JPS5864650A - Optical information reproducer - Google Patents
Optical information reproducerInfo
- Publication number
- JPS5864650A JPS5864650A JP56164468A JP16446881A JPS5864650A JP S5864650 A JPS5864650 A JP S5864650A JP 56164468 A JP56164468 A JP 56164468A JP 16446881 A JP16446881 A JP 16446881A JP S5864650 A JPS5864650 A JP S5864650A
- Authority
- JP
- Japan
- Prior art keywords
- light
- optical
- light beam
- information medium
- beam spot
- 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
Classifications
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
- G11B7/12—Heads, e.g. forming of the optical beam spot or modulation of the optical beam
Landscapes
- Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Head (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、光ビームにて凹凸状態に記録した情報を再生
する光学的情報再生装置に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical information reproducing apparatus that reproduces information recorded in an uneven manner using a light beam.
この種の装置では、＄１図、第２図のように透明樹脂１
′の底面に凹凸状ビット２′を形成し、この凹凸２′部
分に金属蒸着３′をした情報媒中′を使用し、前記凹凸
２′の光ビーム５′に対する光干渉による回折効果を利
用して情報の読み取りを行うものであるが、この読み取
りを行う光学的ピックアップ装置の前記情報媒体に対す
る角度ずれ、また情報媒体の重付誤差等の情報媒体の角
度誤差によ抄、光ビーム５′の入射角が光ビーム５″の
ように変化するとコマ収差が発生して情報媒体へ照射さ
れるビームスポット６′の光量の円形分布（第３図）が
大きくくずれ、スポットの光量が楕円形（第４図）にス
ポット径６′が拡大される。前記コマ収差の大小は、情
報媒体４′に光ビーム５′を一定径のビームスポット６
′に集束させる集束レンズの開口数（以下Ｎ、入と呼ぶ
）の大小に関係してお妙、コマ収差を小さくするために
はＮ、 Ａ、を小さくすれば良い。ところが前記ビーム
スポットの径φと、光ビーム５′の波長λと、Ｎ、 Ａ
、との関係はφＸλ／ Ｎ、 Ａ、 −−−
−−−−（１）の関係にあ怜、前述の如く、Ｎ、ム、を
小さくするとφが大きくなることになる。、このように
ビームスポット６′の径が大きくなると云うことは、ビ
ット２′により形成される情報トラック７′の数本にビ
ームスポット６′がまたがる惧れにつながり、８Ｎ比の
低下の原因になる。熱論上記の関係式から波長λを小さ
くすることも考えられるが、現在この種の装置に使用さ
れるレーザーダイオードの発生光ビームの波長は７８０
ｎｍｍと規格化されてお９、またレーザーダイオードの
波長を下げると、生産性、寿命、温度特性が著しく劣化
し、波長λをむやみに下けられないのが現況である。従
って情報媒体の角度誤差を極力少なくするため、ピック
アップ装置及び情報媒体の保持には細心の注意を払う必
要があった。In this type of device, transparent resin 1 is used as shown in Figure 1 and Figure 2.
A concave-convex bit 2' is formed on the bottom surface of the information medium ', and a metal vapor deposition 3' is applied to the concave-convex part of the concave-convex part of the information medium ', and the diffraction effect due to optical interference of the concavo-convex part 2' with respect to the light beam 5' is utilized. However, due to the angular deviation of the optical pickup device that performs this reading with respect to the information medium, and the angular error of the information medium such as the weighting error of the information medium, the light beam 5' When the incident angle of the light beam 5'' changes, comatic aberration occurs, and the circular distribution of the light intensity of the beam spot 6' (Fig. 3) irradiated onto the information medium is greatly distorted, and the light intensity of the spot becomes elliptical (Fig. 3). (Fig. 4), the spot diameter 6' is enlarged.The magnitude of the comatic aberration is determined by
It may be related to the numerical aperture (hereinafter referred to as "N") of the focusing lens that focuses the light on . However, the diameter φ of the beam spot, the wavelength λ of the light beam 5', N, A
, the relationship is φXλ/N, A, ---
---Unfortunately, as mentioned above, as N and M are reduced, φ becomes larger. If the diameter of the beam spot 6' increases in this way, there is a risk that the beam spot 6' will span several of the information tracks 7' formed by the bit 2', causing a decrease in the 8N ratio. Become. Thermal theory From the above relational expression, it is possible to reduce the wavelength λ, but the wavelength of the light beam generated by the laser diode currently used in this type of device is 780 nm.
The current situation is that the wavelength λ cannot be lowered unnecessarily because the productivity, life span, and temperature characteristics of a laser diode will be significantly degraded if the wavelength of the laser diode is lowered. Therefore, in order to minimize the angular error of the information medium, it is necessary to pay close attention to the pickup device and the holding of the information medium.
また上記レーザーダイオードは、温度によって発光部の
屈折率変化により、波面が時間と共に変化をし、光ビー
ムの光強度分布が変化する（第５図のＮからＮ′へ）。Further, in the laser diode, the wavefront changes with time due to a change in the refractive index of the light emitting part depending on the temperature, and the light intensity distribution of the light beam changes (from N to N' in FIG. 5).
すると複数の光電素子より成る、所謂差動型光電素子８
′のように各光電素子の光普差により諸信号を検出する
ものでは、光ビームの光強度分布の変化が、差動型光電
素子の検出信号に直流バイアス的変化を与え（第６図（
ａ）から第６図（ｂ） ） 、前記ビームスポットの各
種制御信号の検出に悪影響を与えるという欠点が生じる
。Then, a so-called differential photoelectric element 8 consisting of a plurality of photoelectric elements
In the case where various signals are detected by the optical aberrations of each photoelectric element, as shown in Fig.
(a) to FIG. 6(b)), there arises a drawback that the detection of various control signals of the beam spot is adversely affected.
本発明は上記の点に鑑みて、情報媒体の角度誤差による
ビームスポットの形状変化を極力少なくし、またレーザ
ーダイオードからの光ビームの光強度分布が温度によっ
て変化しても各種制御信号の検出に悪影響を与えないよ
うにした光学的情報再生装置を提供することを目的とす
る。In view of the above points, the present invention minimizes changes in the shape of the beam spot due to angular errors in the information medium, and also detects various control signals even if the light intensity distribution of the light beam from the laser diode changes due to temperature. It is an object of the present invention to provide an optical information reproducing device that does not have any adverse effects.
以下本発明の好適な実施例を図面に従い説明する。Preferred embodiments of the present invention will be described below with reference to the drawings.
第７図に示すようにル−ザーダイオードｌがら発する光
ビーム２は、レンズ８、偏光ビームスプリッタ−４，４
分の１波長板５、反射体６及び集束レンズ７を経て情報
媒体８上にビームスポット９として集束される。そして
情報媒体８の凹凸ビットの光干渉による回折を受けた反
射光ビームｌＯは、前記集束レンズ７、反射体６．４分
の１波長板５にて偏光ビームスプリッタ−４に達し、前
記光ビーム２０光軸と直角方向に偏向され、レンズ１１
を経て、差動型光電素子１２の受光面を照射する。As shown in FIG.
The beam is focused as a beam spot 9 onto an information medium 8 through a half-wave plate 5, a reflector 6, and a focusing lens 7. The reflected light beam 10, which has undergone diffraction due to optical interference of the concave and convex bits of the information medium 8, reaches the polarizing beam splitter 4 through the focusing lens 7 and the reflector 1/4 wavelength plate 5, and the light beam 20 is deflected in a direction perpendicular to the optical axis, and the lens 11
After that, the light receiving surface of the differential photoelectric element 12 is irradiated.
この際、前記レーザーダイオード１から情報媒体８に達
する光ビーム２の光路中で、しかも光ビーム２の光軸Ｘ
中央部の光を遮断する０第７図においては集束レンズ７
の中央部に光遮断部１８を形成した。At this time, in the optical path of the light beam 2 reaching the information medium 8 from the laser diode 1, and in addition, the optical axis
In Figure 7, the focusing lens 7 blocks the light in the center.
A light blocking portion 18 was formed in the center of the.
このため集束レンズ７は輪帯開口の状態となる。Therefore, the focusing lens 7 is in a state of annular aperture.
一般に、第８図（ａ）のような円形開口の状態と、第８
図（ｂ）のような輪帯開口の状態との同一距離上でのビ
ームスポットの径は、光ビーム２の波長、光束径が同一
であれば、輪帯開口にて生ずるビームスポットの径の方
が小さくなる。ところが本発明の光学的情報再生装置の
如きものでは、ビームスポット９の径は第９図のように
、ビット１４とビット外の部分を照射するに充分な長さ
が必要であるため、ビームスポット９の径は規格により
定まっている。ここでビームスポット９の径φ、光ビー
ム２の波長λ、集束レンズ７のＮ、 Ａ、の関係は前述
の式（１）と同様であり、円形開口にて得られるビーム
スポット径と同一径を輪帯開口にて得るには、波長λを
大きく、マたＮ、ム、を小さくすることができる。この
ことは、前述したようにレーザーダイオードｌにおいて
生産性、特性の安定したものを使用できることになり、
またＮ、 Ａ、の小さな集束レンズ７を使用することに
より、情報媒体８０角度誤差によるコマ収差を小さくで
きることを意味する。Generally, the state of the circular opening as shown in FIG.
The diameter of the beam spot at the same distance from the state of the annular aperture as shown in Figure (b) is the same as the diameter of the beam spot generated at the annular aperture if the wavelength of the light beam 2 and the diameter of the beam are the same. is smaller. However, in the optical information reproducing apparatus of the present invention, the diameter of the beam spot 9 needs to be long enough to irradiate the bit 14 and the area outside the bit, as shown in FIG. The diameter of No. 9 is determined by the standard. Here, the relationship between the diameter φ of the beam spot 9, the wavelength λ of the light beam 2, and the N and A of the focusing lens 7 is the same as the above equation (1), and the diameter is the same as the beam spot diameter obtained with a circular aperture. In order to obtain this with an annular aperture, the wavelength λ can be made large and the numbers N and N can be made small. As mentioned above, this means that laser diodes with stable productivity and characteristics can be used.
This also means that by using the converging lens 7 with small N and A, it is possible to reduce the coma aberration caused by the angular error of the information medium 80.
ｆ（（ｃ、光ビーム２０光軸Ｘ中央部の光を遮断するこ
とは、ビームスポット９の光強度の最大値Ｍ付近を遮断
することになる。このことはレーザーダイオード１より
発する光ビームの光強度分布が温度によって変化したと
しても、光強度の最大値Ｍ付近が遮断されることにより
、反射光ビーム１０が前記差動型光電素子１２の受光面
を照射する時、生じるビームスポット１５においても光
強度分布の最大値部分−が遮断されることから、この光
強度分布の変化（ＭからＭｌ ）が差動型光電素子１２
による信号検出に大きな影響を与えないことになる。す
なわち、第９図のように情報媒体８上の響を強く受け、
光ビーム２の光軸中央部の光を遮断してビームスポット
１５の全体光量が減じたとしても、各種信号の検出には
さほど影響を与えるものではない。f((c) Blocking the light at the center of the optical axis X of the light beam 20 means blocking the vicinity of the maximum light intensity M of the beam spot 9. Even if the light intensity distribution changes depending on the temperature, the vicinity of the maximum value M of the light intensity is blocked, so that when the reflected light beam 10 irradiates the light receiving surface of the differential photoelectric element 12, the beam spot 15 that is generated is Since the maximum value portion of the light intensity distribution is blocked, this change in the light intensity distribution (from M to Ml) is caused by the difference in the differential photoelectric element 12.
This will not have a significant effect on signal detection. In other words, as shown in Figure 9, the sound on the information medium 8 is strongly affected,
Even if the light at the center of the optical axis of the light beam 2 is blocked and the overall light intensity of the beam spot 15 is reduced, it does not significantly affect the detection of various signals.
上記実施例では、集束レンズ７の中央部に光遮断部１８
を形成しているが、本発明ではレーザーダイオードｌか
ら情報媒体８に入射する光ビーム２の光路中で、しかも
光ビーム２の光軸の略中央部であれば、いずれの箇所で
光遮断しても良い。In the above embodiment, the light blocking portion 18 is provided at the center of the focusing lens 7.
However, in the present invention, the light can be blocked at any point in the optical path of the light beam 2 entering the information medium 8 from the laser diode 1, and at approximately the center of the optical axis of the light beam 2. It's okay.
ただし、上述の如く集束レンズ７等の光学部品の中央部
に光遮断の加工をすることが容易であって、レンズであ
れば、その製造工程中、芯出加工の研削時にレンズの中
央部分も同時に研削し、この研削部分に塗料をぬる様に
すれば、光遮断を容易かつ確実にできる。However, as mentioned above, it is easy to process light blocking in the center of optical parts such as the focusing lens 7, and if it is a lens, the center part of the lens can also be processed during centering grinding during the manufacturing process. By grinding at the same time and applying paint to the ground part, light shielding can be easily and reliably achieved.
本発明の上記の諸点に鑑み、穀も好ましいλ、Ｎ、 Ａ
、を求めた結果、
λ＝ ？ ８０ ｎ ｍ ｍ〜８８０ｎｍｍＮ、Ａ、＝
０．８８〜０．４８
となった。In view of the above points of the present invention, grains are also preferable λ, N, A
, the result is λ= ? 80 nm ~ 880 nm N, A, =
It was 0.88 to 0.48.
上述の如く、本発明は凹凸によって情報を記録した情報
媒体に、レーザーダイオードから発生した光ビームを集
束レンズ等の光学系を介してビームスポットとし集束し
壬、前記凹凸との光干渉による光回折効果にて生じる光
学的変化を差動型光電素子に入射して、情報信号及び前
記ビームスポットの諸制御信号を検出する光学的情報再
生装置において、前記レーザーダイオードから情報媒体
へ光学系を介して入射する光ビームの光軸の中心部分を
光遮断してなるために、輪帯開口を介して光ビームは情
報媒体へ入射し、ビームスポットの径を変化させずに、
光ビームの波長を大きく、かつ集束レンズの開口数を小
さくでき、レーザーダイオードの特性が良いものを選択
できるようになり、しかも情報媒体の角度誤差によるビ
ームスポット形状のくずれを防止でき、更にレーザーダ
イオードの発生光ビームが温度変化に伴ないその光強度
分布を変化しても、差動型光電素子による諸信号検出に
影響を与えないようにできる等の効果が生じる０As described above, the present invention focuses a light beam generated from a laser diode into a beam spot through an optical system such as a condenser lens on an information medium on which information is recorded by unevenness, and then performs optical diffraction due to optical interference with the unevenness. In an optical information reproducing device that detects an information signal and various control signals of the beam spot by inputting optical changes caused by the effect into a differential photoelectric element, the laser diode is transferred from the laser diode to the information medium via an optical system. Since the central part of the optical axis of the incident light beam is blocked, the light beam enters the information medium through the annular aperture, without changing the diameter of the beam spot.
It is now possible to increase the wavelength of the light beam and decrease the numerical aperture of the focusing lens, and it is now possible to select a laser diode with good characteristics.In addition, it is possible to prevent the beam spot shape from being distorted due to angular errors in the information medium. Even if the light intensity distribution of the generated light beam changes due to temperature changes, it is possible to prevent the detection of various signals by the differential photoelectric element from being affected.
第１図は情報媒体の一部を示す斜視図、第２図は光ビー
ムと情報媒体の入射状態を示す説明図、第８図、第４図
は光ビームの情報媒体の入射角の変化にて生じる光強度
分布の変化を示す説明図・第５図はレーザーダイオード
の発生光ビームの温度変化により生ずる光強度分布の変
化を示す説明図、第６図（ａ）、第６図（ｂ）は光ビー
ムの光強度分布の変化が差動型光電素子上のビームスポ
ットの光量分布に変化を与えることを示す説明図、第７
図は本実施例の光学系を示す図、第８図（ａ）、第８図
（ｂ）は光ビームと集束レンズとの関係を示す図、第９
図は情報媒体上でのビットとビームスポットとの関係を
示す図、第１Ｏ図は本発明の遮断効果と光ビームの光強
度分布の変化との関係を示す図、第１１図は差動型光電
素子上でのビームスポットと遮断効果の関係を示す図で
ある。
１・争レーザーダイオード、２・・光ビーム、Ｘ・・光
ビームの光軸、７・・集束レンズ、８・・情報媒体、９
・・ビームスポット、１２・・差動型光電素子〇
特許出願人 萬世工業株式会社
第８図Ｃ１５）パへ６図（６）
第９１″１
に
箒Ｉｆ図 第１０図Fig. 1 is a perspective view showing a part of the information medium, Fig. 2 is an explanatory diagram showing the incident state of the light beam and the information medium, and Figs. 8 and 4 show changes in the incident angle of the light beam to the information medium. Figure 5 is an explanatory diagram showing changes in the light intensity distribution caused by temperature changes in the light beam generated by the laser diode. Figures 6(a) and 6(b) 7 is an explanatory diagram showing that a change in the light intensity distribution of a light beam causes a change in the light intensity distribution of a beam spot on a differential photoelectric element.
The figure shows the optical system of this embodiment, FIG. 8(a) and FIG. 8(b) show the relationship between the light beam and the focusing lens, and FIG.
The figure shows the relationship between bits and beam spots on the information medium, Figure 1O shows the relationship between the blocking effect of the present invention and changes in the light intensity distribution of the light beam, and Figure 11 shows the differential type. FIG. 3 is a diagram showing the relationship between a beam spot on a photoelectric element and a blocking effect. 1. Laser diode, 2.. Light beam, X.. Optical axis of light beam, 7.. Focusing lens, 8.. Information medium, 9.
...Beam spot, 12...Differential photoelectric element〇Patent applicant Mansei Kogyo Co., Ltd. Fig. 8 C15) Pa to Fig. 6 (6) Fig. 91''1 Broom If Fig. 10
Claims (1)
、レーザーダイオード（１）から発生した光ビーム（２
）を集束レンズ（７）等の光学系を介してビームスポッ
ト（９）として集束し千、前記凹凸との光干渉による光
回折効果にて生じる光学的変化を差動型光電素子（１２
）に入射して、情報信号及び前記ビームスポット（９）
の諸制御信号を検出する光学的情報再生装置において、
前記レーザーダイオード（１）から情報媒体（８）へ光
学系を介して入射する光ビーム（２）を光軸（Ｘ）の中
心部分を光遮断してなる光学的情報再生装置。 ２ 前記光学系の内、光ビーム（２）を情報媒体（８）
上に任意の径に集束する集束レンズク７）の中央部に光
遮断部（１８）を形成してなる特許請求の範囲第１項記
載の光学的情報再生装置。[Claims] l. A light beam (2
) is focused as a beam spot (9) through an optical system such as a focusing lens (7), and the optical change caused by the light diffraction effect due to light interference with the unevenness is transferred to a differential photoelectric element (12).
), the information signal and the beam spot (9)
In an optical information reproducing device that detects various control signals of
An optical information reproducing device in which a light beam (2) entering the information medium (8) from the laser diode (1) via an optical system is blocked at the center of the optical axis (X). 2 In the optical system, the light beam (2) is connected to the information medium (8).
2. The optical information reproducing device according to claim 1, wherein a light blocking portion (18) is formed in the center of a focusing lens (7) converging to an arbitrary diameter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56164468A JPS5864650A (en) | 1981-10-14 | 1981-10-14 | Optical information reproducer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56164468A JPS5864650A (en) | 1981-10-14 | 1981-10-14 | Optical information reproducer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS5864650A true JPS5864650A (en) | 1983-04-18 |
Family
ID=15793746
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56164468A Pending JPS5864650A (en) | 1981-10-14 | 1981-10-14 | Optical information reproducer |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5864650A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0346844A2 (en) * | 1988-06-14 | 1989-12-20 | Nec Corporation | Optical head apparatus |
| EP0411525A2 (en) * | 1989-08-02 | 1991-02-06 | Hitachi, Ltd. | A method of making optical disk master and an optical disk |
| EP0510283A2 (en) * | 1991-04-23 | 1992-10-28 | Pioneer Electronic Corporation | Optical pickup device |
| US5313450A (en) * | 1991-12-27 | 1994-05-17 | Matsushita Electric Industrial Co., Ltd. | Optical disk drive |
-
1981
- 1981-10-14 JP JP56164468A patent/JPS5864650A/en active Pending
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0346844A2 (en) * | 1988-06-14 | 1989-12-20 | Nec Corporation | Optical head apparatus |
| EP0411525A2 (en) * | 1989-08-02 | 1991-02-06 | Hitachi, Ltd. | A method of making optical disk master and an optical disk |
| EP0510283A2 (en) * | 1991-04-23 | 1992-10-28 | Pioneer Electronic Corporation | Optical pickup device |
| US5313450A (en) * | 1991-12-27 | 1994-05-17 | Matsushita Electric Industrial Co., Ltd. | Optical disk drive |
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