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EP0339722A1
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Arrangement for optically scanning a magneto-optical carrier
Assignee: Koninklijke Philips NV
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Filing: 1989-04-20
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Granted: —
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Expires: 2009-04-20
Abstract
Abstract The arrangement comprises an integrated beam-separating element comprising a supporting body (30) on which both a semi-transparent mirror (22) and a polarization-sensitive beam-splitting layer (26) are provided. The layer (26) splits the beam (25) coming from the magneto-optical record carrier into two sub-beams (27 and 28) which are orthogonally polarized. The two sub-beams (27 and 28) are incident on a single multiple photodiode (44). The supporting body may be made of a birefringent material and in that case the beam-splitting layer may be dispensed with.
Inventors
- 👤 Peter Ferdinand Greve
- 👤 Albert Smid
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 05:29
CPC Classifications
G; G11; G11B; G11B11/00; G11B11/10; G11B11/105; G11B11/10532; G11B7/00; G11B7/12; G11B7/135; G11B7/1395
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
180 words
An arrangement for optically scanning a radiation-reflecting information plane of a magneto-optical record carrier, said arrangement comprising a radiation source unit for supplying a linearly polarized scanning beam, an objective system for focusing the scanning beam to a scanning spot in the information plane, a beam-separating element arranged in the radiation path between the radiation source unit and the scanning spot for separating the scanning beam originating from the radiation source unit and the radiation beam reflected from the information plane, means for splitting the reflected radiation beam into two sub-beams and a radiation-sensitive detection system for converting the sub-beams into electric signals, characterized in that the beam-separating element comprises a transparent supporting body having a first and a second surface which are substantially parallel to each other and whose normals extend at an acute angle to the chief ray of the incident radiation beams, a semi-transparent mirror being arranged on the first surface for separating the scanning beam and the reflected radiation beam, said beam-separating element being further adapted to split the reflected beam into two orthogonally polarized sub-beams.
Claim 2
Dependent Claim
180 words
An arrangement for optically scanning a radiation-reflecting information plane of a magneto-optical record carrier, said arrangement comprising a radiation source unit for supplying a linearly polarized scanning beam, an objective system for focusing the scanning beam to a scanning spot in the information plane, a beam-separating element arranged in the radiation path between the radiation source unit and the scanning spot for separating the scanning beam originating from the radiation source unit and the radiation beam reflected from the information plane, means for splitting the reflected radiation beam into two sub-beams and a radiation-sensitive detection system for converting the sub-beams into electric signals, characterized in that the beam-separating element comprises a transparent supporting body having a first and a second surface which are substantially parallel to each other and whose normals extend at an acute angle to the chief ray of the incident radiation beams, a semi-transparent mirror being arranged on the first surface for separating the scanning beam and the reflected radiation beam, said beam-separating element being further adapted to split the reflected beam into two orthogonally polarized sub-beams.
Claim 3
Dependent Claim
40 words
An arrangement as claimed in Claim 1, characterized in that a reflecting layer which is sensitive to the polarization direction is provided on the first surface for splitting the beam reflected in the information plane into two orthogonally polarized sub-beams.
Claim 4
Dependent Claim
44 words
An arrangement as claimed in Claim 1, characterized in that a reflecting layer which is sensitive to the polarization direction is provided on the second surface of the supporting body for splitting the beam reflected in the information plane into two orthogonally polarized sub-beams.
Claim 5
Dependent Claim
42 words
An arrangement as claimed in Claim 2 or 3, characterized in that the radiation-sensitive detection system comprises two sub-systems for detecting the two orthogonally polarized sub-beams and in that the two sub-systems are arranged on the same side of the supporting body.
Claim 6
Dependent Claim
17 words
An arrangement as claimed in Claim 1, characterized in that the supporting body comprises a birefringent material.
Claim 7
Dependent Claim
29 words
An arrangement as claimed in Claim 1, 2, 3, 4 or 5, characterized in that at least one prism is arranged on a surface of the transparent supporting body.
Claim 8
Dependent Claim
34 words
An arrangement as claimed in Claim 4 or 5 in which the radiation-sensitive detection system comprises a multiple photodiode, characterized in that the two sub-beams are incident on different areas of the multiple photodiode.
Claim 9
Dependent Claim
70 words
An arrangement as claimed in any one of the preceding Claims in which the radiation source unit and the radiation-sensitive detection system are fixedly connected together, characterized in that the radiation source unit and the radiation-sensitive detection system are fixedly connected to the supporting body and in that an optical element for aligning the scanning beam is arranged in the radiation path between the radiation source and the beam-separating element.
Claim 10
Dependent Claim
74 words
An arrangement as claimed in any one of Claims 1 to 7 in which the radiation source unit and the radiation-sensitive detection system are fixedly connected together, characterized in that the radiation source unit and the radiation-sensitive detection system are fixedly connected to the supporting body and in that an optical element for aligning the sub-beam is arranged in the radiation path of a sub-beam between the beam-separating element and the radiation-sensitive detection system.
References Cited (Backward Citations)
EP0199565A2
Cited
EP0208538A1
Cited
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