JPS5986019A

JPS5986019A - Objective for recording and reproduction of optomagnetic disk

Info

Publication number: JPS5986019A
Application number: JP19521182A
Authority: JP
Inventors: Yoji Kubota; 洋治久保田
Original assignee: Sankyo Seiki Manufacturing Co Ltd
Current assignee: Nidec Instruments Corp
Priority date: 1982-11-09
Filing date: 1982-11-09
Publication date: 1984-05-18
Also published as: JPS6327683B2

Abstract

PURPOSE:To obtain a small-sized lightweight lens which has large numerical aperture and operation distance by allowing the lens system of four-group constitution which consists of a biconvex or convex meniscus lens, concave meniscus lens, biconvex lens, and cemented lens of a biconvex and a biconcave lens successively from a light source side to meet specific requirements. CONSTITUTION:The lens system of four-group constitution consists of the biconvex or convex meniscus lens I , concave meniscus lens II, biconvex lens III, and cemented lens IV of the biconvex and biconcave lenses successively from the light source side and meets specific requirements, i.e. 0.55<r5/r6<1.05 and 0.95< r3/d3<1.75, where r5 and r6 are the radii of curvature of the surfaces of the group III on the sides of the light source and a disk 6, r3 is the radius of curvature of the light-source side surface of the 2nd group II, and d3 is the thickness of the 2nd group lens II. Consequently, the small-sized, lightweight lens which has large numerical aperture and sufficient operation distance is obtained.

Description

【発明の詳細な説明】本発明は、高密度ディスクに用いる光磁気デ、Ｃスク記
録用及び再生用対物レンズに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an objective lens for recording and reproducing magneto-optical disks and C disks used in high-density disks.

従来ビ７オｆイスクやデ５ｒジタルオーディオティスク
などの高密度ディスクに用いられている光学レンズ系は
デジタル１８号を非常に高密度でディスクに記録し、そ
れを読みとるために高い製（′１・精瓜ど微小の調整が
必要とされる。又ぞの記録・再生の１＝めのス・１物レ
ンスは光線どして半う９）本し−リ”−を用いるＩｃめ
人さな開口数Ｎ　Ａ　’（−ありながら波面収差が小さ
く略回析限界内にあることが要求される。しかしレンズ
系を振動さゼる為軒帛小ハリ目つある程度双子の作動距
離Ｗ　Ｄをらつことかの−Ｚよれる。又無即に小Ｉ％Ｉ
Ｉ化しょうどづるど極６に；：に小さな曲率半径をもつ
レンズ系になりがｔ：ｌであるか！ｌ！作−しできる限
り緩′Ｘ′１かな曲４′にづることが望。トしく、更に
光軸が僅かに倒れてし）Ａ−カスｎｆ能＜ｒ大きな有効
像円が必要である。The optical lens system conventionally used for high-density discs such as V7OF discs and digital audio discs records Digital No. 18 on discs at a very high density, and requires high-quality ( 1. Microscopic adjustment is required.The 1st lens of recording and playback is 9) Ic person who uses the light beam and the 1st object lens. Although the numerical aperture is small, the wavefront aberration is required to be small and approximately within the diffraction limit. However, in order to vibrate the lens system, the working distance of the twins is to some extent W D -Z is twisted.Also, small I%I immediately
If the lens system has a small radius of curvature at pole 6, it will be t:l! l! I would like to write the song as loosely as possible. (In addition, the optical axis is slightly tilted) A-Cus nf ability < r A large effective image circle is required.

しかし現在までの対物レンズは聞［］数Ｎへは人きいも
のがあったが、良りｆに波面収差が補ｊ１−さねた面積
が極めて小さく、レンズ系の中に製（′（−十国′　難
な曲率半径の小さい面か含まれる傾向がｄうり、作動距
離が充分でないものが多かった。更にカバ−ガラスを名
産するど収差が回折限界を越えて光束が充分に絞りきれ
ないものがあっＩこ。However, although the objective lenses to date have had problems with respect to the number N, the wavefront aberration is compensated for by f. In many cases, the working distance was not sufficient, as there was a tendency for surfaces with a small radius of curvature to be included.Furthermore, in the case of cover glasses, the aberrations exceeded the diffraction limit and the light beam could not be narrowed down sufficiently. There's something.

本発明の目的は、上記欠点を克服し、高密度ディスクに
記録・再生するための大きな開［１数で小！１す、軽小
で、充分４ｒ作動距離を有し、波面収差が良好に補正さ
れ、且つ収差が充分に補正された人さな右効像円を持つ
対物１ノンズの光磁気デ、ｒスク記録用及び再生用対物
レンズを提ｖＡ１Ｊることである。The purpose of the present invention is to overcome the above-mentioned drawbacks and provide a large opening for recording and reproducing on high-density disks. 1.The objective is light and small, has a sufficient 4r working distance, has wavefront aberrations well corrected, and has a human-like right effect circle with sufficiently corrected aberrations.1. The objective is to provide recording and reproducing objective lenses.

本発明の特徴は、光源側より順に両凸レンズ又は光源側
に凹面を向けた凸メニスカスレンズの第１　ｎＹ　＋ノ
ンズと、光源側に凹面を向りた凹メニスカスレンズの第
２群レンズと、両凸レンズの第３群１ノンスと、両凸レ
ンズ及び両凹レンズを接Ａ　１）Ｉｃ第４群レンズな配
して構成した開［］数が太きイ【充分作動距離を持ち小
型軽小で比較的製作が容易なことＣある。A feature of the present invention is that, in order from the light source side, the first nY + non-lens is a biconvex lens or a convex meniscus lens with a concave surface facing the light source side, the second group lens is a concave meniscus lens with a concave surface facing the light source side, and The 3rd group of convex lens, 1 nonce, and the biconvex lens and the biconcave lens are arranged in close contact with A1) Ic 4th group lens. C. It is easy to manufacture.

以１・、図示の実施例で本発明を説明する。光磁気ディ
スク記録用及び再生用対物レンズは第１図が第１実施例
で、光源Ａ側より順に両凸１ノンズ１の第１　Ｊ’、Ｙ
　ｌノンスＩと、光河；側に凹面を向りた凹メニスカス
レンズ２の第２群レンズ１１と、両凸レンズ３の第３　
ＪｉＹレンレン１）と、両凸レンズ４及び両凹レンズ５
を接合した第１１群レンズ１ｖとににつ（構成されてい
る。なお符＠　６　ＶＪ：ディスクのカバーガラスであ
る。In the following, the present invention will be explained with reference to the illustrated embodiments. The first embodiment of the objective lens for magneto-optical disk recording and reproduction is shown in FIG.
l nonce I, the second group lens 11 of the concave meniscus lens 2 with the concave surface facing the optical side, and the third group lens 11 of the biconvex lens 3.
JiY Lenlen 1), biconvex lens 4 and biconcave lens 5
It is composed of the 11th group lens 1v, which is cemented with the 11th group lens 1v.

上記第１図のレンズどカバーガラスに（」シたｒ〕目は
次の通りである。The eye on the cover glass of the lens shown in FIG. 1 is as follows.

ｒ；各１ノンス′及びカバーカラスの曲率半径、ｒ３；
第２群レンズの光源側面の曲率半径、ｒ、Ｊ３Ｊ：び１
゛。；第３４Ｙレンズの光源側面及びディスク側面の人
々の曲率半径、ｄｓ；第２群レンズの肉厚、上記第１図における各レンズとカバーカラスの数値は次
の通りである。ｔμシ符号は、１１：レンズの屈折率（
波ＬＣ８３０ｎｍ）ν；レレンのアツベ数ｒ、＝３２，０８８ｄ＋＝　０．２８１　　　ＩＩ　＝　１．６１２１！ｉ
　　ν＝ＧＯ１３１’２　＝　−３，３０８ｄ２＝　０
．１！’ｉ５１’３”　−１，０５３ｄ３＝ｏ、７４８　　　１１２＝　１，７８２７８　　
　シ、、＝２！ｉ、！１ｒ４＝　　　１．７８５　　　
　　　ｄ４　＝０．１００ｒ、＝２，４８０１ｂ＝　０，４３３　　　　ｎ、＝　１．（ｉ１２１５
ν３＝　Ｇｏ、３１゛、＝−３，２３０ｄｌ、＝０．０
２７＋′　＝１．０３６ｄ７＝　０．５５８　　　１１４　＝　１．Ｇ１２１５
　　　ν４　”　Ｇ　Ｏ、３ｒ８＝　−２，４８２ｄｓ　＝０．１８７　　　　１１．＝＝　１，７８４７
８　　　ν＝４２．３１・、＝　４．７１１（１＋＋　
＝　０．３００１’、　ｏ　＝［Ｚ＋ｄ、ｏ＝　０．３２０　　　　１１６　＝　１．５１１
゛１１−ゲノ全系の焦点距ｌｌ１ｉＢ　＝１．０００　、間［］数Ｎ
△＝０．！ｒ。r; radius of curvature of each nonce' and cover crow, r3;
Radius of curvature of the light source side of the second group lens, r, J3J:bi1
゛. The radius of curvature of the light source side and disk side of the 34th Y lens; ds; The thickness of the second group lens; The numerical values of each lens and cover glass in FIG. 1 above are as follows. The tμ code is 11: refractive index of the lens (
Wave LC830nm) ν; Reren's Atsube number r, = 32,088 d+ = 0.281 II = 1.6121! i
ν=GO131'2=-3,308d2=0
．． 1! 'i51'3" -1,053 d3=o, 748 112= 1,78278
Shi,,=2! i,! 1r4= 1.785
d4 = 0.100r, = 2,480 1b = 0,433 n, = 1. (i1215
ν3=Go, 31゛, =-3,230dl, =0.0
27+' = 1.036 d7 = 0.558 114 = 1. G1215
ν4 ” G O, 3r8 = −2,482 ds =0.187 11. == 1,7847
8 ν=42.31・,=4.711(1++
= 0.3001', o = [Z+ d, o = 0.320 116 = 1.511
゛11-The focal length of the entire genome system ll1iB = 1.000, the number of gaps N
△=0. ! r.

作ｉ１Ｊ　ｖｒｉ　対（Ｗ　Ｄ　＝　０．３Ｇ第１図は
第２実施例で光源Δ側より順に光源側に凹面を向けた凸
メニスカスレンズ１′の第’ｌ　ＩＣＹレンズ１′と、
光源側に凹面を向りた凹メニスカスレンズ２の第２群レ
ンズｌと、両凸レンズ３の訝１３　（ＩＹレレン１１と
、両凸レンズ４及び両凹レンズ５を接合した第４群レン
ズ１■ど（、二よって構成されでいる。Figure 1 shows a second embodiment of the convex meniscus lens 1' with its concave surface facing the light source in order from the light source Δ side.ICY lens 1'
The second group lens 1 of the concave meniscus lens 2 with its concave surface facing the light source side, the convex 13 of the biconvex lens 3 (IY lens 11, and the fourth group lens 1, which is made by cementing the biconvex lens 4 and the biconcave lens 5) , and two.

、［２第４図にお４）る各１ノンスとカバーカラスの数
値は次の通りである。, [4) in Figure 4] The numerical values of each nonce and cover callus are as follows.

１’、　＝　−２６７，５６０ｄ＋＝　０．２７７　　１１　、＝　１．６１２１．’
＋　　シ、＝　００，３１’　＝　　３．１８２　　　
　ｄ２＝　０．１００１’＝−１，０７３ｄ　、１　＝０−７　！ｉ　３　　　１１２−１．７８
２７８　　　シ、＝２Ｓ、、’＋１・＝　−１，７２８
（１，＝　０．１０／１・、＝２．５４０ｄ、＝　０．４３８　　１＋　＝　１．６１２ｉ！ｉ　
　　レーＧＯ，３１・＝−３，１１３ｄ　＝０．０３０１”　＝　１ｊ１３４ｄ７＝０，５Ｃ＋５　　　　ｎ、＝１．（ｉ１２１．’
＋　　　ｖ４＝ＧＯ，３１・ニー２，４１３ｄ　＝０．１８８　　　ｎ□−＝１．７８４７８　　シ
、＝７１２，３１・、＝４．１７６ｄ　−０，３７２ｄ１ｏ＝　０．３２Ｏｎ、、＝　１．５１”ｌ　＋”　
’ゞ゛仝系の焦点距Ｉｌｌ　ｆ　＝　１．ｔｌｏｏ　、聞［１
数Ｎ△＝０．５０作動距距離　＋）　＝　０．３６光）娃気フ２イスク記録用及び再生用対物１ノンスが１
−１記のように構成されるど、人きに１開１’−１１！
　Ｎ△と充分な１′［動用１ｍ＋　Ｗ　Ｉ）と、光＋１
１＋が昂かに倒れてもフォーカス可能な充分収差が補Ｉ
Ｆされた大きな有効角内が１１６保され、かつ曲率半径
が最も小（＼なものでし焦点距離どｌ１ｊｌ程度どしｌ
このて製作盲動４１低廉４【対物レンズが１ｇられる。1', = -267,560 d+= 0.277 11, = 1.6121. '
+ C, = 00,31' = 3.182
d2=0.1001'=-1,073 d,1=0-7! i 3 112-1.78
278 し、=2S、,'+1・=-1,728
(1, = 0.10/1・, = 2.540 d, = 0.438 1+ = 1.612i!i
Le GO, 31・=−3,113d=0.030 1”=1j134 d7=0,5C+5 n,=1.(i121.'
+ v4=GO, 31・knee 2,413 d =0.188 n□−=1.78478 ci,=712,31・,=4.176 d −0,372 d1o=0.32On,,=1. 51"l +"
'ゞ゛The focal length of the system Ill f = 1. tloo, listen [1
Number N△=0.50 working distance +) = 0.36 light) 2 objects for recording and playback 1 nonce 1
Although it is constructed as shown in -1, it is 1 open 1'-11!
N△ and sufficient 1' [dynamic 1m + W I) and light +1
The aberrations are compensated for enough to enable focus even when the 1+ is completely tilted.
116 within the large effective angle F
This makes the blind movement 41 inexpensive 4 [objective lens weighs 1g.

上記実ｔＭ例を）−一足する光（籠気アイスク記録用及
び再生用対物レンズの条件は次の通りである。The conditions for the recording and reproducing objective lenses are as follows.

（１）　　　０．５！ｉ＜　ｌ　ｌ゛！ｌ／　ｌ’ａｌ
　＜　１．０５（２＞　　　０．９！ｉ＜　ｒ３／　ｄ
３’＜　１．７５上記のＸ！、＋’ｔ−について、（１）　　（１，５５＜　ｌ　ｒ、／　ｒ、ｌ　＜　１
．０５なる条（′１は、球面収差を補正するための条件
であり、上限を超えるど補正過剰、上限を越えると補ｉ
ｆ不足と／、ｒる。(1) 0.5! i < l l゛! l/ l'al
< 1.05 (2>0.9!i< r3/ d
3'< 1.75 X above! , +'t-, (1) (1,55< l r, / r, l < 1
．． 05 ('1 is the condition for correcting spherical aberration; if the upper limit is exceeded, the correction will be overcorrected; if the upper limit is exceeded, the correction will be
f shortage/, r.

（’；！　　５　　　　０．９！ｉ＜　　ｒ　３．’＋
Ｊ　　、＜　　１　、７’、＋なる条件は、（′［動用
離をどるための条件てあり、上限を越えるど有効角内を
ＩＩＴｒ保づることが困ｎどなり、（−限を越えると所
望の作動距匍ｔをとることか困却となる。(';! 5 0.9!i< r 3.'+
J , < 1, 7', + is a condition for reducing the ('[dynamic distance. It is difficult to determine the working distance t.

木弁明は上述のように構成されたから、比較的製作が容
易であり、作！ＩＪ　ｆｆ１ｌｊｉロＪ充ヅ１艮い距阿
（が１９られ、開口数Ｎ△と有効角内とが人きい対物レ
ンズで、かつ小ｊｐｉ軽吊どなる雪優れた効果を炎する
光磁気デーｒスク記録用及び再生用対物１ノンスを提供
づることがでさる。Since the wooden Benmei is constructed as described above, it is relatively easy to produce, and it is easy to make! It is an objective lens with a distance of 19, a large numerical aperture N△ and a large effective angle, and a magneto-optical disc that produces an excellent effect even when the snow is light. It is possible to provide one nonce for recording and reproduction purposes.

[Brief explanation of the drawing]

第１図、第４図は光磁気ｊ′イスク記録用及び再９−用
対物レンズの第１実施例及び第２実施例のレンズ構成図
、第２図、第５３図は同波面収差図、第３図、第６図は
同球面収差・正弦系（′（−・非点収差・歪曲収差の各
収差図である。１．３．４・・・両凸レンズ、１′・・・凸メニスカス
レンズ、２・・・凹メニスカスレンズ、５・・・両凹レ
ンズ、ｄ・・・軸上面間隔、１゛・・・曲率半径、１、
ビ・・・第１　ＢＹレンズ、）Ｉ・・・第２群レンズ、
１１１・・・第３群１ノンズ、（■・・・第２群レンズ
。出願人　株式会ネｉ、二協精ａ製（′；＝所皿面に２以
内皿面　５′λ以内５図非点収差　　　歪曲収差り1 and 4 are lens configuration diagrams of the first and second embodiments of the objective lens for magneto-optical j′ isk recording and reproduction, and FIGS. 2 and 53 are wavefront aberration diagrams, Figures 3 and 6 are aberration diagrams of the same spherical aberration, sine system ('(-, astigmatism, and distortion aberration. 1.3.4... double-convex lens, 1'... convex meniscus) Lens, 2...Concave meniscus lens, 5...Biconcave lens, d...Axis upper surface distance, 1゛...Curvature radius, 1,
B...1st BY lens,) I...2nd group lens,
111... 3rd group 1 nons, (■... 2nd group lens. Applicant Nei Co., Ltd., manufactured by Nikkyosei A ('; = within 2 on the plate surface, 5' within 5'λ on the plate surface) Astigmatism Distortion

Claims

[Claims] In order from the light source side, the first lens group is a biconvex lens or a convex meniscus lens with a concave surface facing the light source side, and the second lens group Y is a concave meniscus lens with a concave surface facing the light source side. The lens is equipped with a third lens group consisting of a biconvex lens and a fourth lens group consisting of a biconvex lens and a biconcave lens. (1) O,,55< l l”, / l°61<
1.0! i(2) O,Q! i< r3/ d3<
1.7! iHowever, 1゛5 and 1゛. is 1. 3rd interval
The radii of curvature of the light source side surface and the disk side surface of the 8Y lens, 1.3 represent the radius of curvature of the light source side surface of the second lens group 1 lens, and d3 represents the thickness of the second lens group.