| 摘要 |
An optical data storage medium ( 10 ) for recording by means of a focused radiation beam ( 9 ) having a wavelength lambda is described. The beam enters through an entrance face ( 8 ) of the medium during recording. The medium at least comprises a substrate ( 1 ), including a guide groove with a depth g. The guide groove is present at the side of the substrate opposite to the entrance face. A recording stack ( 2, 3 ) of layers is present adjacent the substrate ( 1 ) at the side of the guide groove. The stack includes a write once recording layer ( 2 ) of a material having a complex refractive index ñ<SUB>R</SUB>=n<SUB>R</SUB>-i*k<SUB>R </SUB>at the wavelength lambda and having a thickness d<SUB>RG </SUB>in the groove portion and a thickness d<SUB>RL </SUB>in the portion between grooves. A non-metallic layer ( 3 ) of a substantially transparent material, is present adjacent the write-once recording layer ( 2 ). The groove depth g is in the range (lambda/655)*20 nm<g<(lambda/655)*140 nm with lambda expressed in nm. This range achieves a sufficient push-pull tracking signal and a sufficient modulation of recorded marks.
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