JP2639659B2 - Light head - Google Patents
Light headInfo
- Publication number
- JP2639659B2 JP2639659B2 JP62277707A JP27770787A JP2639659B2 JP 2639659 B2 JP2639659 B2 JP 2639659B2 JP 62277707 A JP62277707 A JP 62277707A JP 27770787 A JP27770787 A JP 27770787A JP 2639659 B2 JP2639659 B2 JP 2639659B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- diffraction grating
- light receiving
- recording medium
- light emitting
- 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 - Lifetime
Links
Description
【発明の詳細な説明】 〔産業上の利用分野〕 本発明は光ヘッドに用いられている回折格子の構造に
関する。The present invention relates to a structure of a diffraction grating used in an optical head.
従来、回折格子をビームスプリッタとして用いた光ヘ
ッドとしては特開昭62−172538の様なものがあった。Conventionally, there has been an optical head using a diffraction grating as a beam splitter as disclosed in Japanese Patent Application Laid-Open No. Sho 62-172538.
しかし、前述の従来技術では、半導体レーザから出た
光が、回折格子を通過してディスクへ到達せずに、回折
格子の半導体レーザ側の面で反射されてフォトダイオー
ドに入り、ディスクからの信号以外の出力を生じさせて
しまうという問題点を有する。However, in the above-described conventional technology, the light emitted from the semiconductor laser does not reach the disk through the diffraction grating, but is reflected by the semiconductor laser-side surface of the diffraction grating, enters the photodiode, and the signal from the disk is emitted. There is a problem that an output other than the above is generated.
そこで本発明はこのような問題点を解決するもので、
その目的とするところは、発光手段から放射された光が
回折格子で反射されて直接受光手段に入射したり、回折
格子で反射された光が迷光として受光手段に入射するこ
とを抑制し、受光手段によって検出される信号のS/N比
の低下を防止することにある。Therefore, the present invention solves such a problem,
The purpose is to suppress the light radiated from the light emitting means being reflected by the diffraction grating and directly entering the light receiving means, or to suppress the light reflected by the diffraction grating from entering the light receiving means as stray light. An object of the present invention is to prevent a decrease in the S / N ratio of a signal detected by the means.
本発明の光ヘッドは、 記録媒体に光を照射する発光手段と、前記記録媒体か
らの反射光を受光する受光手段と、前記発光手段から前
記記録媒体への光経路内及び前記記録媒体から前記受光
手段への光経路内に配置され、前記反射光を分割して前
記受光手段に入射させる回折格子と、を備えた光ヘッド
において、 前記受光手段は前記回折格子に関して前記発光手段と
同じ側に配置されるとともに、前記受光手段の受光面は
前記回折格子に向かって配置され、 前記回折格子は単層膜または多層膜の無反射コーティ
ング層を有することを特徴とする。The optical head of the present invention includes: a light emitting unit that irradiates a recording medium with light; a light receiving unit that receives reflected light from the recording medium; and an optical path from the light emitting unit to the recording medium and from the recording medium. A diffraction grating disposed in an optical path to a light receiving unit, for splitting the reflected light and entering the light receiving unit, wherein the light receiving unit is on the same side as the light emitting unit with respect to the diffraction grating. The light-receiving surface of the light-receiving means is disposed toward the diffraction grating, and the diffraction grating has a single-layer film or a multi-layer anti-reflection coating layer.
第１図は本発明の実施例における光ヘッドの主要構成
図である。FIG. 1 is a main configuration diagram of an optical head according to an embodiment of the present invention.
半導体レーザ10から出た光は回折格子11を通過して対
物レンズ13でディスク14の一点に集光される。ディスク
14の情報を含んだ反射光は再び対物レンズ13を通って回
折格子11で回折されて、その回折光16がフォトダイオー
ド15に入って情報が検出される。Light emitted from the semiconductor laser 10 passes through the diffraction grating 11 and is condensed by the objective lens 13 onto one point of the disk 14. disk
The reflected light including the information of 14 is again diffracted by the diffraction grating 11 through the objective lens 13, and the diffracted light 16 enters the photodiode 15 to detect the information.
回折格子11はガラス基板の表面にフォトエッチングで
凹凸が形成されており、もう一方の面には真空蒸着法で
形成したMgF2の薄膜で無反射コーティング12を施してあ
る。The diffraction grating 11 has an uneven surface formed by photoetching on the surface of a glass substrate, and has a non-reflective coating 12 made of a MgF 2 thin film formed by a vacuum evaporation method on the other surface.
回折格子としては透明体の凹凸だけでなく、基板表面
に形成された金属薄膜をエッチングして形成した透過率
の周期的変化を用いても良い。As the diffraction grating, not only the unevenness of the transparent body but also a periodic change in transmittance formed by etching a metal thin film formed on the substrate surface may be used.
また、無反射コーティングとしては多層膜を用いても
良く、回折格子の形成されている面に形成しても良い。Further, a multi-layer film may be used as the anti-reflection coating, and may be formed on the surface on which the diffraction grating is formed.
なお、本実施例は光ヘッドに用いられている回折格子
について無反射コーティングを施したが、この発明は他
のデバイスにおいて用いられている回折格子にも適用で
きる。In this embodiment, the diffraction grating used in the optical head is provided with an antireflection coating. However, the present invention can be applied to a diffraction grating used in another device.
本発明の光ヘッドは、回折格子に関して発光手段と同
じ側に受光手段を配置するとともにその受光面を回折格
子へ向けて配置しても、回折格子が単層膜または多層膜
の無反射コーティング層を有しているので、回折格子で
反射されて直接に受光手段に入射したり、回折格子で反
射された光が迷光となって受光手段に入射することがな
くなり、回折格子をビームスプリッタとして用いた小型
光ヘッドでありながら、S/N比の高い信号を検出できる
という効果を奏する。The optical head of the present invention has a structure in which the light receiving means is arranged on the same side as the light emitting means with respect to the diffraction grating and the light receiving surface is arranged to face the diffraction grating. Therefore, the light reflected by the diffraction grating and directly incident on the light receiving means, and the light reflected by the diffraction grating does not enter the light receiving means as stray light, so that the diffraction grating can be used as a beam splitter. Although it is a small optical head, it has an effect that a signal having a high S / N ratio can be detected.
さらに、発光手段から記録媒体へ到る光の伝送効率が
向上するので、光出力の小さい安価な発光手段を使用で
き、光ヘッドのコスト低減が可能になるという効果を奏
する。Further, since the transmission efficiency of light from the light emitting means to the recording medium is improved, an inexpensive light emitting means having a small optical output can be used, and the cost of the optical head can be reduced.
第１図は本発明の光ヘッドの実施例を示す主要構成図。 10……半導体レーザ 11……回折格子 12……無反射コーティング 13……対物レンズ 14……ディスク 15……フォトダイオード 16……回折光 FIG. 1 is a main configuration diagram showing an embodiment of an optical head according to the present invention. 10 Semiconductor laser 11 Diffraction grating 12 Antireflection coating 13 Objective lens 14 Disk 15 Photodiode 16 Diffracted light
Claims (1)
録媒体から前記受光手段への光経路内に配置され、前記
反射光を分割して前記受光手段に入射させる回折格子
と、 を備えた光ヘッドにおいて、 前記受光手段は前記回折格子に関して前記発光手段と同
じ側に配置されるとともに、前記受光手段の受光面は前
記回折格子に向かって配置され、 前記回折格子は単層膜または多層膜の無反射コーティン
グ層を有することを特徴とする光ヘッド。1. A light emitting means for irradiating a recording medium with light; a light receiving means for receiving reflected light from the recording medium; and an optical path from the light emitting means to the recording medium and from the recording medium to the light receiving means. A diffraction grating that is disposed in an optical path to the light source and splits the reflected light into the light receiving unit.The light receiving unit is disposed on the same side of the diffraction grating as the light emitting unit. An optical head, wherein a light receiving surface of the light receiving means is arranged toward the diffraction grating, and the diffraction grating has a single-layer film or a multilayer anti-reflection coating layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62277707A JP2639659B2 (en) | 1987-11-02 | 1987-11-02 | Light head |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62277707A JP2639659B2 (en) | 1987-11-02 | 1987-11-02 | Light head |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01119929A JPH01119929A (en) | 1989-05-12 |
| JP2639659B2 true JP2639659B2 (en) | 1997-08-13 |
Family
ID=17587193
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62277707A Expired - Lifetime JP2639659B2 (en) | 1987-11-02 | 1987-11-02 | Light head |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2639659B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100430754C (en) * | 2003-07-10 | 2008-11-05 | 柯尼卡美能达精密光学株式会社 | Optical component and optical pickup apparatus |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR930005785B1 (en) * | 1988-06-23 | 1993-06-24 | 샤프 가부시끼가이샤 | Optical pick-up device |
| EP0608432B1 (en) * | 1992-07-14 | 2001-02-21 | Seiko Epson Corporation | Polarizing element and optical element, and optical head |
| JP5565371B2 (en) * | 2011-04-22 | 2014-08-06 | パナソニック株式会社 | Optical pickup device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS62124635A (en) * | 1985-11-25 | 1987-06-05 | Toshiba Corp | Optical pickup head |
-
1987
- 1987-11-02 JP JP62277707A patent/JP2639659B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN100430754C (en) * | 2003-07-10 | 2008-11-05 | 柯尼卡美能达精密光学株式会社 | Optical component and optical pickup apparatus |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH01119929A (en) | 1989-05-12 |
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