JPS628101A - Fresnel lens - Google Patents
Fresnel lensInfo
- Publication number
- JPS628101A JPS628101A JP14849285A JP14849285A JPS628101A JP S628101 A JPS628101 A JP S628101A JP 14849285 A JP14849285 A JP 14849285A JP 14849285 A JP14849285 A JP 14849285A JP S628101 A JPS628101 A JP S628101A
- Authority
- JP
- Japan
- Prior art keywords
- annular groove
- concentric annular
- fresnel lens
- concentric
- pitch
- 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
Landscapes
- Viewfinders (AREA)
- Overhead Projectors And Projection Screens (AREA)
Abstract
Description
【発明の詳細な説明】 炎丘皇1 本発明はフレネルレンズに関する。[Detailed description of the invention] Flame Emperor 1 The present invention relates to a Fresnel lens.
1且且l
フレネルレンズはカメラのピントレンズや投影機の視野
レンズとして用いられ、輪帯状の小レンズを同心円状に
配列し全体としてレンズの働きをするものである。1. A Fresnel lens is used as a focusing lens for a camera or a viewing lens for a projector, and consists of small annular lenses arranged in a concentric circle, and the lens as a whole functions as a lens.
従来、全体として凸レンズとして働くフレネルレンズは
第3図に示すものが知られている。第3図はかかるフレ
ネルレンズの子午面(光軸2を含む平面)における部分
断面図を示している。図中、フレネルレンズの一方の屈
折面は光軸Zに垂直な平面1であり、相対向する他の一
方の屈折面はその子午面による断面形状が鋸歯状となる
同心円環溝群2で構成されている。同心円環溝群2を構
成する一つの鋸歯形上部平面3は平面1と協動してプリ
ズムを形成する。一般に制作技術上の観点か :ら同
心円環溝群2の各々の同心円環溝は一定の繰 1返6
間隔(,1−t:’ツア)8−、、あ。。よえ、同心、
:環溝群2は、その鋸歯形上部平面3の法線と光軸
との成す角θmが次式(I)の如き関係にて形成される
とき好適であることが知られている。Conventionally, a Fresnel lens that functions as a convex lens as a whole is shown in FIG. 3. FIG. 3 shows a partial cross-sectional view of such a Fresnel lens in a meridian plane (a plane including the optical axis 2). In the figure, one refractive surface of the Fresnel lens is a plane 1 perpendicular to the optical axis Z, and the other opposing refractive surface is composed of a group of concentric annular grooves 2 whose cross-sectional shape along the meridian plane is serrated. has been done. One serrated upper plane 3 constituting the group of concentric annular grooves 2 cooperates with the plane 1 to form a prism. Generally speaking, from a manufacturing technical point of view: Each concentric annular groove of the concentric annular groove group 2 has a certain number of repetitions 16
Interval (, 1-t: 'Tsua) 8-,, ah. . Yo, concentric,
It is known that the annular groove group 2 is suitable when the angle θm formed between the normal line of the sawtooth-shaped upper plane 3 and the optical axis is formed according to the following equation (I).
tan θm
=D/(n−1)D+n2F−Fl置=f)(I)ここ
でDは同心円環溝の光軸からの距離すなわち半径、fは
フレネルレンズの焦点距離、nはフレネルレンズの透明
媒質の屈折率である。tan θm = D/(n-1)D+n2F-Fl position=f) (I) Here, D is the distance from the optical axis of the concentric annular groove, that is, the radius, f is the focal length of the Fresnel lens, and n is the transparency of the Fresnel lens. It is the refractive index of the medium.
かかるフレネルレンズの平面1に入射した平行光線α1
は透明媒質を通過し対向する鋸歯彫工部平面3で屈折さ
れて焦点Fを含む面上に成仏がりを持って収束すること
になる。つまり該広がりが最小散乱円ということになる
。A parallel ray α1 incident on the plane 1 of such a Fresnel lens
passes through the transparent medium, is refracted by the opposing sawtooth carving plane 3, and converges on the plane containing the focal point F with a convergence. In other words, this spread is the minimum scattering circle.
従来のフレネルレンズでは、入射平行光の第1屈折面で
ある平面1と、第2屈折面である鋸歯彫工部平面3との
プリズム屈折作用のみにより焦光しているので、上記鋸
歯形状部を構成する同心円環溝群の繰り返し間隔S(ピ
ッチ)及びF数(フレネルレンズの直径りに対する焦点
距離fの値f/D)によって該フレネルレンズの最小散
乱円が決定されてしまう。従って、フレネルレンズの制
作技術及び回折効果により繰返し間隔(ピッチ)Sの下
限が制約される従来のフレネルレンズでは最小散乱円を
更に小さくするように改善することは困難であった。In conventional Fresnel lenses, light is focused only by the prism refraction effect between the plane 1, which is the first refracting surface of the incident parallel light, and the sawtooth carved part plane 3, which is the second refracting surface. The minimum scattering circle of the Fresnel lens is determined by the repetition interval S (pitch) and the F number (the value f/D of the focal length f relative to the diameter of the Fresnel lens) of the concentric ring groove group. Therefore, it has been difficult to improve the minimum scattering circle of the conventional Fresnel lens, in which the lower limit of the repeating interval (pitch) S is restricted by Fresnel lens production techniques and diffraction effects.
1肚立且1
本発明の目的は、上記欠点を解消しフレネルレンズを最
小散乱円に関して改良することである。The object of the present invention is to eliminate the above-mentioned drawbacks and to improve the Fresnel lens with respect to the minimum scattering circle.
本発明のフレネルレンズは、第1及び第2屈折面に光軸
を中心とする同一ピッチの同心円環溝群を有し、子午面
における第1及び第2屈折面の断面は鋸歯状であり、か
つ第1屈折面における最内周の同心円環溝の半径と第2
屈折面における最内周の同心円環溝の半径とが異なって
いることを特徴とする。The Fresnel lens of the present invention has a group of concentric annular grooves with the same pitch centered on the optical axis on the first and second refractive surfaces, and the cross sections of the first and second refractive surfaces in the meridian plane are sawtooth, and the radius of the innermost concentric annular groove in the first refracting surface and the second
It is characterized in that the radius of the innermost concentric annular groove on the refracting surface is different.
友−呈−1
以下に、本発明の一実施例を第1図に基づいて説明する
。Friend-Presentation-1 Below, one embodiment of the present invention will be described based on FIG.
第1図は本発明のフレネルレンズの子午面における部分
断面図である。第1図における第3図に示した同一構成
を示す部分は同一符号で示している。FIG. 1 is a partial sectional view of the Fresnel lens of the present invention in a meridian plane. Components in FIG. 1 having the same configuration as shown in FIG. 3 are designated by the same reference numerals.
かかるフレネルレンズの一方の屈折面がその子午面の断
面形状が鋸歯状となる第1同心円環溝群4で構成されて
おり、相対向する他の一方の屈折面も第1同心円環溝群
4と略同−の形状の第2同心円環溝群5にて形成されて
おり、第1及び第2同心円環溝群4.5の各々の環状の
鋸歯彫工部平面3は光軸2を中心として同一ピッチSに
て配置されており、更に第1同心円環溝群4のビッヂと
第2同心円環溝群5のピッチとが半ピッチずれるように
形成されている。One refractive surface of the Fresnel lens is composed of a first concentric annular groove group 4 whose meridian plane has a sawtooth cross-sectional shape, and the other opposing refractive surface is also composed of a first concentric annular groove group 4. The plane 3 of each annular sawtooth carved part of the first and second concentric annular groove groups 4.5 is formed with the optical axis 2 as the center. They are arranged at the same pitch S, and furthermore, the pitches of the first concentric annular groove group 4 and the pitch of the second concentric annular groove group 5 are shifted by a half pitch.
すなわち、フレネルレンズ両面における各々の共軸な同
心円環溝のピッチが等しくかつそれぞれの面の光軸に最
も近い同心円環溝の半径がS/2の差を有するように形
成されている。ここで、光軸を中心とする該半径は、子
午面における光軸と各々の傾斜した鋸歯彫工部平面3の
中心との距離をとっている。また、フレネルレンズとし
て上記(I)式を満たす如き各々の鋸歯形上部面によっ
て両同心円環溝群が形成されていることは云うまでもな
い。That is, the pitches of the coaxial concentric annular grooves on both surfaces of the Fresnel lens are equal, and the radii of the concentric annular grooves closest to the optical axis of each surface are formed to have a difference of S/2. Here, the radius centered on the optical axis is the distance between the optical axis and the center of each inclined serration plane 3 in the meridian plane. It goes without saying that, as a Fresnel lens, both concentric annular groove groups are formed by each sawtooth-shaped upper surface that satisfies the above formula (I).
第1図における光線追跡によると、光線α1は第1同心
円環溝群4の鋸歯彫工部平面3においてスネルの式に基
づいて屈折し、これら屈折した光線を光線α2とする。According to the ray tracing in FIG. 1, the ray α1 is refracted at the plane 3 of the sawtooth carved portion of the first concentric annular groove group 4 based on Snell's equation, and these refracted rays are designated as the ray α2.
更に光線゛α2は透明媒質を通過し第2同心円環溝群5
の鋸歯形上部平面3で屈折して光線α3となり焦点F近
傍に収束する。Furthermore, the light ray α2 passes through the transparent medium and enters the second concentric ring groove group 5.
It is refracted by the sawtooth-shaped upper plane 3 and becomes a light ray α3, which converges near the focal point F.
ここで第3図の従来のフレネルレンズの場合と比較する
と、第3図では光線α3が平行であったことになり、第
1図の本実施例のフレネルレンズの場合では第2同心円
環溝群5の鋸歯彫工部平面3により光線α3が焦点Fに
より小さな点として焦光するように収束するさせること
が可能となる。Here, when compared with the case of the conventional Fresnel lens shown in FIG. 3, the light ray α3 is parallel in FIG. 3, and in the case of the Fresnel lens of this embodiment shown in FIG. The serrated plane 3 of No. 5 allows the light ray α3 to be converged to a focal point F as a smaller point.
すなわち、レンズの両回折面に光軸を中心とする同一ピ
ッチの同心円環溝群を有し、子午面における両回折面の
断面が鋸歯状であり、かつ一方の屈折面における光軸に
最近傍の同心円環溝の半径と他方の屈折面における光軸
に最近傍の同心円環溝の半径とが異なることによって、
第1同心円環溝群4と第2同心円環溝群5の鋸歯形が半
径方向にて半ピッチづつずれている結果、本実施例のフ
レネルレンズは、第2図に示す従来のフレネルレンズに
おける鋸歯形のピッチを本実施例の第1及び第2同心円
環溝群4.5のピッチSに対して、半ピッチS/2にし
たフレネルレンズと同様の特性が得られ最小散乱用も約
1/2となる。That is, both diffractive surfaces of the lens have a group of concentric annular grooves with the same pitch centered on the optical axis, the cross section of both diffractive surfaces in the meridian plane is serrated, and the grooves closest to the optical axis on one refractive surface are serrated. Due to the difference between the radius of the concentric annular groove and the radius of the concentric annular groove closest to the optical axis on the other refractive surface,
As a result of the serrations of the first concentric annular groove group 4 and the second concentric annular groove group 5 being shifted by half a pitch in the radial direction, the Fresnel lens of this embodiment is different from the serrations of the conventional Fresnel lens shown in FIG. The same characteristics as the Fresnel lens obtained by setting the pitch of the shape to half the pitch S/2 of the pitch S of the first and second concentric annular groove groups 4.5 in this embodiment are obtained, and the minimum scattering is also reduced to about 1/2. It becomes 2.
また、上記実施例では第1及び第2同心円環溝群4.5
を相対向する2つの屈折面とする単体レンズにつき例示
したが、第1及び第2同心円環溝群の相対的関係を維持
しつつそれぞれを別体のレンズに備えさせても良い。Further, in the above embodiment, the first and second concentric annular groove groups 4.5
Although a single lens having two opposing refractive surfaces is shown as an example, the first and second concentric annular groove groups may be provided in separate lenses while maintaining the relative relationship between them.
さらにまた、上記実施例では第1同心円環溝群4と第2
同心円環溝群5とのピッチのずれが1/2ビツヂの場合
のフレネルレンズを示したが、繰返し間隔(ピッチ)S
の下限が制約される場合でも、本発明の場合上記ピッチ
SのずれがO<S〈1の範囲となるように第1同心円環
溝群4と第2同心円環溝群5とを形成すれば最小散乱用
を従来のものより小さくすることが出来る。Furthermore, in the above embodiment, the first concentric annular groove group 4 and the second
The Fresnel lens shown has a pitch deviation of 1/2 bit from the concentric ring groove group 5, but the repetition interval (pitch) S
Even if the lower limit of is restricted, in the case of the present invention, if the first concentric annular groove group 4 and the second concentric annular groove group 5 are formed so that the deviation of the pitch S is in the range of O<S<1. The minimum scattering value can be made smaller than that of the conventional method.
上記実施例において、第2同心円環溝群5を入射面とし
て第1同心円環溝群4を出射面とすれば焦点Fの点光源
の光を平行光束化することが出来る。In the above embodiment, if the second concentric annular groove group 5 is used as the entrance plane and the first concentric annular groove group 4 is used as the exit plane, the light from the point light source at the focal point F can be converted into a parallel beam.
q IIJI oと泳星
以上のように、本発明によれば、両層折面に光軸を中心
とする同一ピッチの同心円環溝群を有し、子午面におけ
る両層折面の断面は鋸歯状であり、かつ一方の屈折面に
おける光軸に最近傍の同心円環溝の半径と、他方の屈折
面における光軸に最近傍の同心円環溝の半径とに差をも
たせてそれぞれの同心円環溝が交互に両層折面に現れる
ような第1及び第2屈折面を具備せしめることで、従来
のフレネルレンズよりも形状の細かい細密性を必要とせ
ずに、最小散乱用をより小さく抑えることが出来る。As described above, according to the present invention, the bilayer folding surface has a group of concentric annular grooves with the same pitch centered on the optical axis, and the cross section of the bilayer folding surface in the meridian plane has a sawtooth shape. The concentric annular grooves are shaped like a shape, and each concentric annular groove has a difference between the radius of the concentric annular groove closest to the optical axis on one refracting surface and the radius of the concentric annular groove closest to the optical axis on the other refractive surface. By providing the first and second refractive surfaces such that the two refracting surfaces alternately appear, the minimum scattering value can be kept smaller without requiring a finer shape than a conventional Fresnel lens. I can do it.
また、第1及び第2の屈折面の組合せで、従来のフレネ
ルレンズのピッチをSとすると8/2をピッチとするフ
レネルレンズと同等の最小散乱用に抑えることが可能と
なる。従って、本発明によれば従来の加工技術で軽量か
つ安価に制作でき、しかも小さな最小散乱用をもつフレ
ネルレンズを得ることが出来る。Further, by combining the first and second refractive surfaces, if the pitch of a conventional Fresnel lens is S, it is possible to suppress the scattering to a minimum value equivalent to that of a Fresnel lens having a pitch of 8/2. Therefore, according to the present invention, it is possible to obtain a Fresnel lens that can be produced lightweight and inexpensively using conventional processing techniques and has a small minimum scattering value.
第1図は本発明のフレネルレンズの部分断面図、第2図
は第1図と等価の従来のフレネルレンズの部分断面図、
第3図は従来のフレネルレンズの子午面における部分断
面図である。
主要部分の符号の説明
1・・・・・・平面
2・・・・・・同心円環溝群
3・・・・・・鋸歯彫工部平面FIG. 1 is a partial sectional view of the Fresnel lens of the present invention, FIG. 2 is a partial sectional view of a conventional Fresnel lens equivalent to FIG.
FIG. 3 is a partial sectional view of a conventional Fresnel lens in a meridian plane. Explanation of symbols of main parts 1...Plane 2...Concentric ring groove group 3...Sawtooth carved part plane
Claims (2)
チの同心円環溝群を有し、子午面における第1及び第2
屈折面の断面は鋸歯状であり、かつ第1屈折面における
最内周の同心円環溝の半径と第2屈折面における最内周
の同心円環溝の半径とが異なっていることを特徴とする
フレネルレンズ。(1) The first and second refractive surfaces have a group of concentric annular grooves with the same pitch centered on the optical axis, and the first and second refractive surfaces
The cross section of the refracting surface is sawtooth, and the radius of the innermost concentric annular groove on the first refracting surface is different from the radius of the innermost concentric annular groove on the second refracting surface. Fresnel lens.
第2屈折面における最内周の同心円環溝の半径との差が
半ピッチであることを特徴とする特許請求の範囲第1項
記載のフレネルレンズ。(2) The difference between the radius of the innermost concentric annular groove on the first refracting surface and the radius of the innermost concentric annular groove on the second refracting surface is a half pitch. Fresnel lens described in item 1.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP14849285A JPS628101A (en) | 1985-07-05 | 1985-07-05 | Fresnel lens |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP14849285A JPS628101A (en) | 1985-07-05 | 1985-07-05 | Fresnel lens |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS628101A true JPS628101A (en) | 1987-01-16 |
Family
ID=15453962
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP14849285A Pending JPS628101A (en) | 1985-07-05 | 1985-07-05 | Fresnel lens |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS628101A (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2016025316A (en) * | 2014-07-24 | 2016-02-08 | オリンパス株式会社 | Illumination optical system, lighting system, and illumination optical element |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61129602A (en) * | 1984-11-29 | 1986-06-17 | Nissan Motor Co Ltd | Construction of fresnel lens |
-
1985
- 1985-07-05 JP JP14849285A patent/JPS628101A/en active Pending
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS61129602A (en) * | 1984-11-29 | 1986-06-17 | Nissan Motor Co Ltd | Construction of fresnel lens |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2016025316A (en) * | 2014-07-24 | 2016-02-08 | オリンパス株式会社 | Illumination optical system, lighting system, and illumination optical element |
US10180234B2 (en) | 2014-07-24 | 2019-01-15 | Olympus Corporation | Illumination optical system, illumination apparatus, and illumination optical element |
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