JPH0125046B2 - - Google Patents
Info
- Publication number
- JPH0125046B2 JPH0125046B2 JP56141677A JP14167781A JPH0125046B2 JP H0125046 B2 JPH0125046 B2 JP H0125046B2 JP 56141677 A JP56141677 A JP 56141677A JP 14167781 A JP14167781 A JP 14167781A JP H0125046 B2 JPH0125046 B2 JP H0125046B2
- Authority
- JP
- Japan
- Prior art keywords
- conical
- mirror
- light beam
- convex surface
- condenser lens
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 230000003287 optical effect Effects 0.000 claims description 31
- 238000005286 illumination Methods 0.000 claims description 20
- 230000004907 flux Effects 0.000 claims description 7
- 238000010586 diagram Methods 0.000 description 6
- NCGICGYLBXGBGN-UHFFFAOYSA-N 3-morpholin-4-yl-1-oxa-3-azonia-2-azanidacyclopent-3-en-5-imine;hydrochloride Chemical compound Cl.[N-]1OC(=N)C=[N+]1N1CCOCC1 NCGICGYLBXGBGN-UHFFFAOYSA-N 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 2
- 229910052753 mercury Inorganic materials 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000002093 peripheral effect Effects 0.000 description 2
- 230000004075 alteration Effects 0.000 description 1
- 230000008030 elimination Effects 0.000 description 1
- 238000003379 elimination reaction Methods 0.000 description 1
- 210000001747 pupil Anatomy 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70058—Mask illumination systems
- G03F7/70091—Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B21/00—Microscopes
- G02B21/06—Means for illuminating specimens
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Optics & Photonics (AREA)
- Microscoopes, Condenser (AREA)
- Lenses (AREA)
- Optical Elements Other Than Lenses (AREA)
Description
【発明の詳細な説明】
本発明は、超高圧水銀ランプのような放電型光
源の照明光学系に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an illumination optical system for a discharge type light source such as an ultra-high pressure mercury lamp.
従来、この種の光源は
第１図ａミラー集光タイプ
ｂレンズ集光タイプ
ｃバツクミラータイプ
のように、ミラー又はレンズを組合せて集光させ
ていた。ここでのミラー集光タイプは、光源から
放射されるすべての光束を集光できるものとし
て、一番効率の良いものであつた。しかし、光軸
の近傍に光束は存在せず、角度分布的には中心の
抜けた照明光束になつてしまう欠点があつた。す
なわち、物体に対して透過光として照明し、対物
レンズにおいて結像する顕微鏡などにこの照明系
を用いると、対物レンズの入射瞳に対して、中心
を通る光束が存在せず、円環状の分布を持つてし
まう。このことは、多少の収差を含有した実際の
対物レンズに対し、周辺光束のみを使うことにな
り、余り望ましいことではない。 Conventionally, this type of light source condenses light by combining mirrors or lenses, as shown in Fig. 1 (a) Mirror condensing type, (b) Lens condensing type, and (c) Back mirror type. The mirror condensing type used here was the most efficient as it could condense all the luminous flux emitted from the light source. However, there was a drawback that there was no light beam near the optical axis, and the illumination light beam was not centered in terms of angular distribution. In other words, when this illumination system is used in a microscope, etc., where an object is illuminated as transmitted light and an image is formed in the objective lens, there is no light flux passing through the center of the objective lens entrance pupil, and there is a circular distribution. I end up having one. This means that only the peripheral light beam is used for the actual objective lens which contains some aberrations, which is not very desirable.
また対物レンズのN.A.に対応して、照明光の
N.Aを規定する場合、中心を通る光束がないた
め、絶対光量としても不利な面があつた。通常、
照明N.A.／対物N.A.＝σ
とした場合、σは１より多少小さな値になるよう
照明N.A.を設定すると、対物レンズは深度、解
像とも一番良くなる。すなわちこの種の照明系で
は照明光束のN.Aを限定するために、絞りを光量
の多い円環部に入れる必要があり、有効に使われ
る光量は減る。例えば設定したσに合致するよう
焦点距離の短いコンデンサーレンズを使うことも
考えられる。しかし実際の光源ではなく、大きさ
を持つているため、焦点距離が短くなるとコンデ
ンサーレンズの後で平行になるべき光束が、光軸
に対し角度を持つようになり、やはり絞りで遮断
されムダになる光量が多くなる。 In addition, depending on the NA of the objective lens, the illumination light
When specifying NA, there was a disadvantage in terms of absolute light quantity as there was no light flux passing through the center. Normally, when illumination NA/objective NA = σ, if the illumination NA is set so that σ is a value slightly smaller than 1, the objective lens will have the best depth and resolution. In other words, in this type of illumination system, in order to limit the NA of the illumination luminous flux, it is necessary to place the aperture in an annular portion with a large amount of light, which reduces the amount of effectively used light. For example, it is possible to use a condenser lens with a short focal length to match the set σ. However, since it is not an actual light source and has a size, when the focal length becomes short, the light beam that should be parallel after the condenser lens becomes angled to the optical axis, and is blocked by the diaphragm and is wasted. The amount of light increases.
本発明では、第１図ａで示される従来の超高圧
水銀ランプのミラー集光タイプという効率の良い
集光法において、欠点であつた光量分布を改善し
より効率の高い理想的なミラー集光型逆エキスパ
ンドアフオーカル照明光学系を提供することを目
的としている。 The present invention improves the light intensity distribution, which was a drawback of the conventional ultra-high pressure mercury lamp mirror condensing type, which is an efficient light condensing method, as shown in Fig. 1a, and achieves a more efficient and ideal mirror condensing method. The purpose of this invention is to provide an inversely expanded focal illumination optical system.
以下本発明を添付図面の実施例によつて詳述す
る。 The present invention will be explained in detail below with reference to embodiments of the accompanying drawings.
第２図は本発明の１つの実施例を示した光学系
で、公知の如く楕円ミラー１の一方の焦点０上に
光源を設けると他方の焦点０′上に集光する。そ
してこの光束をコンデンサーレンズ２で平行系に
する。本発明の特徴はこの後方に第１面及び第２
面を円錐状に加工したプリズム３を配設したもの
である。 FIG. 2 shows an optical system showing one embodiment of the present invention. As is well known, when a light source is provided on one focal point 0 of an elliptical mirror 1, the light is focused on the other focal point 0'. This luminous flux is then made into a parallel system by a condenser lens 2. The feature of the present invention is that the first surface and the second surface
A prism 3 whose surface is machined into a conical shape is provided.
すなわち、円錐状プリズム３は、第２図に示し
た光路の様子から分かるように、コンデンサーレ
ンズ２からの平行光束を光軸に向けて屈折させる
ためにコンデンサーレンズ２側に凸面を向けた円
錐状凸面と、この円錐状凸面により光軸に向かつ
て屈折された光束を光軸とほぼ平行に射出させる
ために円錐状凸面とほぼ同一の傾斜角を持つ円錐
状凹面とを有している。そして、この円錐状プリ
ズムは、円錐状凸面と円錐状凹面の各頂点が共に
コンデンサーレンズ２の光軸に一致するようにコ
ンデンサーレンズ２による平行光束中に配置され
ている。 That is, as can be seen from the optical path shown in FIG. 2, the conical prism 3 has a conical shape with a convex surface facing the condenser lens 2 in order to refract the parallel light beam from the condenser lens 2 toward the optical axis. It has a convex surface and a conical concave surface having approximately the same inclination angle as the conical convex surface in order to emit the light beam refracted toward the optical axis by the conical convex surface substantially parallel to the optical axis. This conical prism is placed in the parallel light beam of the condenser lens 2 such that the vertices of the conical convex surface and the conical concave surface both coincide with the optical axis of the condenser lens 2.
第１図ａのものでは光軸近傍の光束は存在しな
いが、本発明では上記円錐状プリズム３により、
光軸より離れた平行光束を、光軸近傍までシフト
させ、理想的な光量分布としたものである。 In the case of FIG. 1a, there is no light beam near the optical axis, but in the present invention, the conical prism 3 allows
The parallel light beam away from the optical axis is shifted to the vicinity of the optical axis to create an ideal light quantity distribution.
例えば焦点０上の光源がα＝β＝45゜として立
体状に均等に光を放射しているとすると、第１図
ａ及び第２図の最終的な平行系でのスポツトダイ
ヤグラムはそれぞれ第３図及び第４図のようにな
る。 For example, if a light source at the focal point 0 radiates light uniformly in a three-dimensional shape with α = β = 45 degrees, the spot diagrams in the final parallel system in Figures 1a and 2 will be 3D, respectively. The result will be as shown in Fig. 4.
本発明の円錐状プリズム３は本実施例に限るこ
となく２つのプリズムに分解しても、凸としての
円錐と凹としての円錐があれば同様な効果を持
ち、このように分けることにより、プリズムを通
る光路長が短かくなれば、透過率の点で有利にな
ることは云う迄もない。 The conical prism 3 of the present invention is not limited to this embodiment, and even if it is separated into two prisms, it will have the same effect as long as there is a convex cone and a concave cone. Needless to say, a shorter optical path length will be advantageous in terms of transmittance.
更に第５図示のように円錐状プリズム３をフレ
ネル型３′にしても同等の効果を得ることができ
る。 Furthermore, the same effect can be obtained by using a Fresnel type prism 3' instead of the conical prism 3 as shown in FIG.
尚本発明の前記実施例では、光源を理想的な点
光源として説明した。即ち、点光源より角度αで
出た光線は、楕中ミラー１の内側絞り及び光源の
指向性により最も光軸に近い光線として、コンデ
ンサーレンズ２を通つた後、第６図に詳記した如
くHoのの高さで光軸と平行な光線となる。第２
図では、同様の光線は円錐状プリズム３により、
Ho＝Δhだけシフトして光軸と重つている（H1
＝０）。 In the above embodiments of the present invention, the light source was described as an ideal point light source. In other words, the light rays emitted from the point light source at an angle α pass through the condenser lens 2 as the light rays closest to the optical axis due to the inner aperture of the elliptical mirror 1 and the directivity of the light source, and then, as detailed in FIG. At the height of Ho, the ray becomes parallel to the optical axis. Second
In the figure, a similar ray of light is transmitted by a conical prism 3.
It is shifted by Ho=Δh and overlaps with the optical axis (H 1
=0).
しかし一般に光源は有限な大きさを持つており
コンデンサーレンズ３の後で、円錐状プリズム３
に入る光線は光軸に平行なものばかりではない。 However, in general, the light source has a finite size, and after the condenser lens 3, a conical prism 3 is used.
The rays that enter the light are not always parallel to the optical axis.
確かに点光源の場合には
Δh＝Ho
が望ましいが、光源が有限の大きさを持つている
ため
１／２Ho＜Δh＜2Ho ……(1)
とすることが望ましい。光軸に平行な光束だけを
考えると、左辺では補正不足、右辺では補正過多
になるが、大きさを持つた光源では、ともに中抜
けがなくなり、照明光として良い結果が得られ
る。 It is true that Δh=Ho is desirable in the case of a point light source, but since the light source has a finite size, it is desirable to set 1/2Ho<Δh<2Ho...(1). If only the light beam parallel to the optical axis is considered, the left side will be under-corrected and the right side will be over-corrected, but with a large light source, there will be no hollow spots in both cases and good results will be obtained as illumination light.
即ち、第６図に示すようにΔhとプリズム３の
頂角の半分、すなわち円錐状凸面及び円錐状凹面
の傾斜角θ、屈折率ｎ、中心厚ｄの関係式はΔh
＝ｄ tan（π／２−sin-1cosθ／ｎ−θ）で示される
。 That is, as shown in FIG. 6, the relational expression between Δh and half of the apex angle of the prism 3, that is, the inclination angle θ of the conical convex surface and the conical concave surface, the refractive index n, and the center thickness d is Δh
= d tan (π/2−sin −1 cosθ/n−θ).
また、より厳密には、
Δh＝ｄ sinθ（cosθ−sinθtan sin-1cosθ／ｎ）
……（1′）
と表される。而して、光源を２次曲面ミラーで集
光させる場合について考える。例えば楕円ミラー
１では第１焦点面０に点光源を置くと、第２焦点
０′に集光するので、コンデンサーレンズ３でア
フオーカル系にした場合、楕円ミラー１の中央開
口部によりコンデンサーレンズ３の後では第３図
示のように半径Dsの円型ケラレを生じる。また、
放物面ミラー１では焦点０に点光源を置くと、平
行光束（アフオーカル系）となり、やはり中央開
口部に対して半径Dsの円型ケラレを生じる。Moreover, more precisely, it is expressed as Δh=d sinθ(cosθ−sinθtan sin −1 cosθ/n) (1′). Consider now the case where the light source is focused by a quadratic curved mirror. For example, in the case of the elliptical mirror 1, if a point light source is placed at the first focal plane 0, the light will be focused at the second focal point 0'. Later, as shown in the third diagram, a circular vignetting with a radius Ds occurs. Also,
In the parabolic mirror 1, when a point light source is placed at the focal point 0, it becomes a parallel light beam (afocal system), which also causes circular vignetting with a radius Ds relative to the central aperture.
本発明では円錐状プリズム３の形状、屈折率ｎ
とケラレ半径Dsの関係を以下のようにすること
が望ましい。即ち、
１／２Ds≦ｄ tan（π／２−sin-1cosθ／ｎ−θ）
≦2Ds ……(2)
この範囲で円錐状プリズム３を規定することに
より、大きさを持つた光源に対しても、光量的に
も、中抜けの解消についても実用上は有効に作用
させることができる。 In the present invention, the shape of the conical prism 3, the refractive index n
It is desirable that the relationship between Ds and the vignetting radius Ds is as follows. That is, 1/2Ds≦d tan (π/2−sin -1 cosθ/n−θ) ≦2Ds ...(2) By defining the conical prism 3 within this range, it is possible to However, it can be effectively used in terms of light quantity and elimination of hollow spots.
上記条件の下限を外れる場合には、入射平行光
束のシフト量が少ないために光軸中心において未
だ光量の分布の低下を来す恐れがあり、逆に上記
条件の上限を越える場合にも光軸中心において光
量が低下して均一性を維持することが難しくなつ
てしまう。尚、より厳密には前記（1′）式に基づ
いて、
Ds／２≦ｄ sinθ（cosθ−sinθtan sin-1cosθ／
ｎ）
≦2Ds ……（2′）
とすることが望ましい。 If the lower limit of the above conditions is exceeded, there is a risk that the light intensity distribution will still decrease at the center of the optical axis due to the small amount of shift of the incident parallel light beam; conversely, if the upper limit of the above conditions is exceeded, the optical axis The amount of light decreases at the center, making it difficult to maintain uniformity. More precisely, based on equation (1') above, Ds/2≦d sinθ(cosθ−sinθtan sin -1 cosθ/
n) ≦2Ds...(2') is desirable.
以上述べた如く本発明によれば、光軸上から周
辺部に亘つて理想的な光量分布の照明系が得られ
る。 As described above, according to the present invention, an illumination system with an ideal light amount distribution from the optical axis to the peripheral portion can be obtained.
第１図は従来の照明系、第２図は本発明の照明
系、第３図は従来の照明系の光量分布を示すスポ
ツトダイヤグラム、第４図は本発明の照明系の光
量分布を示すスポツトダイヤグラム、第５図は本
発明の円錐状プリズムの他の実施例、第６図は本
発明の円錐状プリズムの説明図である。
主要部分の符号の説明、１……楕円ミラー、２
……コンデンサーレンズ、３……円錐状プリズ
ム。
Figure 1 is a conventional illumination system, Figure 2 is an illumination system of the present invention, Figure 3 is a spot diagram showing the light amount distribution of the conventional illumination system, and Figure 4 is a spot diagram showing the light amount distribution of the illumination system of the present invention. The diagram, FIG. 5 is another embodiment of the conical prism of the present invention, and FIG. 6 is an explanatory diagram of the conical prism of the present invention. Explanation of symbols of main parts, 1... Elliptical mirror, 2
...Condenser lens, 3...Conical prism.
Claims (1)
円環状の光量分布を持つて集光される光束を平行
光束に変換するためのコンデンサーレンズとを有
するミラー集光型照明光学系において、前記コン
デンサーレンズからの前記円環状の光量分布を有
する平行光束を光軸に向けて屈折させるために該
コンデンサーレンズ側に凸面を向けた円錐状凸面
と該円錐状凸面により光軸に向かつて屈折された
光束を光軸とほぼ平行に射出させるために前記円
錐状凸面とほぼ同一の傾斜角を持つ円錐状凹面と
を有する円錐状屈折部材を、前記円錐状凸面及び
前記円錐状凹面の頂点が共に前記コンデンサーレ
ンズの光軸に一致する如く前記コンデンサーレン
ズによる平行光束中に配置したことを特徴とする
ミラー集光型照明光学系。 ２ 前記２次曲面を有する反射鏡は楕円鏡であ
り、前記円環状の光量分布を持つて集光される光
束は前記楕円鏡による放電型光源からの光束であ
ることを特徴とする特許請求の範囲第１項記載の
ミラー集光型照明光学系。 ３ 前記円錐状屈折部材は前記円錐状凸面と円錐
状凹面とからなる円錐状プリズムであり、該円錐
状プリズムの前記円錐状凸面及び円錐状凹面の傾
斜角をθ、該円錐状プリズムの中心厚をｄ、屈折
率をｎとするとき、前記反射鏡及び前記コンデン
サーレンズから供給される平行光束の光軸上の円
形ケラレの半径Dsに対して、 Ds／２≦ｄ tan（π／２−sin-1cosθ／ｎ−θ） ≦2Ds の条件を満足することを特徴とする特許請求の範
囲第１項乃至第２項記載のミラー集光型照明光学
系。[Scope of Claims] 1. A mirror condensing type having a reflecting mirror having a quadratic curved surface and a condenser lens for converting the light beam condensed by the reflecting mirror with an annular light intensity distribution into a parallel light beam. In the illumination optical system, in order to refract the parallel light beam having the annular light intensity distribution from the condenser lens toward the optical axis, a conical convex surface has a convex surface facing the condenser lens side, and the conical convex surface refracts the parallel light beam having the annular light intensity distribution toward the optical axis. A conical refractive member having a conical convex surface and a conical concave surface having approximately the same inclination angle as the conical convex surface is used to emit the refracted light beam substantially parallel to the optical axis. 1. A mirror condensing illumination optical system, characterized in that the concave surface is arranged in a parallel light beam generated by the condenser lens so that the apexes of the concave surface both coincide with the optical axis of the condenser lens. 2. The reflecting mirror having the quadratic curved surface is an elliptical mirror, and the luminous flux condensed with the annular light quantity distribution is a luminous flux from a discharge type light source by the elliptical mirror. A mirror condensing illumination optical system according to scope 1. 3. The conical refractive member is a conical prism consisting of the conical convex surface and the conical concave surface, and the inclination angle of the conical convex surface and the conical concave surface of the conical prism is θ, and the center thickness of the conical prism is When d is the refractive index and n is the refractive index, Ds/2≦d tan(π/2−sin 3. The mirror condensing illumination optical system according to claim 1, wherein the mirror condensing illumination optical system satisfies the following condition: -1 cos θ/n−θ) ≦2Ds.
Priority Applications (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56141677A JPS5843416A (en) | 1981-09-10 | 1981-09-10 | Reverse expand afocal illuminating optical system of mirror condensing type |
| US06/416,029 US4498742A (en) | 1981-09-10 | 1982-09-08 | Illumination optical arrangement |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56141677A JPS5843416A (en) | 1981-09-10 | 1981-09-10 | Reverse expand afocal illuminating optical system of mirror condensing type |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5843416A JPS5843416A (en) | 1983-03-14 |
| JPH0125046B2 true JPH0125046B2 (en) | 1989-05-16 |
Family
ID=15297627
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56141677A Granted JPS5843416A (en) | 1981-09-10 | 1981-09-10 | Reverse expand afocal illuminating optical system of mirror condensing type |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5843416A (en) |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4812957A (en) * | 1985-07-23 | 1989-03-14 | Fusion Systems Corporation | Optical system for uniform illumination of a plane surface |
| JPS62178207A (en) * | 1986-01-31 | 1987-08-05 | Dainippon Screen Mfg Co Ltd | Optical system for illumination |
| US4719547A (en) * | 1986-09-19 | 1988-01-12 | Minnesota Mining And Manufacturing Company | Illumination system for overhead projector |
| DE3851485T2 (en) * | 1987-07-17 | 1995-01-19 | Dainippon Screen Mfg | Optical system for increasing the illuminance in peripheral object zones. |
| JPH02250016A (en) * | 1989-03-23 | 1990-10-05 | Mitsutoyo Corp | Vertical dark field illuminating device |
| JP3278896B2 (en) * | 1992-03-31 | 2002-04-30 | キヤノン株式会社 | Illumination apparatus and projection exposure apparatus using the same |
| JP2012191148A (en) * | 2011-03-14 | 2012-10-04 | Ricoh Co Ltd | Surface-emitting laser module, optical scanning device, and image forming device |
-
1981
- 1981-09-10 JP JP56141677A patent/JPS5843416A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5843416A (en) | 1983-03-14 |
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