution-surface having a section where an angular frequency is constant, and said section having a shape which generally represents at least a part of an ellipse or a circle; a medium allowing group-velocity directions toward an inside of the section to allow said medium to exhibit a lens effect; a finite thickness defined by a distance between two parallel planarized surfaces of the medium; a first focusing point at an inside position of the lens; and a second focusing point at an outside position of the lens. The first-side waveguide is positioned for incidence of a wavelength-multiplexed optical signal into the lens. The plurality of second-side waveguide is so aligned that terminals thereof are positioned at respective focusing points of respectively different-wavelength components included in the wavelength-multiplexed optical signal.

Abstract: The invention relates to novel intraocular lenses. The lenses are capable of post-operative adjustment of their optical properties, including conversion from single focal lenses to multifocal lenses.

Abstract: A lens array 22C has convex lenses 221 and 221C arranged in alternate and staggering manner to one another. In combination with a condenser lens 23, the convex lenses 221 form images of respective convex lenses 211 of a lens array 21 on a plane 24 to be illuminated in overlapping so that an illuminance distribution on the plane 24 is almost uniform, while the convex lenses 221C whose focal length is longer than that of the convex lenses 211 make on the plane 24 an illuminance distribution of a mountain-shape. Flat plate portions and concave lenses may be employed instead of the convex lenses 221C. A polarization conversion element comprises two elements and an element disposed therebetween with its longitudinal direction being perpendicular to the two element. The images of a light emitting part are included in band-shaped useful incident areas.

Abstract: One surface of the substrate constituting a diffraction type lens is formed with a zone plate exhibiting a smaller converging action with respect to a first wavelength &lgr;1 of light and a greater converging action with respect to a second wavelength &lgr;2 of light, whereas the other surface is formed with a zone plate exhibiting a smaller converging action with respect to the second wavelength &lgr;2 of light and a greater converging action with respect to the first wavelength &lgr;1 of light. The substrate is transparent to the first and second wavelengths &lgr;1 and &lgr;2 of light. Each of the zone plates comprises concentric gratings having a stepped cross section.

Abstract: One surface of an objective lens is provided with a zonal part which acts such that the quantity of light having a wavelength of &lgr;1 is apparently canceled in the outer peripheral portion of the luminous flux due to an interference effect, whereas the quantity of light having a wavelength of &lgr;2 in the outer peripheral part is kept as it is. The zonal part has such a step that light supposed to pass a position corresponding to the zonal part if the zonal part does not exist and light passing a position at which the zonal part is formed if the zonal part exists generate therebetween a phase difference satisfying a predetermined conditional expression. The numerical aperture at a boundary position of the step has a value between two numerical apertures for the respective wavelengths &lgr;1 and &lgr;2.

Abstract: One surface of the substrate constituting a diffraction type lens is formed with a zone plate exhibiting a smaller converging action with respect to a first wavelength &lgr;1 of light and a greater converging action with respect to a second wavelength &lgr;2 of light, whereas the other surface is formed with a zone plate exhibiting a smaller converging action with respect to the second wavelength &lgr;2 of light and a greater converging action with respect to the first wavelength &lgr;1 of light. The substrate is transparent to the first and second wavelengths &lgr;1 and &lgr;2 of light. Each of the zone plates comprises concentric gratings having a stepped cross section.

Abstract: An optical pickup apparatus for reproducing information from or recording onto one of different kinds of optical information recording medium comprises a first light source for emitting first light flux whose wavelength is &lgr;1; a second light source for emitting second light flux whose wavelength is &lgr;2, wherein &lgr;2 is greater than &lgr;1; a converging optical system comprising an objective lens having an optical axis and divided three (first, second and third) portions; and a photo detector. The following conditional formula is satisfied for an amount of the first light flux not less than 30% of the total amount of the first light flux passing the first portion: 0.06≧SC1/f1≧0.

Abstract: An objective lens includes a refractive lens having a positive refractive power, and a diffractive lens structure having a plurality of concentric ring-shaped steps that are formed on a lens surface of the refractive lens. The objective lens is a biconvex plastic lens having first and second aspherical surfaces. The diffractive lens structure has such a wavelength dependence that at least two diffracted beams having different wavelengths with the same diffraction order form appropriate wavefronts for at least two kinds of optical discs having cover layers of different thickness, respectively. Further, the diffractive lens structure has a predetermined power at any points in a middle ring area that is concentrically arranged about the optical axis at a middle range of the radius of the refractive lens.

Abstract: A lens focusing system provides a lens in an optical path between a scene and a photosensitive detector to properly focus a first set of wavelengths of light. At least one representation of the scene is captured. The focal point is adjusted for a second different set of wavelengths of light. This focal adjustment may be made by moving the lens and/or the detector, offsetting the position of the lens from the first position by a predetermined amount. An alternative method would impose at least a second lens in the optical path, thereby providing focus for a different wavelength. This alternative system may include various combinations of fixed and movable lenses. At least one representation of the image is captured using this different set of wavelengths of light. The different sets of wavelengths of light can include infrared light, visible light, and subsets and combinations thereof.

Abstract: An optical element has a coating thereon to reflect energy, such as light, of a first polarization into a first focus zone and to allow energy, such as light, of a second polarization orthogonal to the first polarization, to reach a second optical element. The second optical element, which may be reflective, diffractive, holographic, aspherical or have other optical characteristics, acts upon the energy to focus it into a second focus zone. A polarization changing element can be placed between the energy source and the optical element or the polarization can be changed by rotating the energy source. The ability to position energy into different focus zones allows for high speed processing and for the generation of useful beam patterns, such as aiming beams.

Abstract: A flow cell 2, a composite lens 15, and first to third detectors 16 to 18 are arranged in this sequence in the light pathway of light emitted from a laser light source 1. The composite lens 15 is configured by a convex lens 15a, and lens elements 15b and 15c. These lenses have different focal lengths. When the posture of the composite lens is correct, light impinging on the convex lens forms an image on the first detector. Therefore, the positioning of the composite lens is enabled. When particles in the flow cell are irradiated with laser light, forward scatter is produced. Forward small angle scatter having a small scattering angle impinges on the first lens element 15b to be collected thereby, and is then received by the second detector 17. Forward large angle scatter having a large scattering angle impinges on the second lens element 15c in the outermost periphery to be collected thereby, and is then received by the third detector 18 which is remotest from the composite lens.

Abstract: A portable electronic device having a variable focus display comprises a housing (512), supporting an image generating apparatus (518, 610, 710, 810), a lens (514, 612, 712, 812), and an optical element (520, 620, 720, 730, 820). The optical element has zero optical power and is located along an optical axis between the image generating apparatus and the lens.

Abstract: The object of the prevent invention is to provide an optical system for producing variable refraction with minimized dispersion. A first material with a first apex angle in a first state and a second material with a second apex angle in a first state produce a first net refraction angle in at least two frequencies of electromagnetic radiation such that the beams that entered parallel exit parallel (to within a controllable tolerance). Said first material with said first apex angle in a second state and said second material with said second apex angle in a second state produce a second net refraction angle in at least two frequencies of electromagnetic radiation such that the beams that entered parallel exit parallel (to within a controllable tolerance).

Abstract: An optical pickup device which includes an objective lens having a numerical aperture of 0.7 or more collects light emitted from a light source and irradiates an optical recording medium. The objective lens and an antireflection film formed thereon are set so that the intensity of light incident on the outermost rim of the objective lens is 45% or more and 80% or less of the intensity of incident light from the light source to the center of the objective lens. According to the configuration, it is possible to provide an optical pickup device including a high NA objective lens which can suppress a reduction in the light amount at the lens rim.

Abstract: An optical system of an optical pick-up that is capable of using optical discs DVD and CD. The system includes a light source portion for selectively emitting a first laser beam (650 nm) and a second laser beam (780 nm), and an objective lens for converging the laser beam from the light source portion onto an recording layer of the optical disc. The objective lens is provided with a transmittance controlling phase grating in a peripheral region to have a wavelength dependence such that the transmittance for the first laser beam is higher than the transmittance for the second laser beam. The transmittance controlling phase grating is formed as a plurality of concentric grooves. Each of the grooves has a rectangular cross-section in a plane containing an optical axis of the objective lens.

Abstract: A luminous flux diameter variable type objective lens having a wavelength selectivity is disposed within a luminous flux. Arranged on a surface of the lens are a first region 11 with no diffraction gratings, and a second region 12 with diffraction gratings. The diffraction gratings each having a rectangular cross section are linearly arranged in the second region 12. The thickness (height) h of the diffraction grating 12A is set to such a value that the ratio of ± first-order diffracted light becomes much greater for the light having a wavelength of 780 nm used for CD-R, whereas the ratio of zero-order diffracted light becomes substantially 100% for the light having a wavelength of 635 nm used for DVD.

Abstract: A magneto optic or optical disk drive comprises a laser source for providing laser beam, and a lens or compound lens for focussing the laser onto a currently inserted recording disk with specific overcoat thickness. In one embodiment, the lens is a compound lens that can focus aberration-free spots on different types of disk media having recording layers located under overcoats of different thicknesses. When a specific disk is inserted, only one spot in focussed onto the current recording layer. Furthermore, if the disk spins rapidly, it can wobble. The lens or compound lens comprises different regions where the focal length may vary slightly and continuously or discretely. Because of this, as the disk wobbles, the lens can nonetheless continue to focus laser light onto a small spot on the recording media, providing increased depth of focus in the vicinity of the currently inserted recording media.

Abstract: An optical pickup apparatus for reproducing information from or recording onto one of different kinds of optical information recording medium comprises a first light source for emitting first light flux whose wavelength is &lgr;1; a second light source for emitting second light flux whose wavelength is &lgr;2, wherein &lgr;2 is greater than &lgr;1; a converging optical system comprising an objective lens having an optical axis and divided three (first, second and third) portions; and a photo detector. The following conditional formula is satisfied for an amount of the first light flux not less than 30% of the total amount of the first light flux passing the first portion: 0.06≧SC1/f1≧0.

Abstract: An optical pickup apparatus for reproducing information from or recording onto one of different kinds of optical information recording medium comprises a first light source for emitting first light flux whose wavelength is &lgr;1; a second light source for emitting second light flux whose wavelength is &lgr;2, wherein &lgr;2 is greater than &lgr;1; a converging optical system comprising an objective lens having an optical axis and divided three (first, second and third) portions; and a photo detector. The following conditional formula is satisfied for an amount of the first light flux not less than 30% of the total amount of the first light flux passing the first portion: 0.06≧SC1/f1≧0.

Abstract: A switching device for multiple (dual) focus points of multiple (dual) optical paths in a scanning optical path device is disclosed. The scanning optical path means comprising: a glass arranged for supporting a document, a reflector blow the glass, a primary lens with respect to the reflector, a sensing element behind the primary lens. At least two lenses of different thickness are arranged between the reflector and primary lens. In switching, various scanning optical paths or multiple (dual) optical paths switching operation are performable so that the focus points are higher than the surface of the glass. Thus, the original document (a film) has a proper gap with the surface of the glass on the platform for avoiding Newton ring (interference strips) effect so as to acquire a clear scanning effect. Another, the original document of an auto paper feeder can be focused correctly.

Abstract: An imaging optical system includes a liquid crystal lens including a first body formed of a substantially transparent birefringent liquid crystal member, a second body formed of a substantially transparent birefringent liquid crystal member, and two pairs of electrodes for adding an electric field or a magnetic field onto the first body and the second body. A rear face of the first body is aligned perpendicular to a front face of the second body, the first body and the second body have substantially symmetrical shape against a plane perpendicular to an optical axis and a plurality of optical elements are arranged front and after the liquid crystal lens. The liquid crystal lens has two distinct focal points. The system automatically switches between these focal points, based on the position of the lens with respect to the object being observed.

Abstract: A lens for angularly overlapping a central portion of an optical beam with an outer portion of the beam is disclosed. The lens comprises a lens body having an optical axis, a rear surface on said lens body for receiving an optical beam, and a front surface on said lens body that includes inner and outer portions. The outer surface portion is inclined at a greater angle from the optical axis than the inner surface portion so that the outer portion of a beam transmitted through the lens from its rear surface to said outer surface portion is refracted by a lesser angle than an inner portion of the beam which reaches said inner surface portion.

Abstract: A multiple focal distance light collecting optical device, is characterised in that it consists of a monoblock structure formed of at least a first and a second transparent material (8, 10) formed into lenses (12, 14, 16,) which are applied against and attached to each other the refractive indices and radii of curvature of the faces of such lenses being determined to focus the light rays so as to create an image in accordance with at least two different focal distances (A, B).

Abstract: A flow cell 2, a composite lens 15, and first to third detectors 16 to 18 are arranged in this sequence in the light pathway of light emitted from a laser light source 1. The composite lens 15 is configured by a convex lens 15a, and lens elements 15b and 15c. These lenses have different focal lengths. When the posture of the composite lens is correct, light impinging on the convex lens forms an image on the first detector. Therefore, the positioning of the composite lens is enabled. When particles in the flow cell are irradiated with laser light, forward scatter is produced. Forward small angle scatter having a small scattering angle impinges on the first lens element 15b to be collected thereby, and is then received by the second detector 17. Forward large angle scatter having a large scattering angle impinges on the second lens element 15c in the outermost periphery to be collected thereby, and is then received by the third detector 18 which is remotest from the composite lens.

Abstract: An objective lens for condensing a light beam, has at least one of annular grooves and ridges producing a phase difference. Each of the annular groove and ridge is formed concentrically on at least one of an incident surface which said light beam is introduced, and an emission surface which said light beam is emitted.

Abstract: An objective lens that allows spherical aberration to be suppressed during the reproduction of a CD without sacrificing reproduction characteristics of a DVD, has a first numerical aperture comprising a refracting surface that is in rotatory symmetry about an optical axis. A part of the refracting surface is displaced along the optical axis as an annular concave (or convex) portion centered on the optical axis. The annular concave (or convex) portion has a certain inner diameter r.sub.1 and a certain outer diameter r.sub.2 that reduce RMS aberration V to a value close to a minimum value. The annular portion has a certain depth (or height).

Abstract: The present invention relates to an apparatus for forming fine patterns in semiconductor devices, display devices and micro-electro-mechanical systems and more particularly to an image projecting system using an optical component, which is made of birefringent material, in the lithography techniques. The lithography apparatus according to the present invention comprises an optical lens system in which an image of a photomask is transferred to an object by a light source, wherein said optical lens system comprises a plurality of isotropic optical unit and at least one birefringent optical unit, said birefringent optical unit including at least one of said birefringent optical components.

Abstract: A scanning device for optical record carriers is provided with an objective lens (7) suitable for scanning record carriers (1, 21) having a transparent substrate (2, 23) of different thicknesses. The lens comprises an outer annular part (25) and an inner central part (26) within the annular part. Only the central part of the lens is used for forming a focus through a first substrate (2) having a first thickness. The central part is corrected for the spherical aberration of the first substrate. The annular and central part of the lens are used for forming a focus through a second substrate (23) having a different, second thickness. The annular part is corrected for the spherical aberration of the second substrate.

Abstract: A light strength equalizing device for a light source is provided. The device includes an illuminated area, a light source emitting a light for illuminating along a light path the illuminated area with different light strengths, and a compensating device mounted in the light path for respectively compensating the different light strengths in order to equalize the different light strengths on the illuminated area.

Abstract: An improved auto-focus system for a digital camera has a lens designed to have the focus of two spectra offset from each other by a predetermined amount. The two offset spectra are used to calculate two focus signals. Once the two focus signals are calculated the correct direction to move the lens system to set the optimum focus can be determined.

Abstract: A multi-focal lens with both a power portion and a functional portion, where the power portion imparts a majority of the optical power and magnification characteristics to the multi-focal lens and has a front side with both a main focal surface and a secondary focal surface that is discontinuous relative to the main focal surface and where the functional portion has a rear side that is shaped like the front side of the power portion with the rear side of the functional portion being affixed to the front side of the power portion.

Abstract: A condenser lens to be used for an optical head capable of recording or reading information on or from optical disks having different substrate thicknesses in an optical disk device such as a CD or the like. A light beam emitted from a laser light source is focused by a condenser lens to form a minute spot. The incident surface of the condenser lens is divided into a plurality of division areas which are sufficiently small with respect to the lens opening. The division areas constitute first and second lens surfaces, that is, parts of lens surfaces of two different lenses. The light beam is focused by the first lens surface to form a minute spot on a first optical disk and by the second lens surface to from a minute spot on a second optical disk. The two lenses can be optimized independently and be designed readily. One condenser lens having the first and second lens surfaces can form two kinds of light beam spots and adaptable to two optical disks having different substrate thicknesses.

Abstract: A compound objective lens is composed of a hologram lens or transmitting a part of incident light without any diffraction to form a beam of transmitted light and diffracting a remaining part of the incident light to form a beam of first-order diffracted light, and an objective lens for converging the transmitted light to form a first converging spot on a front surface of a thin type of first information medium and converging the diffracted light to form a second converging spot on a front surface of a thick type of second information medium. Because the hologram selectively functions as a concave lens for the diffracted light, a curvature of the transmitted light differs from that of the diffracted light.

Abstract: An optical lens is disclosed that is suitable for use in a line scanner or analogous device. The lens has multiple optical axes individually corresponding to a respective refractive combination comprising a first and an opposing second refractive surface. The lens is movable, preferably by rotation about an axis, relative to an axis of light propagation so as to permit selection of a desired refractive combination by aligning the optical axis of the refractive combination with the axis of light propagation.

Abstract: A multi-focal lens with both a power portion and a functional portion where the power portion imparts a majority of the optical power and magnification characteristics to the multi-focal lens and has a front side with both a main focal surface and a secondary focal surface that is recessed relative to the main focal surface and where the functional portion has a rear side that is shaped like the front side of the power portion with the rear side of the functional portion being affixed to the front side of the power portion.

Abstract: An image detection system (10) uses an optical configuration for both image forming and calibration phases of operation. A field lens (20) has an inner portion (36) of a conventional prescription to allow for collection of scene based energy for an opto-electronic approximation of the infrared detail within the afocal field of view by a focal plane array (32). The field lens (20) also has an outer portion (38) that collects far field energy from a scene area (A.sub.I) through a converging point (P.sub.I). The energy collected from the scene area (A.sub.I) is indicative of the average energy level within the scene. The electrical equivalent values of all energy received from the unique area (A.sub.I) is stored in a multidimensional range used for subsequent gain and offset calibration coefficient calculations.

Abstract: A dual-focus objective lens for an optical pickup which is compatible with both 0.6 mm and 1.2 mm disks is compensated in its aberration with respect to a light spot on a recording plane of the loaded disk and is composed of a first lens and a second lens. The loaded positions of the 0.6 mm disk and 1.2 mm disk in view of the second lens are different from each other. An optical pickup having the dual-focus objective lens can reproduce a signal with a high signal-to-noise ratio and has improved light efficiency. Also, an optical pickup enabling recording as well as reproduction is obtained.

Abstract: An optical system for alternative or simultaneous direction of light from two scenes to the eye of a viewer comprising (a) a first lens having a first focal length; (b) a second lens having a second focal length, the first and second lenses being positioned aside one another in front of one of the eyes of the viewer, such that a single light beam from any of the scenes passes only through one of the first and second lenses; and (c) an optical arrangement for directing incident light originating from the first scene and passing through the first lens into the eye of the viewer, and at the same time, for directing incident light originating from the second scene and passing through the second lens into the eye of the viewer, the optical arrangement being positioned between the first and second lenses and the eye of the viewer.

Abstract: A multi-color optical display system (10) employs a multi-powered reflective combiner (20) that together with a monochromatic or partly color-corrected relay lens (16) longitudinally corrects a multi-colored image. The combiner typically includes two surfaces (82, 90) of different optical powers with a reflective coating (106, 108) on each of the surfaces. The coatings are chosen to each reflect a specific wavelength range of colored light used in the system and to transmit all other wavelengths. The curvature of each surface is dictated by the aberrations in the color image created by the relay lens. Specifically, each surface is positioned so that its focus (86, 94) coincides with the focal point (58, 60) of the corresponding color component in an intermediate image (18) created by the relay lens so that the final virtual image (22) reflected by the combiner is longitudinally color corrected.

Abstract: A lens device which can be used as an objective lens in an optical pickup apparatus includes an objective lens provided along a light path facing a disc and having a predetermined effective diameter, and light controlling means provided along the light path for controlling the light in an intermediate region between near and far axes of an incident light beam, thus providing a simplified and inexpensive device for using discs of differing thickness in a single disc drive, by reducing the spherical aberration effect.

Abstract: A scanner with an extended depth of focus for electro-optically reading indicia having parts of different light reflectivity, comprises a collection optical system for collecting radiation reflected from objects in the field of view along plural different optical axes and an optical detector for detecting radiation collected by the collection optical system along each of the plural different optical axes and for generating electrical output signals indicative thereof. The scanner further includes processing circuitry for processing the output signals of the optical detector by comparing the output signals of the optical detector with one another, a memory for storing the detector output signals and further processing circuitry receiving the stored output signals of the optical detector from the memory and selectively outputting one of the received signals to a decoder.

Abstract: A projection lens system with a high resolving power and a wide exposure area which is effectively corrected for various aberrations including chromatic aberration and which is compact and has minimal production problems in a case where there is a limitation on vitreous materials usable as a lens material. The projection lens system (10) includes a plurality of lenses, at least one of which is a diffractive optical element (DOE) (11). The DOE (11) has a pitch arrangement in which it has a positive power in a paraxial region thereof, and wherein the positive power continuously changes to a less positive power, and then to a negative power as the distance from the optical axis of the DOE (11) increases toward the periphery thereof. Since the DOE (11) produces large aberrations which are opposite in sign to aberrations produced in the refracting system, it is possible to effectively correct various aberrations in the projection lens system (10) and also axial chromatic aberration.

Abstract: A variable focus color corrected field lens for accepting rays having a divergence of from 0, wherein the rays are collimated, to a divergence of 10 milliradians full angle and directing the rays to the same point of an optical system. The present lens is corrected for wavelengths from the ultraviolet to the red spectrum of wavelengths for directing the wavelengths to the same point.

Abstract: A multi-facet lens member for use in an optical device such as a conventional camera or a video camera, comprising: (a) a multi-facet optical lens having at least four optical surfaces arranged in at least two pairs, each pair of the optical surfaces being adapted to provide a predetermined effective focal length in a light path; and (b) a rotational member for rotating the multi-facet optical lens so as to position a desired pair of the optical surfaces in the light path and provide a desired effective focal length for the optical device. The multi-facet optical lens member can be used alone or in conjunction with other conventional optical lens to obtain optimum effect. In an example embodiment of a fouri-facet lens member, one arrangement of the optical surfaces provides an effective focal length of 25 mm, thus representing a wide-angle lens. By a simple 90 degrees rotation of the lens member, an effective length of 90 mm can be obtained, thus representing a telephoto lens, from the same optical device.

Abstract: A miniature fixed-focal-length lens system includes a lens group which consists of a plurality of lenses and has a positive refracting power and a stop disposed on the object side of the lens group. The lens nearest to the object in the lens group is a meniscus lens which is concave to front and has a positive refracting power and the lens remotest from the object in the lens group is a lens which is convex to rear and has a positive refracting power.

Abstract: An optical connector comprises a series of transparent substrates 50-53 including a refraction type lens 10 embedded in the central substrate 50, two beam deflection elements 40 and 41 offset from the optical axis of the lens 10, a light emitting element 20 directly below the beam deflection element 40, and a light detecting element 30 directly above the beam deflection element 41. The lens 10 is designed to have identical meridional and sagittal focal lengths so that meridional and sagittal images of obliique incident beams may be formed on the same spot on the light detecting element 30. Beam of light emitted from the light emitting element 20 are deflected by the beam deflection element 40 and enters the lens 10 obliquely. The beams, passing through the lens 10 and the deflection element 41 are cllimated within a small spot on the light detecting element 30 since the lens 10 has identical meridional and sagittal focal lengths.

Abstract: The present invention relates to a method of preparing an optical fiber for optimum coupling with a phototransducer, comprising the following steps: cleaving an end surface on an optical fiber; and depositing a succession of convex lenses on said cleaved surface over the core of the fiber, the lenses being in axial alignment and of decreasing radii of curvature on going away from the fiber. The present invention also provides a system obtained by implementing the method.

Abstract: The phase conjugation device includes at least one non-linear medium and an optical focussing system producing at least two focal points within the non-linear medium and capable of focussing light at these two points.

Abstract: An optical pickup device for condensing the light from a light source on a signal recording surface by an objective lens and for detecting the return light from the signal recording surface by a light detection unit is disclosed. The optical pickup device is capable of recording and/or reproducing at least two different sorts of optical recording media. The light beam radiated from a light source is condensed by an objective lens. An aperture varying unit varies the size of an aperture of the objective lens depending upon the sorts of the optical recording media. The return light from the optical recording medium is detected by a light detection unit. The size of the aperture of the objective lens for condensing the light from the light source is varied depending upon the difference in substrate thickness of the different sorts of the optical recording media, thus assuring high-quality recording/reproduction for two or more different sorts of optical recording media.