US 6,661,765 B2Granted

Optical pickup apparatus

AssigneeOlympus Optical Co., Ltd.

InventorsJunichi Nakano, Nobuyoshi Iwasaki, Daisuke Matsuo, Shohei Kobayashi

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Abstract

A laser beam emitted from a laser source provided at a silicon substrate passes through a hologram element formed of a translucent flat plate and a grating, thereby being subjected to NA conversion executed by an NA converting lens, passing through a polarizing film of a polarization beam splitter, and converging onto a magneto-optical disk via a collimator lens and an objective. A part of back-reflection from the magneto-optical disk, which is reflected by a polarizing film of the polarization beam splitter, is reflected by a reflection surface of the splitter, then branched into two polarized light beams by a Wollaston prism, and guided to one light receiving element group. On the other hand, another part of the back-reflection, which passes through the polarization beam splitter, is branched into two beams by the hologram element and guided to the other light receiving element groups.

Claims18

Dependent claims

An optical pickup apparatus for executing at least one of data recording and reproduction by applying a laser beam to a data recording medium, comprising:

a semiconductor substrate having a main surface;
a light source for emitting a laser beam in a direction substantially perpendicular to the main surface of the semiconductor substrate;
an NA converter for receiving the laser beam emitted from the light source and for outputting the laser beam so that a divergent angle of the outputted laser beam is smaller than a divergent angle of the received laser beam, wherein the NA converter has a numerical aperture between 0.15 and 0.25 on a side of the light source;
an objective opposed to the data recording medium;
a first beam branching unit for permitting one of transmission therethrough and reflection therefrom of the laser beam outputted from the NA converter to thereby guide the laser beam to the data recording medium via the objective so that the laser beam reflects from the data recording medium, wherein the first beam branching unit also transmits therethrough and reflects therefrom a part of and another part of the laser beam reflecting from the data recording medium and then passing through the objective, respectively, thereby branching the laser beam in two directions;
and
a first light receiving element provided at the semiconductor substrate for receiving the laser beam branched by the first beam branching unit.

4 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/748,940Filed 27 Dec 2000
Priority: JP 2000-01072119 Jan 2000
Published: US 2001/0008538 A119 Jul 2001
Granted: 9 Dec 2003
Term ends: Not estimatedThe source records don’t support an estimate.

Classification13 codes

G11B 7/139
Means for guiding the beam from the source to the record carrier or from the record carrier to the detector: numerical aperture control means
G11B 7/123
Heads, e.g. forming of the optical beam spot or modulation of the optical beam: integrated head arrangements, e.g. with source and detectors…
G11B 7/1353
Means for guiding the beam from the source to the record carrier or from the record carrier to the detector: diffractive elements, e.g. holograms…
G11B 7/1356
Means for guiding the beam from the source to the record carrier or from the record carrier to the detector: double or multiple prisms, i.e.…