发明授权
US07079470B2 Diffraction device for reading and/or writing a record carrier 失效
用于读取和/或写入记录载体的衍射装置

Diffraction device for reading and/or writing a record carrier
摘要:
A device for reading and/or writing a record carrier (13), the device comprising converging means (35, 45, 47, 106, 108) for focusing a radiation beam (27, 101) originating from a radiation source (25) on the record carrier (13). The converging means comprises polarization means (103) and a diffraction grating (107) of birefringent material. Dependent on the direction of polarization, the radiation beam (101) is focused on one of two possible surfaces corresponding to DVD and DVR, respectively. A diffraction grating (107) is present in a central area of the radiation beam (101) and causes diffraction of a first order for one direction of polarization of the radiation beam (101) and diffraction of a second, higher, order for a second direction of polarization of the radiation beam (101). The diffraction grating (107) is made of birefringent material.
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