Abstract: A record carrier on which information may be optically recorded and/or read, having a disc-shaped substrate with a spiral or concentric pattern of preformed tracks thereon and a radiation-sensitive layer extending over such track pattern. The tracks are in the form of ridges of substantially constant width and having a periodic radial wobble of a substantially constant mean frequency, which frequency is modulated by a position-information signal identifying the relative positions of the tracks in the track pattern. Apparatus for forming such a track pattern includes means for modulating the radial track wobble in accordance with the position-information signal.

Abstract: A record-carrier body is described, in which a user can record information by means of optical radiation, which record-carrier body has a relief structure of optically detectable servo-track portions and sector addresses. If the maximum width of the servo-track portions and the areas in the sector addresses is at least of the order of half the track period, the servo track portions can be tracked in an optimum manner and the sector-address areas and the information areas recorded by the user provide a read signal of high amplitude.

Abstract: A record carrier body is disclosed which is, provided with sector addresses and servo-track portions. The maximum width of the servo-track portions is at least 60% of the track period, in a direction transverse to the track direction, and is at least of the order of twice the maximum width of the sector-address areas. This makes it possible to obtain an improved tracking signal in addition to a satisfactory address signal. An improved information signal can be obtained by recording the information in the lands between the servo tracks. An apparatus is disclosed for recording sector addresses and servo track portions on the record carrier body.

Abstract: Apparatus is described for pre-forming a relief structure of optically detectable servo-track portions and sector addresses on the recording layer of a record-carrier body, the maximum transverse width of the servo-track portions and sector addresses being the same and exceeding approximately 1/2 the track period P.sub.r but being less than approximately 3/4 P.sub.r. This enables the servo-track portions to be tracked in an optimum manner by a radiation beam and the sector-addresses and the information recorded by the user produce a read-out signal of high amplitude.

Abstract: An optical record carrier body having a planar substrate with elongated generally parallel servo tracks thereon separated by lands extending there-between, the lands having a flat surface coplanar with the substrate surface and a recording layer thereon on which information can be recorded by a beam of radiation. Sector addresses are provided between successive segments of the lands, each sector address having optically detectable areas. The maximum transverse width of each servo track is at least 60% of the track period and at least twice the maximum transverse width of the sector address areas. Apparatus is disclosed for recording the servo tracks and sector addresses on a substrate, as well as apparatus for recording information on the successive segments of the lands between the sector addresses.

Abstract: A method and apparatus for scanning a plurality of concentric or spiral tracks on the surface of a rotating disc-shaped record carrier with a beam of radiation which may be modulated with information to be recorded on such surface. The beam is produced by an optical head and is directed at a target point on the record carrier by a positioning device and a deflection device, the positioning device radially displacing the optical head and the deflection device radially deflecting the radiation beam produced by the optical head. The composite resultant motion of the target point on the carrier is in a radial direction and includes a non-reversing component produced by the positioning device and a reciprocating component produced by the deflection device.