JPS6322370B2 - - Google Patents

Info

Publication number
JPS6322370B2
JPS6322370B2 JP57115607A JP11560782A JPS6322370B2 JP S6322370 B2 JPS6322370 B2 JP S6322370B2 JP 57115607 A JP57115607 A JP 57115607A JP 11560782 A JP11560782 A JP 11560782A JP S6322370 B2 JPS6322370 B2 JP S6322370B2
Authority
JP
Japan
Prior art keywords
light
optical
beam splitter
receiving element
light source
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.)
Expired
Application number
JP57115607A
Other languages
Japanese (ja)
Other versions
JPS598145A (en
Inventor
Michiharu Abe
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ricoh Co Ltd
Original Assignee
Ricoh Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Ricoh Co Ltd filed Critical Ricoh Co Ltd
Priority to JP57115607A priority Critical patent/JPS598145A/en
Publication of JPS598145A publication Critical patent/JPS598145A/en
Publication of JPS6322370B2 publication Critical patent/JPS6322370B2/ja
Granted legal-status Critical Current

Links

Classifications

    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording 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
    • G11B7/08Disposition or mounting of heads or light sources relatively to record carriers
    • G11B7/09Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
    • G11B7/0908Disposition or mounting of heads or light sources relatively to record carriers with provision for moving the light beam or focus plane for the purpose of maintaining alignment of the light beam relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for focusing only
    • GPHYSICS
    • G11INFORMATION STORAGE
    • G11BINFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00Recording 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
    • G11B7/12Heads, e.g. forming of the optical beam spot or modulation of the optical beam
    • G11B7/135Means for guiding the beam from the source to the record carrier or from the record carrier to the detector

Landscapes

  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Automatic Focus Adjustment (AREA)
  • Optical Recording Or Reproduction (AREA)
  • Optical Head (AREA)

Description

【発明の詳細な説明】 この発明は光学式情報記録媒体からの信号再生
等に用いられる光ピツクアツプ、特に合焦検出の
ための光学系を簡単にした光ピツクアツプに関す
る。
DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical pickup used for signal reproduction from an optical information recording medium, and more particularly to an optical pickup with a simplified optical system for focus detection.

光学式ビデオデイスク、光学式デジタルオーデ
イオデイスク、記録・再生可能の光デイスクメモ
リ等に用いられる光ピツクアツプにおいては、半
導体レーザ等の光源からの光を記録媒体上に常に
スポツトを形成させるため、合焦状態を検出して
対物レンズと記録媒体との距離を一定に制御す
る。
In optical pickups used for optical video discs, optical digital audio discs, recordable/playable optical disc memories, etc., the light from a light source such as a semiconductor laser is focused to always form a spot on the recording medium. The distance between the objective lens and the recording medium is controlled to be constant by detecting the state.

この合焦状態の検出のために一般に利用される
非点収差法は、記録媒体からの反射光束中に大き
い非点収差を生ずる集光光学系を配置し、これに
よつて生ずる互に直角な2つの焦線の中間で光束
断面が円形となる位置に受光素子を置き、光束断
面の変形で焦点外れを検出するようにしている。
The astigmatism method, which is generally used to detect this in-focus state, places a condensing optical system that produces a large astigmatism in the reflected light beam from the recording medium, and the resulting A light-receiving element is placed at a position where the beam cross section is circular between the two focal lines, and defocusing is detected by deformation of the beam cross section.

上記の非点収差を作るためには、従来はシリン
ドリカルレンズ等非球面光学素子を用いていたた
め、コストも高く、部品点数も多いものとなつて
いた。
Conventionally, aspherical optical elements such as cylindrical lenses have been used to create the above-mentioned astigmatism, resulting in high costs and a large number of parts.

本発明者は先に、この非点収差を作るための光
学系として1枚の球面反射鏡を用い、ほぼ45゜の
入射角で入射させることにより唯1つの光学素子
で集光作用と大きい非点収差を作る作用とを持た
せることを提案した。すなわち、第1図に示すよ
うに、半導体レーザ等の光源10からの光はコリ
メータレンズ20で平行光束となり、偏光ビーム
スプリツタ30、1/4λ板40を経て円偏光とな
り、集光レンズ50によつて情報記録面100上
に径約1.6μmのスポツトを結ぶ。反射光は集光レ
ンズ50によつて再び平行光束とされ、1/4λ板
40により入射光と90゜偏光面が回転した直線偏
光となり、偏光ビームスプリツタ30で全反射さ
れ、球面凹面鏡60で再び反射・集光されて受光
素子70に入射する。受光素子70は、周知の4
分割素子を用いることが出来る。この素子は、第
2図に示すように、放射状に4分割されたA、
B、C、Dの分割域からなる。この素子70への
入射光は、球面反射鏡60の光軸に入射角が約
45゜で入射する平行光束であり、反射・集光され
た光束は大きい非点収差を生じる。受光素子70
は、対物レンズ50によるスポツトが丁度記録面
100上にあるとき反射鏡60からの集束光の2
つの焦線の中間でビーム断面形状が第2図aに示
すように円形となる位置に置かれる。記録面10
0が集光レンズ50に近づき或いは遠ざかれば反
射鏡60による集束位置が変位し、素子70への
入射光束断面は第2図b,cのように変化する。
素子70の(A+C)−(B+D)の出力によつて
合焦エラー信号が得られ、フオーカシングアクチ
ユエータ80により対物レンズの合焦制御を行
う。また、素子70に対する光束の入射位置のず
れは、配置により(A+B)−(C+D)あるいは
(A−C)あるいは(B−D)あるいは(A+D)
−(B+C)のどれかによつて検出されるが、ト
ラツキングエラー信号を与え、トラツキングアク
チユエータ90により対物レンズ50をその光軸
と直角方向に駆動してトラツキング修正を行う。
The present inventor previously used a single spherical reflector as an optical system to create this astigmatism, and by making the light incident at an angle of incidence of approximately 45°, the inventors achieved a light focusing effect and a large aberration using only one optical element. It was proposed to have the effect of creating point aberration. That is, as shown in FIG. 1, light from a light source 10 such as a semiconductor laser becomes a parallel beam of light at a collimator lens 20, becomes circularly polarized light after passing through a polarizing beam splitter 30 and a 1/4λ plate 40, and is sent to a condenser lens 50. Therefore, spots with a diameter of about 1.6 μm are connected on the information recording surface 100. The reflected light is made into a parallel light beam again by the condenser lens 50, becomes linearly polarized light whose polarization plane is rotated by 90 degrees with respect to the incident light by the 1/4λ plate 40, is totally reflected by the polarizing beam splitter 30, and is reflected by the spherical concave mirror 60. The light is reflected and focused again and enters the light receiving element 70. The light receiving element 70 is a well-known 4
Split elements can be used. As shown in Figure 2, this element is radially divided into four parts A,
It consists of divided areas B, C, and D. The incident light on this element 70 has an incident angle of approximately
It is a parallel beam of light that enters at an angle of 45 degrees, and the reflected and condensed beam produces a large astigmatism. Light receiving element 70
is 2 of the focused light from the reflecting mirror 60 when the spot formed by the objective lens 50 is exactly on the recording surface 100.
The beam is placed at a position midway between the two focal lines so that the cross-sectional shape of the beam becomes circular as shown in FIG. 2a. Recording surface 10
0 approaches or moves away from the condensing lens 50, the convergence position by the reflecting mirror 60 shifts, and the cross section of the incident light flux to the element 70 changes as shown in FIGS. 2b and 2c.
A focusing error signal is obtained from the (A+C)-(B+D) output of the element 70, and the focusing actuator 80 performs focusing control of the objective lens. Also, the deviation of the incident position of the light beam on the element 70 is (A+B)-(C+D), (A-C), (B-D), or (A+D) depending on the arrangement.
-(B+C), a tracking error signal is applied, and the tracking actuator 90 drives the objective lens 50 in a direction perpendicular to its optical axis to perform tracking correction.

この光ピツクアツプは、ビームスプリツタ30
後の集光系が球面レンズ1枚であり、構造が簡単
でコストも低く勝れたものではあるが、反射鏡6
0を必要とし、この反射鏡で約90゜光路を屈折さ
せる必要があるため、光ピツクアツプの光学配置
に一定の制限を受けることとなる。
This optical pick-up consists of a beam splitter 30
The latter condensing system consisted of one spherical lens, which had a simple structure and low cost, but the reflector 6
0 and it is necessary to refract the optical path by approximately 90 degrees with this reflecting mirror, which imposes certain restrictions on the optical arrangement of the optical pickup.

この発明は、上記の非点収差を生じさせるため
の斜入射の球面反射面を、偏光ビームスプリツタ
の反射面と兼用することによつて上記の球面反射
鏡60を不必要とし、部品点数を更に減らすと共
に光学配置の制約を除いたものである。
This invention eliminates the need for the spherical reflecting mirror 60 by using the spherical reflecting surface of oblique incidence for producing the above-mentioned astigmatism as the reflecting surface of the polarizing beam splitter, thereby reducing the number of parts. This further reduces the number of optical elements and eliminates restrictions on optical arrangement.

以下図面を参照してこの発明の実施例について
説明する。
Embodiments of the present invention will be described below with reference to the drawings.

第3図はこの発明の光ピツクアツプの基本構成
を示し、図中の符号は第1図と対応するものは同
じ符号で示す。この発明においては、偏光ビーム
スプリツタ35の反射面は凹球面となつており、
記録面100からの反射光はこの反射面36で反
射され、光路を約90゜屈折されると共に大きい非
点収差を有する集光光束となる。一見して明らか
なように、反射鏡60のような余計な光学素子を
必要とせず、受光素子70をビームスプリツタ3
5の側面に配置することも可能となり、素子配置
の自由度が増す。
FIG. 3 shows the basic configuration of the optical pickup of the present invention, and the symbols in the figure that correspond to those in FIG. 1 are indicated by the same symbols. In this invention, the reflective surface of the polarizing beam splitter 35 is a concave spherical surface,
The reflected light from the recording surface 100 is reflected by the reflecting surface 36, and the optical path is refracted by about 90 degrees, and becomes a condensed light beam having a large astigmatism. As is clear at first glance, the light receiving element 70 can be connected to the beam splitter 3 without the need for an extra optical element such as the reflecting mirror 60.
It is also possible to arrange the element on the side surface of the element 5, increasing the degree of freedom in element arrangement.

第4図に示す実施例は第3図の基本構成に球面
レンズ67を加えたものである。これにより受光
素子70上のビーム径が小さくなるので低価格で
応答性の高い受光面積の小さい受光素子を用いる
ことが出来る。また、偏光ビームスプリツタ35
と受光素子70との間隔を狭くすることが出来る
ので、光学系全体をコンパクトに構成することが
出来る。
The embodiment shown in FIG. 4 has a spherical lens 67 added to the basic configuration shown in FIG. This reduces the beam diameter on the light-receiving element 70, allowing the use of a low-cost light-receiving element with high responsiveness and a small light-receiving area. In addition, the polarizing beam splitter 35
Since the distance between the light receiving element 70 and the light receiving element 70 can be narrowed, the entire optical system can be configured compactly.

第5図に示す実施例は直角プリズム38を用
い、光源10から記録面100に至る光路を90゜
屈折させたものである。これにより光学系の高さ
を薄くすることが出来る。
The embodiment shown in FIG. 5 uses a right-angle prism 38 to bend the optical path from the light source 10 to the recording surface 100 by 90 degrees. This allows the height of the optical system to be reduced.

第6図に示す実施例は直角プリズム38に代え
て全反射ミラー39を用いたものである。トラツ
キングを行うときに、集光レンズ50と全反射ミ
ラー39を一体にして矢印方向に変移させれば、
トラツキングに伴う光軸ずれを防ぐことが出来
る。
The embodiment shown in FIG. 6 uses a total reflection mirror 39 in place of the right angle prism 38. When tracking, if the condensing lens 50 and the total reflection mirror 39 are integrally moved in the direction of the arrow,
Optical axis deviation due to tracking can be prevented.

第7図に示す実施例は、光源10とコリメータ
レンズ20の間に偏光ビームスプリツタ35を配
置した例である。ビームスプリツタ35と1/4λ
板40を光ビーム径の小さいところに配置すると
小型のものを使用することが出来るので、光学系
を軽量化することが出来る。
The embodiment shown in FIG. 7 is an example in which a polarizing beam splitter 35 is arranged between the light source 10 and the collimator lens 20. Beam splitter 35 and 1/4λ
By arranging the plate 40 at a location where the light beam diameter is small, a small plate can be used, and the weight of the optical system can be reduced.

上記各実施例の説明では、ビームスプリツタ3
5は偏光ビームスプリツタとして説明したが、コ
ストあるいはビームスプリツタを透過して光源へ
戻る光の影響等を考慮してハーフミラーによるも
の等、他種のビームスプリツタを使用してもよい
ことは云う迄もない。
In the description of each of the above embodiments, the beam splitter 3
5 has been explained as a polarizing beam splitter, but other types of beam splitters, such as those using a half mirror, may be used in consideration of cost or the influence of light passing through the beam splitter and returning to the light source. Needless to say.

また、第4図および第7図の実施例の構成によ
ればビームスプリツタの反射面は凸面としても実
施可能である。しかし、この場合は光路長が長く
なるので、光学系をコンパクトにするためには凹
面反射面とするほうが好ましい。
Furthermore, according to the configurations of the embodiments shown in FIGS. 4 and 7, the reflecting surface of the beam splitter can also be implemented as a convex surface. However, in this case, the optical path length becomes long, so in order to make the optical system compact, it is preferable to use a concave reflective surface.

このように、この発明によれば、記録面からの
反射光路中に非点収差を生じさせるための光学素
子を挿入する必要がなくなり、ピツクアツプの部
品点数を減らすことが出来、調整組立が容易にな
り、受光素子配置の自由度もまして光ピツクアツ
プの小型化・軽量化を計ることが出来る。
As described above, according to the present invention, there is no need to insert an optical element to cause astigmatism in the reflected optical path from the recording surface, the number of parts of the pickup can be reduced, and adjustment and assembly can be easily performed. Therefore, it is possible to reduce the size and weight of the optical pickup as well as the degree of freedom in arranging the light receiving elements.

【図面の簡単な説明】[Brief explanation of drawings]

第1図は光ピツクアツプの先行例の光路図、第
2図は受光素子と信号取出しの説明図、第3図な
いし第7図はこの発明の光ピツクアツプの第1な
いし第5実施例のそれぞれの光路図である。 10:光源、20:コリメータレンズ、30,
35:ビームスプリツタ、40:1/4λ板、5
0:集光レンズ、60:反射光、70:4分割受
光素子、80:フオーカシングアクチユエータ、
90:トラツキングアクチユエータ、100:記
録面、38:直角プリズム、67:球面レンズ。
Fig. 1 is an optical path diagram of a prior example of an optical pickup, Fig. 2 is an explanatory diagram of a light receiving element and signal extraction, and Figs. It is an optical path diagram. 10: light source, 20: collimator lens, 30,
35: Beam splitter, 40: 1/4λ plate, 5
0: Condensing lens, 60: Reflected light, 70: 4-split light receiving element, 80: Focusing actuator,
90: Tracking actuator, 100: Recording surface, 38: Right angle prism, 67: Spherical lens.

Claims (1)

【特許請求の範囲】[Claims] 1 半導体レーザー光源から出射されるレーザー
ビームを情報記録媒体上にビームスポツトとして
形成する対物レンズと、前記半導体レーザー光源
と前記対物レンズの間に配置されたビームスプリ
ツタと、前記ビームスプリツタからの反射光を受
光する分割型受光素子とからなり、前記ビームス
プリツタの反射面を凹面として非点収差光束を生
じさせることを特徴とする光学式ピツクアツプ。
1 an objective lens that forms a laser beam emitted from a semiconductor laser light source as a beam spot on an information recording medium; a beam splitter disposed between the semiconductor laser light source and the objective lens; 1. An optical pick-up comprising a split type light receiving element for receiving reflected light, the beam splitter having a reflecting surface as a concave surface to generate an astigmatic light beam.
JP57115607A 1982-07-05 1982-07-05 Optical pickup Granted JPS598145A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP57115607A JPS598145A (en) 1982-07-05 1982-07-05 Optical pickup

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP57115607A JPS598145A (en) 1982-07-05 1982-07-05 Optical pickup

Publications (2)

Publication Number Publication Date
JPS598145A JPS598145A (en) 1984-01-17
JPS6322370B2 true JPS6322370B2 (en) 1988-05-11

Family

ID=14666822

Family Applications (1)

Application Number Title Priority Date Filing Date
JP57115607A Granted JPS598145A (en) 1982-07-05 1982-07-05 Optical pickup

Country Status (1)

Country Link
JP (1) JPS598145A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0218640U (en) * 1988-07-18 1990-02-07
US9708104B2 (en) 2010-05-18 2017-07-18 Intercontinental Great Brands Llc Reclosable flexible packaging and methods for manufacturing same

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60192124U (en) * 1984-05-30 1985-12-20 アルプス電気株式会社 optical pick up
US4733065A (en) * 1984-06-27 1988-03-22 Canon Kabushiki Kaisha Optical head device with diffraction grating for separating a light beam incident on an optical recording medium from a light beam reflected therefrom
JPS6145434A (en) * 1984-08-09 1986-03-05 Sankyo Seiki Mfg Co Ltd Beam splitter of optical information recording and reproducing device
JPS6183115U (en) * 1984-11-05 1986-06-02
JP2612436B2 (en) * 1985-10-15 1997-05-21 三菱電機株式会社 Automatic focusing device
JP2001034999A (en) * 1999-05-14 2001-02-09 Fujitsu Ltd Optical information storage and optical element

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH0218640U (en) * 1988-07-18 1990-02-07
US9708104B2 (en) 2010-05-18 2017-07-18 Intercontinental Great Brands Llc Reclosable flexible packaging and methods for manufacturing same

Also Published As

Publication number Publication date
JPS598145A (en) 1984-01-17

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