JPS63187427A - Optical pickup - Google Patents
Optical pickupInfo
- Publication number
- JPS63187427A JPS63187427A JP62018361A JP1836187A JPS63187427A JP S63187427 A JPS63187427 A JP S63187427A JP 62018361 A JP62018361 A JP 62018361A JP 1836187 A JP1836187 A JP 1836187A JP S63187427 A JPS63187427 A JP S63187427A
- Authority
- JP
- Japan
- Prior art keywords
- luminous flux
- reflected
- nearly
- optical
- laser light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000003287 optical effect Effects 0.000 title claims abstract description 40
- 230000004907 flux Effects 0.000 claims abstract description 15
- 239000010408 film Substances 0.000 abstract description 11
- 239000004065 semiconductor Substances 0.000 abstract description 7
- 239000010409 thin film Substances 0.000 abstract description 2
- 230000010287 polarization Effects 0.000 description 15
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000003989 dielectric material Substances 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Optical Head (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は光ディスクに記録された信号を再生するための
光ピックアップに係り、特にレーザ光源の発生するノイ
ズを低減するのに好適な光ピックアップに関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical pickup for reproducing signals recorded on an optical disk, and particularly relates to an optical pickup suitable for reducing noise generated by a laser light source. .
従来光ピックアップにおいてレーザ光源の発するレーザ
光の光学的雑音を低減する方法として、特公昭５６−５
２６０６号公報に開示されているようにル−ザ光源と対
物レンズとの光路中に４分の１改長板を設け、光ディス
クからの反射光の偏光方向を、レーザ光源の発するレー
ザ光の偏光方向に対して直交させる方法が知られている
。As a method for reducing the optical noise of the laser light emitted by the laser light source in conventional optical pickups,
As disclosed in Japanese Patent Application No. 2606, a quarter changer plate is provided in the optical path between the laser light source and the objective lens, and the polarization direction of the reflected light from the optical disk is changed to the polarization direction of the laser light emitted by the laser light source. A method of making the direction orthogonal is known.
上記従来技術に用いる４分の１波長板は人工水晶の結晶
から、その結晶軸に対して精密な角度で平板を切出し、
かつその平板の厚さを精密に制御することが必要である
ためはなはだ高価であるという問題があった。The quarter-wave plate used in the above conventional technology is made by cutting a flat plate from an artificial quartz crystal at a precise angle to the crystal axis.
Moreover, since it is necessary to precisely control the thickness of the flat plate, there is a problem that it is extremely expensive.
本発明の目的は安価な光学素子により光ディスクからの
反射光の偏光方向をレーザ光源の発Ｔるレーザ光の偏光
方向に対して直交させ、レーザ光の光学的雑音を防止し
た光ピックアップを提供することにある。An object of the present invention is to provide an optical pickup that uses an inexpensive optical element to make the polarization direction of reflected light from an optical disk perpendicular to the polarization direction of laser light emitted from a laser light source, thereby preventing optical noise in the laser light. There is a particular thing.
上記目的はレーザ光源と対物レンズとの元路中−に反射
ミラー？設け、反射ミラーにより反射した。Is the purpose of the above a reflection mirror in the path between the laser light source and the objective lens? was set up and reflected by a reflective mirror.
光束に略４分の１波長の位相差を発生させる反射膜を反
射ミラーの反射面に形成することにより達成される。This is achieved by forming a reflective film on the reflective surface of the reflective mirror that generates a phase difference of approximately 1/4 wavelength in the light beam.
上記した反射ミラーは４分の１波長板と同様な作用を行
なうために、レーザ光源の発するレーザ光の光学的雑音
を防止できる。Since the above-mentioned reflecting mirror performs the same function as a quarter-wave plate, it can prevent optical noise in the laser light emitted by the laser light source.
以下本発明の詳細を図に示す実施例により説明する。第
１図は本発明による光ピックアップの第１の実施例であ
り、第２図は第１図に示す元ピックアップの一部である
。レーザ光源である半導体レーザ１より出射した光束１
１はハーフミラ−２に入射する。ハーフミラ−の片面に
は光半透過膜２αが形成されており、光束１１の一部の
光束１２はハーフミラ−を透過するが残りの一部の光束
１３はハーフミラ−で反射してコリメータレンズ３によ
り略平行な光束に変換され、反射ミラー４の反射面に形
成された反射膜４αで反射する。反射ミラー４で反射し
た光束１４は対物レンズ５により光ディスク６上に集束
される。光ディスク６からの反射光は対物レンズ５によ
り略平行な光束１５に変換されて反射ミラー４の反射膜
４αで反射してコリメータレンズ３に入射する。フリメ
ータレンズ６を透過した光束１６はハーフミラ−２に入
射し、一部の光束１８はハーフミラ−で反射して半導体
レーザ１に戻るが、残りの１部の光束１７はハーフミラ
−２を透過して光検出器７に入射する。光検出器７の出
力信号より光ディスク乙に記録された情報信号、フォー
カス誤差信号、トラッキング誤差信号等が検出できるが
、本発明の本質とは関係がないために詳細な説明は省略
する。次に半導体レーザ１の出射する光束１１の光学的
雑音の低減方法について′説明する。光束１１は略直線
偏光であり、その偏光方向は半導体レーザ１の接合面に
平行な方向である。The details of the present invention will be explained below with reference to embodiments shown in the drawings. FIG. 1 shows a first embodiment of an optical pickup according to the present invention, and FIG. 2 shows a part of the original pickup shown in FIG. Luminous flux 1 emitted from a semiconductor laser 1 that is a laser light source
1 enters the half mirror 2. A light semi-transmissive film 2α is formed on one side of the half mirror, and a part of the light flux 12 of the light flux 11 passes through the half mirror, but the remaining part of the light flux 13 is reflected by the half mirror and is transmitted by the collimator lens 3. The light is converted into a substantially parallel light beam and reflected by a reflective film 4α formed on the reflective surface of the reflective mirror 4. The light beam 14 reflected by the reflection mirror 4 is focused onto the optical disk 6 by the objective lens 5. The reflected light from the optical disk 6 is converted by the objective lens 5 into a substantially parallel light beam 15, reflected by the reflective film 4α of the reflective mirror 4, and incident on the collimator lens 3. The light beam 16 that has passed through the frimeter lens 6 enters the half mirror 2. A part of the light beam 18 is reflected by the half mirror and returns to the semiconductor laser 1, but the remaining part of the light beam 17 passes through the half mirror 2. and enters the photodetector 7. Information signals, focus error signals, tracking error signals, etc. recorded on the optical disc B can be detected from the output signal of the photodetector 7, but detailed explanations thereof will be omitted since they are not related to the essence of the present invention. Next, a method for reducing optical noise in the light beam 11 emitted from the semiconductor laser 1 will be explained. The light beam 11 is substantially linearly polarized light, and its polarization direction is parallel to the bonded surface of the semiconductor laser 1.
半導体レーザの光束１１の光軸回りの位置は、反射ミラ
ー４に入射する光束１３の偏光方向が第２図の矢印Ａで
示されるようにＺ軸、Ｙ軸に対して略４５゜で交わる方
向となるように配置されている。ここで反射膜４αは光
束１３を効率よく反射するとともに、反射した光束１４
に対してレーザ光の波長の略４分の１波長の位相差を発
生させるように、たとえば誘電体等の薄膜で構成されて
いる。このため光束１４は矢印Ｂで示す円偏光となる。The position of the light beam 11 of the semiconductor laser around the optical axis is in the direction in which the polarization direction of the light beam 13 incident on the reflection mirror 4 intersects at approximately 45 degrees with the Z-axis and the Y-axis, as shown by arrow A in FIG. It is arranged so that. Here, the reflective film 4α efficiently reflects the light beam 13, and also reflects the reflected light beam 14.
For example, it is made of a thin film such as a dielectric material so as to generate a phase difference of approximately 1/4 of the wavelength of the laser beam. Therefore, the light beam 14 becomes circularly polarized light as indicated by arrow B.
光ディスク６からの反射光１５は矢印Ｃで示すように矢
印Ｂとは逆回りの円偏光となり、反射ミラー４で反射し
た光束１６は、矢印Ａと略直交する矢印りに示す略直線
偏光となる。その結果、光束１１と光束１８との偏光方
向は略直交することとなり、レーザ光の光学的雑音を防
止することができる。本実施例においては反射ミラー４
に入射する光束１６の偏光方向はＺ軸、 Ｙ４ｑｌｌ！
に対して略４５°で交わる矢印Ａの方向としたが、これ
は矢印りの方向でも良く、このときは光ディスク６から
の反射光の光束１６の偏光方向は矢印Ａの方向となる。Reflected light 15 from the optical disc 6 becomes circularly polarized light in the opposite direction to arrow B, as shown by arrow C, and light beam 16 reflected by reflection mirror 4 becomes substantially linearly polarized light, as shown by arrow A, which is substantially perpendicular to arrow A. . As a result, the polarization directions of the light beam 11 and the light beam 18 are substantially orthogonal, and optical noise in the laser beam can be prevented. In this embodiment, the reflecting mirror 4
The polarization direction of the light beam 16 incident on is the Z axis, Y4qll!
Although the direction of the arrow A intersects at approximately 45 degrees with respect to the optical disk 6, the direction of the arrow A may be used instead.In this case, the polarization direction of the light beam 16 of the reflected light from the optical disk 6 will be in the direction of the arrow A.
更に光束１３の偏光方向はＹ軸と平行または垂直、また
は任意の角度でもよい。この場合は光束１６の偏光方向
に対応して九反射ミラー４が略４分の１波長の位相差を
発生さ。Further, the polarization direction of the light beam 13 may be parallel or perpendicular to the Y axis, or may be at any angle. In this case, nine reflecting mirrors 4 generate a phase difference of approximately 1/4 wavelength corresponding to the polarization direction of the light beam 16.
せて光束１４が円偏光となるように反射膜４α２栴成。In addition, a reflective film 4α2 is formed so that the light beam 14 becomes circularly polarized light.
する。do.
第３図は本発明による元ピックアップの第２の。FIG. 3 shows the second original pickup according to the present invention.
実施例であり、第１ｐ４と同一な部品には同一な番号が
付しである。第３図は反射ミラー８のみが第１図と異な
る。反射ミラー８の反射膜８αは、その入射光の光束１
３の偏光方向に対応して反射光の光束１４に４分の１ｔ
ＪＩ長の位相差ご発生させて光束１４が同偏光となるよ
うに構成されている。This is an example, and the same parts as in the first p4 are given the same numbers. FIG. 3 differs from FIG. 1 only in the reflection mirror 8. The reflective film 8α of the reflective mirror 8 reflects the luminous flux 1 of the incident light.
Corresponding to the polarization direction of 3, the reflected light beam 14 has a quarter t.
A phase difference of JI length is generated so that the light beams 14 have the same polarization.
第４図は本発明による元ピックアップの第３の実施例で
あり、第１図と同一な部品には同一な番号が付しである
。第４図においてはその反射光に対して４分の１波長の
位相差を発生させる反射ミラーの機能をハーフミラ−９
が備えている。ハーフミラ−９の光半透過膜９αは、そ
の入射光の光束１１の偏光方向に対応して、反射光の光
束１３に４分の１波長の位相差を発生させて光束１３？
！−円偏光にするように構成されている。その結果光束
１１と光束１８との偏光方向は直交してレーザ光の光学
的雑音を防止できる。FIG. 4 shows a third embodiment of the original pickup according to the present invention, in which the same parts as in FIG. 1 are given the same numbers. In Figure 4, the function of the reflecting mirror that generates a phase difference of 1/4 wavelength for the reflected light is shown in the half mirror 9.
is equipped. The light semi-transmissive film 9α of the half mirror 9 generates a quarter-wave phase difference in the reflected light beam 13 in accordance with the polarization direction of the incident light beam 11, so that the light beam 13?
! - configured to circularly polarize light; As a result, the polarization directions of the light beam 11 and the light beam 18 are orthogonal, and optical noise in the laser beam can be prevented.
本発明によれば、レーザ光源と対物レンズとの光路中に
反射ミラーを設け、反射ミラーにより反射した光束に略
４分の１波長の位相差を発生させる反射膜を反射ミラー
の反射面に形成しているために、高価な４分の１波長板
を使用することなしにレーザ光の光学的雑音を防止でき
る。According to the present invention, a reflective mirror is provided in the optical path between the laser light source and the objective lens, and a reflective film that generates a phase difference of approximately 1/4 wavelength in the light beam reflected by the reflective mirror is formed on the reflective surface of the reflective mirror. Therefore, optical noise in the laser beam can be prevented without using an expensive quarter-wave plate.
第１図は本発明による光ピックアップ第１の実施例、第
２図は第１図の光ピックアップの一部、第３図、第４図
は本発明による光ピックアップのそれぞれ第２．第３の
実施例。
１・・・半導体レーザ、
２．９・・・ハーフミラ−１
４，８・・・反射ミラー、
５・・・対物レンズ、
６・・・光ディスク、
７・・・光検出器。
第 １ 国FIG. 1 shows a first embodiment of the optical pickup according to the present invention, FIG. 2 shows a part of the optical pickup shown in FIG. 1, and FIGS. 3 and 4 show second embodiments of the optical pickup according to the invention. Third example. DESCRIPTION OF SYMBOLS 1... Semiconductor laser, 2.9... Half mirror-1 4, 8... Reflection mirror, 5... Objective lens, 6... Optical disk, 7... Photodetector. 1st country
Claims (1)
光ディスク上に集束するための対物レンズと、光ディス
クからの反射光束を検出するための光検出器とを備えた
光ピックアップにおいて、レーザ光源と対物レンズとの
光路中に反射ミラーを設け、反射ミラーにより反射した
光束に略４分の１波長の位相差を発生させる反射膜を反
射ミラーの反射面に形成したことを特徴とする光ピック
アップ。1. In an optical pickup equipped with a laser light source, an objective lens for focusing the laser light emitted by the laser light source onto an optical disk, and a photodetector for detecting the reflected light flux from the optical disk, the laser light source and the objective An optical pickup characterized in that a reflective mirror is provided in an optical path with a lens, and a reflective film is formed on the reflective surface of the reflective mirror to generate a phase difference of approximately 1/4 wavelength in the light beam reflected by the reflective mirror.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62018361A JPS63187427A (en) | 1987-01-30 | 1987-01-30 | Optical pickup |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62018361A JPS63187427A (en) | 1987-01-30 | 1987-01-30 | Optical pickup |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS63187427A true JPS63187427A (en) | 1988-08-03 |
Family
ID=11969554
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62018361A Pending JPS63187427A (en) | 1987-01-30 | 1987-01-30 | Optical pickup |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS63187427A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008305525A (en) * | 2007-06-11 | 2008-12-18 | Sony Corp | Optical pickup and optical disk |
| CN101964197A (en) * | 2009-07-24 | 2011-02-02 | 三洋电机株式会社 | Optical picking-up device |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5595912A (en) * | 1979-01-11 | 1980-07-21 | Pioneer Video Corp | Polarizing beam splitter |
| JPS58169351A (en) * | 1982-03-31 | 1983-10-05 | Pioneer Video Corp | Optical information reading device |
| JPS58208701A (en) * | 1982-05-28 | 1983-12-05 | Sano Kiko Kk | Beam splitter |
-
1987
- 1987-01-30 JP JP62018361A patent/JPS63187427A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5595912A (en) * | 1979-01-11 | 1980-07-21 | Pioneer Video Corp | Polarizing beam splitter |
| JPS58169351A (en) * | 1982-03-31 | 1983-10-05 | Pioneer Video Corp | Optical information reading device |
| JPS58208701A (en) * | 1982-05-28 | 1983-12-05 | Sano Kiko Kk | Beam splitter |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008305525A (en) * | 2007-06-11 | 2008-12-18 | Sony Corp | Optical pickup and optical disk |
| CN101964197A (en) * | 2009-07-24 | 2011-02-02 | 三洋电机株式会社 | Optical picking-up device |
| JP2011028807A (en) * | 2009-07-24 | 2011-02-10 | Sanyo Electric Co Ltd | Optical pickup device |
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