JPS61126532A - Phase type optical low-pass filter - Google Patents
Phase type optical low-pass filterInfo
- Publication number
- JPS61126532A JPS61126532A JP24912984A JP24912984A JPS61126532A JP S61126532 A JPS61126532 A JP S61126532A JP 24912984 A JP24912984 A JP 24912984A JP 24912984 A JP24912984 A JP 24912984A JP S61126532 A JPS61126532 A JP S61126532A
- Authority
- JP
- Japan
- Prior art keywords
- pass filter
- type optical
- optical low
- mtf
- phase
- 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.)
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Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本考案は、単管式カラービデオカメラや固体撮像素子を
用いたカラービデオカメラ等に使用さｎル光学的ローパ
スフィルタに関する。DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical low-pass filter used in a single-tube color video camera, a color video camera using a solid-state image sensor, and the like.
一般にストライプ状色分解フィルタを使用した単管式カ
ラービデオカメラや、離散的画素構造を有する固体撮像
素子に用いたカラービデオカメラでは、被写体像を光学
的・に空間フンプリングして撮像出力を得る。Generally, in a single-tube color video camera using a striped color separation filter or a color video camera using a solid-state image sensor having a discrete pixel structure, the image output is obtained by optically and spatially compressing a subject image.
このようなカラービデオカメラの取扱うことのできる絵
柄の細かさはサンプリング周波数に関連して決まり、そ
れ以上の高空間周波数成分が含まれると偽信号発生の原
因となる。The fineness of images that can be handled by such a color video camera is determined in relation to the sampling frequency, and if higher spatial frequency components are included, it will cause false signals.
友とえは今、被写体の像が上記ストライプ状色分解フィ
ルタ上に形成された時に、このストライプ状色分解フィ
ルタの空間周波数と同一の周波数成分が被写体像に混在
していた場合、この同一の周波数成分によシ偽信号が発
生し、再生画像に被写体の色と無関係な色がついてしま
う。Now, when the image of the subject is formed on the striped color separation filter, if the same frequency component as the spatial frequency of the striped color separation filter is mixed in the subject image, this same False signals are generated due to frequency components, and the reproduced image has a color unrelated to the color of the subject.
このため上記カメラでは被写体の高空間周波数成分を制
限する光学的ローパスフィルタが撮像光学系に必要とな
る。For this reason, the camera requires an optical low-pass filter for limiting high spatial frequency components of the subject in the imaging optical system.
従来、上記光学的ローパスフィルタとして、水晶の複屈
折全利用したものがある。水晶を使用し几光学的ローパ
スフィルタは、水晶の複屈折を利用して、ストライプ状
色分解フィルタの空間周波数成分の画像に対して、光学
的なほけを与え、この空間周波数の属する周波数帯域よ
りも低い空間周波数に対しては極力高い鮮像度を維持す
るものであり、水晶の厚さで光学的ローパスフィルタと
しての特性を変えることができるという特徴をもってい
る。しかじ、水晶の原料コストが高く、まｔ団体撮像素
子の場合のように数枚の水晶が必要となると、その製造
上の問題が多く量産性に適さない。Conventionally, as the above-mentioned optical low-pass filter, there is one that makes full use of the birefringence of quartz crystal. An optical low-pass filter that uses crystal uses the birefringence of the crystal to give an optical blur to the image of the spatial frequency components of the striped color separation filter. It also maintains as high image sharpness as possible for low spatial frequencies, and has the characteristic that the characteristics as an optical low-pass filter can be changed by changing the thickness of the crystal. However, the raw material cost of the crystal is high, and when several pieces of crystal are required as in the case of a group image sensor, there are many manufacturing problems and it is not suitable for mass production.
そＯでグラスチック等金用い几位相型光学的ローパスフ
ィルタが提案さｎている。A phase-type optical low-pass filter using metal such as glass has been proposed.
位相製光学的ローパスフィルタは結像光学系の瞳関数の
自己相関関数がこの系の云達関数ｃ以下ＭＴＦと記す。The phase-based optical low-pass filter is expressed as MTF, where the autocorrelation function of the pupil function of the imaging optical system is less than or equal to the output function c of this system.
）を与えることに注目し、この瞳関数に波長特性音もた
せて目的とする任意の特性を得るものである。), and by adding wavelength characteristic sound to this pupil function, desired arbitrary characteristics can be obtained.
たとえば位相差を与える縞状の薄膜を透明な基板上に形
成し、これ全光学系の瞳関数の変わる場所に挿入するこ
とによって瞳関数の位相項を変えて、光学的ローパスフ
ィルタの特性をもたせるようにしたものである。For example, by forming a striped thin film that provides a phase difference on a transparent substrate and inserting it in a place where the pupil function of the entire optical system changes, the phase term of the pupil function is changed, giving it the characteristics of an optical low-pass filter. This is how it was done.
聞
従来例としてたとえば特＃昭４８−２７７４３号公報記
載のものが知らｎている。As a conventional example, the one described in Japanese Patent No. 48-27743 is known.
ところで従来の位相型光学的ローパスフィルタはその製
法が蒸着によるものであり、上記縞状の周期構造は第３
図に示すように、その断面が矩形であった。″また矩形
に準じる形状であつ几。By the way, the conventional phase-type optical low-pass filter is manufactured by vapor deposition, and the striped periodic structure is
As shown in the figure, its cross section was rectangular. ``Also, it has a shape similar to a rectangle.
従来の位相型光学的ローパスフィルタはその周期構造の
断面が矩形ま几は矩形に準じる形状であった。この几め
画像の構成要素の中で特に重要な被写体像の低空間周波
数域におけるＭＴＦの値が低く、鮮像度低下の原因とな
り、ま几該位相型光−ンが画面上に現われる等の問題が
あった。In conventional phase-type optical low-pass filters, the cross section of the periodic structure is rectangular or the shape is similar to a rectangle. The MTF value in the low spatial frequency range of the subject image, which is particularly important among the components of this refined image, is low, causing a decrease in image sharpness and causing phase-type light to appear on the screen. There was a problem.
本発明はこのような問題点を解消した位相型光学的ロー
パスフィルタを提供すること全目的とするＯ
Ｃ手段〕
本発明は透明基板上に縞状に、凸部を、その断面形状が
滑らかに立ち上がるように形成して成るものである。ま
た周期長ｐに対して上記凸部幅ａ’ｉｏ、５ｐ≦ａ≦ｐ
の範囲で設定するとともに、この位相型光学的ローパス
フィルタの遮断空間周波ａｒｃにおけるＭＴＦの値がＭ
ＴＦ（ｒｃ）≦０．３となる範囲で上記周期長ｐと上記
凸部の厚さｄｉ段設定て成るものである。The present invention aims to provide a phase-type optical low-pass filter that eliminates such problems.] The present invention provides a method for forming convex portions in a striped manner on a transparent substrate with a smooth cross-sectional shape. It is formed so that it stands up. In addition, for the period length p, the above-mentioned convex width a'io, 5p≦a≦p
The MTF value at the cutoff spatial frequency arc of this phase-type optical low-pass filter is M
The periodic length p and the thickness di of the convex portion are set in a range such that TF(rc)≦0.3.
透明基板上に上記凸部金、その断面が滑らかに立ち上が
るように形成したので、この位相型光学的ローパスフィ
ルタを使用したカラービデオカメラでは絞り全絞り込ん
だとき上記周期構造のパターンが画面上に現わｎる現象
が解消さ几る。The above-mentioned convex metal is formed on a transparent substrate so that its cross section rises smoothly, so in a color video camera using this phase-type optical low-pass filter, when the aperture is fully stopped, the pattern of the above-mentioned periodic structure appears on the screen. The wandering phenomenon has been resolved.
また上記周期長ｐに対し上記凸部幅ａを０．５ｐ≦ａ≦
ｐの範囲で設定するとともに、遮断空間周波数ｒｃにお
けるＭＴＦの値がＭＴＦ（ｒｃ）≦０．３ となる範
囲で上記周期長ｐと上記凸部厚さｄＴｈ設定したので、
被写体像の低空間周波数域における上記ＭＴＦの値が向
上する。Also, the width a of the convex portion is set to 0.5p≦a≦ with respect to the periodic length p.
The period length p and the convex thickness dTh are set within the range of p, and the period length p and the convex thickness dTh are set within the range where the value of MTF at the cut-off spatial frequency rc is MTF(rc)≦0.3.
The MTF value in the low spatial frequency range of the subject image is improved.
以下、本発明に係る位相型光学的ローパスフィルタにつ
いて実施例を図面を参照して説明する。Embodiments of the phase-type optical low-pass filter according to the present invention will be described below with reference to the drawings.
第１図は本発明に係る位相型光学的ローパスフィルタの
第１実施例の構造を示す斜視図である０この第１実施例
においては、位相型光学的ローパスフィルタ１は円筒レ
ンズ状の周期構造が基板２の両面に形成されている。こ
の周期構造の１周期の断面は第２図に示すように円弧状
の凸部３と平部４から成る。FIG. 1 is a perspective view showing the structure of a first embodiment of a phase-type optical low-pass filter according to the present invention. In this first embodiment, a phase-type optical low-pass filter 1 has a periodic structure in the form of a cylindrical lens. are formed on both sides of the substrate 2. The cross section of one period of this periodic structure consists of an arcuate convex portion 3 and a flat portion 4, as shown in FIG.
また上記凸部３と上記平部４からなる縞の方向比とえは
図１のｙ方向は、被写体像のぼけを生じさせる方向と直
角にすれば良い０ま几この光学的ぼけを生じさせる方向
が一方向の場合は上記基板２の一面だけに上記周期構造
を形成すｎは良い。Furthermore, the direction ratio of the stripes formed by the convex portions 3 and the flat portions 4, for example, the y direction in FIG. When the direction is one direction, it is preferable to form the periodic structure on only one surface of the substrate 2.
第１図に示す位相型光学的ローパスフィルタ１は、集光
レンズとして機能するレンテイキュラーレンズと同様な
形状をしているが、第２図に示す周期長ｐ１凸部幅ａ１
凸部厚さｄ（ｄは数千ス〕が小さい友め、レンズよりも
回折格子としての性質が強く現わ扛る０
第４図は第１図に示した位相型光学的ローパスフィルタ
の凸部３幅ａがａ；０．７ｐであるときのＭＴＦ特性を
実線で、第３図に示した従来例の位相型光学的ローパス
フィルタ５において凸部６幅ａがａ＝０．５ｐであると
きのＭＴＦ特性を破線で示すＭＴＦ％性図である。The phase-type optical low-pass filter 1 shown in FIG. 1 has a shape similar to a lenticular lens that functions as a condensing lens, but has a period length p1 a convex width a1 shown in FIG.
Since the convex thickness d (d is several thousand squares) is small, its properties as a diffraction grating are stronger than those of a lens.0 Figure 4 shows the convex part of the phase-type optical low-pass filter shown in Figure 1. The solid line indicates the MTF characteristic when the width a of the portion 3 is a; 0.7p, and the width a of the convex portion 6 is a=0.5p in the conventional phase-type optical low-pass filter 5 shown in FIG. It is an MTF% characteristic diagram showing the MTF characteristics at the time with a broken line.
空間周波数をｒ１遮遮断量周波数をｒｃとすると第４図
においては、ｒ≦０．４ｒｃである低空間周波数域では
、第１図に示した凸部３が円弧状である上記位相型光学
的ローパスフィルタ１のＭＴＦ値が、第３図に示し几従
来例の上記位相型光学的ローパスフィルタ５のＭＴＦ値
よりも太きい。If the spatial frequency is r1 and the cutoff amount frequency is rc, then in FIG. The MTF value of the low-pass filter 1 is larger than the MTF value of the conventional phase-type optical low-pass filter 5 shown in FIG.
０．４≦ｒ≦ｒｃの範囲では逆に、従来例の上記位相型
光学的ローパスフィルタ５のＭＴＦ値の方が、凸部３が
円弧状である上記位相型光学的ローパスフィルタ１のＭ
ＴＦ値よシも大きくなっている。まｆｃｒｃ≦ｒの高空
間周波数域でＭＴＦ値が増加していくが、こｎは偽信号
発生の原因となる。Conversely, in the range of 0.4≦r≦rc, the MTF value of the phase-type optical low-pass filter 5 of the conventional example is higher than the MTF value of the phase-type optical low-pass filter 1 whose convex portion 3 is arcuate.
The TF value has also increased. Although the MTF value increases in a high spatial frequency region where fcrc≦r, this n causes the generation of false signals.
従ってこｎらの点を改良するために上記周期長ｐと上記
凸部３厚さｄを調整する。Therefore, in order to improve these points, the period length p and the thickness d of the convex portion 3 are adjusted.
上記周期長ｐと上記凸部３厚さｄ’に大きくして第５図
（ａ）のＭＴＦ特性曲線上のＱ点が遮断空間周波数とな
るように設定すると、第５図（ｂ）に示すようにｒ≦ｒ
ｃの範囲では、上記凸部３が円弧状である上記位相型光
学的ローパスフィルタ１のＭＴＦ値が、従来例の上記位
相型光学的ローパスフィルタ５のＭＴＦ値よりも大きく
なる。When the period length p and the thickness d' of the convex portion 3 are increased and set so that the Q point on the MTF characteristic curve in FIG. 5(a) becomes the cut-off spatial frequency, the result is shown in FIG. 5(b). so that r≦r
In the range c, the MTF value of the phase-type optical low-pass filter 1 in which the convex portion 3 is arcuate is larger than the MTF value of the phase-type optical low-pass filter 5 of the conventional example.
また、第５図（ｂ）のＭＴＦ特性図においてｒｃ≦ｒ≦
ｒ の範囲は第５図（ａ）の破線の下側を折り返した部
分であるが、この範囲ではＭＴＦの変化が小さいので、
偽信号の発生を抑圧することができる。Moreover, in the MTF characteristic diagram of FIG. 5(b), rc≦r≦
The range of r is the part folded down below the broken line in Figure 5(a), and since the change in MTF is small in this range,
The generation of false signals can be suppressed.
第６図は、第１図に示し几凸部３が円弧状である上記位
相型光学的ローパスフィルタ１の上記凸部３幅ａｋ変化
させ九場合のＭＴＦ特性図である。FIG. 6 is an MTF characteristic diagram when the width ak of the convex portion 3 of the phase-type optical low-pass filter 1 shown in FIG. 1 is changed in the shape of an arc.
上記凸部３幅ａがａ＝０．３ｐのときは低空間周波数域
でＭＴＦの値が小さくなっている。従って低空間周波数
域でＭＴＦの値を向上させるという条件から上記凸部３
幅ａの範囲１ｏ、ｓｐ≦ａ≦ｐと定める。When the width a of the convex portion 3 is a=0.3p, the MTF value is small in the low spatial frequency range. Therefore, from the condition of improving the MTF value in the low spatial frequency range, the convex portion 3
The range 1o of width a is defined as sp≦a≦p.
また上記周期長ｐ１上記凸部３厚さｄの値は、遮断空間
周波数ｒｃでの緑色光あるいは遮断したい特定の波長の
ＭＴＦの値がＭＴＦ（ｒｃ）≦０．３の範囲で選ぶ。こ
の範囲であれば十分に偽信号の発生を抑圧することがで
きる。Further, the values of the periodic length p1 and the thickness d of the convex portion 3 are selected such that the MTF value of the green light at the cutoff spatial frequency rc or a specific wavelength to be cut is within the range of MTF(rc)≦0.3. Within this range, the generation of false signals can be sufficiently suppressed.
従って第１図に示す第工実権例においては０．５≦ａ≦
ｐの範囲で上記凸部３幅ａを設定し、ＭＴＦ（ｒｃ）≦
０．３となるよう上記周期長ｐと上記凸部３厚みｄ？段
設定ることにより、低空間周波数域でＭＴＦ値が従来例
よりも大きく、偽信号発生も抑圧する位相型光学的ロー
パスフィルタが実現できる。Therefore, in the first example of practical rights shown in Figure 1, 0.5≦a≦
The width a of the convex portion 3 is set within the range of p, and MTF(rc)≦
The periodic length p and the thickness d of the convex portion 3 are adjusted to be 0.3? By setting the stages, it is possible to realize a phase-type optical low-pass filter that has a larger MTF value than the conventional example in the low spatial frequency range and suppresses the generation of false signals.
また、第１実施例の位相型光学的ローパスフィルタを使
用したカラービデオカメラでは、絞り全絞りこんだとき
に周期構造のパターンが画面上に現わ九る現象が解消し
た。Furthermore, in the color video camera using the phase-type optical low-pass filter of the first embodiment, the phenomenon in which a periodic structure pattern appears on the screen when the aperture is fully closed has been eliminated.
上記現象は、周期構造の断面の凸部の形状変化の大きさ
に影響さ几ると考えられる。It is thought that the above phenomenon is influenced by the magnitude of the shape change of the convex portion in the cross section of the periodic structure.
今、断面の形状’ｚ ｆ （ｘ）とすると、従来例のよ
うに断面の凸部６が矩形であると形状の変化率ｄｆ Ｃ
ｘ） ／ ｄｘが０から凶に変化する点が周期的に存在
する。第１図に示すように、断面の凸部３が円弧上であ
るとｄｆ（ｘ） ／ ｄｘが０がら急激に変化する点は
あるが、上記凸部３厚さｄが上記凸部３幅ａに比べて非
常に小さく、形状が滑らかであるためｄｆ （ｘＪ ／
ｄｘは大きな値とはならない。Now, if the shape of the cross section is 'z f (x), if the convex part 6 of the cross section is rectangular as in the conventional example, the rate of change in shape df C
x) / There are periodically points where dx changes from 0 to negative. As shown in Fig. 1, when the cross section of the convex part 3 is on an arc, there is a point where df(x)/dx changes rapidly from 0, but the thickness d of the convex part 3 is equal to the width of the convex part 3. Since it is very small compared to a and has a smooth shape, df (xJ /
dx does not take a large value.
従ってこのｄｆ （ｘ ）／ ｄｘが極端に大きな値と
なる点を周期的に有する凸部６が矩形の従来の位相型光
学的ローパスフィルタ５を使用したカラービデオカメラ
では絞り全絞り込んだときに周期構造のパターンが画面
上古に現ゎｎる現象を生じ、第■実施例に示すようにｄ
ｆ（Ｘ）／ｄｘが大きな直７と〆らない上記位相型光学
的ローパスフィルターを使用したカラービデオカメラで
は上記現象が生じなくなったものと考えらｎる。Therefore, in a color video camera using a conventional phase-type optical low-pass filter 5 in which the convex portion 6 has a rectangular shape and periodically has points where this df (x)/dx becomes an extremely large value, when the aperture is fully stopped down, the period The pattern of the structure causes a phenomenon that appears on the screen, and as shown in Example ①,
It is thought that the above phenomenon no longer occurs in a color video camera using the phase-type optical low-pass filter that does not have a large straight-7 f(X)/dx.
第１図に示す断面の凸部３が円弧状である位相型光学的
ローパスフィルターは上記周期長ｐ１凸部３幅ａに比べ
て上記凸部３厚さｄぽ非常に小さく、また円弧という微
妙な形状を形成する必要がある。In the phase-type optical low-pass filter in which the convex part 3 in the cross section shown in Fig. 1 is arc-shaped, the thickness d of the convex part 3 is very small compared to the period length p1 and the width a of the convex part 3, and the shape of the convex part 3 is slightly arc-shaped. It is necessary to form a shape.
プラスチック等を用いてこのような形状の上記位相型光
学的ローパスフィルタ１を製造するためには、たとえば
半導体プロセス技術を利用して高精度に製作さ九る成型
用金型を用いる。この成型用金型によりプラステンクモ
ールド成型することで上記位相型光学的ａ−バスフィル
タ１の製造が可能である。In order to manufacture the phase-type optical low-pass filter 1 having such a shape using plastic or the like, a molding die that is manufactured with high precision using, for example, semiconductor process technology is used. The above-mentioned phase type optical a-bass filter 1 can be manufactured by performing plastic molding using this molding die.
第７図は本発明に係る位相型光学的ローパスフィルタの
第２実施例を示す斜視図である。第２実施例の位相型光
学的ローパスフィルタ９においては、基板８の断面の６
部７は台形である。このように凸部７を台形にすると、
円弧状のものよりもさらに精度良く製作することが可能
であり、ま几円弧状のものと同様の性能全維持する。FIG. 7 is a perspective view showing a second embodiment of the phase-type optical low-pass filter according to the present invention. In the phase-type optical low-pass filter 9 of the second embodiment, 6
Section 7 is trapezoidal. If the convex part 7 is made trapezoidal in this way,
It can be manufactured with higher precision than a circular arc shape, and maintains all the same performance as a circular arc shape.
低空間周波数域で高いＭＴＦ値を持つ条件から、この台
形の形状は第８図に示す底辺ａｌ と上辺ａ２全、０．
５ｐ≦ａ１≦ｐ、ｏ、ｏ≦ａ２≦０．８ａ１と定める。Due to the condition of having a high MTF value in the low spatial frequency range, this trapezoidal shape has the base al, the upper side a2, and 0.
It is determined that 5p≦a1≦p, o, and o≦a2≦0.8a1.
また周期長ｐ１上記凸部７厚さｄは遮断空間周波数ｒｃ
ての緑色光あるいは遮断したい特定の波長のＭＴＦが
、ＭＴＦ（ｒｃ）≦０．３になるように定める。Also, the period length p1 and the thickness d of the convex portion 7 are the cut-off spatial frequency rc
The MTF of all green light or a specific wavelength to be blocked is determined so that MTF(rc)≦0.3.
第１実施例、第２実施例に示す位相型光学的ローパスフ
ィルタ１，９は、撮像系の撮像レンズと結像面（撮像管
の光電面あるいは固体撮像素子）の間に配置して使用す
る。あるいは撮像レンズの瞳に配置して使用しても良い
。The phase-type optical low-pass filters 1 and 9 shown in the first and second embodiments are used by being placed between the imaging lens of the imaging system and the imaging plane (the photocathode of the imaging tube or the solid-state imaging device). . Alternatively, it may be used by placing it on the pupil of the imaging lens.
以上説明したように、本発明によｎば被写体像の低空間
周波数域におけるＭＴＦの値が、従来の位相型光学的ロ
ーパスフィルタよりも高く、かつ偽信号の発生を抑圧す
る位相型光学的ローパスフィルタを実現できる。ま九本
発明に係る位相型光学的ローパスフィルタを使用したカ
ラービデオカメラにおいては、従来例のような絞りを絞
り込んだときに周期構造のパターンが現わｎる現象を解
消することができる。As explained above, according to the present invention, the MTF value in the low spatial frequency range of the subject image is higher than that of the conventional phase-type optical low-pass filter, and the phase-type optical low-pass filter suppresses the generation of false signals. A filter can be realized. (9) In a color video camera using a phase-type optical low-pass filter according to the present invention, it is possible to eliminate the phenomenon in which a periodic structure pattern appears when the aperture is stopped down as in the conventional example.
第１図は本発明に係る位相型光学的ローパスフィルタの
第１実施例の構造金示す斜視図であり第２図は上記第１
実施例の周期構造の一周期金示す断面図である。
第３図は従来の位相型光学的ローパスフィルタフィ／ｌ
／夕のＭＴＦ特性図である。
第５図は第１実権例の位相型光学的ローパスフィルタに
おいて周期長と凸部厚さを変化して得らｎるＭＴＦ特性
図である。
第６図は第１実施例の位相型光学的ローパスフィルタに
おいて凸部幅ａｔ変化して得らｎるＭＴＦ特性図である
。
第７図は本発明に係る第２実施例の構造を示す斜視図で
あり、第８図はこの第２実施例の周期構造の一周期金示
す断面図である。
１．５．９・・・位相型光学的ローパスフィルタ２８・
・・基板
３．６．７・・・凸部FIG. 1 is a perspective view showing the structure of a first embodiment of a phase-type optical low-pass filter according to the present invention, and FIG.
FIG. 2 is a cross-sectional view showing one period of the periodic structure of the example. Figure 3 shows a conventional phase-type optical low-pass filter filter.
/Evening MTF characteristic diagram. FIG. 5 is an MTF characteristic diagram obtained by changing the period length and the thickness of the convex portion in the phase-type optical low-pass filter of the first practical example. FIG. 6 is an MTF characteristic diagram obtained by varying the convex portion width at in the phase-type optical low-pass filter of the first embodiment. FIG. 7 is a perspective view showing the structure of a second embodiment of the present invention, and FIG. 8 is a sectional view showing one period of the periodic structure of the second embodiment. 1.5.9... Phase-type optical low-pass filter 28.
...Substrate 3.6.7...Protrusion
Claims (1)
設定するとともに、遮断空間周波数ｒｃにおける伝達関
数ＭＴＦの値がＭＴＦ（ｒｃ）≦０．３となる範囲で上
記周期長ｐと凸部厚さｄを設定し、上記幅ａと上記厚さ
ｄの凸部を透明基板上に滑らかに立ち上がるように形成
したことを特徴とする位相型光学的ローパスフィルタ。The convex width a is set in the range of 0.5p≦a≦p for the period length p, and the above period is set in the range where the value of the transfer function MTF at the cut-off spatial frequency rc is MTF(rc)≦0.3. A phase-type optical low-pass filter characterized in that the length p and the thickness d of the convex portion are set, and the convex portion having the width a and the thickness d is formed on a transparent substrate so as to rise smoothly.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24912984A JPS61126532A (en) | 1984-11-26 | 1984-11-26 | Phase type optical low-pass filter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP24912984A JPS61126532A (en) | 1984-11-26 | 1984-11-26 | Phase type optical low-pass filter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS61126532A true JPS61126532A (en) | 1986-06-14 |
Family
ID=17188363
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP24912984A Pending JPS61126532A (en) | 1984-11-26 | 1984-11-26 | Phase type optical low-pass filter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61126532A (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS64916A (en) * | 1987-06-23 | 1989-01-05 | Canon Inc | Photographing lens |
| JPH01254912A (en) * | 1988-04-04 | 1989-10-11 | Nippon Hoso Kyokai <Nhk> | Optical low-pass filter |
| US8194209B2 (en) | 2006-07-05 | 2012-06-05 | Nikon Corporation | Optical low-pass filter, camera, imaging apparatus, and method for producing optical low-pass filter |
| CN109579738A (en) * | 2019-01-04 | 2019-04-05 | 北京理工大学 | A kind of two-value striped defocus optical projection system low-frequency filter characteristics measurement method |
-
1984
- 1984-11-26 JP JP24912984A patent/JPS61126532A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS64916A (en) * | 1987-06-23 | 1989-01-05 | Canon Inc | Photographing lens |
| JP2605719B2 (en) * | 1987-06-23 | 1997-04-30 | キヤノン株式会社 | Shooting lens |
| JPH01254912A (en) * | 1988-04-04 | 1989-10-11 | Nippon Hoso Kyokai <Nhk> | Optical low-pass filter |
| JPH07111514B2 (en) * | 1988-04-04 | 1995-11-29 | 日本放送協会 | Optical low pass filter |
| US8194209B2 (en) | 2006-07-05 | 2012-06-05 | Nikon Corporation | Optical low-pass filter, camera, imaging apparatus, and method for producing optical low-pass filter |
| JP5104755B2 (en) * | 2006-07-05 | 2012-12-19 | 株式会社ニコン | Optical low-pass filter, camera, imaging device, and optical low-pass filter manufacturing method |
| CN109579738A (en) * | 2019-01-04 | 2019-04-05 | 北京理工大学 | A kind of two-value striped defocus optical projection system low-frequency filter characteristics measurement method |
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