[go: up one dir, main page]
More Web Proxy on the site http://driver.im/

JPH1068876A - Ftheta lens - Google Patents

Ftheta lens

Info

Publication number
JPH1068876A
JPH1068876A JP22792996A JP22792996A JPH1068876A JP H1068876 A JPH1068876 A JP H1068876A JP 22792996 A JP22792996 A JP 22792996A JP 22792996 A JP22792996 A JP 22792996A JP H1068876 A JPH1068876 A JP H1068876A
Authority
JP
Japan
Prior art keywords
lens
object side
elements
good
telecentricity
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.)
Pending
Application number
JP22792996A
Other languages
Japanese (ja)
Inventor
Yoshio Mochida
省郎 持田
Kazuo Ueno
和夫 上野
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.)
Panasonic Holdings Corp
Original Assignee
Matsushita Electric Industrial 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 Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Priority to JP22792996A priority Critical patent/JPH1068876A/en
Publication of JPH1068876A publication Critical patent/JPH1068876A/en
Pending legal-status Critical Current

Links

Landscapes

  • Lenses (AREA)
  • Mechanical Optical Scanning Systems (AREA)

Abstract

PROBLEM TO BE SOLVED: To obtain fθ lens which is composed of three elements, has a good telecentric characteristic, is well corrected of aberrations and has a good fθ characteristic by forming the fθ lens composed of the three elements in three groups so as to satisfy specific conditions. SOLUTION: This fθ lens is composed of the lens group composed of the three elements in three groups consisting, successively from an object side toward an image plane side, a first lens 1 of a negative meniscus lens of which the concave face is directed to the object side, a second lens 2 of a positive meniscus lens of which the concave face is directed toward the object side and a third lens 3 of a positive meniscus lens of which the convex face is directed toward the object side. The lens is so formed as to satisfy the conditions -0.9<f1 /f<-0.4, d2 /f<0.06, N1 , N2 , N3 >2, -1.2<r1 /d0 <-0.8 by defining the focal length of the entire system as f, the refractive indices of the first lens 1 to the third lens 3 as N1 to N3 , the distance from the deflection plane of a deflector to the first lens 1 as d0 , the air spacing between the first and second lenses 1, 2 as d2 and the radius of curvature of the incident surface of the first lens 1 as r1 .

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【0001】[0001]

【発明の属する技術分野】本発明は、3枚構成でかつテ
レセントリックな特性を有する大口径のfθレンズであ
って、特に使用する光源の波長が10μm以上と波長の
長い光走査系に好適に適用できるfθレンズに関するも
のである。
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large-diameter f.theta. Lens having a three-element configuration and telecentric characteristics, and is particularly suitably applied to an optical scanning system having a light source having a wavelength as long as 10 .mu.m or more. It relates to a fθ lens that can be used.

【0002】[0002]

【従来の技術】レーザプリンタやファクシミリ、また検
査装置やレーザ加工装置等における光走査装置は、光源
からの光束を回転多面鏡等の偏向装置により偏向し、偏
向した光束を結像レンズ系によって走査面上にスポット
として結像させるように構成されており、偏向装置によ
り等角速度的に偏向された光束を像面にスポットとして
結像させるとともに等速度的な走査を可能にするために
大口径のfθレンズが用いられている。
2. Description of the Related Art An optical scanning device in a laser printer, a facsimile, an inspection device, a laser processing device, or the like deflects a light beam from a light source by a deflecting device such as a rotary polygon mirror, and scans the deflected light beam by an imaging lens system. It is configured to form an image as a spot on a surface. An fθ lens is used.

【0003】このとき、fθレンズの焦点距離をfとす
ると、走査面上像高Yと偏向装置により光軸より偏向さ
れた角度θとの間に、等速性を示すfθ特性といわれる Y=f・θ なる関係が成立する。
At this time, assuming that the focal length of the fθ lens is f, there is a fθ characteristic which shows uniform velocity between the image height Y on the scanning surface and the angle θ deflected from the optical axis by the deflecting device. The relationship f · θ holds.

【0004】ところで、上記各機器や装置に使用されて
いる光源の波長は1μm以下と短く、一般のガラスが使
用されている。しかし、光源の波長が10μm以上と波
長の長い光走査系に適用されたfθレンズは殆どない状
況である。
Incidentally, the wavelength of the light source used in each of the above devices and apparatuses is as short as 1 μm or less, and ordinary glass is used. However, there is almost no fθ lens applied to an optical scanning system in which the wavelength of the light source is as long as 10 μm or more.

【0005】また、一般的なfθレンズはテレセントリ
ックではなく、走査面がデフォーカスすると、fθ特性
が得られない等の問題が生じ、レーザ検査装置やレーザ
加工装置等において、特にレーザが斜めに入射して突出
物の影になる部分の検査が不備になったり、奥行きのあ
る加工が傾斜してしまうと言った問題が生じる。
Further, a general fθ lens is not telecentric, and if the scanning surface is defocused, there arises a problem that fθ characteristics cannot be obtained, and a laser is obliquely incident on a laser inspection device, a laser processing device, or the like. As a result, there arises a problem that inspection of a portion which becomes a shadow of the protrusion is inadequate, and that a deep machining is inclined.

【0006】テレセントリック性を有するfθレンズと
しては、例えば特開昭62−254112号公報、特開
平2−93511号公報等に開示されているが、それら
は最低6枚のレンズで構成して所望の特性が得られるよ
うにしている。
Japanese Patent Application Laid-Open Nos. 62-254112 and 2-93511 disclose f-theta lenses having telecentricity, for example. Characteristics are obtained.

【0007】[0007]

【発明が解決しようとする課題】しかしながら、上記f
θレンズのように最低6枚構成となるのでは、テレセン
トリック性が得られ、また各種の収差を補正しやすいも
のであっても、全体が長くて大きくなるので、小型化、
軽量化、低コスト化の要請に応えられないという問題が
あった。
However, the above f
With at least six lenses like a θ lens, telecentricity can be obtained, and even if it is easy to correct various aberrations, the whole becomes long and large.
There was a problem that demands for weight reduction and cost reduction could not be met.

【0008】一方、3枚構成程度のもので、各種収差を
十分に補正でき、テレセントリック性やfθ性を十分に
満足するものは未だ提供されていない。
On the other hand, there has not yet been provided a lens having about three lenses, which can sufficiently correct various aberrations and sufficiently satisfy telecentricity and fθ property.

【0009】本発明は、上記従来の問題点に鑑み、3枚
構成でかつテレセンリック性が良好であり、また収差を
良好に補正し、fθ特性の良好なfθレンズを提供する
ことを目的としている。
SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-described conventional problems, and has as its object to provide an fθ lens having a three-element configuration, good telecentricity, good aberration correction, and good fθ characteristics. I have.

【0010】[0010]

【課題を解決するための手段】本発明のfθレンズは、
種々検討を重ねた結果、3群3枚構成のfθレンズにお
いて、光源の波長が長くても良好に光を透過させるには
高屈折率な材料を用いること、各レンズと全体の焦点距
離の相互関係、さらに偏向面から第1レンズまでの距離
と第1レンズの入射面の曲率半径の相互関係が、fθレ
ンズ全体の主要な特性、例えば球面収差、非点収差、f
θ特性、テレセントリック性を大きく左右することが判
明したことによって達成されたものである。
The fθ lens according to the present invention comprises:
As a result of various studies, a high refractive index material was used to transmit light well even if the wavelength of the light source was long in the three-group three-element fθ lens. The relationship between the distance from the deflecting surface to the first lens and the radius of curvature of the entrance surface of the first lens is the main characteristic of the entire fθ lens, such as spherical aberration, astigmatism, f
This has been achieved because it has been found that the θ characteristic and the telecentricity greatly influence.

【0011】すなわち、物体側から像面側に向かって順
に、物体側に凹面を向けた負のメニスカスレンズの第1
レンズと、物体側に凹面を向けた正のメニスカスレンズ
の第2レンズと、物体側に凸面を向けた正のメニスカス
レンズの第3レンズとから成る3群3枚構成とし、全系
の焦点距離をf、第1レンズの焦点距離をf1 、第1、
第2、第3レンズの屈折率をN1 、N2 、N3 、偏向装
置の偏向面から第1レンズまでの距離をd0 、第1レン
ズと第2レンズの空気間隔をd2 、第1レンズの入射面
の曲率半径をr1 として、 (1)−0.9<f1 /f<−0.4 (2)d2 /f<0.06 (3)N1 、N2 、N3 >2 (4)−1.2<r1 /d0 <−0.8 なる条件を満足させたものである。
That is, in order from the object side to the image plane side, the first of the negative meniscus lens having a concave surface facing the object side
A three-group three-lens configuration including a lens, a second lens of a positive meniscus lens having a concave surface facing the object side, and a third lens of a positive meniscus lens having a convex surface facing the object side, and the focal length of the entire system Is f, the focal length of the first lens is f 1 , the first,
The refractive indices of the second and third lenses are N 1 , N 2 , N 3 , the distance from the deflecting surface of the deflecting device to the first lens is d 0 , the air gap between the first and second lenses is d 2 , Assuming that the radius of curvature of the entrance surface of one lens is r 1 , (1) −0.9 <f 1 /f<−0.4 (2) d 2 /f<0.06 (3) N 1 , N 2 , N 3> is 2 (4) -1.2 <those to satisfy r 1 / d 0 <-0.8 becomes conditions.

【0012】上記条件(1)〜(4)は、球面収差、非
点収差、fθ特性、テレセントリック性といった主要な
特性を所望の範囲に抑えるのに有効に働く。(1)の条
件の上限を越えると、球面収差がオーバーに、主・副走
査方向の非点収差、fθ特性、テレセントリック性がア
ンダーになる。また、下限を越えると球面収差がアンダ
ーに、fθ特性、テレセントリック性がオーバーにな
る。(2)の条件以上になると、主・副走査方向の非点
収差、テレセントリック性がオーバーとなり、諸収差が
悪化する。(3)の条件以下であると、長い波長が透過
しなくなり、レンズとしての機能を果たさなくなる。
(4)の条件の上限を越えると、球面収差がオーバー
に、主・副走査方向の非点収差、fθ特性、テレセント
リック性がアンダーになる。また、下限を越えると球面
収差がアンダーに、fθ特性、テレセントリック性がオ
ーバーになる。
The above conditions (1) to (4) work effectively to suppress the main characteristics such as spherical aberration, astigmatism, fθ characteristics, and telecentricity to a desired range. If the upper limit of the condition (1) is exceeded, spherical aberration will be excessive, and astigmatism in the main and sub scanning directions, fθ characteristics, and telecentricity will be under. If the lower limit is exceeded, the spherical aberration will be under, and the fθ characteristic and telecentricity will be over. Above the condition (2), astigmatism and telecentricity in the main and sub-scanning directions become excessive, and various aberrations deteriorate. If the condition (3) is not exceeded, a long wavelength is not transmitted, and the lens does not function.
If the upper limit of the condition (4) is exceeded, spherical aberration will be excessive, and astigmatism in the main and sub scanning directions, fθ characteristics, and telecentricity will be under. If the lower limit is exceeded, the spherical aberration will be under, and the fθ characteristic and telecentricity will be over.

【0013】したがって、上記(1)〜(4)の条件を
満足することによって、光源の波長が長くても、3枚構
成でかつテレセントリック性が良好であり、また収差を
良好に補正し、fθ特性の良好なfθレンズを提供でき
る。
Therefore, by satisfying the above conditions (1) to (4), even if the wavelength of the light source is long, a three-element configuration and good telecentricity can be obtained, aberration can be corrected well, and fθ An fθ lens having good characteristics can be provided.

【0014】[0014]

【発明の実施の形態】以下、本発明の大口径のfθレン
ズの一実施形態を図1〜図3を参照しながら説明する。
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a large-aperture fθ lens according to the present invention will be described below with reference to FIGS.

【0015】図1において、本実施形態のfθレンズ
は、物体側から像面側に向かって順に、物体側に凹面を
向けた負のメニスカスレンズの第1レンズ1と、物体側
に凹面を向けた正のメニスカスレンズの第2レンズ2
と、物体側に凸面を向けた正のメニスカスレンズの第3
レンズ3とから成る3群3枚構成のレンズ群にて構成さ
れている。4はこのfθレンズ系を透過した光束が結像
する像面である。また、物体側には、面走査を可能とす
るため第1偏向装置5と第2偏向装置6の2つの偏向装
置が配設されている。
In FIG. 1, an fθ lens according to the present embodiment includes, in order from the object side to the image plane side, a first lens 1 of a negative meniscus lens having a concave surface facing the object side, and a concave surface facing the object side. Second lens 2 of positive meniscus lens
And the third of the positive meniscus lens with the convex surface facing the object side
It is composed of a three-lens group composed of three lenses. Reference numeral 4 denotes an image plane on which a light beam transmitted through the fθ lens system forms an image. Further, on the object side, two deflecting devices, that is, a first deflecting device 5 and a second deflecting device 6 are arranged to enable surface scanning.

【0016】このような基本構成を持ったfθレンズに
おいて、fを全系の焦点距離、物体側から第i番目のレ
ンズの焦点距離をfi 、Fはレンズ系のFナンバー、2
ωは偏向角、物体側から第i番目のレンズ面曲率半径を
i (i=1〜6)、第2偏向装置6(偏向面)から第
1レンズ1までの距離をd0 、第i番目と第i+1番目
の面間隔をdi (i=1〜6)、第j番目のレンズの屈
折率をnj (j=1〜3)として、以下に実施例を示
す。
[0016] In fθ lens having such a basic configuration, the focal length of the entire system and f, the focal distance f i of the i-th lens from the object side, F is the F-number of the lens system, 2
ω is the deflection angle, the i-th lens surface curvature radius from the object side r i (i = 1 to 6), the distance from the second deflection device 6 (deflecting surface) to the first lens 1 d 0, the i An example will be described below, where the distance between the i-th and (i + 1) -th surfaces is d i (i = 1 to 6), and the refractive index of the j-th lens is n j (j = 1 to 3).

【0017】(実施例1)表1に第1実施例を示し、図
2にこの第1実施例におけるレンズの諸収差を示す。
(Embodiment 1) Table 1 shows the first embodiment, and FIG. 2 shows various aberrations of the lens in the first embodiment.

【0018】[0018]

【表1】 [Table 1]

【0019】図2から本実施例のfθレンズは収差を良
好に補正していることが分かる。
FIG. 2 shows that the fθ lens of this embodiment satisfactorily corrects the aberration.

【0020】(実施例2)表2に第2実施例を示し、図
3にこの第2実施例におけるレンズの諸収差を示す。
(Embodiment 2) Table 2 shows a second embodiment, and FIG. 3 shows various aberrations of the lens in the second embodiment.

【0021】[0021]

【表2】 [Table 2]

【0022】図3から本実施例のfθレンズは収差を良
好に補正していることが分かる。
FIG. 3 shows that the fθ lens of this embodiment satisfactorily corrects aberrations.

【0023】なお、図2、図3において、(a)はFナ
ンバーによる球面収差(単位mm)の変化を示し、
(b)は偏向角によるサジタル像面(S)とメリジオナ
ル像面(M)における非点収差(単位mm)の変化を示
し、(c)は偏向角による歪曲収差(単位%)の変化を
示す。
In FIGS. 2 and 3, (a) shows a change in spherical aberration (unit: mm) depending on the F number.
(B) shows a change in astigmatism (unit mm) in the sagittal image plane (S) and the meridional image plane (M) depending on the deflection angle, and (c) shows a change in distortion (unit%) according to the deflection angle. .

【0024】[0024]

【発明の効果】本発明の大口径fθレンズによれば、以
上の説明から明らかなように、3枚構成であることによ
り小型軽量で低コストにて構成でき、かつ光源の波長が
長くても、テレセントリック性が良好で、また収差を良
好に補正し、fθ特性の良好なfθレンズを実現するこ
とができる。
According to the large-aperture fθ lens of the present invention, as is apparent from the above description, the three-lens configuration allows the configuration to be small, light and low in cost, and even if the wavelength of the light source is long. , The telecentricity is good, and the aberration is satisfactorily corrected, so that an fθ lens with good fθ characteristics can be realized.

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

【図1】本発明のfθレンズの一実施形態の構成図であ
る。
FIG. 1 is a configuration diagram of an embodiment of an fθ lens of the present invention.

【図2】同実施形態の第1の実施例の各種収差を示す図
である。
FIG. 2 is a diagram showing various aberrations of the first example of the embodiment.

【図3】同実施形態の第2の実施例の各種収差を示す図
である。
FIG. 3 is a diagram showing various aberrations of a second example of the embodiment.

【符号の説明】[Explanation of symbols]

1 第1レンズ 2 第2レンズ 3 第3レンズ 4 像面 DESCRIPTION OF SYMBOLS 1 1st lens 2 2nd lens 3 3rd lens 4 Image plane

Claims (1)

【特許請求の範囲】[Claims] 【請求項1】 物体側から像面側に向かって順に、物体
側に凹面を向けた負のメニスカスレンズの第1レンズ
と、物体側に凹面を向けた正のメニスカスレンズの第2
レンズと、物体側に凸面を向けた正のメニスカスレンズ
の第3レンズとから成る3群3枚構成のfθレンズであ
って、全系の焦点距離をf、第1レンズの焦点距離をf
1 、第1、第2、第3レンズの屈折率をN1 、N2 、N
3 、偏向装置の偏向面から第1レンズまでの距離を
0 、第1レンズと第2レンズの空気間隔をd2 、第1
レンズの入射面の曲率半径をr1 として、 (1)−0.9<f1 /f<−0.4 (2)d2 /f<0.06 (3)N1 、N2 、N3 >2 (4)−1.2<r1 /d0 <−0.8 なる条件を満足させたことを特徴とするfθレンズ。
1. A first meniscus lens having a concave surface facing the object side and a second meniscus lens having a concave surface facing the object side in order from the object side to the image surface side.
An fθ lens composed of three lenses and a third meniscus lens having a positive meniscus lens having a convex surface facing the object side, wherein the focal length of the entire system is f and the focal length of the first lens is f
1, first, second, the refractive index of the third lens N 1, N 2, N
3. The distance from the deflecting surface of the deflecting device to the first lens is d 0 , the air gap between the first lens and the second lens is d 2 ,
Assuming that the radius of curvature of the entrance surface of the lens is r 1 , (1) −0.9 <f 1 /f<−0.4 (2) d 2 /f<0.06 (3) N 1 , N 2 , N 3 > 2 (4) -1.2 <r 1 / d 0 <−0.8 An fθ lens characterized by satisfying the following condition:
JP22792996A 1996-08-29 1996-08-29 Ftheta lens Pending JPH1068876A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP22792996A JPH1068876A (en) 1996-08-29 1996-08-29 Ftheta lens

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP22792996A JPH1068876A (en) 1996-08-29 1996-08-29 Ftheta lens

Publications (1)

Publication Number Publication Date
JPH1068876A true JPH1068876A (en) 1998-03-10

Family

ID=16868510

Family Applications (1)

Application Number Title Priority Date Filing Date
JP22792996A Pending JPH1068876A (en) 1996-08-29 1996-08-29 Ftheta lens

Country Status (1)

Country Link
JP (1) JPH1068876A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6980367B2 (en) 2002-10-17 2005-12-27 Canon Kabushiki Kaisha Scanning type display optical system
JP2007328364A (en) * 2007-08-06 2007-12-20 Canon Inc Scanning display optical system

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6980367B2 (en) 2002-10-17 2005-12-27 Canon Kabushiki Kaisha Scanning type display optical system
JP2007328364A (en) * 2007-08-06 2007-12-20 Canon Inc Scanning display optical system

Similar Documents

Publication Publication Date Title
EP0360233B1 (en) Telecentric f-theta lens system
JP2001281604A (en) Collimator lens and optical scanner using the same
JPH11271606A (en) Collimator lens and optical scanning device using the same
US5136412A (en) Fθ lens and scanning optical system using the same
JP3339934B2 (en) f / θ lens
JPH0990216A (en) Telecentric ftheta lens
JPS61286810A (en) Lens for optical scanning system
JP3392984B2 (en) Scan lens
JPH1068876A (en) Ftheta lens
EP1376195B1 (en) Optical scanner
JP3121452B2 (en) Optical scanning device
JP3018852B2 (en) Scanning device
JPS61175607A (en) Scanning optical system
JPH11281911A (en) Optical scanning optical system
JP2511904B2 (en) Optical beam scanning device
JP3752004B2 (en) Scanning lens
JPH0252307A (en) Ftheta lens
JPH1039205A (en) Scanning lens
JP3266350B2 (en) fθ lens and optical scanning device
JP2583856B2 (en) Optical beam scanning device
JP3364525B2 (en) Scanning imaging lens and optical scanning device
JP2020118776A (en) Scanning optical device
JPS6321619A (en) Scanning optical system with correction for surface tilt
JPH0364724A (en) F-theta lens
JPH0921944A (en) Scanning lens