JP2001066499A - Optical system provided with diffraction optical device - Google Patents
Optical system provided with diffraction optical deviceInfo
- Publication number
- JP2001066499A JP2001066499A JP23965899A JP23965899A JP2001066499A JP 2001066499 A JP2001066499 A JP 2001066499A JP 23965899 A JP23965899 A JP 23965899A JP 23965899 A JP23965899 A JP 23965899A JP 2001066499 A JP2001066499 A JP 2001066499A
- Authority
- JP
- Japan
- Prior art keywords
- optical element
- optical system
- diffractive optical
- lens group
- reduction
- 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
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/42—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect
- G02B27/4205—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant
- G02B27/4211—Diffraction optics, i.e. systems including a diffractive element being designed for providing a diffractive effect having a diffractive optical element [DOE] contributing to image formation, e.g. whereby modulation transfer function MTF or optical aberrations are relevant correcting chromatic aberrations
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B13/00—Optical objectives specially designed for the purposes specified below
- G02B13/22—Telecentric objectives or lens systems
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/144—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only
- G02B15/1445—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being negative
- G02B15/144515—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having four groups only the first group being negative arranged -+++
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B15/00—Optical objectives with means for varying the magnification
- G02B15/14—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective
- G02B15/145—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only
- G02B15/1455—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being negative
- G02B15/145527—Optical objectives with means for varying the magnification by axial movement of one or more lenses or groups of lenses relative to the image plane for continuously varying the equivalent focal length of the objective having five groups only the first group being negative arranged -+-++
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1814—Diffraction gratings structurally combined with one or more further optical elements, e.g. lenses, mirrors, prisms or other diffraction gratings
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1842—Gratings for image generation
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1861—Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Projection Apparatus (AREA)
- Transforming Electric Information Into Light Information (AREA)
- Lenses (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、縮小側におかれた
液晶パネルなどによる表示画像を拡大投影するための光
学系に関し、特に回折光学素子を用いた小型で、諸収差
を良好に補正することができ、回折光学素子の入射角度
依存性の低減を達成することのできるかつ（さらに）投
射型表示装置等に好適な光学系の実現を目指すものであ
る。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical system for enlarging and projecting a display image on a liquid crystal panel or the like disposed on a reduction side, and more particularly to a small-sized optical system using a diffractive optical element, which satisfactorily corrects various aberrations. It is an object of the present invention to realize an optical system capable of achieving a reduction in the incident angle dependence of the diffractive optical element and (further) suitable for a projection display device or the like.
【０００２】[0002]
【従来の技術】液晶パネルなどの表示画像を拡大投影す
る液晶プロジェクタなどの投射型の表示装置は近年大幅
にその性能が向上し、様々な場所で使用されるようにな
ったものの、表示画像の画質、画像の明るさ、小型化、
軽量化などの点に関してより一層の向上が求められてい
る。2. Description of the Related Art Projection-type display devices such as a liquid crystal projector for enlarging and projecting a display image on a liquid crystal panel have been greatly improved in recent years, and have been used in various places. Image quality, image brightness, miniaturization,
Further improvements are required in terms of weight reduction and the like.
【０００３】高画質をねらう液晶プロジェクタとして、
赤、青、緑の波長領域用にそれぞれ液晶パネルを配置す
るいわゆる３板式のものが知られている。この３板式の
ものは、３つの液晶パネルに表示がされた画像を、スク
リーン上に重ねてカラー画像として表示するために光路
上にダイクロイックプリズムなどの色合成光学系を用い
ている。このダイクロイックプリズム中のダイクロイッ
ク膜の角度依存性により発生する投射画像の色むらや、
液晶パネルの視向性により発生するコントラスト低下を
防ぐために、投射光学系には縮小側の像面に対してテレ
セントリック性が要求される。また、３つの液晶パネル
の拡大画像の色ずれを少なくするため、投射レンズに
は、倍率色収差を低減することが要求される。さらに、
近年比較的明るい部屋の中でも画像を観察できるように
するため、液晶パネルにはマイクロレンズが採用される
ようになった。このため液晶パネルより放射する光の立
体角が大きくなり、この光を有効利用するため投射レン
ズには、より明るい投射レンズが求められるようになっ
た。As a liquid crystal projector aiming at high image quality,
A so-called three-panel type in which liquid crystal panels are respectively arranged for red, blue, and green wavelength regions is known. The three-panel type uses a color synthesizing optical system such as a dichroic prism on an optical path in order to superimpose images displayed on three liquid crystal panels on a screen and display them as color images. Color unevenness of the projected image caused by the angular dependence of the dichroic film in this dichroic prism,
In order to prevent a decrease in contrast caused by the directivity of the liquid crystal panel, the projection optical system is required to have telecentricity with respect to the image plane on the reduction side. Further, in order to reduce the color shift of the enlarged images of the three liquid crystal panels, the projection lens is required to reduce chromatic aberration of magnification. further,
In recent years, microlenses have come to be used in liquid crystal panels so that images can be observed even in relatively bright rooms. For this reason, the solid angle of the light emitted from the liquid crystal panel is increased, and a brighter projection lens is required for the projection lens in order to effectively use the light.
【０００４】近年、回折光学素子を用いて光学性能を向
上するという技術が、ＳＰＩＥ ｖｏｌ．１３５４ Ｉ
ｎｔｅｒｎａｔｉｏｎａｌ Ｌｅｎｓ Ｄｅｓｉｇｎ
Ｃｏｎｆａｒｅｎｃｅ（１９９０）等の文献や特開平１
０−１１５７７７号公報、特開平１１−０６４７２６号
公報等で開示されている。これらは、光学系中の屈折面
と回折面とでは、ある基準波長の光線に対する色収差の
でかたが逆であるという物理現象を利用したものであ
る。これは回折光学素子が、通常の光学ガラスが正の分
散を有するのに対して、負の分散特性（νｄ＝−３．４
５３）を有することを意味している。また、回折光学素
子には、つよい異常分散性（θg．Ｆ＝０．２９５６）
がある。加えて、回折光学素子の周期的構造を変化させ
ることで、非球面レンズ的な効果をも持たせることがで
きるという特性を有する。前述した、負の分散や強い異
常分散性を利用した色収差の補正効果と、この非球面効
果を利用して光学性能の大幅な向上を期待できる。さら
にこのような回折光学素子の特性は、微細な形状により
発現するため、空間的な占有率が非常に低く、軽量小型
化を達成しやすい。前記特開平１０−１１５７７７号公
報、特開平１１−０６４７２６号公報等は、こうした回
折光学素子の特性を利用し光学系の性能向上、小型化を
達成したものである。[0004] In recent years, a technique for improving optical performance using a diffractive optical element has been developed in SPIE vol. 1354 I
international Lens Design
References such as Conference (1990) and
This is disclosed in, for example, Japanese Patent Application Laid-Open No. 0-115777 and Japanese Patent Application Laid-Open No. 11-064726. These use a physical phenomenon that the refracting surface and the diffractive surface in the optical system have the opposite chromatic aberrations with respect to a light beam having a certain reference wavelength. This is because the diffractive optical element has a negative dispersion characteristic (νd = −3.4) while the ordinary optical glass has a positive dispersion.
53). Further, the diffractive optical element has a strong anomalous dispersion (θ g .F = 0.2956).
There is. In addition, by changing the periodic structure of the diffractive optical element, the diffractive optical element has a characteristic that an effect like an aspheric lens can be provided. The above-described chromatic aberration correction effect using negative dispersion and strong anomalous dispersion, and a significant improvement in optical performance can be expected using this aspherical effect. Further, since the characteristics of such a diffractive optical element are manifested by a fine shape, the spatial occupancy is very low, and it is easy to achieve a reduction in weight and size. JP-A-10-115777, JP-A-11-064726, and the like use such characteristics of a diffractive optical element to achieve an improvement in the performance and miniaturization of an optical system.
【０００５】回折光学素子を投射光学系などに用いる場
合、回折効率を考慮しなければならない。屈折光学系の
場合、ある屈折面に入射した１本の光線は、屈折後も１
本の光線であるが、回折においては、回折により、複数
の次数に分離してしまい、この時入射した光線のエネル
ギーは、格子形状に依存した形で次数にそれぞれ分離し
てしまう。所望の次数の光線（設計次数）の回折効率を
１に近づけるように格子形状を決定する必要がある。さ
らに回折効率は、波長および格子に入射する角度に大き
く依存するため、十分考慮しなければならない。When a diffractive optical element is used in a projection optical system or the like, it is necessary to consider diffraction efficiency. In the case of a refractive optical system, one light beam incident on a certain refraction surface remains 1 after refraction.
Although it is a book light, in diffraction, it is separated into a plurality of orders by diffraction, and the energy of the incident light beam is separated into orders depending on the lattice shape at this time. It is necessary to determine the grating shape so that the diffraction efficiency of a light beam of a desired order (design order) approaches 1. Further, the diffraction efficiency greatly depends on the wavelength and the angle of incidence on the grating, and must be sufficiently considered.
【０００６】図１３は、ある１つの材料により形成され
た単層の回折光学素子の回折効率の例を示したものであ
る。図１３に示したように、ある特定の波長における回
折効率は高いものの、設計波長より離れた波長の回折効
率は大きく低下していることがわかる。この回折効率の
低下している波長域においては、設計次数以外の回折効
率が高くなっておりフレア等の画像劣化を起こしてしま
う。このような、回折効率の波長依存性を低減する様な
構成が、特開平１０−１３３１４９号公報等や、本出願
人による特願平１０−３９６３９号公報において開示さ
れている。特開平１０−１３３１４９号公報等の技術
は、分散の異なる２つの材料により回折格子を形成し、
波長による位相差を低減することで単層の回折格子にみ
れるような回折効率の波長依存性を低減させたものであ
る。図１４は、特開平１０−１３３１４９号公報の技術
にみられるような回折光学素子の回折効率の例である。
特開平１０−１３３１４９号公報の中では、２つの材料
を密着させた構成であったが、その材料どうしを空気層
をはさんで分離した構成で、図１４はしめしている。こ
のように、空気層をはさむことにより、２つの材料の選
択性が広がり、光学特性を向上させることが可能とな
る。このような構成の回折光学素子を本出願人による特
願平１０−３９６３９号公報に記載されている。以下こ
の技術により構成される回折素子の形状を単層型の回折
光学素子に対して、積層型の回折光学素子とよぶことに
する。FIG. 13 shows an example of the diffraction efficiency of a single-layer diffractive optical element formed of one material. As shown in FIG. 13, the diffraction efficiency at a specific wavelength is high, but the diffraction efficiency at wavelengths farther than the design wavelength is significantly reduced. In the wavelength region where the diffraction efficiency is low, the diffraction efficiency other than the design order is high, and image deterioration such as flare occurs. Such a configuration for reducing the wavelength dependence of the diffraction efficiency is disclosed in Japanese Patent Application Laid-Open No. Hei 10-133149 and Japanese Patent Application No. 10-39639 by the present applicant. Japanese Patent Application Laid-Open No. Hei 10-133149 discloses a technique in which a diffraction grating is formed from two materials having different dispersions.
By reducing the phase difference due to wavelength, the wavelength dependence of diffraction efficiency as seen in a single-layer diffraction grating is reduced. FIG. 14 shows an example of the diffraction efficiency of a diffractive optical element as seen in the technique disclosed in Japanese Patent Application Laid-Open No. 10-133149.
Japanese Patent Application Laid-Open No. 10-133149 discloses a configuration in which two materials are brought into close contact with each other. However, FIG. 14 shows a configuration in which the materials are separated from each other with an air layer interposed therebetween. As described above, by sandwiching the air layer, the selectivity between the two materials is expanded, and the optical characteristics can be improved. A diffractive optical element having such a configuration is described in Japanese Patent Application No. 10-39639 by the present applicant. Hereinafter, the shape of a diffractive element formed by this technique will be referred to as a laminated diffractive optical element with respect to a single-layer diffractive optical element.
【０００７】[0007]
【発明が解決しようとする課題】特開平１０−１１５７
７７号公報、特開平１１−０６４７２６号公報に開示さ
れている光学系は、ＣＣＤ等の固体撮像素子に対して用
いられる撮影レンズであり、回折光学素子をテレセント
リックに近い光路上に設けることで、諸収差とくに色収
差を大きく低減させている。テレセントリックに近い光
路上に設けているため、主光線に対しても回折光学素子
への入射角が、ほぼ垂直となるため角度依存性を受けに
くい構成となっている。しかしながら、光学系のＦ値
は、２．８程度であり、それよりＦ値の小さい光学系に
対しては、マージナル光線の回折光学素子への入射角が
大きくなってしまうため、回折効率が大きく低下してし
まう。さらに、積層型の回折光学素子は、格子の深さが
深いため、回折効率の角度依存性が大きく、Ｆ値の小さ
い光学系の場合、マージナル光線の回折光学素子への入
射角が大きくなってしまうという点に問題を有してい
る。又、特願平１０−３９６３９号公報のように格子間
に空気層を有するような積層型の回折光学素子を構成す
ることが難しい。SUMMARY OF THE INVENTION Japanese Patent Application Laid-Open No. H10-1157
No. 77, the optical system disclosed in JP-A-11-064726 is a photographing lens used for a solid-state imaging device such as a CCD, and by providing a diffractive optical element on an optical path close to telecentric, Various aberrations, especially chromatic aberration, are greatly reduced. Since it is provided on an optical path close to telecentric, the angle of incidence on the diffractive optical element with respect to the principal ray is almost perpendicular, so that it is hardly affected by the angle dependency. However, the F-number of the optical system is about 2.8. For an optical system having a smaller F-number, the angle of incidence of the marginal ray on the diffractive optical element becomes large, so that the diffraction efficiency is large. Will drop. Furthermore, since the laminated type diffractive optical element has a large grating depth, the angle dependence of the diffraction efficiency is large, and in the case of an optical system having a small F value, the incident angle of the marginal ray to the diffractive optical element becomes large. There is a problem in that it is. Also, it is difficult to configure a laminated diffractive optical element having an air layer between lattices as disclosed in Japanese Patent Application No. 10-39639.
【０００８】そこで、本発明は、上記従来のものにおけ
る課題を解決し、小型で、諸収差特に倍率色収差を良好
に補正することができ、回折光学素子の入射角度依存性
の低減を図ることが可能な、特に液晶プロジェクタなど
の投射型の表示装置等に好適な光学系を提供することを
目的とするものである。Accordingly, the present invention solves the above-mentioned problems in the conventional art, is compact, can favorably correct various aberrations, especially lateral chromatic aberration, and reduces the dependence of the diffractive optical element on the incident angle. It is an object of the present invention to provide an optical system which is possible, particularly suitable for a projection type display device such as a liquid crystal projector.
【０００９】[0009]
【課題を解決するための手段】本発明は、上記課題を達
成するために、回折光学素子を有する光学系を、つぎの
（１）〜（１３）のように構成したことを特徴とするも
のである。 （１）本発明の光学系は、縮小側像面に形成される画像
を拡大投影し、縮小側像面に対して略テレセントリック
の光学系において、前記光学系が絞りを有し、かつ絞り
と縮小側像面との光路間に回折光学素子を有することを
特徴としている。 （２）本発明の光学系は、前記回折光学素子と縮小側像
面との間の屈折力が正であることを特徴としている。 （３）本発明の光学系は、前記回折光学素子が、２つの
隣接する光学要素間に設けられていることを特徴として
いる。 （４）本発明の光学系は、前記回折光学素子が、分散の
異なる２つの材料により形成されている２つの回折光学
素子を近接配置した構成を有する回折光学素子であるこ
とを特徴としている。 （５）本発明の光学系は、前記回折光学素子と縮小側像
面との光路間の屈折力が、投射光学系の広角側の焦点距
離をｆｗ、回折光学素子と縮小側像面間の光路の焦点距
離をｆdoe-imgとしたとき、 ０．０＜ｆｗ／ｆdoe-img＜０．２ なる条件式を満足することを特徴としている。 （６）本発明の光学系は、拡大側より順に、負の屈折力
を有する第１レンズ群、正の屈折力を有する第２レンズ
群、絞り、及びそれに続く正または負の１つ以上のレン
ズ群、正の屈折力を有する固定のレンズ群を有し、か
つ、縮小側の像面に対して略テレセントリックな光学系
において、前記絞りと縮小側像面の間に回折光学素子を
有することを特徴としている。 （７）本発明の光学系は、前記回折光学素子と縮小側像
面との光路間が正の屈折力で有ることを特徴としてい
る。 （８）本発明の光学系は、前記第２群が、広角側から望
遠側への変倍時において縮小側から拡大側へ移動するこ
とを特徴としている。 （９）本発明の光学系は、前記回折光学素子は、２つの
隣接する光学要素間に設けられていることを特徴として
いる。 （１０）本発明の光学系は、前記回折光学素子が、分散
の異なる２つの材料により形成されている２つの回折光
学素子を近接配置した構成を有する回折光学素子である
ことを特徴としている。 （１１）本発明の光学系は、前記回折光学素子と縮小側
像面との光路間の屈折力が、投射光学系の広角側の焦点
距離をｆｗ、回折光学素子と縮小側像面間の光路の焦点
距離をｆdoe-imgとしたとき、 ０．０＜ｆｗ／ｆdoe-img＜０．２ なる条件式を満足することを特徴としている。 （１２）本発明の光学系は、前記回折光学素子の焦点距
離をｆdoeとしたとき、 ０．０１≦ｆｗ／ｆdoe＜０．０５ なる条件式を満足することを特徴としている。 （１３）本発明の光学系は、前記回折光学素子が、前記
正の屈折力を有する固定のレンズ群中に設けられている
ことを特徴としている。In order to achieve the above object, the present invention is characterized in that an optical system having a diffractive optical element is constructed as in the following (1) to (13). It is. (1) An optical system according to the present invention enlarges and projects an image formed on a reduction-side image plane. In an optical system that is substantially telecentric with respect to the reduction-side image plane, the optical system has a stop. It is characterized by having a diffractive optical element between the optical path with the image plane on the reduction side. (2) The optical system according to the present invention is characterized in that the refractive power between the diffractive optical element and the image plane on the reduction side is positive. (3) The optical system according to the present invention is characterized in that the diffractive optical element is provided between two adjacent optical elements. (4) The optical system according to the present invention is characterized in that the diffractive optical element is a diffractive optical element having a configuration in which two diffractive optical elements formed of two materials having different dispersions are arranged close to each other. (5) In the optical system of the present invention, the refractive power between the optical path between the diffractive optical element and the image plane on the reduction side is fw, the focal length on the wide angle side of the projection optical system, and the distance between the diffractive optical element and the image plane on the reduction side. When the focal length of the optical path is f doe-img , the conditional expression 0.0 <fw / f doe-img <0.2 is satisfied. (6) The optical system according to the present invention includes, in order from the magnification side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a stop, and one or more positive or negative lenses following the first lens group. A lens group, having a fixed lens group having a positive refractive power, and having a diffractive optical element between the stop and the reduction-side image plane in an optical system that is substantially telecentric with respect to the reduction-side image plane. It is characterized by. (7) The optical system according to the present invention is characterized in that the optical path between the diffractive optical element and the image plane on the reduction side has a positive refractive power. (8) The optical system according to the present invention is characterized in that the second lens unit moves from the reduction side to the enlargement side during zooming from the wide-angle side to the telephoto side. (9) The optical system according to the present invention is characterized in that the diffractive optical element is provided between two adjacent optical elements. (10) The optical system according to the present invention is characterized in that the diffractive optical element is a diffractive optical element having a configuration in which two diffractive optical elements formed of two materials having different dispersions are arranged close to each other. (11) In the optical system of the present invention, the refractive power between the optical path of the diffractive optical element and the image plane on the reduction side is fw, the focal length on the wide angle side of the projection optical system, and the distance between the diffractive optical element and the image plane on the reduction side. When the focal length of the optical path is f doe-img , the conditional expression 0.0 <fw / f doe-img <0.2 is satisfied. (12) The optical system according to the present invention is characterized in that, when the focal length of the diffractive optical element is f doe , the conditional expression 0.01 ≦ fw / f doe <0.05 is satisfied. (13) The optical system of the present invention is characterized in that the diffractive optical element is provided in a fixed lens group having the positive refractive power.
【００１０】[0010]
【発明の実施の形態】つぎに、本発明の実施の形態につ
いて説明する。上記（１）のように、回折光学素子を絞
りと縮小像面との光路間に設ける構成により、軸外主光
線の光軸からの高さが高い位置に配置することで、諸収
差とくに倍率色収差を大きく低減させることができる。
また、上記（２）のように、回折光学素子と縮小像面と
の光路間に正の屈折力を配置する構成により、マージナ
ル光線の発散角を減ずることができ、回折光学素子への
入射角の変動を小さくすることが可能となる。また、上
記（３）及び（９）のように、回折光学素子を２つの光
学要素間に形成する構成により、回折光学素子をこれら
の光学要素間で保護することも可能となる。また、上記
（４）及び（１０）のように、回折光学素子を分散の異
なる２つの材料により形成されている積層回折光学素子
で構成することが可能となり波長依存性の小さい回折効
率特性を得ることできる。また、上記（５）及び（１
１）のように、回折光学素子と縮小側像面との光路間の
屈折力が、０．０＜ｆｗ／ｆdoe-img＜０．２なる条件
式を満足させるように構成することで、主光線とマージ
ナル光線に対して発散角を減ずることができ、回折光学
素子への入射角の変動を小さくすることが可能となる。
また、上記（６）のように、拡大側より順に、負の屈折
力を有する第１レンズ群、正の屈折力を有する第２レン
ズ群、絞り、及びそれに続く正または負の１つ以上のレ
ンズ群、正の屈折力を有する固定のレンズ群を備え、縮
小側の像面に対して略テレセントリックの光学系におい
て、前記絞りと縮小側像面の間に回折光学素子を有する
構成を採り、また上記（７）のように回折光学素子と縮
小側像面との光路間に正の屈折力を有するように構成す
ることで、回折光学素子により諸収差とくに倍率色収差
を大きく低減させるとともに、回折効率の角度依存性に
よる回折効率の低下を防ぐことができ、フレアの発生を
押さえることが可能となる。また、上記（８）のように
前記第２群が、広角側から望遠側への変倍時において縮
小側から拡大側へ移動するように構成することにより、
さらに具体的には、第１レンズ群と固定の正の屈折力を
有するレンズ群は、変倍に関して固定されており、第２
群が、広角側から望遠側への変倍に対し物体側へ移動
し、第２レンズ群と固定のレンズ群の間で、変倍時の像
面の移動を補正するように構成することで、光学系の射
出瞳位置の変動を少なくすることが可能となる。また、
上記（１２）のように、回折光学素子のパワーをｆdoe
としたとき、 ０．０１≦ｆｗ／ｆdoe≦０．０５ なる条件式を満足するように構成することにより、倍率
色収差を適正に補正することが可能となる。例えば、上
記条件式の下限を下回ると、回折光学素子による倍率色
収差の補正が不足となり、上限を上回ると補正過剰とな
ってしまう。望ましくは、０．０１≦ｆｗ／ｆdoe≦
０．０２ の範囲とするのがよい。Next, an embodiment of the present invention will be described. As described in the above (1), by providing the diffractive optical element between the optical path between the stop and the reduced image plane, by arranging the off-axis principal ray at a high position from the optical axis, various aberrations, especially magnification, are obtained. Chromatic aberration can be greatly reduced.
Further, as described in (2) above, by arranging a positive refractive power between the optical paths of the diffractive optical element and the reduced image plane, the divergence angle of the marginal ray can be reduced, and the angle of incidence on the diffractive optical element Can be reduced. Further, as described in the above (3) and (9), the configuration in which the diffractive optical element is formed between the two optical elements makes it possible to protect the diffractive optical element between these optical elements. Further, as described in the above (4) and (10), the diffractive optical element can be constituted by a laminated diffractive optical element formed of two materials having different dispersions, and a diffraction efficiency characteristic with small wavelength dependence is obtained. I can do it. In addition, the above (5) and (1)
By configuring so that the refractive power between the optical paths between the diffractive optical element and the image plane on the reduction side satisfies the condition of 0.0 <fw / f doe-img <0.2 as in 1), The divergence angle of the chief ray and the marginal ray can be reduced, and the variation of the incident angle to the diffractive optical element can be reduced.
In addition, as in the above (6), in order from the magnification side, a first lens group having a negative refractive power, a second lens group having a positive refractive power, a diaphragm, and one or more of the following positive or negative positive and negative lenses A lens group, comprising a fixed lens group having a positive refractive power, in a substantially telecentric optical system with respect to the image plane on the reduction side, adopting a configuration having a diffractive optical element between the stop and the image plane on the reduction side, Further, by configuring the optical path between the diffractive optical element and the image plane on the reduction side to have a positive refractive power as described in (7) above, various aberrations, especially chromatic aberration of magnification, are greatly reduced by the diffractive optical element, and A decrease in diffraction efficiency due to the angle dependence of efficiency can be prevented, and the occurrence of flare can be suppressed. Further, by configuring the second lens unit to move from the reduction side to the enlargement side during zooming from the wide-angle side to the telephoto side as described in (8) above,
More specifically, the first lens group and the lens group having a fixed positive refractive power are fixed with respect to zooming, and
The group moves to the object side for zooming from the wide-angle side to the telephoto side, and corrects the movement of the image plane during zooming between the second lens group and the fixed lens group. In addition, it is possible to reduce the fluctuation of the exit pupil position of the optical system. Also,
As described in (12) above, the power of the diffractive optical element is set to f doe
By satisfying the following condition: 0.01 ≦ fw / f doe ≦ 0.05, it is possible to appropriately correct lateral chromatic aberration. For example, when the value goes below the lower limit of the conditional expression, the correction of the chromatic aberration of magnification by the diffractive optical element becomes insufficient, and when the value goes above the upper limit, the correction becomes excessive. Desirably, 0.01 ≦ fw / f doe ≦
It is better to be in the range of 0.02.
【００１１】[0011]
【実施例】以下に、本発明の実施例について説明する。 ［実施例１］図１は、本発明に係る実施例１の光学系の
断面を示したものである。図中（ａ），（ｂ）はそれぞ
れ広角側、望遠側を示している。また、図２（ａ），
（ｂ）は、本実施例の広角側、望遠側の収差図であり、
表１は、本実施例の光学系の構成要素の数値である。図
２に於いては、球面収差図は縦軸が瞳の割合を、横軸が
縦収差量を表している。また非点収差図は、縦軸が像高
を、横軸が収差量を表している。また歪曲収差図では縦
軸が像高を、横軸が歪曲を表している。以下収差図はこ
の表記である。さらに、図３（ａ），（ｂ）は、広角
側、望遠側の像高による倍率色収差を表したものであ
る。図３ではｆｉｅｌｄ１〜ｆｉｅｌｄ５まではそれぞ
れ縮小側像面での０（軸上）、５割、７割、９割、１０
割の像高を表している。以下、倍率色収差の表記に関し
ての像高はこれと同様である。物拡大側の距離は３６０
０ｍｍである（以下同様）。これらの図に示したよう
に、諸収差良好な投射光学系が実現できている。Embodiments of the present invention will be described below. [Embodiment 1] FIG. 1 shows a cross section of an optical system according to Embodiment 1 of the present invention. In the figures, (a) and (b) show the wide-angle side and the telephoto side, respectively. In addition, FIG.
(B) is an aberration diagram on the wide-angle side and the telephoto side of the present embodiment,
Table 1 shows numerical values of components of the optical system according to the present embodiment. In FIG. 2, in the spherical aberration diagram, the vertical axis represents the pupil ratio, and the horizontal axis represents the longitudinal aberration amount. In the astigmatism diagram, the vertical axis represents the image height, and the horizontal axis represents the aberration amount. In the distortion diagram, the vertical axis represents image height, and the horizontal axis represents distortion. Hereinafter, the aberration diagram is this notation. FIGS. 3A and 3B show chromatic aberration of magnification depending on the image height on the wide-angle side and the telephoto side. In FIG. 3, 0 to 1 (on the axis), 50%, 70%, 90%, 10%
This represents the image height of the image. Hereinafter, the image height regarding the expression of the chromatic aberration of magnification is the same as this. The distance on the object enlargement side is 360
0 mm (the same applies hereinafter). As shown in these figures, a projection optical system with good various aberrations can be realized.
【００１２】本実施例においては、図１に示すように、
拡大側より負のパワーを有する第１レンズ群Ｇ１、正の
パワーを有する第２レンズ群Ｇ２、絞り、負のパワーを
有する第３レンズ群Ｇ３、正のパワーを有する第４レン
ズ群Ｇ４、正のパワーを有する第５レンズ群Ｇ５と、色
合成プリズムＰとからなる投射光学系が構成されてい
る。そして、第２レンズ群Ｇ２が広角側から望遠側に変
倍する時に対して縮小側から拡大側に移動する構成であ
り、像面ｉｍｇを補正するように第３レンズ群、第４レ
ンズ群が移動する構成となっている。変倍時、第１レン
ズ群Ｇ１と第５レンズ群Ｇ５は、縮小側像面に対して固
定であり、拡大側の距離変動にあわせて第１レンズ群が
可動である。縮小側像面ｉｍｇに配置される不図示の画
像表示素子からの光を、拡大側に投影するものであり、
光線は縮小側より入射する。また、この変倍時固定の第
５レンズ群Ｇ５に、積層型の回折光学素子が設けられ、
具体的には、図５に示されるように第２４面Ｓ２４と第
２５面Ｓ２５に積層回折光学素子が形成される構成が採
られている。In this embodiment, as shown in FIG.
A first lens group G1 having a negative power from the magnification side, a second lens group G2 having a positive power, an aperture, a third lens group G3 having a negative power, a fourth lens group G4 having a positive power, a positive A projection optical system including a fifth lens group G5 having the following power and a color combining prism P is configured. The second lens group G2 moves from the reduction side to the enlargement side with respect to zooming from the wide-angle side to the telephoto side. The third lens group and the fourth lens group are configured to correct the image plane img. It is configured to move. During zooming, the first lens group G1 and the fifth lens group G5 are fixed with respect to the image plane on the reduction side, and the first lens group is movable in accordance with a change in distance on the enlargement side. Light from an image display element (not shown) arranged on the reduction-side image plane img is projected on the enlargement side.
Light rays enter from the reduction side. Further, a laminated diffractive optical element is provided in the fifth lens group G5 fixed at the time of zooming,
Specifically, as shown in FIG. 5, a configuration is adopted in which a laminated diffractive optical element is formed on the 24th surface S24 and the 25th surface S25.
【００１３】回折光学素子の表記にあたっては、位相関
数で示している。位相関数は で与えられる関数であり、λは設計波長、ｃ１〜ｃ７は
位相係数、ｒは光軸からの高さである。本実施例では、
設計次数１次、設計波長ｄ線としている。本実施例にお
いては、設計次数を１次としているため、位相差が２π
となるように、格子のピッチが決定される。In the description of the diffractive optical element, it is represented by a phase function. The phase function is Λ is a design wavelength, c1 to c7 are phase coefficients, and r is a height from the optical axis. In this embodiment,
The design order is the first order, and the design wavelength is d-line. In this embodiment, since the design order is the first order, the phase difference is 2π.
The pitch of the grating is determined so that
【００１４】ここでの積層型の回折光学素子について
は、特開平１０−１３３１４９号公報、特開平１０−３
９６３９号公報に記載の積層型の回折光学素子のよう
に、２つの分散の異なる材料で構成された回折光学素子
を近接配置した回折光学素子である。図４は（ａ）は、
このような回折光学素子における位相関数の例を示した
ものである。前述したように、設計次数としては、１次
光としているので、回折光学素子のピッチは位相差が２
πとなるように決定される。つぎに、特開平１０−１３
３１４９号公報に記載の積層回折光学素子のごとく、異
なる２種類の材料により回折光学素子を決定するための
方法について説明する。表１では、第２５面に位相関数
を表記しているが、実際には回折光学素子を２つの面に
形成するため、第２４面と第２５面上に回折光学素子を
形成する。本実施例では、第２３面と第２４面の間の光
学材料１（ｎｄ＝１．５１３，νｄ＝５０．０）、第２
５面と第２６面の光学材料２（ｎｄ＝１．６３５，νｄ
＝２２．８）により構成される場合を示している。この
時、光学材料１、２の回折光学素子部の高さをそれぞれ
ｈ１、ｈ２とすれば、 ｈ１（ｎ１−１）−ｈ２（ｎ２−１）／λ＝１ が略成り立つようにｈ１、ｈ２が決定される。ここで、
ｎ１，ｎ２は、波長λでの屈折率である。図５は、この
ようにして回折光学素子を構成した本実施例の概略を示
したものである。本実施例では（ｎ１＝１．５１３，ν
１＝５０．０）の材料１と、（ｎ２＝１．６３５，ν２
＝２２．８）の材料２のそれぞれ厚みを９．５μｍ，
６．８μｍとしている。また、両材料より構成される格
子（回折光学素子）間に空気層を設けている。The laminated type diffractive optical element is disclosed in Japanese Patent Application Laid-Open Nos. 10-133149 and 10-3.
It is a diffractive optical element in which two diffractive optical elements made of materials having different dispersions are arranged close to each other, such as a laminated diffractive optical element described in JP-A-9639. FIG. 4A shows
It shows an example of a phase function in such a diffractive optical element. As described above, since the design order is primary light, the pitch of the diffractive optical element has a phase difference of two.
It is determined to be π. Next, JP-A-10-13
A method for determining a diffractive optical element using two different materials, such as the laminated diffractive optical element described in Japanese Patent No. 3149, will be described. In Table 1, the phase function is described on the 25th surface. However, since the diffractive optical element is actually formed on two surfaces, the diffractive optical elements are formed on the 24th and 25th surfaces. In this embodiment, the optical material 1 (nd = 1.513, vd = 50.0) between the 23rd surface and the 24th surface,
The optical material 2 on the 5th and 26th surfaces (nd = 1.635, vd
= 22.8). At this time, assuming that the heights of the diffractive optical element portions of the optical materials 1 and 2 are h1 and h2, respectively, h1 and h2 are such that h1 (n1-1) −h2 (n2-1) / λ = 1 substantially holds. Is determined. here,
n1 and n2 are refractive indexes at the wavelength λ. FIG. 5 schematically shows the present embodiment in which the diffractive optical element is configured as described above. In this embodiment, (n1 = 1.513, ν
1 = 50.0) and (n2 = 1.635, ν2
= 22.8), the thickness of each of the materials 2 is 9.5 μm,
It is 6.8 μm. In addition, an air layer is provided between gratings (diffractive optical elements) made of both materials.
【００１５】本実施例では、回折光学素子の構成として
図示したように正のパワーを有する回折光学素子を拡大
側に配置したが、これに限定するものでない。ただし、
入射角を考慮すると拡大側に正の屈折力を配置した方が
望ましい。表１では、材料の厚みを０．０５と記してい
るがこれは、回折光学素子部の厚みではなく、回折光学
素子を構成するベース部分の厚みを考慮して示してい
る。しかしながら、回折光学素子の構成についてはこれ
に限定するものではない。また、本実施例において第３
面が非球面レンズとなっており、この非球面は で表される。In this embodiment, a diffractive optical element having a positive power is arranged on the magnifying side as shown in the drawing as a configuration of the diffractive optical element, but the present invention is not limited to this. However,
Considering the incident angle, it is desirable to arrange a positive refractive power on the enlargement side. In Table 1, the thickness of the material is described as 0.05, but this is not taken into consideration of the thickness of the diffractive optical element portion, but is taken into consideration in consideration of the thickness of the base portion constituting the diffractive optical element. However, the configuration of the diffractive optical element is not limited to this. In the present embodiment, the third
The surface is an aspheric lens, and this aspheric surface It is represented by
【００１６】本実施例では、積層型の回折光学素子の構
成についてのみ示したが、単層型の回折光学素子を適用
することも可能である。また、本実施例では、回折光学
素子の形成されるベース面の曲率を０（平面）とした
が、より入射角を緩和するように曲面形状にするとさら
に効果的である。図６は、本実施例において、回折光学
素子の形成される面に曲率半径（ｒ＝３００）を持たせ
た場合である。これにより格子部分に入射する角度の変
化をさらに小さくすることが可能となり、回折効率の角
度依存性をさらに小さくすることができる。また、図６
に示したように回折光学素子部を対向させることによ
り、回折光学素子部を密封することができるのでヽ回折
光学素子の形状を保護することが可能となる。また、２
つの格子部の間に空気層を設けていることにより、２つ
の格子を構成する材料の機械的特性（熱膨張）などを考
慮する必要がなくなり材料の選択のはばがひろがる。In this embodiment, only the configuration of the laminated type diffractive optical element is shown, but a single-layer type diffractive optical element can be applied. Further, in this embodiment, the curvature of the base surface on which the diffractive optical element is formed is set to 0 (flat surface). However, it is more effective to form the curved surface so as to further reduce the incident angle. FIG. 6 shows a case where the surface on which the diffractive optical element is formed has a radius of curvature (r = 300) in this embodiment. This makes it possible to further reduce the change in the angle of incidence on the grating portion, thereby further reducing the angle dependence of the diffraction efficiency. FIG.
By making the diffractive optical element portions face each other as shown in (1), the diffractive optical element portion can be sealed, so that the shape of the diffractive optical element can be protected. Also, 2
By providing the air layer between the two grid portions, it is not necessary to consider the mechanical properties (thermal expansion) of the material forming the two grids, and the selection of the material is widened.
【００１７】[0017]
【表１】 ［実施例２］図７は、本発明に係る実施例２の光学系の
断面を示したものである。図７（ａ），図７（ｂ）はそ
れぞれ広角側、望遠側を示している。また、図８
（ａ），図８（ｂ）は、本実施例の広角側、望遠側の収
差図であり、表２は、本実施例の光学系の構成要素の数
値である。さらに、図９（ａ），図９（ｂ）は、広角
側、望遠側の像高毎の倍率色収差を表したものである。
これらの図に示したように、諸収差が良好な投射光学系
が実現できている。本実施において、回折光学素子の表
記については、実施例１と同様である。[Table 1] Second Embodiment FIG. 7 shows a cross section of an optical system according to a second embodiment of the present invention. FIGS. 7A and 7B show the wide-angle side and the telephoto side, respectively. FIG.
FIGS. 8A and 8B are aberration diagrams on the wide-angle side and the telephoto side of the present embodiment, and Table 2 shows numerical values of components of the optical system of the present embodiment. 9A and 9B show the chromatic aberration of magnification for each image height on the wide-angle side and the telephoto side.
As shown in these figures, a projection optical system with good various aberrations can be realized. In this embodiment, the notation of the diffractive optical element is the same as that of the first embodiment.
【００１８】本実施例では、拡大側より負のパワーを有
する第１レンズ群Ｇ１、正のパワーを有する第２レンズ
群Ｇ２、絞り、正のパワーを有する第３レンズ群Ｇ３、
正のパワーを有する第４レンズ群Ｇ４と、色合成プリズ
ムＰとからなる投射光学系であり、第２レンズ群Ｇ２が
広角側から望遠側に変倍する時に対して縮小側から拡大
側に移動する構成であり、像面ｉｍｇを補正するように
第３レンズ群が移動する構成となっている。変倍時、第
１レンズ群Ｇ１と第４レンズ群Ｇ４は、縮小側像面に対
して固定であり、拡大側像面の距離変動にあわせて第１
レンズ群が可動である。In this embodiment, a first lens group G1 having a negative power from the magnification side, a second lens group G2 having a positive power, an aperture, a third lens group G3 having a positive power,
A projection optical system including a fourth lens group G4 having a positive power and a color combining prism P, which moves from the reduction side to the enlargement side when the second lens group G2 zooms from the wide-angle side to the telephoto side. The third lens group moves so as to correct the image plane img. At the time of zooming, the first lens group G1 and the fourth lens group G4 are fixed with respect to the reduction-side image plane, and the first lens group G1 and the fourth lens group G4 are adjusted in accordance with a change in the distance of the enlargement-side image plane.
The lens group is movable.
【００１９】[0019]
【表２】 ［実施例３］図１０は、本発明に係る実施例３の光学系
の断面を示したものである。図１０（ａ），図１０
（ｂ）はそれぞれ広角側、望遠側を示している。また、
図１１（ａ），図１１（ｂ）は、本実施例の広角側、望
遠側の収差図であり、表３は、本実施例の光学系の構成
要素の数値である。さらに、図１２（ａ），図１２
（ｂ）は、広角側、望遠側の像高による倍率色収差を表
したものである。これらの図に示したように、諸収差が
良好な投射光学系が実現できている。本実施例におい
て、回折光学素子の表記については、実施例１と同様で
ある。[Table 2] Third Embodiment FIG. 10 shows a cross section of an optical system according to a third embodiment of the present invention. FIG. 10 (a), FIG.
(B) shows the wide-angle side and the telephoto side, respectively. Also,
FIGS. 11A and 11B are aberration diagrams on the wide-angle side and the telephoto side of the present embodiment, and Table 3 shows numerical values of components of the optical system of the present embodiment. Further, FIG.
(B) shows the chromatic aberration of magnification depending on the image height on the wide-angle side and the telephoto side. As shown in these figures, a projection optical system with good various aberrations can be realized. In the present embodiment, the notation of the diffractive optical element is the same as that of the first embodiment.
【００２０】本実施例では、拡大側より負のパワーを有
する第１レンズ群Ｇ１、正のパワーを有する第２レンズ
群Ｇ２、絞り、正のパワーを有する第３レンズ群Ｇ３、
正のパワーを有する第４レンズ群Ｇ４と、色合成プリズ
ムＰとからなる投射光学系であり、第２レンズ群Ｇ２が
広角側から望遠側に変倍する時に対して縮小側から拡大
側に移動する構成であり、像面ｉｍｇを補正するように
第３レンズ群が移動する構成となっている。変倍時、第
１レンズ群Ｇ１と第４レンズ群Ｇ４は、縮小側像面に対
して固定であり、拡大側像面の距離変動にあわせて第１
レンズ群が可動である。In the present embodiment, a first lens group G1 having a negative power from the magnification side, a second lens group G2 having a positive power, an aperture, a third lens group G3 having a positive power,
A projection optical system including a fourth lens group G4 having a positive power and a color combining prism P, which moves from the reduction side to the enlargement side when the second lens group G2 zooms from the wide-angle side to the telephoto side. The third lens group moves so as to correct the image plane img. At the time of zooming, the first lens group G1 and the fourth lens group G4 are fixed with respect to the reduction-side image plane, and the first lens group G1 and the fourth lens group G4 are adjusted in accordance with a change in the distance of the enlargement-side image plane.
The lens group is movable.
【００２１】[0021]
【表３】 実施例２、３では回折光学素子の構成については、実施
例１と同様である。また、実施例１と同様に回折光学素
子の形成される面に曲率をつけるとさらに効果的であ
る。その場合、入射角を考慮して、縮小側の像面に対し
て凸面を向ける様に構成することが望ましい。又、図６
にはＳ２８が像面ｉｍｇに対して凸の形状をしている
が、テレセントリック系であるためこの面を平面として
も、材料の屈折率によって入射角を緩和することができ
る。また、本実施例においては、最も縮小側像面に近い
固定のレンズ群中に回折光学素子を設け、テレセントリ
ック性と、倍率色収差の補正を行えるように構成した
が、レンズタイプとしては、このズーム光学系でなくと
もこの配置であれば同様の効果が得られる。[Table 3] In the second and third embodiments, the configuration of the diffractive optical element is the same as that of the first embodiment. Further, as in the first embodiment, it is more effective to provide a curvature on the surface on which the diffractive optical element is formed. In that case, it is desirable that the convex surface be directed to the image plane on the reduction side in consideration of the incident angle. FIG.
Although S28 has a convex shape with respect to the image surface img, the angle of incidence can be reduced by the refractive index of the material even if this surface is flat because it is a telecentric system. In this embodiment, a diffractive optical element is provided in the fixed lens group closest to the image plane on the reduction side, so that telecentricity and chromatic aberration of magnification can be corrected. A similar effect can be obtained if this arrangement is used instead of the optical system.
【００２２】[0022]
【発明の効果】以上に説明したとおり、本発明によれ
ば、回折光学素子を用いることにより、小型で、諸収差
特に倍率色収差を良好に補正することができ、回折光学
素子の入射角度依存性の低減を図ることが可能な、特に
液晶プロジェクタなどの投射型の表示装置等に好適な光
学系を実現することができる。As described above, according to the present invention, by using the diffractive optical element, it is possible to satisfactorily correct various aberrations, especially chromatic aberration of magnification, by using the diffractive optical element, and to make the diffractive optical element depend on the incident angle. In particular, an optical system suitable for a projection display device such as a liquid crystal projector can be realized.
【図１】本発明に係る実施例１の光学系の断面図であ
り、（ａ）は広角側、（ｂ）は望遠側をそれぞれ示した
ものである。FIG. 1 is a cross-sectional view of an optical system according to a first embodiment of the present invention, in which (a) illustrates a wide-angle side and (b) illustrates a telephoto side.
【図２】本発明に係る実施例１の光学系の収差図であ
り、（ａ）は広角側、（ｂ）は望遠側の収差を表したも
のである。FIGS. 2A and 2B are aberration diagrams of the optical system according to the first embodiment of the present invention, in which FIG. 2A illustrates aberration on the wide-angle side and FIG. 2B illustrates aberration on the telephoto side.
【図３】本発明に係る実施例１の光学系の収差図であ
り、（ａ）は広角側、（ｂ）は望遠側の像高による倍率
収差を表したものである。FIGS. 3A and 3B are aberration diagrams of the optical system according to the first embodiment of the present invention, in which FIG. 3A illustrates magnification aberration due to image height on the wide-angle side and FIG.
【図４】位相関数とピッチの関係を説明するための図で
ある。FIG. 4 is a diagram for explaining a relationship between a phase function and a pitch.
【図５】本発明に係る実施例１の回折光学素子の概要を
示す図である。FIG. 5 is a diagram showing an outline of a diffractive optical element of Example 1 according to the present invention.
【図６】本発明に係る実施例１の光学系において、回折
光学要素の形成される面に曲率半径（ｒ＝３００）を持
たせた例を示したものである。FIG. 6 shows an example in which a surface on which a diffractive optical element is formed has a radius of curvature (r = 300) in the optical system according to the first embodiment of the present invention.
【図７】本発明に係る実施例２の光学系の断面図であ
り、（ａ）は広角側、（ｂ）は望遠側をそれぞれ示した
ものである。FIGS. 7A and 7B are cross-sectional views of an optical system according to a second embodiment of the present invention, in which FIG. 7A illustrates a wide-angle side and FIG. 7B illustrates a telephoto side.
【図８】本発明に係る実施例２の光学系の収差図であ
り、（ａ）は広角側、（ｂ）は望遠側の収差を表したも
のである。8A and 8B are aberration diagrams of the optical system according to the second embodiment of the present invention, wherein FIG. 8A illustrates aberration on the wide-angle side and FIG. 8B illustrates aberration on the telephoto side.
【図９】本発明に係る実施例２の光学系の収差図であ
り、（ａ）は広角側、（ｂ）は望遠側の像高による倍率
収差を表したものである。FIGS. 9A and 9B are aberration diagrams of the optical system according to the second embodiment of the present invention, in which FIG. 9A illustrates magnification aberration due to image height on the wide angle side and FIG.
【図１０】本発明に係る実施例３の光学系の断面図であ
り、（ａ）は広角側、（ｂ）は望遠側をそれぞれ示した
ものである。10A and 10B are cross-sectional views of an optical system according to a third embodiment of the present invention, in which FIG. 10A illustrates a wide-angle side and FIG. 10B illustrates a telephoto side.
【図１１】本発明に係る実施例３の光学系の収差図であ
り、（ａ）は広角側、（ｂ）は望遠側の像高による倍率
収差を表したものである。FIGS. 11A and 11B are aberration diagrams of the optical system according to the third embodiment of the present invention, wherein FIG. 11A illustrates magnification aberration due to image height on the wide-angle side and FIG.
【図１２】本発明に係る実施例３の光学系の収差図であ
り、（ａ）は広角側、（ｂ）は望遠側の像高による倍率
収差を表したものである。12A and 12B are aberration diagrams of the optical system according to the third embodiment of the present invention, in which FIG. 12A illustrates magnification aberration due to image height on the wide angle side and FIG.
【図１３】単層の回折光学素子の回折効率の例を示した
ものである。FIG. 13 shows an example of the diffraction efficiency of a single-layer diffractive optical element.
【図１４】積層型の回折光学素子の回折効率の例を示し
たものである。FIG. 14 illustrates an example of the diffraction efficiency of a laminated diffractive optical element.
フロントページの続き (51)Int.Cl.7 識別記号 ＦＩ テーマコート゛(参考） Ｈ０４Ｎ 5/74 Ｈ０４Ｎ 5/74 Ａ Ｆターム(参考） 2H049 AA03 AA04 AA17 AA18 AA51 AA60 AA63 AA65 2H087 KA07 MA12 NA02 PA12 PB15 QA02 QA07 QA14 QA22 QA26 QA33 QA42 QA46 RA05 RA12 RA32 RA41 RA46 SA24 SA26 SA30 SA32 SA44 SA46 SA50 SA52 SA55 SA63 SA64 SA65 SA72 SA75 SA76 SB05 SB14 SB22 SB25 SB33 SB34 SB43 5C058 AA06 EA12 Continued on the front page (51) Int.Cl. 7 Identification code FI Theme coat II (reference) H04N 5/74 H04N 5/74 A F term (reference) 2H049 AA03 AA04 AA17 AA18 AA51 AA60 AA63 AA65 2H087 KA07 MA12 NA02 PA12 PB15 QA02 QA07 QA14 QA22 QA26 QA33 QA42 QA46 RA05 RA12 RA32 RA41 RA46 SA24 SA26 SA30 SA32 SA44 SA46 SA50 SA52 SA55 SA63 SA64 SA65 SA72 SA75 SA76 SB05 SB14 SB22 SB25 SB33 SB34 SB43 5C058 AA06 EA12
Claims (13)
し、縮小側像面に対して略テレセントリックの光学系に
おいて、前記光学系が絞りを有し、かつ絞りと縮小側像
面との光路間に回折光学素子を有することを特徴とする
光学系。An image formed on a reduction-side image plane is enlarged and projected, and in an optical system substantially telecentric with respect to the reduction-side image plane, the optical system has a stop. An optical system comprising a diffractive optical element between the optical paths of the optical system.
折力が正であることを特徴とする請求項１に記載の光学
系。2. The optical system according to claim 1, wherein the refractive power between the diffractive optical element and the image plane on the reduction side is positive.
要素間に設けられていることを特徴とする請求項１また
は請求項２に記載の光学系。3. The optical system according to claim 1, wherein the diffractive optical element is provided between two adjacent optical elements.
材料により形成されている２つの回折光学素子を近接配
置した構成を有する回折光学素子であることを特徴とす
る請求項１〜３のいずれか１項に記載の光学系。4. The diffractive optical element according to claim 1, wherein said diffractive optical element is a diffractive optical element having a configuration in which two diffractive optical elements formed of two materials having different dispersions are arranged close to each other. The optical system according to claim 1.
の屈折力が、投射光学系の広角側の焦点距離をｆｗ、回
折光学素子と縮小側像面間の光路の焦点距離をｆ
doe-imgとしたとき、 ０．０＜ｆｗ／ｆdoe-img＜０．２ なる条件式を満足することを特徴とする請求項１〜４の
いずれか１項に記載の光学系。5. The refracting power between the optical path between the diffractive optical element and the image plane on the reduction side indicates the focal length fw on the wide angle side of the projection optical system, and the focal length on the optical path between the diffractive optical element and the image plane on the reduction side. f
5. The optical system according to claim 1, wherein a conditional expression of 0.0 <fw / f doe-img <0.2 is satisfied, where doe-img is satisfied. 6.
レンズ群、正の屈折力を有する第２レンズ群、絞り、及
びそれに続く正または負の１つ以上のレンズ群、正の屈
折力を有する固定のレンズ群を有し、かつ縮小側の像面
に対して略テレセントリックな光学系において、前記絞
りと縮小側像面の間に回折光学素子を有することを特徴
とする光学系。6. A first lens having a negative refractive power in order from the magnification side.
A lens group, a second lens group having a positive refractive power, a stop, and one or more positive or negative lens groups following the lens group, a fixed lens group having a positive refractive power, and a reduction-side image plane An optical system substantially telecentric with respect to, wherein a diffractive optical element is provided between the stop and a reduction-side image plane.
が正の屈折力で有ることを特徴とする請求項６に記載の
光学系。7. The optical system according to claim 6, wherein the optical path between the diffractive optical element and the image plane on the reduction side has a positive refractive power.
時において縮小側から拡大側へ移動することを特徴とす
る請求項６または請求項７に記載の光学系。8. The optical system according to claim 6, wherein the second lens unit moves from the reduction side to the enlargement side during zooming from the wide-angle side to the telephoto side.
要素間に設けられていることを特徴とする請求項６〜８
のいずれか１項に記載の光学系。9. The diffractive optical element is provided between two adjacent optical elements.
The optical system according to any one of the above.
の材料により形成されている２つの回折光学素子を近接
配置した構成を有する回折光学素子であることを特徴と
する請求項６〜９のいずれか１項に記載の光学系。10. The diffractive optical element according to claim 6, wherein said diffractive optical element is a diffractive optical element having a configuration in which two diffractive optical elements formed of two materials having different dispersions are arranged close to each other. The optical system according to claim 1.
間の屈折力が、投射光学系の広角側の焦点距離をｆｗ、
回折光学素子と縮小側像面間の光路の焦点距離をｆ
doe-imgとしたとき、 ０．０＜ｆｗ／ｆdoe-img＜０．２ なる条件式を満足することを特徴とする請求項６〜１０
のいずれか１項に記載の光学系。11. The refracting power between the optical path between the diffractive optical element and the image plane on the reduction side indicates that the focal length on the wide angle side of the projection optical system is fw,
Let f be the focal length of the optical path between the diffractive optical element and the image plane on the reduction side.
11. The conditional expression of 0.0 <fw / f doe-img <0.2, where doe-img, is satisfied.
The optical system according to any one of the above.
したとき、 ０．０１≦ｆｗ／ｆdoe＜０．０５ なる条件式を満足することを特徴とする請求項６〜１０
のいずれか１項に記載の光学系。12. The optical system according to claim 6, wherein, when the focal length of said diffractive optical element is f doe , a conditional expression 0.01 ≦ fw / f doe <0.05 is satisfied.
The optical system according to any one of the above.
有する固定のレンズ群中に設けられていることを特徴と
する請求項６〜１１のいずれか１項に記載の光学系。13. The optical system according to claim 6, wherein said diffractive optical element is provided in a fixed lens group having said positive refractive power.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23965899A JP2001066499A (en) | 1999-08-26 | 1999-08-26 | Optical system provided with diffraction optical device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23965899A JP2001066499A (en) | 1999-08-26 | 1999-08-26 | Optical system provided with diffraction optical device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2001066499A true JP2001066499A (en) | 2001-03-16 |
Family
ID=17047986
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23965899A Pending JP2001066499A (en) | 1999-08-26 | 1999-08-26 | Optical system provided with diffraction optical device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2001066499A (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006078704A (en) * | 2004-09-08 | 2006-03-23 | Canon Inc | Zoom optical system |
| CN1306306C (en) * | 2003-02-10 | 2007-03-21 | 精工爱普生株式会社 | Projection zoom lens and optical projector with same |
| US7215477B2 (en) | 2004-03-10 | 2007-05-08 | Canon Kabushiki Kaisha | Zoom lens and image display apparatus including the zoom lens |
| EP2108989A1 (en) * | 2008-04-08 | 2009-10-14 | Fujinon Corporation | Wide angle zoom lens for projection and projecting type display device |
| US11048153B2 (en) | 2018-10-17 | 2021-06-29 | Seiko Epson Corporation | Optical device and display device |
| US11317066B2 (en) | 2019-09-30 | 2022-04-26 | Seiko Epson Corporation | Phase modulation element and display device |
| WO2022161262A1 (en) * | 2021-01-26 | 2022-08-04 | 维沃移动通信有限公司 | Microprism, camera module, and electronic device |
-
1999
- 1999-08-26 JP JP23965899A patent/JP2001066499A/en active Pending
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1306306C (en) * | 2003-02-10 | 2007-03-21 | 精工爱普生株式会社 | Projection zoom lens and optical projector with same |
| US7215477B2 (en) | 2004-03-10 | 2007-05-08 | Canon Kabushiki Kaisha | Zoom lens and image display apparatus including the zoom lens |
| CN100380161C (en) * | 2004-03-10 | 2008-04-09 | 佳能株式会社 | Zoom lens and image display apparatus including the zoom lens |
| JP2006078704A (en) * | 2004-09-08 | 2006-03-23 | Canon Inc | Zoom optical system |
| JP4594008B2 (en) * | 2004-09-08 | 2010-12-08 | キヤノン株式会社 | Zoom optical system |
| EP2108989A1 (en) * | 2008-04-08 | 2009-10-14 | Fujinon Corporation | Wide angle zoom lens for projection and projecting type display device |
| US11048153B2 (en) | 2018-10-17 | 2021-06-29 | Seiko Epson Corporation | Optical device and display device |
| US11317066B2 (en) | 2019-09-30 | 2022-04-26 | Seiko Epson Corporation | Phase modulation element and display device |
| WO2022161262A1 (en) * | 2021-01-26 | 2022-08-04 | 维沃移动通信有限公司 | Microprism, camera module, and electronic device |
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