JPS6331767B2

JPS6331767B2 -

Info

Publication number: JPS6331767B2
Application number: JP59269467A
Authority: JP
Inventors: Shoichi Takei; Koji Okajima
Original assignee: TOMIOKA KOGAKU KK
Current assignee: TOMIOKA KOGAKU KK
Priority date: 1984-12-20
Filing date: 1984-12-20
Publication date: 1988-06-27
Also published as: JPS61147212A

Description

【発明の詳細な説明】〔産業上の利用分野〕この発明は、主としてデジタル・オーデイオデ
イスクの主流であるコンパクト・デイスク（以下
「CD」と称略する）を再生する光ピツクアツプの
コリメート系として用いられる半導体レーザー用
コリメーターレンズに関するものである。[Detailed Description of the Invention] [Field of Industrial Application] This invention is mainly used as a collimating system for an optical pickup that plays compact discs (hereinafter referred to as "CDs"), which are the mainstream of digital audio discs. This invention relates to a collimator lens for semiconductor lasers.

[Conventional technology]

CDプレーヤの光ピツクアツプにおいては、一
般に光源として半導体レーザーの光を平行光束に
変換して利用している。この平行光束が良質なも
のでなければ、1μというスポツトサイズを必要
とする対物レンズの性能を十分に引出すことがで
きない。 Optical pickups for CD players generally use semiconductor laser light as a light source, converting it into a parallel beam of light. Unless this parallel light beam is of high quality, the performance of the objective lens, which requires a spot size of 1 μm, cannot be fully exploited.

また、半導体レーザーの光束は発散性を有する
ので、これを有効に利用するためにできる限り大
きなN.A.を持ち、かつ反射等によるエネルギー
の損失を防ぐ上から、少ない枚数で構成されてい
るコリメーターレンズが望まれる。 In addition, since the luminous flux of a semiconductor laser has a diverging property, in order to make effective use of this, a collimator lens has as large an NA as possible, and in order to prevent energy loss due to reflection, etc., the collimator lens is composed of a small number of lenses. is desired.

従来の半導体レーザー用コリメーターレンズと
しては、第２図に示すように、負メニスカスレン
ズ３と両凸レンズ４とを貼り合わせて１群２枚で
構成されたものがある（２はプリズム・ビームス
プリツター）。しかし、このタイプはバルサム貼
り合せの作業が必要で、しかも心出し調整等の問
題が生ずる。 As shown in Fig. 2, conventional collimator lenses for semiconductor lasers include one consisting of two lenses in one group, each consisting of a negative meniscus lens 3 and a biconvex lens 4 (2 is a prism/beam splitter). Tutter). However, this type requires balsam bonding work and also causes problems such as centering adjustment.

また、例えば特開昭58−38915号公報にみられ
るような２群２枚構成のものもあるが、このタイ
プでは２つのレンズ間の空気間隔と偏心に対する
感度が非常に高くなり、調整が容易でない。 There is also a two-group, two-element structure as seen in Japanese Patent Application Laid-Open No. 58-38915, but this type has a very high sensitivity to the air distance and eccentricity between the two lenses, making adjustment easy. Not.

また、近年プラスチツクによる非球面レンズの
実用化が目ざましいが、コリメーターレンズへの
応用を考えると、温度による形状の変化が大き
く、焦点距離の長いコリメーターレンズでは性能
の変化が著しくなり、その利用は困難と思われ
る。 Furthermore, in recent years, aspheric lenses made of plastic have been put into practical use at a remarkable rate, but when considering their application to collimator lenses, the shape changes significantly due to temperature, and the performance of collimator lenses with long focal lengths changes significantly. seems difficult.

[Problem that the invention seeks to solve]

このように、従来の半導体レーザー用コリメー
ターレンズは、バルサム貼り合せ作業を要して生
産性が悪く、心出し調整も面倒であつたり、空気
間隔及び心出し調整が困難であるという問題があ
り、プラスチツクによる安価な非球面レンズの実
用化も困難であつた。 As described above, conventional collimator lenses for semiconductor lasers have problems such as poor productivity due to the balsam bonding process, troublesome centering adjustments, and difficulty in adjusting air spacing and centering. It has also been difficult to commercialize inexpensive aspherical lenses made of plastic.

[Means for solving problems]

上記の問題を解決するため、この発明によるコ
リメーターレンズは、第１図に示すように光束射
出側に凸面を向けた正メニスカス単レンズ１より
成り、その凸面が下記の(1)式で示される非球面で
あつて、第１の発明は(2)に示すパラメーターを有
するものである。 In order to solve the above problem, the collimator lens according to the present invention consists of a positive meniscus single lens 1 with a convex surface facing the light beam exit side as shown in FIG. The first invention is an aspherical surface having the parameters shown in (2).

(1) (2) r₁＝−6.6591，ｄ＝0.1119，ｎ＝1.70399，νd
＝53.9 r₂−0.6411（Ａ＝0.1879，Ｂ＝0.8686）また、第２の発明は条件式(1)は上記の第１の
発明と同一であつて、(3)に示すパラメーターを
有するものである。(1) (2) r ₁ = −6.6591, d = 0.1119, n = 1.70399, νd
=53.9 r ₂ −0.6411 (A=0.1879, B=0.8686) In addition, in the second invention, conditional expression (1) is the same as the above first invention, and has the parameter shown in (3). be.

(3) r₁＝−32.4298，ｄ＝0.1115，ｎ＝1.70399，
νd＝53.9 r₂＝−0.6900（Ａ＝0.1657，Ｂ＝0.7889）ただし、ｘは入射高ｙにおける非球面の頂点
の接平面からの距離、r₂は非球面の頂点付近で
の曲率半径、Ａ、Ｂ、…はそれぞれ入射高の４
乗、６乗、…に比例する項の係数、r₁は球面の
曲率半径、ｄはレンズの肉厚、ｎは波長780nm
に対するレンズの屈折率、νdはｄ線に対する
レンズのアツベ数である。(3) r ₁ = −32.4298, d = 0.1115, n = 1.70399,
νd = 53.9 r ₂ = -0.6900 (A = 0.1657, B = 0.7889) where x is the distance from the tangent plane of the apex of the aspheric surface at the incident height y, r ₂ is the radius of curvature near the apex of the aspheric surface, A , B, ... are the incident heights of 4
The coefficient of the term proportional to the power, the sixth power, etc., r ₁ is the radius of curvature of the spherical surface, d is the thickness of the lens, and n is the wavelength of 780 nm.
The refractive index of the lens for the d-line, νd, is the Abbe number of the lens for the d-line.

パラメーター(2)，(3)はそれぞれ、CDプレーヤ
用コリメーターレンズとしての性能を満たすよう
に非球面を用いて球面収差の補正を試みる時、基
準となる球面からの逸脱量が大きくなつて加工が
困難にならない範囲で良好な収差補正を得るため
の数値である。 Parameters (2) and (3) respectively indicate that when attempting to correct spherical aberration using an aspheric surface to satisfy the performance of a collimator lens for a CD player, the amount of deviation from the reference spherical surface becomes large. These values are for obtaining good aberration correction within a range that does not make it difficult.

〔Example〕

以下、この発明による実施例を示す。 Examples according to this invention will be shown below.

実施例１ｆ＝1.0 NA＝0.16 （−r₂／（ｎ−１）・ｆ＝0.91） r₁＝−6.6591 ｄ＝0.1119 ｎ＝1.70399 νd＝53.9 r₂＝−0.6411（非球面）第２面の非球面係数Ａ＝0.1879 Ｂ＝0.8686 実施例２ｆ＝1.0 NA＝0.16 （−r₂／（ｎ−１）・ｆ＝0.98） r₁＝−32.4298 ｄ＝0.1115 ｎ＝1.70399 νd＝53.9 r₂＝−0.6900（非球面）第２面の非球面係数Ａ＝0.1657 Ｂ＝0.7889 ただし、r₁，r₂は各面の頂点付近の（基準とな
る面の）曲率半径、ｄはレンズの肉厚、ｎは波長
780nmに対するレンズの屈折率、νdはｄ線に対す
るレンズのアツベ数、Ａ、Ｂはそれぞれ入射高の
４乗、６乗に比例する項の係数である。Example 1 f=1.0 NA=0.16 (−r ₂ /(n−1)・f=0.91) r ₁ =−6.6591 d=0.1119 n=1.70399 νd=53.9 r ₂ =−0.6411 (aspherical surface) 2nd surface Aspheric coefficients A=0.1879 B=0.8686 Example 2 f=1.0 NA=0.16 (-r ₂ /(n-1)・f=0.98) r ₁ =-32.4298 d=0.1115 n=1.70399 νd=53.9 r ₂ = -0.6900 (aspherical surface) Aspherical coefficient of the second surface A = 0.1657 B = 0.7889 However, r ₁ and r ₂ are the radius of curvature (of the reference surface) near the apex of each surface, and d is the lens thickness , n is the wavelength
The refractive index of the lens for 780 nm, νd is the Abbe number of the lens for the d-line, and A and B are coefficients of terms proportional to the fourth and sixth powers of the incident height, respectively.

なお、プリズム・ビームスプリツター２はCD
用光ピツクアツプとして使用され得ると思われる
ｎ＝1.51，ｄ＝0.25を用いた。 In addition, Prism Beam Splitter 2 is a CD
We used n=1.51 and d=0.25, which are thought to be able to be used as optical pickups.

第３図及び第４図に、実施例１，２の各収差曲
線図を示す。 3 and 4 show aberration curve diagrams of Examples 1 and 2.

〔Effect of the invention〕

以上説明したように、この発明による半導体レ
ーザ用コリメーターレンズは、１枚のレンズによ
つて構成するので小形軽量化でき、心出しや空気
間隔の調整が不要であり、かつその正メニスカス
単レンズの凸面を(1)式で示され非球面とし、レン
ズの球面の曲率半径r₁、非球面の頂点付近での曲
率半径r₂、肉厚ｄ、屈折率ｎ及びアツベ数νdをパ
ラメーター(2)又は(3)に示すように定めたので、い
ずれの場合にも半導体レーザー用コリメーターレ
ンズとしての充分な光学的性能を有し、収差も良
好なものとなつている。 As explained above, the collimator lens for a semiconductor laser according to the present invention is composed of a single lens, so it can be made smaller and lighter, does not require centering or air gap adjustment, and has a positive meniscus single lens. Let the convex surface of the lens be an aspherical surface expressed by equation (1), and the radius of curvature r ₁ of the spherical surface of the lens, the radius of curvature near the apex of the aspherical surface r ₂ , the wall thickness d, the refractive index n, and the Atsube number νd are expressed as parameters (2 ) or (3), in either case it has sufficient optical performance as a collimator lens for a semiconductor laser and has good aberrations.

[Brief explanation of the drawing]

第１図はこの発明によるレンズ系の構成図、第
２図は従来の１群２枚によるレンズ系の構成図、
第３図及び第４図はそれぞれこの発明の実施例１
及び２の各収差曲線図である。１…コリメーターレンズ（正メニスカス単レン
ズ）、２…プリズム・ビームスプリツター。 Fig. 1 is a block diagram of a lens system according to the present invention, Fig. 2 is a block diagram of a conventional lens system with two elements in one group,
FIG. 3 and FIG. 4 are respectively Embodiment 1 of this invention.
and 2 are each aberration curve diagram. 1... Collimator lens (positive meniscus single lens), 2... Prism beam splitter.

Claims

[Scope of Claims] 1. Consisting of a positive meniscus single lens with a convex surface facing the light beam exit side, the convex surface is an aspheric surface expressed by the following equation (1), and has the parameters shown in (2). Features collimator lens for semiconductor laser. (1) (2) r ₁ = −6.6591, d = 0.1119, n = 1.70399, νd
= 53.9 r ₂ = -0.6411 (A = 0.1879, B = 0.8686) where x is the distance from the tangent plane of the apex of the aspheric surface at the incident height y, r ₂ is the radius of curvature near the apex of the aspheric surface, A, B... is the incident height of 4
The coefficient of the term proportional to the power, the sixth power, etc., r ₁ is the radius of curvature of the spherical surface, d is the thickness of the lens, and n is the wavelength of 780 nm.
The refractive index of the lens for the d-line, νd, is the Abbe number of the lens for the d-line. 2. For use in semiconductor lasers, consisting of a positive meniscus single lens with a convex surface facing the light beam exit side, the convex surface being an aspheric surface represented by the following equation (1), and having the parameters shown in (3). collimator lens. (1) (3) r ₁ = −32.4298, d = 0.1115, n = 1.70399,
νd = 53.9 r ₂ = -0.6900 (A = 0.1657, B = 0.7889) where x is the distance from the tangent plane of the apex of the aspheric surface at the incident height y, r ₂ is the radius of curvature near the apex of the aspheric surface, A , B... are the incident heights of 4, respectively.
_R1 is the radius of curvature of the spherical surface, d is the thickness of the lens, n is the refractive index of the lens for a wavelength of 780 nm, and νd is the Abbe number of the lens for the d-line.