JPS636723Y2 - - Google Patents
Info
- Publication number
- JPS636723Y2 JPS636723Y2 JP19342483U JP19342483U JPS636723Y2 JP S636723 Y2 JPS636723 Y2 JP S636723Y2 JP 19342483 U JP19342483 U JP 19342483U JP 19342483 U JP19342483 U JP 19342483U JP S636723 Y2 JPS636723 Y2 JP S636723Y2
- Authority
- JP
- Japan
- Prior art keywords
- lens
- group
- light source
- objective lens
- surface facing
- 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
Links
- 230000003287 optical effect Effects 0.000 claims description 7
- 230000005499 meniscus Effects 0.000 claims description 4
- 230000004075 alteration Effects 0.000 description 5
- 238000010586 diagram Methods 0.000 description 3
- 239000006059 cover glass Substances 0.000 description 2
- 206010010071 Coma Diseases 0.000 description 1
- 206010073261 Ovarian theca cell tumour Diseases 0.000 description 1
- 208000001644 thecoma Diseases 0.000 description 1
Landscapes
- Lenses (AREA)
- Optical Head (AREA)
Description
【考案の詳細な説明】
本考案は光デイスク（高密度情報記録媒体）用
対物レンズに関するものである。[Detailed Description of the Invention] The present invention relates to an objective lens for an optical disk (high-density information recording medium).
光デイスクに記録された高密度の情報の読み取
りに使用される対物レンズは、高密度の信号を読
み取らなければならないので、その分解能は1μ
程度が要求される。又、この対物レンズはトラツ
キングやフオーカシングのために可動となつてい
る場合が多く、対物レンズとデイスク面との間
隔、即ち作動距離はある程度以上に大きくない
と、対物レンズとデイスク面とが当つてしまうと
云う実用上の不都合が生じる恐れがある。従つ
て、この種対物レンズのバツクフオーカスは、あ
る程度以上に大きくすることが要求される。 The objective lens used to read the high-density information recorded on optical disks must read high-density signals, so its resolution is 1μ.
degree is required. In addition, this objective lens is often movable for tracking and focusing purposes, and unless the distance between the objective lens and the disk surface, that is, the working distance, is greater than a certain level, the objective lens and the disk surface may come into contact with each other. There is a possibility that the practical inconvenience of putting it away may occur. Therefore, the back focus of this type of objective lens is required to be larger than a certain level.
本考案は、上記要求を満足した、高性能で且つ
バツクフオーカスが充分に大きい光デイスク用対
物レンズを提供するものである。 The present invention provides an objective lens for optical disks that satisfies the above requirements and has high performance and a sufficiently large back focus.
本考案のレンズ構成は、３群３枚構成レンズよ
りなり、第１群は両凸の正レンズ、第２群は光源
側に凹面を向けた負のメニスカスレンズ、第３群
は光源側に凸面を向けた正のメニスカスレンズで
構成され、光源側より数えて第ｉ番目の曲率半径
をri、第ｉ番目のレンズ肉厚又は空気間隔をdi、
第ｊ番目レンズの屈折率をNjとするとき、レン
ズ全系の焦点距離ｆ＝1.0と規格化したときのri，
di，Njが以下の数値を有した光デイスク用対物レ
ンズである。 The lens structure of this invention consists of three lenses in three groups: the first group is a biconvex positive lens, the second group is a negative meniscus lens with a concave surface facing the light source, and the third group is a convex lens facing the light source. It is composed of a positive meniscus lens that is oriented to
When the refractive index of the j-th lens is N j , the focal length of the entire lens system is normalized to f = 1.0, r i ,
This is an objective lens for an optical disk in which d i and N j have the following values.
尚、Njは波長790nmにおける数値である。 Note that N j is a value at a wavelength of 790 nm.
r1＝ 2.2533 d1＝0.2193 N1＝1.78506
r2＝−5.4625 d2＝0.0658
r3＝−1.5765 d3＝0.2855 N2＝1.78506
r4＝−3.0344 d4＝0.1754
r5＝ 0.9125 d5＝0.4169 N3＝1.88010
r6＝ 5.1535
バツクフオーカス＝0.630
上記数値を有する本考案にかかるレンズ構成図
を第１図に示すと共に、光デイスクのカバーガラ
スを含むコマ収差及び波面収差図を第２図に示し
た。第２図でわかるように、本考案レンズにおい
ては、光デイスクのカバーガラスを考慮し収差が
良好に補正されている。 r 1 = 2.2533 d 1 = 0.2193 N 1 = 1.78506 r 2 = −5.4625 d 2 = 0.0658 r 3 = −1.5765 d 3 = 0.2855 N 2 = 1.78506 r 4 = −3.0344 d 4 = 0.1754 r 5 = 0.9125 d 5 = 0.4169 N 3 = 1.88010 r 6 = 5.1535 Back focus = 0.630 Fig. 1 shows the configuration of the lens according to the present invention having the above numerical values, and Fig. 2 shows the coma aberration and wavefront aberration diagram including the cover glass of the optical disk. Ta. As can be seen from FIG. 2, in the lens of the present invention, aberrations are well corrected in consideration of the cover glass of the optical disk.
第１図は本考案のレンズ構成図、第２図は本考
案のコマ収差及び波面収差図である。
FIG. 1 is a diagram of the lens configuration of the present invention, and FIG. 2 is a diagram of coma aberration and wavefront aberration of the present invention.
Claims (1)
正レンズ、第２群は光源側に凹面を向けた負のメ
ニスカスレンズ、第３群は光源側に凸面を向けた
正のメニスカスレンズで構成され、光源側より数
えて第ｉ番目の曲率半径をri、第ｉ番目のレンズ
肉厚又は空気間隔をdi、第ｊ番目レンズの屈折率
をNj（ここでNjは波長790nmにおける数値であ
る）とするとき、レンズ全系の焦点距離ｆ＝1.0
と規格化したときのri，di，Njが以下の数値を有
した光デイスク用対物レンズ。 r1＝ 2.2533 d1＝0.2193 N1＝1.78506 r2＝−5.4625 d2＝0.0658 r3＝−1.5765 d3＝0.2855 N2＝1.78506 r4＝−3.0344 d4＝0.1754 r5＝ 0.9125 d5＝0.4169 N3＝1.88010 r6＝ 5.1535[Claim for Utility Model Registration] Consisting of three lenses in three groups, the first group is a biconvex positive lens, the second group is a negative meniscus lens with a concave surface facing the light source, and the third group is facing the light source. It is composed of a positive meniscus lens with a convex surface facing, and the radius of curvature of the i-th lens counting from the light source side is r i , the thickness or air gap of the i-th lens is d i , and the refractive index of the j-th lens is N j (where N j is a value at a wavelength of 790 nm), the focal length of the entire lens system is f = 1.0
An objective lens for optical disks in which r i , d i , and N j have the following values when normalized as: r 1 = 2.2533 d 1 = 0.2193 N 1 = 1.78506 r 2 = −5.4625 d 2 = 0.0658 r 3 = −1.5765 d 3 = 0.2855 N 2 = 1.78506 r 4 = −3.0344 d 4 = 0.1754 r 5 = 0.9125 d 5 = 0.4169 N 3 = 1.88010 r 6 = 5.1535
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19342483U JPS60100717U (en) | 1983-12-15 | 1983-12-15 | Objective lens for optical disk |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP19342483U JPS60100717U (en) | 1983-12-15 | 1983-12-15 | Objective lens for optical disk |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS60100717U JPS60100717U (en) | 1985-07-09 |
| JPS636723Y2 true JPS636723Y2 (en) | 1988-02-26 |
Family
ID=30416019
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP19342483U Granted JPS60100717U (en) | 1983-12-15 | 1983-12-15 | Objective lens for optical disk |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60100717U (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2553508B2 (en) * | 1986-02-18 | 1996-11-13 | 松下電器産業株式会社 | Objective lens |
-
1983
- 1983-12-15 JP JP19342483U patent/JPS60100717U/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS60100717U (en) | 1985-07-09 |
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