Abstract: When recording information in tracks or in a two-dimensional pattern care must be taken not to irradiate the adjacent tracks or pits. This results in a loss of data density on the recording medium because of the track pitch or pit distance that must be observed. A reduction in track pitch is possible to the point where the focused spot of the laser also irradiates the adjacent land area and tracks or pits. This increases the achievable data density of the recording medium. By using grooves and/or by using a dye with special absorption characteristics the effect of the irradiation of the adjacent tracks or pits can be reduced, effectively only recording marks in the desired location.

Abstract: The invention relates to a method of reducing the area on an optical medium used by an optimum write parameter control procedure (OPC) and to an apparatus for carrying out the method. The method makes use of a reference data pattern written using a reference set of write parameters, and a measurement data pattern written using a measurement set of write parameters.

Abstract: An optical recording method is disclosed for writing a two-dimensional data pattern in a phase-change disc, i.e. a optical disc with a phase change material. The effect of thermal cross-erase is used by using the sides of the diffraction limited laser spot to heat up the adjacent track such that previously written data are partly erased. The amount of erasure is well controlled by the applied write strategy and determines the final mark size by erasing the side of the mark facing the laser spot. The mark can be initially written with a laser spot that results in a mark size that is larger than desired and subsequently, when marks in an adjacent track are being recorded, reduced in size by erasing the sides of the mark by irradiating the sides of the mark with the sides of the diffraction limited laser spot that is focused on the adjacent track.

Abstract: The present invention relates to a method and a corresponding apparatus for recording marks representing data in an information layer of a write-once record carrier by irradiating the information layer by means of a radiation beam, wherein a mark is written by a write pulse (10) and said information layer comprises an organic material. In order to reduce pit deterioration which occurs when marks are written after a short space, in particular at high speed write once recording, it is proposed according to the present invention that the write pulse (10) comprises a front portion (21, 22) having a write power level increasing with time.

Abstract: The invention relates to a method of recording marks representing data (1a) in a information layer of a record carrier by irradiating the information layer by means of a pulsed radiation beam, a mark being written by a sequence (1c) of one or more write pulses, said information layer having a phase reversibly changeable between a crystalline phase and an amorphous phase. At least one of the write pulses in the sequence has a gradually rising front edge. This may be either a staircase-shaped write pulse (11) or a write pulse having a write power level which cotinuously increases as a function of time. A write strategy applying such a method is advantageous for recording marks in multi-layer record carriers and in record carriers being recorded at high recording speeds. The invention also relates ta recording apparatus capable of carrying out the method.

Abstract: An optical data storage medium (10) is described for read out using a focused radiation beam (19) with a wavelength ? sand a Numerical Aperture NA. The medium has a substrate (11) and a first stack of layers named L0 (12) comprising a first information layer and optionally at least one further stack of layers named Ln (13), comprising a further information layer. A radiation beam (19) transparent spacer layer (14) is present between each of L0 and Ln. A transmission stack named TS0 with a thickness dTS0 contains all layers between L0 (12) and an entrance face (16) of the medium (10). A transmission stack named TSn with a thickness dTSn contains all layers between Ln (13) and the entrance face (16). The maximum deviation of dTS0 and when applicable dTSn does not exceed a predetermined value DEVdTS0 or DEVdTSn, measured over the information area of the medium (10) and this value is set in dependency of ? and NA.

Abstract: The present invention relates to a method of recording marks representing data in an information layer of a record carrier by irradiating the information layer by means of a pulsed radiation beam, each mark being written by a sequence of pulses, the recorded marks being erasable by irradiating the information layer with an erase radiation beam. In order to achieve a reduction of the temperature of a transparent heat sink of a dual-layer optical recording medium without compromising the direct overwrite of old data, it is proposed according to the present invention that said erase radiation beam has a first erase power level (e1) for a first erase period (t1), a second erase power level (e2) higher than or equal to said first erase power level (e1) for a second erase period (t2), and a third erase power level (e3) lower than said second erase power level (e2) for a third erase period (t3).

Abstract: A dual-stack optical data storage medium (20) is described for read out using a focused radiation beam (29) with a wavelength of 400-410 nm and a Numerical Aperture (NA) of 0.84-0.86. The medium has a substrate (21) and a first stack of layers named L0 (22) comprising a first information layer and a second stack of layers named L1 (23), comprising a second information layer. A radiation beam (29) transparent spacer layer (24) is present between L0 and L1. A transmission stack named TS0 with a thickness dTS0 and an effective refractive index nTS0 contains all layers between L0 and an entrance face (26) of the medium (20). A transmission stack named TS1 with a thickness dTS1 and an effective refractive index nTS1 containing all layers between L1 and the entrance face (26). The spacer layer (24) has a thickness selected from the range 20-30 ?m, the thickness dTS0 in dependence on the refractive index nTS0 and the thickness dTS1 in dependence on the refractive index nTS0 are within a specified area.