Abstract: A target structure including a periodic structure is formed on a substrate. An image of the target structure is detected while illuminating the target structure with a beam of radiation, the image being formed using a first part of non-zero order diffracted radiation while excluding zero order diffracted radiation. Intensity values extracted from a region of interest within the image are used to determine a property of the periodic structure. A processing unit recognizes locations of a plurality of boundary features in the image of the target structure to identify regions of interest. The number of boundary features in each direction is at least twice a number of boundaries of periodic structures within the target structure. The accuracy of locating the region is greater than by recognizing only the boundaries of the periodic structure(s).

Abstract: A target structure including a periodic structure is formed on a substrate. An image of the target structure is detected while illuminating the target structure with a beam of radiation, the image being formed using a first part of non-zero order diffracted radiation while excluding zero order diffracted radiation. Intensity values extracted from a region of interest within the image are used to determine a property of the periodic structure. A processing unit recognizes locations of a plurality of boundary features in the image of the target structure to identify regions of interest. The number of boundary features in each direction is at least twice a number of boundaries of periodic structures within the target structure. The accuracy of locating the region is greater than by recognizing only the boundaries of the periodic structure(s).

Abstract: A rewritable optical record carrier comprising a first substrate carrying a first recording stack of layers, which recording stack comprises, a first dielectric layer, a recording layer comprising a phase-change recording material, a second dielectric layer, and a metal mirror layer. In order to achieve a maximum R*M said first dielectric layer has a thickness d1 in the range of 20 nm to 50 nm, and said second dielectric layer has a thickness d2 according to the relation 0.0225*d22?2.6572*d2+173.3 (nm)<d1<0.0225*d22?2.6572*d2+213.3 (nm) when the mirror layer comprises aluminum, or a thickness d2 according to the relationship 0.0191*d22?2.0482*d2+149.6 (nm)<d1<0.0191*d22?2.0482*d2+189.6 (nm) when the mirror layer comprises silver.

Abstract: A description is given of a multi-stack optical data storage medium (20) for rewritable recording using a focused radiation beam (30) entering through an entrance face (16) of the medium (20) during recording. The medium (20) has a substrate (1). Deposited on a side thereof is a first recording stack (2) with a phase-change type recording layer (6). The first recording stack (2) is present at a position most remote from the entrance face (16). At least one further recording stack (3), with a phase-change type recording layer (12) is present closer to the entrance face (16) than the first recording stack (2). A metal reflective layer of Cu, transparent for the radiation beam (30), is present in the further recording stack (3) and has a thickness between 2 and 10 nm. A transparent spacer layer (9) is present between the recording stacks (2, 3).

Abstract: A rewritable optical record carrier comprising a first substrate carrying a first recording stack of layers, which recording stack comprises, a first dielectric layer, a recording layer comprising a phase-change recording material, a second dielectric layer, and a metal mirror layer. In order to achieve a maximum R*M said first dielectric layer has a thickness d1 in the range of 20 nm to 50 nm, and said second dielectric layer has a thickness d2 according to the relation 0.0225*d22?2.6572*d2+173.3 (nm)<d1<0.0225*d22?2.6572*d2+213.3 (nm) when the mirror layer comprises aluminum, or a thickness d2 according to the relationship 0.0191 *d22?2.0482*d2+149.6 (nm)<d1<0.0191*d22?2.0482*d2+189.6 (nm) when the mirror layer comprises silver.

Abstract: The present invention relates to a multi-stack optical data storage medium (10). The medium comprises a first substrate (1a) with present on a side thereof a first recording stack (13) named L0, a second substrate (1b) with present on a side thereof a second recording stack (12) named L1 comprising a recordable type L1 recording layer (4) having a thickness tRL1 and a complex refractive index n??i*k? at a wavelength ?. A second reflective layer (6) is present adjacent the L1 recording layer (4) at a side most remote from a radiation beam (20) entrance face (11) of the medium. The second recording stack L1 (12) is present at a position closer to the entrance face (11) than the L0 recording stack (13). A radiation beam transparent spacer layer (9) is sandwiched between the recording stacks (12, 13).

Abstract: A rewritable optical data storage medium (20) for high-speed recording by means of a focused radiation beam (10) is described. The medium (20) comprises a substrate (1) carrying a stack (2) of layers. The stack (2) comprises a first dielectric layer (3), a second dielectric layer (5), and a recording layer (4) of a phase-change material of an alloy comprising Sb and Te. The recording layer (4) is interposed between the first dielectric layer (3) and the second dielectric layer (5). The alloy additionally contains 2-10 at. % of Ga, by which a significant improvement of the maximum data rate during direct overwrite is achieved. By furthermore adding 0.5-4.0% of Ge to the alloy the archival life stability is enhanced.

Abstract: A description is given of a rewritable optical storage medium (10) comprising a substrate (1), a first dielectric layer (2), a phase-change recording layer (3) on the basis of Ge—Sb—Te, a second dielectric layer (4), and a metal reflective layer (5). The recording layer (3) is an alloy having the composition GexSbyTez, in atom %, wherein 0<x<15, 50<y<80, 10<z<30 and x+y+z=100, and the recording layer (3) has a thickness selected from the range of 7 to 18 nm. Such a medium (10) is suitable for high data rate recording with a data rate of larger than 25 Mb/s while the recording layer (6) remains relatively thin having a relatively high optical transparency.

Abstract: A description is given of a multi-stack optical data storage medium (20) for rewritable recording using a focused radiation beam (30) entering through an entrance face (16) of the medium (20) during recording. The medium (20) has a substrate (1). Deposited on a side thereof is a first recording stack (2) with a phase-change type recording layer (6). The first recording stack (2) is present at a position most remote from the entrance face (16). At least one further recording stack (3), with a phase-change type recording layer (12) is present closer to the entrance face (16) than the first recording stack (2). A metal reflective layer of Cu, transparent for the radiation beam (30), is present in the further recording stack (3) and has a thickness between 2 and 10 nm. A transparent spacer layer (9) is present between the recording stacks (2, 3).