| 摘要 |
PCT No. PCT/FR90/00234 Sec. 371 Date Nov. 15, 1990 Sec. 102(e) Date Nov. 15, 1990 PCT Filed Apr. 10, 1990 PCT Pub. No. WO90/13117 PCT Pub. Date Nov. 1, 1990.A device for reading an optical recording medium which includes a source (1) for emitting a first light beam (F1) along a main optical axis (01); a beam splitter (2) to direct, along the main optical axis, the first light beam towards the surface of the recording medium (5), and to split a second beam (F2) obtained by reflection of the first beam on the surface of the recording medium so as to form a third beam (F'3) directed along a secondary optical axis; a focusing lens (4) between the splitter (2) and the surface of the recording medium to focus the first beam on the surface; a mask to introduce a dissymmetry into the third beam; and at least one detection device (7) receiving at least one part of the third beam (F'3) and giving at least one electrical signal expressing the detection made. In this device, the mask is formed by part of an external surface of the light-emitting source (1), and the splitter (2) is positioned and made so that the mask is in the focusing plane of the third beam (F'3).
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