JPS62164010A - Infrared ray camera - Google Patents

Abstract

PURPOSE:To focus and image-form the infrared rays from an object with a reflection mirror optical system and to obtain the practically sufficient performance by using a rotational secondary curved surface reflection mirror as a converging optical system. CONSTITUTION:The first large concave mirror 11 is directed to an incident light side, a reflection mirror from a plane mirror 3 for scanning an objective surface is converged and the image of a point 13 to be scanned is formed at a detecting device 6 with a small concave mirror 12. A straight line to link the center of the large concave mirror and the far focus is the optical axis of the incident side, the reflecting direction by the second reflection mirror 12 on the light on the axis is the optical axis of the coming-out side and the outline of the optical arrangement when these both optical axes are specified in parallel to a (z) axis is shown in Fig. (b). When a small mirror 12 is a convex mirror, the Cassegrain-type optical arrangement is executed, the hole is provided at the optical axis part of the first concave mirror 11, and the reflecting light from the small mirror 12 is focused through the hole. Thus, the infrared rays from the object are focused and image-formed by the reflection mirror optical system and the practically sufficient performance can be held.

Description

【発明の詳細な説明】 発明の目的 （産業上の利用分野） この発明は赤外線カメラ、特に回転２次曲面反射鏡を用
いた光学系を有する平面ミラー対物面走査方式の赤外線
カメラに関する。DETAILED DESCRIPTION OF THE INVENTION Object of the Invention (Field of Industrial Application) The present invention relates to an infrared camera, and particularly to a plane mirror object plane scanning type infrared camera having an optical system using a rotating quadratic curved reflector.

（従来技術） 平面ミラー対物面走査方式の赤外線カメラは、建造物の
壁診断用等の目的に使用されており、その構成は第１４
図に示される。すなわち、カメラ１内へ入射窓２から入
射した赤外線は走査鏡３で偏向され、集光レンズ４、リ
レーレンズ５によって検知器６に集光される。一方、カ
メラ内には基準熱源７が配設され、該熱源からの赤外線
はレンズ８で集光レンズ４の集光位置に集光される。こ
の集光位置にはチョッパ反射鏡９が挿脱され、検知器に
入射する赤外光を被写体からのものと基準熱源からのも
のとの切り換えを行う。(Prior art) An infrared camera using a plane mirror object plane scanning method is used for purposes such as diagnosing walls of buildings, and its configuration is as follows.
As shown in the figure. That is, infrared rays entering the camera 1 through the entrance window 2 are deflected by the scanning mirror 3 and focused onto the detector 6 by the condensing lens 4 and the relay lens 5. On the other hand, a reference heat source 7 is disposed within the camera, and infrared rays from the heat source are focused by a lens 8 onto a focusing position of the focusing lens 4. A chopper reflector 9 is inserted into and removed from this light collection position, and switches the infrared light incident on the detector between that from the object and that from the reference heat source.

このような光学系においては、検知器６は常に光学系の
光軸上にある物体のみを検知している。In such an optical system, the detector 6 always detects only objects located on the optical axis of the optical system.

従って光学系は物体高０の被写体に対してのみ十分な収
差補正が行われていればよいこととなり、光学設計には
有利な条件となる。実際には検知器の検知部の面積が０
ではないので、その面積に対応する被写体の大きさを考
慮しなければならないが、実用化されている検知器では
検知部の大きさは直径０．１ｍ以下であり、上記の有利
さに影響を与える程のものではない。Therefore, the optical system only needs to perform sufficient aberration correction for a subject whose object height is 0, which is an advantageous condition for optical design. In reality, the area of the detection part of the detector is 0.
Therefore, it is necessary to consider the size of the object corresponding to the area, but in the detectors in practical use, the size of the detection part is less than 0.1 m in diameter, which has no effect on the above advantages. It's not worth giving.

（この発明が解決しようとする問題点）建造物の壁診断
用赤外線カメラの場合、波長１０μｍ程度の赤外線を検
知するのが最もよいとされているが、この程度の波長の
赤外線を透過させる光学材料は非常に少なく、一般には
材料自体が高価であるゲルマニュームが用いられる。そ
の上ゲルマニュームの屈折率は約４であり、表面反射率
も非常に高いものとなる。そのため、これをレンズとし
て用いる場合１反射防止コーティングをする必要がある
が、コーティング層の厚さも透過赤外線の波長に合わせ
て２〜３μｍと可視光領域では考えられない厚さにしな
ければならず、この点でもコスト高を免れない。(Problem to be solved by this invention) In the case of an infrared camera for diagnosing walls of buildings, it is said that it is best to detect infrared rays with a wavelength of about 10 μm. There are very few materials used, and germanium, which is an expensive material itself, is generally used. Furthermore, the refractive index of germanium is approximately 4, and the surface reflectance is also very high. Therefore, when using this as a lens, it is necessary to apply an anti-reflection coating, but the thickness of the coating layer must also be 2 to 3 μm, which is unthinkable in the visible light region, in accordance with the wavelength of the transmitted infrared rays. In this respect as well, high costs cannot be avoided.

また、検出器の感度や検出信号のＳ／Ｎ比の改善のため
に十分な赤外線エネルギーを入射させようとすれば、口
径４０ｍｍ程度のレンズが必要となる。材料の使用量は
単純に云えば口径の３乗に比例することとなり、口径が
２倍になれば使用量は８倍となり、使用レンズの口径を
大きくすればゲルマニューム材料が高価なためレンズの
コストアップを招く。Furthermore, in order to inject sufficient infrared energy to improve the sensitivity of the detector and the S/N ratio of the detection signal, a lens with an aperture of about 40 mm is required. Simply put, the amount of material used is proportional to the cube of the aperture, so if the aperture doubles, the amount used will increase eight times, and if the aperture of the lens is increased, the cost of the lens will decrease because germanium material is expensive. Invite up.

発明の構成 （問題を解決するための手段） この発明においては、集光光学系として回転２次曲面反
射鏡を用いることにより、従来のようなレンズ材料の制
約を受けない赤外線カメラを得ようとするものである。Structure of the Invention (Means for Solving the Problem) This invention attempts to obtain an infrared camera that is not subject to the limitations of conventional lens materials by using a rotating quadratic curved reflector as a condensing optical system. It is something to do.

すなわち、回転楕円面あるいは回転放物面からなる第１
凹面鏡とこれに対向する回転２次曲面鏡からなる第２の
小鏡を含み、これらの両反射鏡はその焦点を共有し、第
２の小鏡で反射された赤外線の集束点近傍に検知器を配
置する。In other words, the first ellipsoid or paraboloid of revolution
It includes a second small mirror consisting of a concave mirror and a rotating quadratic curved mirror opposing it, and both of these reflecting mirrors share their focal point, and a detector is located near the focal point of the infrared rays reflected by the second small mirror. Place.

第２小鏡が凹面鏡である場合は、両凹面鏡は上記共有焦
点を通る平面に対して互いに逆側に配置される。When the second small mirror is a concave mirror, both concave mirrors are arranged on opposite sides of the plane passing through the shared focal point.

これに対して第２小鏡が凸面鏡である場合はいわゆるカ
セグレン、タイプの光学配置とされ、第１凹面鏡の光軸
部分に孔を設け、第２小鏡からの反射光はこの孔を通っ
て集束することとなる。On the other hand, when the second small mirror is a convex mirror, it is a so-called Cassegrain type optical arrangement, in which a hole is provided at the optical axis of the first concave mirror, and the reflected light from the second small mirror passes through this hole. It will be focused.

また、主として合焦走査を容易にし、結像性能を向上さ
せるため、ゲルマニュームレンズを付加するのが望まし
い。Further, it is desirable to add a germanium lens mainly to facilitate focusing scanning and improve imaging performance.

（実施例） 以下この発明の実施例を示す。(Example) Examples of this invention will be shown below.

（実施例１） 第１図は、長径を回転軸とする回転楕円面よりなる大小
２個の凹面鏡をそれぞれ一方の焦点を共有させ、凹面が
互いに向き合うように、しかも両凹面鏡は上記共有焦点
を通る一平面で分割される空間の互いに反対側にのみあ
るように配置された例である。(Example 1) Fig. 1 shows two large and small concave mirrors each made of an ellipsoid of revolution with the major axis as the axis of rotation. This is an example in which the space is divided by a single plane, and the space is located only on opposite sides of the space.

第１の大凹面鏡１１を入射光側に向け、対物面走査用の
平面ミラー３からの反射光を集光し、小凹面鏡１２で検
知器６に被走査点１３の像を結ぶ。The first large concave mirror 11 is directed toward the incident light side, and the reflected light from the plane mirror 3 for scanning the object plane is collected, and the small concave mirror 12 forms an image of the scanned point 13 on the detector 6 .

第１図（ａ）において共有焦点１４を原点とする三次元
座標系ｘ、ｙ、ｚを図のように定め、それぞれ原点１４
から２では右、ｙでは上、Ｘでは紙面に垂直で裏面に向
かう方向を正とする。このとき両凹面鏡を構成する楕円
の長径方向を２軸と平行もしくはほぼ平行に設定し、大
凹面鏡１１は２≦Ｏおよびｙ≧０の範囲にのみ存在し、
小凹面鏡１２は２≧０およびｙ≦０の範囲にのみ存在す
るように配設される。回転楕円面鏡においては。In FIG. 1(a), a three-dimensional coordinate system x, y, z with the origin at the shared focal point 14 is defined as shown in the figure, and each point is at the origin 14.
For 2, the right direction, for y, the upward direction, and for X, the direction perpendicular to the page and toward the back is positive. At this time, the long axis direction of the ellipse constituting the biconcave mirror is set parallel or almost parallel to the two axes, and the large concave mirror 11 exists only in the range of 2≦O and y≧0,
The small concave mirror 12 is arranged so that it exists only in the range of 2≧0 and y≦0. In a spheroidal mirror.

一方の焦点から出射する光は無収差で他方の焦点に集束
することはよく知られている。大凹面鏡１１の中心と遠
い方の焦点を結ぶ直線を入射側の光軸、軸上光の第２反
射鏡１２による反射方向を出射側の光軸とし、これら両
光軸をＺ軸に平行に定めた場合の光学配置の概略を第１
図（ｂ）に示す。It is well known that light emitted from one focal point is converged to the other focal point without aberration. The straight line connecting the center of the large concave mirror 11 and the far focal point is the optical axis on the incident side, and the direction in which the on-axis light is reflected by the second reflecting mirror 12 is the optical axis on the output side. Both optical axes are parallel to the Z axis. The outline of the optical arrangement in the case of
Shown in Figure (b).

実際には対物面走査用平面ミラー３で光束が折り曲げら
れ、折り曲げられた光軸上に存在する物体上の点１３が
被走査点となり、平面ミラー３の回動走査により物体上
の被走査点が移動するが、図示の簡略化のため省略しで
ある。In reality, the light beam is bent by the object plane scanning plane mirror 3, and a point 13 on the object existing on the bent optical axis becomes the scanned point. moves, but is omitted to simplify the illustration.

上記の光学系において、被走査点１３から発散した光束
の１部は大凹面鏡１１に入射する。壁診断用赤外線カメ
ラの使用状態では物体距離は一般に３ｍ〜Ｌｏｏｍ位で
あり、光学系の大きさに較べて十分に大きく、平行光束
に近い発散光となっている。しかし、大凹面鏡１１の一
方の焦点を３ｍ〜Ｌｏｏｍの距離範囲の何処か一点に採
るとすれば、被走査点がその他の距離にあるときは集束
状態が劣る可能性がある。焦点位置としては最も使用頻
度の高い距離を選んでもよいが、最短被写体距離と最長
被写体距離から関数的に求めてもよい。関数としては、
相加平均、相乗平均などでもよいが、最短、最長面被写
体距離から入射開口を見込む角の平均を取り、この平均
になるような開口角になる距離を選ぶのが最もよい。こ
のような関係を満たす関数は調和平均として知られてお
り、例えば３ｍと１００ｍの調和平均であれば１／　（
（１／３＋１／１００）　／２）　＝５．８ｍとなる。In the above optical system, a portion of the light beam diverging from the scanned point 13 is incident on the large concave mirror 11 . When an infrared camera for wall diagnosis is in use, the object distance is generally about 3 m to 300 m, which is sufficiently large compared to the size of the optical system, and the light is divergent, close to a parallel beam of light. However, if one focal point of the large concave mirror 11 is set at a point somewhere within the distance range of 3 m to 3 m, there is a possibility that the convergence state will be poor if the scanned point is at another distance. The most frequently used distance may be selected as the focal position, but it may also be determined functionally from the shortest subject distance and the longest subject distance. As a function,
An arithmetic mean, a geometric mean, etc. may be used, but it is best to take the average of the angles looking into the entrance aperture from the shortest and longest plane subject distances, and select a distance that will give an aperture angle that is the average. A function that satisfies this relationship is known as a harmonic mean. For example, if the harmonic mean of 3m and 100m is 1/(
(1/3 + 1/100) /2) = 5.8m.

楕円の長径を２ａ、短径を２ｂ、焦点間距離を２０とす
るとき、この発明の、第１反射鏡１１の方程式は次式で
表される。When the major axis of the ellipse is 2a, the minor axis is 2b, and the distance between focal points is 20, the equation of the first reflecting mirror 11 of the present invention is expressed by the following equation.

ニジ」位＋工Ｌ−Ｃユ 、２　　　　８．　　＝１・・・　（１）ａ２＝ｂ２＋
０２　　　　　　　　・・・　（２）このとき、楕円反
射鏡の頂点１１′と焦点１４との距離はａ−ｃで表され
る。また、他の焦点１３の２座標はｚ＝２ｃである。従
って、２ｃを上記の調和平均にとり、ａを与えれば（１
）（２）式から所望の楕円反射鏡の形状を決定すること
が出来る。第２の小凹面鏡１２に関しては上記ａおよび
Ｃを負の数で与えれば上記の関係がそのまま成立する。Niji” rank + engineering L-C Yu, 2 8. =1... (1) a2=b2+
02... (2) At this time, the distance between the vertex 11' of the elliptical reflecting mirror and the focal point 14 is represented by a-c. Further, the two coordinates of the other focal point 13 are z=2c. Therefore, if we take 2c to the above harmonic mean and give a, then (1
) The desired shape of the elliptical reflecting mirror can be determined from equation (2). Regarding the second small concave mirror 12, the above relationship holds true if the above a and C are given as negative numbers.

第２図は第１反射鏡の物体側焦点位置をｚ＝２ｃ＝７ｍ
＋頂点座４ｊＪ　ｚ　＝　ｃ　−ａ　＝　−２０ｒｍ、
小凹面鏡の焦点位置（検知器位置）をｚ　＝　２　ｃ　
＝　−２０ｎｒｎ、頂点座標ｚ＝ｃ−ａ＝５ｍｍ、入射
開口４０ｍ角としたときの物体距離１００ｍに対するス
ポットダイヤグラムである。像面位置は−１８，４３２
とした。（ａ）、（ｂ）、（ｃ）はそれぞれ物点座標（
０，０）、（５０ｎｗｎ、、　５０　ｎｕｎ　）、（５
０ｍｍ　、−５０ｍｍ）に対応する。空間周波数５ｃ／
ｍｍのＭＴＦは（ａ）でＸ方向９４．２％、Ｘ方向８８
．０％、（ｂ）でＸ方向８３．７％、Ｘ方向８４．４％
、（ｃ）でＸ方向８９．４％、Ｘ方向９０．６％であっ
た。壁診断用カメラとして必要なＭＦＴは８０％程度と
言われているので、上記の値はこれを満足している。Figure 2 shows the object side focus position of the first reflecting mirror at z=2c=7m.
+ Vertex seat 4jJ z = c - a = -20rm,
The focal position (detector position) of the small concave mirror is z = 2 c
This is a spot diagram for an object distance of 100 m when = -20nrn, vertex coordinates z = ca = 5 mm, and an incident aperture of 40 m square. Image plane position is -18,432
And so. (a), (b), and (c) are the object point coordinates (
0,0), (50nwn,, 50 nun), (5
0mm, -50mm). Spatial frequency 5c/
The MTF of mm is 94.2% in the X direction and 88% in the X direction in (a).
．． 0%, (b) 83.7% in the X direction, 84.4% in the X direction
, (c), it was 89.4% in the X direction and 90.6% in the X direction. It is said that the MFT required for a wall diagnostic camera is about 80%, so the above value satisfies this.

第３図には物体距離３ｆｆｌのときのスポットダイヤグ
ラムを示す、このときの物点座標は（ａ）０，０、（ｂ
Ｈ，５ｍｎ、１．５部ｗｎ、（ｃ）１．５ｎｎ＋−１，
５ＩＩｎとなる。ＭＴＦは（ａ）でＸ方向９３．８％、
Ｘ方向８３．４％、（ｂ）でＸ方向９０゜９％、Ｘ方向
８４．９％、（ｃ）でＸ方向８１．３％、ｙ方向８２゜
４％となった。中間距離例えば物体距離が丁度７ｍの位
置では、上記条件でＭＴＦは９９％以上となり、結局、
物体距離３ｍ〜Ｌｏｏｍの範囲においてほぼ満足な性能
が得られたことになる。また、第１図（ｂ）では入射側
と出射側の光軸がたがいに平行にされているが、平行に
限られるねけではなく。Figure 3 shows a spot diagram when the object distance is 3ffl.The object point coordinates at this time are (a) 0,0, (b
H, 5mn, 1.5 parts wn, (c) 1.5nn+-1,
5IIn. MTF is 93.8% in the X direction in (a),
83.4% in the X direction, 90°9% in the X direction in (b) and 84.9% in the X direction, and 81.3% in the X direction and 82°4% in the y direction in (c). At an intermediate distance, for example, at a position where the object distance is exactly 7 m, the MTF will be over 99% under the above conditions, and eventually,
This means that almost satisfactory performance was obtained in the object distance range of 3 m to Loom. Furthermore, although the optical axes on the incident side and the output side are parallel to each other in FIG. 1(b), they are not limited to being parallel.

あまり大きな角度でなければＭＴＦに殆ど影響がないこ
とが確かめられている。It has been confirmed that unless the angle is too large, there is almost no effect on MTF.

第４図はこの実施例の反射鏡配置を示す斜視図である。FIG. 4 is a perspective view showing the arrangement of reflecting mirrors in this embodiment.

図から見られるように大凹面鏡１１と小凹面鏡１２との
間が大きく開いており、ここを通って物体からの光束が
直接検知器に入ってしまう恐れがある。これに対しては
、同図（ｂ）に示すように共有焦点１４近傍に小さい開
口１６を持った遮光板１５をｘ−ｚ平面に首けばよい。As can be seen from the figure, there is a large gap between the large concave mirror 11 and the small concave mirror 12, and there is a possibility that the light beam from the object may pass through this gap and directly enter the detector. To solve this problem, a light shielding plate 15 having a small aperture 16 near the common focal point 14 may be placed in the xz plane as shown in FIG. 2(b).

また、被走査点の距離の変化によって集束点の位置も変
化するが、第１図中の矢印Ａのように検知器６を変位さ
せて対応することが出来る。Furthermore, the position of the focal point changes as the distance to the scanned point changes, but this can be accommodated by displacing the detector 6 as indicated by arrow A in FIG.

この実施例は反射鏡だけで構成され、透過レンズを全く
用いていないので、レンズ使用に伴う問題は一切生じな
い。Since this embodiment is composed only of reflecting mirrors and does not use any transmission lenses, there are no problems associated with the use of lenses.

（実施例２） 第５図は、両凹面鏡に回転放物面を用いた例である。回
転軸はＺ軸となっているので、２軸に平行に入射する光
束は全て共有焦点１４に集束し。(Example 2) FIG. 5 is an example in which a paraboloid of revolution is used as a biconcave mirror. Since the rotation axis is the Z axis, all the light beams incident parallel to the two axes are focused on the shared focal point 14.

この焦点から発散する光束は反射後は全てＺ軸に平行な
光束となる。有限距離の物体からの光束は完全な平行光
束ではないが、はぼ平行に近いことは前の実施例の場合
と同じである。出射開口からのほぼ平行な光束は赤外線
透過性の材料、例えばゲルマニュウムのレンズ１７に入
射し、レンズの後側焦点近傍に集束する。実際には被走
査点が無限遠距離にはないため、大凹面鏡からの出射光
束は緩い発散光束となり、小凹面鏡により反射された光
束は発散の度合がより強調されるので、レンズの後側焦
点よりは更に遠い点に集束する。物点距離の変化に対応
するためには検知器６かレンズ１７を光軸方向に動かせ
ばよい。しかし、基準熱源７からの赤外光を検知器６に
入射させるためには集束点の位置は動かないほうが望ま
しい。そのためにはレンズ１７によって合焦を行うのが
よい６大口面鏡の頂点の２座標をＰい小凹面鏡のそれを
Ｐ２とすれば、それぞれの放物面は次式で表される。After being reflected, all of the light beams that diverge from this focal point become parallel to the Z-axis. Although the light beam from an object at a finite distance is not completely parallel, it is nearly parallel, as in the previous embodiment. A substantially parallel beam of light from the exit aperture enters a lens 17 made of an infrared transparent material, for example germanium, and is focused near the rear focal point of the lens. In reality, the point to be scanned is not at an infinite distance, so the light beam emitted from the large concave mirror becomes a loosely diverging light beam, and the light beam reflected by the small concave mirror has a more accentuated degree of divergence, so the back focus of the lens It focuses on a point even further away. In order to respond to changes in the object distance, the detector 6 or the lens 17 may be moved in the optical axis direction. However, in order to allow the infrared light from the reference heat source 7 to enter the detector 6, it is preferable that the position of the focal point does not move. For this purpose, it is preferable to focus using the lens 17.6If the two coordinates of the apex of the large aperture mirror are P and those of the small concave mirror are P2, each paraboloid is expressed by the following equation.

ｘ”＋ｙ”＝−４Ｐ１　（ｚ−１’Ｊ）　　　・・・　
（３）ただし ｙ≧Ｏ（ｉ＝１のとき）＋ｙ≦Ｏ（ｉ＝２のとき）第６
図は上式においてＰ、＝　−３０ｍｍ、　Ｐ、＝　７　
。x"+y"=-4P1 (z-1'J)...
(3) However, y≧O (when i=1) + y≦O (when i=2) 6th
The figure shows P, = -30mm, P, = 7 in the above formula.
.

５ｍ、入射開口４０ｒｍ角としたときの光路を示し。The optical path is shown when the input aperture is 5 m and the incident aperture is 40 rm square.

出射開口はＰ２：Ｐｌによって決るので１０ｍｍ角とな
る。レンズの開口もそれに・一致させて１０ｍｍ角とし
、無限遠物体に対し球面収差を最少にするものとして、
第１面と第２面の曲率半径をそれぞれＲ１＝４０ｍｍ、
　Ｒ，＝８０＋ａｍとしている。同図（ｂ）（ｃ）は物
体距離３ｍ、像面距１ｉｚ＝−５９，９７、物点座標（
０，０）および（１，５ｍｍ、１．５ｍｍ）の場合のス
ポットダイヤグラムを示す。このときのＭＴＦは（ｂ）
でＸ方向９１．４％、ｙ方向９３．１％、（ｃ）でＸ方
向９１゜４％、ｙ方向９２．３％であった。同じ光学系
で物点距離を５０＋ｎ、像面をｚ＝−５６，８２とした
場合のＭＴＦは何れも９４．３％以上となる。Since the exit aperture is determined by P2:Pl, it is 10 mm square. The aperture of the lens is also 10 mm square to match this, and the spherical aberration for objects at infinity is minimized.
The radius of curvature of the first and second surfaces is R1 = 40 mm, respectively.
R,=80+am. In the same figure (b) and (c), the object distance is 3 m, the image plane distance 1iz = -59,97, and the object point coordinates (
0,0) and (1,5 mm, 1.5 mm) are shown. The MTF at this time is (b)
In (c), it was 91.4% in the X direction and 93.1% in the y direction, and in (c), it was 91.4% in the X direction and 92.3% in the y direction. In the same optical system, when the object point distance is 50+n and the image plane is z=-56, 82, the MTF is 94.3% or more.

（実施例３） 第７図は大凹面鏡１１として回転楕円面鏡、小凹面鏡１
２として回転放物面鏡を用いた例である。(Example 3) FIG. 7 shows a spheroidal mirror as a large concave mirror 11 and a small concave mirror 1 as a small concave mirror 1.
2 is an example in which a parabolic mirror of revolution is used.

大凹面鏡１１の形状は（１）、（２）式で表され、小凹
面鏡１２の形状は（３）式で表される。大凹面鏡１１の
物体側焦点位置をｚ＝２ｃ＝６ｍ、頂点座標ｚ＝ａ−ｃ
＝２０ｍｍとしたときの物体距離Ｌｏｏｍに対するスポ
ットダイヤグラムを第８図ニ示ス。物体ａｍ　ハ（ａ　
）　０，０、（ｂ　）　５０ｍｍ、５０ｍｍ。The shape of the large concave mirror 11 is expressed by equations (1) and (2), and the shape of the small concave mirror 12 is expressed by equation (3). The object-side focal point of the large concave mirror 11 is z=2c=6m, and the vertex coordinates are z=a-c.
Figure 8 shows a spot diagram for the object distance Loom when = 20 mm. Object am ha (a
) 0,0, (b) 50mm, 50mm.

像面はｚ＝−４５，１２６とした。このときのＭＴＦは
（ａ）でＸ方向９３．８％、ｙ方向９５．０％、（ｂ）
でＸ方向９１．１％、ｙ方向９５．５％であった。同じ
光学系でより近い物体きよりにたいするＭＴＦは何れも
これより高く、最高９６．８％であった。The image plane was set at z=-45,126. The MTF at this time is (a) 93.8% in the X direction and 95.0% in the y direction, (b)
It was 91.1% in the X direction and 95.5% in the Y direction. The MTF for closer objects using the same optical system was higher than this, with a maximum of 96.8%.

（実施例４） 上記実施例では大凹面鏡１１の物体側焦点位置を２軸上
に置いたので、反射鏡系の光軸はＺ軸と平行にならなか
ったが、第９図に示すように物体側焦点位置のｙ座標を
入射開口の中心と同じにすれば、光軸はＺ軸と平行にな
る。前の実施例と同じに入射開口を４０ｍｍ角とし、物
体側焦点位置を６ｍとすれば、楕円の長径のＺ軸に対す
る傾きは約１１．５’　となる。この構成は両凹面鏡の
光軸が平行になるので設計が容易になり、性能的には実
施例３と殆ど差がなく、ＭＴＦは９５．２〜９７．３％
の間であった。(Example 4) In the above example, since the object side focal point position of the large concave mirror 11 was placed on two axes, the optical axis of the reflecting mirror system was not parallel to the Z axis, but as shown in FIG. If the y-coordinate of the object-side focal position is made the same as the center of the entrance aperture, the optical axis becomes parallel to the Z-axis. Assuming that the entrance aperture is 40 mm square and the object side focal position is 6 m as in the previous embodiment, the inclination of the major axis of the ellipse with respect to the Z axis is approximately 11.5'. In this configuration, the optical axes of the biconcave mirrors are parallel, making the design easier, and there is almost no difference in performance from Example 3, with an MTF of 95.2 to 97.3%.
It was between.

（実施例５） 第１０図は実施例１と同様両凹面鏡を回転楕円面とし、
これにレンズ１７を導入したものである。(Example 5) Figure 10 shows a biconcave mirror with a spheroidal surface as in Example 1,
A lens 17 is added to this.

この場合の性能も実施例３とほぼ同様で、ＭＴＦは９２
６２〜９６，１％の間であった。The performance in this case is also almost the same as in Example 3, and the MTF is 92.
It was between 62 and 96.1%.

これらの実施例においても実施例１と同様の遮光板を挿
入するのがよく、また、レンズもその形状は勿論、２枚
、３枚を用いた複合レンズでもよい等、各種の設計変更
が可能なことは言うまでもない。In these embodiments as well, it is preferable to insert a light-shielding plate similar to that in embodiment 1, and various design changes are possible, such as the shape of the lens as well as a compound lens using two or three lenses. Needless to say.

（実施例６） 第２の小反射鏡を凸面鏡とし、所謂カセグレンタイプの
構成とすることも出来る。第１１図にその１例を示す。(Embodiment 6) It is also possible to use a convex mirror as the second small reflecting mirror to have a so-called Cassegrain type structure. An example is shown in FIG.

大凹面鏡１１と小凸面鏡１２′は共に回転放物面であり
、共軸、共焦点に配置され。Both the large concave mirror 11 and the small convex mirror 12' are paraboloids of revolution, and are arranged coaxially and confocally.

小反射鏡からの反射光は大凹面鏡の中心に設けられた開
口部を通して出射し、検知器６上に集束する。The reflected light from the small reflecting mirror exits through an opening provided at the center of the large concave mirror and is focused on the detector 6.

放物面を表す式（３）において、大凹面鏡１１でＰ１＝
１０ｍｍ、小凸面鏡１２′でＰ、＝２．５ｍｍの場合、
開口を直径４０ｍｍとすれば、凸面鏡による光束のケラ
レは約１／１６　（約６％）となる、Ｇｅレンズは入射
側半径Ｒ１＝２５ｍｍ、出射側半径Ｒ２＝３６ｎｗｎ、
厚さ３ｍｍの凸メニスカスレンズとしたとき、物点が５
０Ｉｎとして集束点位ｉｚ中−３３，７ｍｍ、最小錯乱
円径約１６μｍとなる。In equation (3) representing a paraboloid, P1=
10mm, and when P = 2.5mm with a small convex mirror 12',
If the diameter of the aperture is 40 mm, the vignetting of the light beam due to the convex mirror will be approximately 1/16 (approximately 6%). The Ge lens has an input side radius R1 = 25 mm, an output side radius R2 = 36nwn,
When using a convex meniscus lens with a thickness of 3 mm, the object point is 5.
Assuming 0In, the focal point position iz is -33.7 mm, and the diameter of the circle of minimum confusion is approximately 16 μm.

第１２図の場合はｐ、＝　１５ｍｍ、　ｐ、＝　２　、
５ｍｍ、開口は直径４０ｍｍとし、凸面鏡の有効径もそ
れに比例させて小としたものであるにの場合の最小錯乱
円径は約４．９μｍとなる。In the case of Fig. 12, p, = 15 mm, p, = 2,
5 mm, the diameter of the aperture is 40 mm, and the effective diameter of the convex mirror is made proportionally smaller.The diameter of the circle of least confusion is approximately 4.9 μm.

なお、回転双曲面鏡を用いた場合、−焦点に集束する光
束は反射接地の焦点に無収差で集束する性質を利用して
、この種の反射光学系において小凸面鏡として用いられ
ることは周知であり、この実施例においても利用可能で
ある。It is well known that when a rotating hyperboloid mirror is used, it can be used as a small convex mirror in this type of reflective optical system by taking advantage of the property that the light beam converged to the focal point is converged to the reflective ground focal point without aberration. Yes, and can be used in this embodiment as well.

（実施例７） 第１３図に小凸面鏡を用いた反射光学系を有する赤外線
カメラの全体構成の１例を示す。この光学系では、光軸
を含む光軸近傍の空間は被写体からの有効光束は通らな
いので、レンズ後方のこの空間内に支持棒１８で支持さ
れた反射鏡１９を設け、基準熱源７からの赤外線を集束
光として入射させることで検知器６に基準熱源像を結ば
せることが出来る。(Embodiment 7) FIG. 13 shows an example of the overall configuration of an infrared camera having a reflective optical system using a small convex mirror. In this optical system, since the effective light flux from the subject does not pass through the space near the optical axis including the optical axis, a reflecting mirror 19 supported by a support rod 18 is provided in this space behind the lens, and the space near the optical axis includes the optical axis. A reference heat source image can be formed on the detector 6 by injecting infrared rays as focused light.

発明の効果 この発明は上記のように被写体からの赤外線を反射鏡光
学系によって集束結像させ実用上充分な性能を持たせる
ことが出来たもので、Ｇｅレンズの使用に伴う問題は生
ぜず、低コストの赤外線カメラを得ることが出来る。Effects of the Invention As described above, this invention was able to focus and image the infrared rays from the object using a reflecting mirror optical system, and to have sufficient performance for practical use, and the problems associated with the use of Ge lenses did not occur. A low-cost infrared camera can be obtained.

また１例えば第１０図の光学系はＦナンバーがほぼ２に
なっており、通常レンズだけで構成されているものはＦ
ｌであるのに比して暗過ぎる心配があるが、レンズの焦
点距離を短くして明るさを増すことが出来る。このとき
、レンズの構成枚数を増やすことによってＭＴＦを維持
出来る。1. For example, the optical system shown in Figure 10 has an F number of approximately 2, and an optical system that consists of only a normal lens has an F number of approximately 2.
Although there is a concern that it will be too dark compared to the 1-inch lens, the brightness can be increased by shortening the focal length of the lens. At this time, MTF can be maintained by increasing the number of lenses.

さらにこの種の赤外線カメラは被写体距離が３〜１００
ｍという非常に広い範囲で使用されるため、合焦操作が
必要となる。この目的で検知器を移動させるのは、多く
の場合検知器は冷却装置と一体になっているため困難で
ある。小反射鏡を移動させるのは、両反射鏡を共焦点で
配置するという条件を崩し、性能を維持出来なくなる。Furthermore, this type of infrared camera has a subject distance of 3 to 100
Since it is used over a very wide range of m, a focusing operation is required. Moving the detector for this purpose is difficult as the detector is often integrated with the cooling system. Moving the small reflector breaks the condition of arranging both reflectors in a confocal position, making it impossible to maintain performance.

このためＧｅレンズを導入し、合焦用とするのが有利で
ある。For this reason, it is advantageous to introduce a Ge lens and use it for focusing.

上記のようにＭＴＦの向上、明るさの増加および合焦の
ためＧｅレンズを用いることが有利であるが、小反射鏡
の出射開口は大反射鏡の入射開口に比して両反射鏡の相
似比の割で小となり、上記の実施例では、出射開口４０
ｍｍ角に対して出射開口は１０ｒｎｆｆｉ角となってお
り、レンズの大きさも１／４以下、従ってその材料の使
用料は１７６４にも低下し、大幅なコスト低下が可能で
ある。As mentioned above, it is advantageous to use a Ge lens to improve MTF, increase brightness, and focus, but the exit aperture of the small reflector is similar to that of both reflectors compared to the input aperture of the large reflector. In the above embodiment, the output aperture 40
The exit aperture is 10 rnffi angle compared to the mm angle, and the size of the lens is less than 1/4, so the cost of the material used can be reduced to 1764 mm, making it possible to significantly reduce costs.

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

第１図はこの発明の赤外線カメラ用反射光学系の１実施
例の構成を示す断面図、第２図、第３図はそのスポット
ダイヤグラム、第４図はその反射鏡配巴を示す斜視図お
よび断面図、第５図、第６図は実施例２の構成を示す断
面図およびそのスポットダイヤグラム、第７図、第８図
は実施例３の構成を示す断面図およびそのスポットダイ
ヤグラム、第９図、第１０図は実施例４および実施例５
の構成を示す断面図、第１１図、第１２図は実施例６の
構成を示す光路図、第１３図は実施例６を用いた赤外線
カメラの構成図、第１４図は公知の赤外線カメラの構成
図である。 １：赤外線カメラ　　　２：赤外線入射窓３：走査鏡　
　　　　　４：集光レンズ５：リレーレンズ　　　６：
検知器 ７：基準熱源　　　　　８：レンズ ９：チョッパ反射鏡　　１１：大口面鏡１２：小凹面鏡
　　　　１２′　：小凸面鏡１３：被走査点　　　　１
４：共有焦点１５：遮光板　　　　　１６：開口部 １７：レンズ　　　　　１８：支持棒 １９：反射鏡 特許出願人　株式会社　リ　コ　− 出願人代理人　弁理士　佐藤文男 （他２名） ＄２図 （ｂ） 駆　　　３　　　図 （ｂ） 第４図 ｙＬ　　　６　　　図 （−０，１、−Ｑ、ｌ　） （ｂ）　　　　　　　　　　　　　　　　（ｃ）簗　　
　７　　　図 ≠　　　８　　　図 ４（９図 ５１ｔ１０　　　　図FIG. 1 is a sectional view showing the configuration of one embodiment of the reflective optical system for an infrared camera according to the present invention, FIGS. 2 and 3 are spot diagrams thereof, and FIG. 4 is a perspective view showing the arrangement of the reflective mirrors. 5 and 6 are cross-sectional views showing the configuration of Example 2 and their spot diagrams; FIGS. 7 and 8 are cross-sectional views showing the configuration of Example 3 and their spot diagrams; FIG. 9; , FIG. 10 shows Example 4 and Example 5.
11 and 12 are optical path diagrams showing the configuration of Example 6, FIG. 13 is a configuration diagram of an infrared camera using Example 6, and FIG. 14 is a diagram of a known infrared camera. FIG. 1: Infrared camera 2: Infrared entrance window 3: Scanning mirror
4: Condensing lens 5: Relay lens 6:
Detector 7: Reference heat source 8: Lens 9: Chopper reflector 11: Large mirror 12: Small concave mirror 12': Small convex mirror 13: Scanned point 1
4: Shared focus 15: Light shielding plate 16: Opening 17: Lens 18: Support rod 19: Reflector Patent applicant Rico Co., Ltd. - Applicant's agent Patent attorney Fumio Sato (2 others) $2 Figure (b) Kaku 3 Figure (b) Figure 4 yL 6 Figure (-0, 1, -Q, l) (b) (c) Glans
7 Figure ≠ 8 Figure 4 (9 Figure 51t10 Figure

Claims (1)

【特許請求の範囲】 １）平面ミラー対物面走査方式の赤外線カメラにおいて
、入射開口部を上記平面ミラーに向けた回転２次曲面か
らなる第１凹面鏡とこれに対向する回転２次曲面からな
る第２の小鏡を含み、これらの両反射鏡はその焦点を共
有し、第２の小鏡からの出射赤外線の集束点近傍に検知
器を配置することを特徴とする赤外線カメラ ２）平面ミラー対物面走査方式の赤外線カメラにおいて
、入射開口部を上記平面ミラーに向けた回転２次曲面か
らなる第１凹面鏡とこれに対向する回転２次曲面からな
る第２の凹面小鏡を含み、これらの両反射鏡はその焦点
を共有すると共に上記共有焦点を通る一平面に関し互い
に逆側に配置され、上記小鏡からの出射赤外線の集束点
近傍に検知器を配置することを特徴とする赤外線カメラ
３）平面ミラー対物面走査方式の赤外線カメラにおいて
、入射開口部を上記平面ミラーに向け中心部に光通過用
の孔を設けた回転２次曲面からなる第１凹面鏡と、これ
に対向し上記光通過用の孔とほぼ同じ大きさの回転２次
曲面からなる第２の凸面小鏡を含み、これらの両反射鏡
はその焦点を共有し、第２の小鏡からの出射赤外線の集
束点近傍に検知器を配置することを特徴とする赤外線カ
メラ ４）平面ミラー対物面走査方式の赤外線カメラにおいて
、入射開口部を上記平面ミラーに向けた回転２次曲面か
らなる第１凹面鏡とこれに対向する回転２次曲面からな
る第２の小鏡を含み、これらの両反射鏡はその焦点を共
有し、第２の小鏡からの出射赤外線は赤外線透過材料に
よって作られたレンズを介して集束され、該集束点近傍
に検知器を配置することを特徴とする赤外線カメラ[Scope of Claims] 1) In an infrared camera of a plane mirror object plane scanning type, a first concave mirror is formed of a rotating quadratic curved surface with an entrance aperture facing the plane mirror, and a second concave mirror is formed of a rotating quadratic curved surface opposite to the first concave mirror. An infrared camera comprising two small mirrors, both of which share a focal point, and a detector is disposed near the focal point of the infrared light emitted from the second small mirror.2) Flat mirror objective. A surface scanning type infrared camera includes a first concave mirror made of a rotational quadratic curved surface with an incident aperture facing the plane mirror, and a second concave small mirror made of a rotational quadratic curved surface opposing the first concave mirror, and both of these mirrors are provided. An infrared camera 3) characterized in that the reflecting mirrors share a focal point and are arranged on opposite sides of each other with respect to a plane passing through the shared focal point, and a detector is arranged near the focal point of the infrared rays emitted from the small mirror. In an infrared camera of a plane mirror object plane scanning type, a first concave mirror is formed of a rotating quadratic curved surface with an entrance aperture facing the plane mirror and a hole for passing light in the center, and a first concave mirror opposite to this and having a hole for passing light. It includes a second convex small mirror consisting of a rotating quadratic curved surface with approximately the same size as the hole, and both of these reflecting mirrors share their focal point, and the infrared rays emitted from the second small mirror are detected near the convergence point. 4) In an infrared camera of a plane mirror object plane scanning type, a first concave mirror consisting of a rotating quadratic curved surface with an entrance aperture facing the plane mirror, and a rotating second concave mirror opposite thereto; It includes a second small mirror with a curved surface, both of these reflecting mirrors share their focal point, and the outgoing infrared rays from the second small mirror are focused through a lens made of an infrared transparent material, and the focused An infrared camera characterized by placing a detector near a point