Abstract: A device for optically scanning a surface (2) with a focal spot (11) formed by an objective lens (10). The objective lens is electromagnetically suspended in a stationary coil system (14) comprising a plurality of coil pairs located one behind the other in a given direction. The coil system can move the objective lens in five or six degrees of freedom. A radiation beam is displaced parallel to itself via a pivotal mirror (22) and a scanning lens (23) so as to track the movement of the objective lens in said direction. A communicator (96) drives only those coils of the coil system which are proximate to the objective system at a given moment.

Abstract: A polygonal scanning mirror for an optical recorder is magnetically suspended and rotated about a scanning axis. To control position of the scanning mirror, a curved surface mirror is fixed with respect to, and rotates with, the scanning mirror for receiving a radiation beam and reflecting it onto a detector array. The reflected radiation beam is preferably focused by an astigmatic imaging system. Output signals from the detector array are used to control electromagnets of the suspension system.

Abstract: A device in which a radiation source generates a radiation beam of a first wavelength. The scanning spot 7 generated by this radiation beam follows the centerline 13 of a track 8 to be scanned on a first type of record carrier designed for this wavelength. When a second type of record carrier is being read, in which the information is stored in a phase structure designed for a wavelength which is longer than the first wavelength, the read spot 7 follows the edge of a track 38 to be read instead of the centerline 18. In this way it is possible to generate a satisfactory information signal not only from the first type of record carrier but also from the second type of record carrier.

Abstract: An optical system for determining the position and/or orientation of an object (10), for example, a freely suspended rotatable polygon mirror, comprises a convex mirror (24) on the rotation axis (11) of the polygon mirror and a plane mirror (25) perpendicular to the rotation axis. A convergent radiation beam is projected on the convex mirror (24). The reflected radiation is subsequently focused on a detection system (40, 45) via an astigmatic imaging system (75, 78, 51). A substantially parallel radiation beam is incident on the plane mirror (25), which beam, after reflection, is also focused to a radiation spot (34a) on the detection system (40, 46). The position and the shape of the radiation spots (34, 34a) are a measure of the position and the orientation of the polygon mirror (10). After processing, the output signals of the radiation detection system are applied to elements (91), for example electromagnets for stabilizing the polygon mirror (10).

Abstract: A scanning device comprises a rotatable mirror and a drive unit. The drive unit comprises a rotor section which carries the mirror and which is rotatable about an axis of rotation (19), which rotor section has a disc-shaped at least partly permanent-magnetic rotor body (13). The drive unit further comprises a stationary stator section with coils (9) extending in the magnet field of the rotor body to generate electromagnetic driving forces acting on the rotor body to provide the rotary drive of the mirror, and coils (11) disposed in the magnet field of the rotor body to generate electromagnetic bearing forces acting on the rotor body, for electromagnetically supporting the rotatable rotor section relative to the stator section.

Abstract: In order to pivot a pivotal arm (60) carrying an optical scanner (5), use is made of at least one coil (13) and at least one permanent magnet (16, 17), the coil being arranged on the pivotal arm or on a frame supporting the arm and the permanent magnet being arranged on the frame or on the arm. The coil (13) has a substantially straight active coil section (14) which is arranged near the pivotal axis (8) about which the pivotal arm is pivotable and which extends transversely of the longitudinal axis of the pivotal arm. The ends of this coil section are interconnected by a further coil section (15) which is, for example, concentric with the pivotal spindle and which extends at that side of the pivotal axis which is remote from the scanning unit.

Abstract: A method and apparatus are revealed for recording information on a record carrier (1) having a magneto-optical recording layer (2), a pattern of magnetic domains (23, 24) having a first and a second direction of magnetization being formed in the recording layer (2). In accordance with the method, areas (22) of the recording layer are heated by the radiation pulses (20). The heated areas (22) are magnetized by means of a coil (12) which is energized with energizing-current pulses (21) which lag the radiation pulses (20) to such an extent that cooling of the areas (22) takes place substantially during the generation of the energizing pulses (12).

Abstract: Disclosed is a system for optically recording information on a disc-shaped record carrier body along an information track, with the write spot being accurately guided in the radial and tangential directions. The record carrier body comprises a servo track formed by a constant and large number of servo areas per revolution of the servo track. In addition to a write spot, the write apparatus also projects a servo spot on the servo track. The tangential speed and the radial position of the servo spot relative to the servo track are determined from the modulated servo beam and used to correct the tangential speed and the radial position of the write spot, which is locked to the servo spot.

Abstract: Replica lens having a transparent lens body comprising one or more correction layers of a synthetic resin as well as a bonding layer of a synthetic resin with which the lens body is bonded to one or more auxiliary means or optical components, as well as a method of manufacturing the replica lens.

Abstract: The invention relates to a device for directing a radiation beam towards a recording surface of a rotating disc for recording and/or scanning a recording track without mechanical contact. The device comprises a frame (101), an objective holder (103) having an objective (19) with an optical axis (17), two elongate leaf springs (113, 115) which are arranged one above the other for movably supporting the objective holder relative to the frame, and an electromagnetic actuator (121A; 121B1, 121B2) for the controlled movement of the objective. One (113) of the leaf springs is elastically extensible in its longitudinal direction (113B) to allow pivotal movements of the objective about a pivotal axis 125 which extends transversely of a plane containing the optical axis and intersecting the leaf springs. (FIG.

Abstract: Disclosed is a system for optically recording information on a disc-shaped record carrier body along an information track, with the write spot being accurately guided in the radial and tangential directions. The record carrier body comprises a servo track formed by a constant and large number of servo areas per revolution of the servo track. In addition to a write spot, the write apparatus also projects a servo spot on the servo track. The tangential speed and the radial position of the servo spot relative to the servo track are determined from the modulated servo beam and used to correct the tangential speed and the radial position of the write spot, which is locked to the servo spot.

Abstract: A scanning unit for an optical disc record carrier includes a radiation-sensitive detection system having a plurality of detection elements on which is formed a reflected image of the scanning spot on the track structure of the record carrier. A tracking error signal is derived by combining the output signals of detection elements situated on respective sides of a boundary line between two halves of the detection system, and comparing with each other the combined signals from both halves. Several different such tracking error signals are derived, for boundary lines having different orietations with respect to the direction of the track instantaneously being scanned. The tracking error signal corresponding to a boundary line most nearly parallel to the direction of such track will be of greatest amplitude, and is selected as the tracking error signal used for controlling the scanning unit to follow the center line of such track.

Abstract: An electro-optical device is able to follow the information structure (2) of a moving information carrier (3) with a radiation spot 17 in two directions, of which one extends in a plane perpendicular to the other. A lens system (5) is fixed in a lens mounting (9) which relative to a frame (4) may perform pivotal movements about a pivotal axis (10) parallel to the optical axis (6) of the lens system and translational movements along the pivotal axis (10) by means of electromagnetic actuator means (14, 13) which are symmetrically located with respect to the pivotal axis. The lens mounting (9) is of elongate form and its parts which are situated on opposite sides of the pivotal axis (11) have substantially the same mass and mass distribution.

Abstract: An optical scanning unit with an objective for the focussing a beam of radiation along an optical axis into a scanning spot on the surface of an information carrier. The scanning unit also has an electromagnetic drive for correcting the position of the objective with respect to the information carrier. The drive has an objective mount supported in an annular, moving magnetic member which is axially magnetized and is arranged coaxially about the optical axis. The drive is further provided with fixed coils which interact with the magnetic member via an air gap. The fixed coils are arranged along at least three radial planes which are normal to the optical axis. Two planes lie in the area of the axial ends of the centrally positioned magnetic member and the third central plane which extends between the two outer radial planes.

Abstract: An electro-optical apparatus comprising an objective (7) scans an optical disc (3) having a transparent protective layer (5) by means of a radiation beam (10) which, through the transparent layer, is focussed on a reflecting recording surface (4). The objective moves along the optical axis (19) for focussing the radiation beam on the recording layer and moreover performs limited pivotal movements. The position of the optical axis of the objective is corrected for obliquity of the surface of the optical disc, correction means (22A, B) being provided to tilt the objective through a correction angle, so that the angle between the optical axis and the normal to the disc surface is reduced.

Abstract: An optical scanning unit with an objective for focussing a beam into a scanning spot on the surface of an information carrier and an electromagnetic drive for continuous correction of the position of the objective with respect to the information carrier. The objective is mounted in a movable ring-shaped magnetic body of a permanent-magnetic material which is arranged coaxially about the optical axis and which has magnetic poles at the axial ends. The drive is provided with sets of fixed coils which interact with the magnetic body via an air gap. Each set of coils has a first segmental coil arrangement having two active coil parts extending parallel in the peripheral direction of the magnetic body and located in the vicinity of the axial ends of the centrally positioned magnetic body. The unit is further equipped with at least one second coil arrangement which is positioned at least partially between the active coil parts of the above-mentioned first segmental arrangement.

Abstract: An electro-optical device for recording and/or reading recording tracks in a recording surface of an optically readable disk by means of a radiation beam, includes a frame (43), a turntable supporting means (45) for a turntable (55) which is rotatable about an axis of rotation (57), an objective supporting means for an objective (15) having an optical axis (24), a focussing actuator (24) for moving the objective along the optical axis, and guide means for moving the objective and/or the turntable relative to each other between a first position, in which the optical axis and the axis of rotation are situated nearer each other, and a second position, in which these axes are situated more remote from each other. In the case of an oblique position of said surface of the disk, correction means reduce the angle between the optical axis and the normal to the disc surface at the location where the optical axis intersects the disk surface.

Abstract: An optical scanning unit is described, which unit comprises a radiation source (1), an objective lens (3) and a translational-position and angular-position detection system for determining the translational position and the angular position of the objective lens within the scanning unit. This system comprises a conical-ring mirror (5) which is centered and fixed relative to the objective lens and a radiation-sensitive detection system (9) which is arranged in the path of the radiation reflected from the mirror and which comprises two detectors which are spaced by an annular strip (12) and are each divided into four quadrants (13-20). The scanning unit further comprises an electromagnetic system comprising an annular permanent magnet (70) around the objective lens and at least six magnet coils (71-76) which are arranged in two axially shifted planes (80, 81).

Abstract: An opto-electronic apparatus for inscribing and/or reading recording tracks on a record carrier by means of a radiation beam comprises an objective mounted in an objective holder. The objective holder is supported in a frame by bearing arrangement for movement in accordance with a number of desired degrees of freedom and the apparatus includes electromagnetic actuator means for driving the objective holder in accordance with the desired directions of movement. The bearing arrangement of the objective holder on the frame comprises electromagnetic bearing means for counteracting movements in accordance with at least one undesired degree of freedom.

Abstract: An electro-optical device for reading an information disc comprises an optical system which is movable relative to the disc by at least one electro-magnetic actuator. The optical system is supported by elongated members whose length is great relative to their thickness and which are pretensioned in the longitudinal direction by magnets which cooperate with each other via an air gap, enabling the use of very flexible supporting elements, for example guys which have a low resistance to bending and a very low mass.