JP4013738B2

JP4013738B2 - Infrared search and tracking device

Info

Publication number: JP4013738B2
Application number: JP2002326627A
Authority: JP
Inventors: 博敏小川
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2002-11-11
Filing date: 2002-11-11
Publication date: 2007-11-28
Anticipated expiration: 2022-11-11
Also published as: JP2004162942A

Description

【０００１】
【発明の属する技術分野】
この発明は、波長３〜５μｍ帯付近の赤外線及び波長８〜１２μｍ帯付近の赤外線を用いて対空目標を捜索・探知するための赤外線捜索追尾装置に関するものである。
【０００２】
【従来の技術】
従来の赤外線捜索追尾装置は、入射赤外線を波長帯域にわたって、積分してしまっている。（例えば、非特許文献１参照）
【０００３】
【非特許文献１】
Ronald G. Driggers, Paul Cox,Timothy Edwards著、「Introduction to infrared and electro-optical systems」Artech House Publishers出版、1999年P.321-323
【０００４】
【発明が解決しようとする課題】
目標が放射する赤外線には、目標前面が空力加熱により放射する赤外線、排気口が放射する赤外線、排気ガスが放射する赤外線があり、それぞれスペクトル特性が異なっている。従って、この赤外線スペクトル情報を得ることができれば目標機体のアスペクト角を知ることができる。しかし、従来の赤外線捜索追尾装置は、センサの感度波長帯域で赤外線を積分していたため、スペクトル情報は失われ目標のアスペクトは判断できなくなってしまっていた。そのため、目標の脅威度（接近目標か、離遠目標か、自分にまっすぐ向いているのか、別の方向に向かっているのか）が判定できず、適切な対処を行いにくいという問題があった。
【０００５】
この発明は、かかる問題点を解決するためになされたもので、目標のスペクトル情報を抽出して、そのおおよそのアスペクト角を推定することにより、目標の自機に対する脅威度を判定する装置を得ることを目的とする。
【０００６】
【課題を解決するための手段】
この発明に係わる赤外線捜索追尾装置は、３〜４μｍ帯に感度を持つ第１のセンサと、４〜５ｍ帯に感度を持つ第２のセンサと、８〜１２μｍ帯に感度を持つ第３のセンサと、前記第１、第２、第３のセンサ出力を比較する信号強度比較回路を備えるものである。
【０００７】
【発明の実施の形態】
実施の形態１．
以下、この発明の実施の形態１を図について説明する。図１において１は目標からの赤外線を集光するための集光光学系、２は波長３〜５μｍ帯付近の赤外線と波長８〜１２μｍ帯付近の赤外線を分離する第１のダイクロックミラー、３は波長３〜５μｍ帯付近に感度のあるセンサであり、前記赤外線センサ３の前には第２のダイクロックミラー６が置かれている。前記第２のダイクロックミラーは波長３〜４μｍ帯付近と波長４〜５μｍ帯付近の光を分離する。
また、波長３〜４μｍ帯付近／波長４〜５μｍ帯付近／波長８〜１２μｍ帯付近の赤外線を電気信号に変換した場合の信号強度比較回路５が置かれており、各センサの信号出力が比較される。
【０００８】
次に動作について説明する。図２は、航空機の赤外線放射源を示したものである。航空機の赤外線放射源には８機体前面（空力加熱）、９排気口、１０排気ガスがある。図３は、１１が機体前面の赤外線放射の分光輝度特性、１２が排気口の赤外線放射分光輝度特性を示したものである。図４の１３は排気ガスの分光強度特性（相対値）を示したものである。ここから、機体の赤外線分光強度のスペクトル特性は図５のようになる。即ち、
(1)機体後方：高温の排気口内部が見える方向−波長３〜５μｍ帯の黒体放射が支配的
(2)斜め後方：排気口内部がわずかに見える方向−機体後方から見た場合に比べて波長３〜５μｍ帯の黒体放射の量が減り、排気ガスが放射する波長４〜４．５μｍ帯の選択放射が目立ち始める。
(3)斜め前方：機体の前方で排気ガスが見える範囲−排気ガスが放射する波長４〜４．５μｍ帯の選択放射と機体の空力加熱が放射する波長８〜１２μｍ帯の黒体放射の両方が観測できる。
(4)真正面：排気ガスが見えないため、機体の空力加熱による波長８〜１２μｍ帯の黒体放射が支配的になる。
波長３〜４μｍ帯付近／波長４〜５μｍ帯付近／波長８〜１２μｍ帯付近の各赤外線センサは地上で基準光源７を用いて較正しておくことにより目標の赤外線強度を推定することができる。この原理を以下に示す。基準光源は温度Ｔの黒体炉である。当該黒体炉から放射される赤外線放射強度は
【０００９】
波長３〜４μｍ帯：
【００１０】
【数１】

【００１１】
波長４〜５μｍ帯：
【００１２】
【数２】

【００１３】
波長８〜１２μｍ帯：
【００１４】
【数３】

【００１５】
で与えられることが知られている。ただし、Ｗ（λ,Ｔ）はプランクの式であり、
【００１６】
【数４】

【００１７】
で与えられる。ｃ_１は第一放射定数（3.7415×10^4W/cm^2μm）、Ｃ_２は第二放射定数（1.439×10^4μmK）、λは波長（μｍ）、Aは黒体炉の光源面積（cm^2）である。前記黒体炉を見た時の各センサ出力は
【００１８】
波長３〜４μｍ帯付近のセンサ出力：
【数５】

【００１９】
波長４〜５μｍ帯付近のセンサ出力：
【００２０】
【数６】

【００２１】
波長８〜１２μｍ帯付近のセンサ出力：
【数７】

【００２２】
となる。ただし、式（５）、（６）、（７）においてＲ[cｍ]は較正時の黒体炉とセンサとの距離（Ｒは本来、波長３〜４μｍ帯付近／波長４〜５μｍ帯付近／波長８〜１２μｍ帯付近の各赤外線センサ毎に異なるが、各センサの離隔距離に比べて大きいため、その差は無視することができるとする）、S１(λ)［V・μm/W］は波長３〜５μｍ帯のセンサ分光感度、S2（λ） [V・μm/W]は波長８〜１２μｍ帯のセンサ分光感度である。ある較正温度Ｔ_ｏの黒体炉を見た時のセンサ出力は波長３〜４μｍ帯付近/波長４〜５μｍ帯付近/波長８〜１２μｍ帯付近の各赤外線センサそれぞれでN1（T0），N2（T0），N3(T0)となる。当該値を信号処理の中で基準として記録しておき、任意の信号を受信した時にその信号出力と基準を比較することにより、受信信号源と黒体との強度比が算出できる。
即ち、
【００２３】
【数８】

【００２４】
となり、目標輝度を推定することができる。ただし、λ１、λ２は波長３〜４μｍ帯付近／波長４〜５μｍ帯付近／波長８〜１２μｍ帯を代表する表記である。式（７）を用いて、目標の観測信号を換算すると目標のアスペクトに応じて、各センサの出力信号の大きさは、図６のような関係になる。即ち
目標を真後ろ（排気口の深奥部が見える方位）から観測している時：
波長３〜４μｍ帯出力信号＞波長４〜５μｍ帯出力信号＞波長８〜１２μｍ帯出力信号
目標の斜め後方（排気口の一部及び排気ガスが見える方位）から観測している時：
波長３〜４μｍ帯出力信号≒波長４〜５μｍ帯出力信号＞波長８〜１２μｍ帯出力信号
目標の斜め前方（排気ガスと空力加熱が見える方位）から観測している時：
波長３〜４μｍ帯出力信号≒０
波長４〜５μｍ帯出力信号＞波長８〜１２μｍ帯出力信号
目標が真正面（空力加熱のみが見える方位）を向いている時：
波長３〜４μｍ帯出力信号≒０
波長４〜５μｍ帯出力信号≒０
波長８〜１２μｍ帯出力信号＞０
の関係が成り立つ。９の信号強度比較回路でこの関係を判定し、目標のアスペクト角の推定を行うことができる。
【００２５】
また、目標特有のスペクトル情報を利用しているため、波長２μｍ以下に大きな分光強度を持つ太陽反射によるクラッタを除去し易くなり、誤探知を避ける効果も得られる。
【００２６】
また、波長３〜５μｍの赤外線を波長３〜４μｍ／波長４〜５μｍに分離するのにダイクロックミラーを利用したが、図７に示すように回転円盤の中に波長３〜５μｍ帯センサ付近を透過するフィルタ、波長３〜４μｍ帯を透過するフィルタ、波長４〜５μｍ帯を透過するフィルタを取り付けた円盤１４を回転させて前記で説明した関係を求めてもよい。
【００２７】
さらに、波長３〜５μｍ帯センサ３と波長８〜１２μｍ帯センサ４の２種類を用いたが、図８に示すように簡易的に波長３〜５μｍだけを用いてもよい。ただし、この場合は自分に対して真正面を向いている目標の探知が困難になる。
【００２８】
また、光学フィルタを取り付けた回転円盤７の代わりに、図９に示すように波長３〜５μｍ帯のセンサ３を２台置きダイクロックミラーで分離した波長３〜４μｍ帯と波長４〜５μｍ帯の赤外線を入射させてもよい。
【００２９】
また、波長３〜５μｍ帯センサの代わりに図１０に示すように波長３〜５μｍ帯を分光する分光強度計１８をおいて、分光強度特性を直接計測してもよい。
【００３０】
【発明の効果】
以上のように、目標のスペクトル情報を抽出して、そのおおよそのアスペクト角を推定することにより、目標の自機に対する脅威度を判定する装置を得ることができる。
【図面の簡単な説明】
【図１】この発明の実施の形態１による赤外線捜索追尾装置の機能ブロック図である。
【図２】航空目標の主要な赤外線放射源を示す図である。
【図３】航空機目標の前面と排気口の分光赤外線強度特性である。
【図４】航空機目標の排気ガスの分光強度特性である。
【図５】航空機目標の観測アスペクト角に応じた分光スペクトル強度の関係である。
【図６】航空機目標の観測アスペクト角と波長帯域に応じた出力信号の関係である。
【図７】この発明の実施の形態１による赤外線捜索追尾装置の機能ブロック図である。
【図８】この発明の実施の形態１による赤外線捜索追尾装置の機能ブロック図である。
【図９】この発明の実施の形態１による赤外線捜索追尾装置の機能ブロック図である。
【図１０】この発明の実施の形態１による赤外線捜索追尾装置の機能ブロック図である。
【符号の説明】
１赤外線集光光学系、
２波長３〜５μｍ帯／波長８〜１２μｍ帯分離のための、第１のダイクロックミラー、
３波長３〜５μｍ帯センサ、４波長８〜１２μｍ帯センサ、
５波長３〜４μｍ帯付近／波長４〜５μｍ帯付近／波長８〜１２μｍ帯付近の赤外線を電気信号に変換した場合の信号強度比較回路、
６波長３〜４μｍ帯／波長４〜５μｍ帯分離のための、第２のダイクロックミラー、
７基準光源、
８航空機目標の空力加熱赤外線放射源、
９航空機目標の排気口赤外線放射源、
１０航空機目標の排気ガス赤外線放射源、
１１航空機目標の空力赤外線放射源の分光輝度特性、
１２航空機目標の排気口の分光輝度特性、
１３航空機目標の排気口の分光強度特性（相対値）、
１４波長３〜５μｍ帯／波長３〜４μｍ帯／波長４〜５μｍ帯透過フィル
タを組み込んだ回転円盤、
１５波長３〜４μｍ帯信号／波長４〜５μｍ帯信号／信号強度比較回路、
１６波長３〜５μｍ帯分光強度計。 [0001]
BACKGROUND OF THE INVENTION
The present invention relates to an infrared search and tracking device for searching and detecting an anti-air target using infrared rays in the vicinity of a wavelength band of 3 to 5 μm and infrared rays in the vicinity of a wavelength of 8 to 12 μm.
[0002]
[Prior art]
In the conventional infrared search and tracking device, the incident infrared ray is integrated over the wavelength band. (For example, see Non-Patent Document 1)
[0003]
[Non-Patent Document 1]
Ronald G. Driggers, Paul Cox, Timothy Edwards, `` Introduction to infrared and electro-optical systems '', Artech House Publishers, 1999, P.321-323
[0004]
[Problems to be solved by the invention]
The infrared rays emitted from the target include infrared rays emitted from the front surface of the target by aerodynamic heating, infrared rays emitted from the exhaust port, and infrared rays emitted from the exhaust gas, each having different spectral characteristics. Therefore, if this infrared spectrum information can be obtained, the aspect angle of the target aircraft can be known. However, since conventional infrared search and tracking devices integrate infrared rays in the sensitivity wavelength band of the sensor, the spectrum information is lost and the target aspect cannot be determined. For this reason, there is a problem in that it is difficult to determine the target threat level (approach target, remote target, whether you are facing straight away or whether you are facing in another direction), and it is difficult to take appropriate measures.
[0005]
The present invention has been made to solve such a problem, and obtains an apparatus for determining the degree of threat to a target device by extracting target spectrum information and estimating an approximate aspect angle thereof. For the purpose.
[0006]
[Means for Solving the Problems]
An infrared search and tracking device according to the present invention includes a first sensor having sensitivity in the 3-4 μm band, a second sensor having sensitivity in the 4-5 m band, and a third sensor having sensitivity in the 8-12 μm band. And a signal intensity comparison circuit for comparing the first, second, and third sensor outputs.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiment 1 of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a condensing optical system for condensing infrared rays from a target, 2 is a first dichroic mirror for separating infrared rays in the vicinity of a wavelength of 3 to 5 μm and infrared rays in the vicinity of a wavelength of 8 to 12 μm, 3 Is a sensor having a sensitivity in the vicinity of a wavelength band of 3 to 5 μm, and a second dichroic mirror 6 is placed in front of the infrared sensor 3. The second dichroic mirror separates light in the vicinity of the wavelength band of 3 to 4 μm and light in the vicinity of the wavelength band of 4 to 5 μm.
In addition, a signal intensity comparison circuit 5 is provided in the case where infrared light in the vicinity of the wavelength 3-4 μm band / wavelength 4-5 μm band / wavelength 8-12 μm band is converted into an electrical signal, and the signal output of each sensor is compared. Is done.
[0008]
Next, the operation will be described. FIG. 2 shows an infrared radiation source of an aircraft. Infrared radiation sources for aircraft include eight fronts (aerodynamic heating), nine exhaust ports, and 10 exhaust gases. FIG. 3 shows the spectral luminance characteristics of infrared radiation 11 on the front surface of the aircraft, and 12 shows the infrared radiation spectral luminance characteristics of the exhaust port. 4 in FIG. 4 shows the spectral intensity characteristic (relative value) of the exhaust gas. From here, the spectral characteristics of the infrared spectral intensity of the airframe are as shown in FIG. That is,
(1) Rear of the aircraft: The direction in which the inside of the hot exhaust port can be seen-Black body radiation in the wavelength range of 3-5 μm is dominant
(2) Diagonally backward: Direction in which the inside of the exhaust port is slightly visible-The amount of blackbody radiation in the wavelength band of 3 to 5 μm is reduced compared to when viewed from the rear of the aircraft, and the wavelength band of 4 to 4.5 μm emitted by the exhaust gas. The selective radiation begins to stand out.
(3) Diagonally forward: The range where the exhaust gas can be seen in front of the aircraft-both the selective emission of the wavelength 4 to 4.5 μm band emitted by the exhaust gas and the black body radiation of the wavelength 8 to 12 μm band emitted by the aerodynamic heating of the aircraft Can be observed.
(4) Directly in front: Since exhaust gas is not visible, black body radiation in the wavelength band 8-12 μm due to aerodynamic heating of the aircraft becomes dominant.
Each infrared sensor in the vicinity of the wavelength 3-4 μm band / wavelength 4-5 μm band / wavelength 8-12 μm band can be estimated by calibrating the reference light source 7 on the ground. This principle is shown below. The reference light source is a black body furnace having a temperature T. The infrared radiation intensity emitted from the blackbody furnace is
Wavelength 3-4 μm band:
[0010]
[Expression 1]

[0011]
Wavelength 4-5 μm band:
[0012]
[Expression 2]

[0013]
Wavelength 8-12 μm band:
[0014]
[Equation 3]

[0015]
It is known to be given in Where W (λ, T) is Planck's formula,
[0016]
[Expression 4]

[0017]
Given in. c ₁ is a first radiation constant (3.7415 × 10 ^ 4W / cm ^ 2μm), the C ₂ second radiation constant (1.439 × 10 ^ 4μmK), λ is the wavelength ([mu] m), A is the light source area of the blackbody furnace ( cm ^ 2). Each sensor output when looking at the blackbody furnace is:
Sensor output near wavelength 3-4μm band:
[Equation 5]

[0019]
Sensor output near wavelength 4-5μm band:
[0020]
[Formula 6]

[0021]
Sensor output near wavelength 8-12μm band:
[Expression 7]

[0022]
It becomes. However, in the equations (5), (6), and (7), R [cm] is the distance between the black body furnace and the sensor at the time of calibration (R is originally near the wavelength 3-4 μm band / wavelength 4-5 μm band / S1 (λ) [V · μm / W] is different for each infrared sensor in the vicinity of the wavelength band of 8-12 μm, but the difference is negligible because it is larger than the separation distance of each sensor) Sensor spectral sensitivity in the wavelength band of 3 to 5 μm, S2 (λ) [V · μm / W] is the sensor spectral sensitivity in the wavelength band of 8 to 12 μm. There the calibration temperature T sensor output when viewed blackbody furnace _o in each of the infrared sensors in the vicinity of a wavelength 3~4μm band around / wavelength 4~5μm band around / wavelength 8~12μm band N1 (T0), N2 ( T0) and N3 (T0). The value is recorded as a reference in signal processing, and the intensity ratio between the received signal source and the black body can be calculated by comparing the signal output with the reference when an arbitrary signal is received.
That is,
[0023]
[Equation 8]

[0024]
Thus, the target luminance can be estimated. However, λ1 and λ2 are notations representative of the vicinity of wavelength 3-4 μm band / wavelength 4-5 μm band / wavelength 8-12 μm band. When the target observation signal is converted using Equation (7), the magnitude of the output signal of each sensor has a relationship as shown in FIG. 6 according to the target aspect. That is, when observing the target from directly behind (the direction in which the deep part of the exhaust port can be seen):
Wavelength 3 to 4 μm band output signal> Wavelength 4 to 5 μm band output signal> Wavelength 8 to 12 μm band output signal When observing obliquely behind the target (direction in which part of the exhaust port and exhaust gas can be seen):
Wavelength 3-4 μm band output signal ≈ Wavelength 4-5 μm band output signal> Wavelength 8-12 μm band output signal When observing from diagonally forward (direction where exhaust gas and aerodynamic heating can be seen):
Wavelength 3-4μm band output signal ≒ 0
Wavelength 4-5 μm band output signal> Wavelength 8-12 μm band output signal When the target is facing directly in front (direction where only aerodynamic heating can be seen):
Wavelength 3-4μm band output signal ≒ 0
Wavelength 4-5 μm band output signal ≒ 0
Wavelength 8-12μm band output signal> 0
The relationship holds. This signal strength comparison circuit 9 can determine this relationship and estimate the target aspect angle.
[0025]
In addition, since target-specific spectral information is used, it becomes easy to remove clutter due to solar reflection having a large spectral intensity at a wavelength of 2 μm or less, and an effect of avoiding false detection can be obtained.
[0026]
A dichroic mirror was used to separate infrared light having a wavelength of 3 to 5 μm into a wavelength of 3 to 4 μm and a wavelength of 4 to 5 μm. However, as shown in FIG. The relationship described above may be obtained by rotating a disk 14 to which a filter that transmits light, a filter that transmits a wavelength band of 3 to 4 μm, and a filter that transmits a wavelength band of 4 to 5 μm are rotated.
[0027]
Furthermore, although two types of the wavelength 3-5 μm band sensor 3 and the wavelength 8-12 μm band sensor 4 are used, only the wavelength 3-5 μm may be used simply as shown in FIG. However, in this case, it becomes difficult to detect a target that is facing the person in front.
[0028]
Further, instead of the rotating disk 7 to which the optical filter is attached, as shown in FIG. 9, the wavelength 3-4 μm band and the wavelength 4-5 μm band are obtained by placing two sensors 3-3 μm wavelength bands separated by a dichroic mirror. Infrared rays may be incident.
[0029]
Further, instead of using the wavelength 3-5 μm band sensor, a spectral intensity meter 18 that splits the wavelength 3-5 μm band as shown in FIG. 10 may be used to directly measure the spectral intensity characteristics.
[0030]
【The invention's effect】
As described above, by extracting the target spectrum information and estimating the approximate aspect angle, it is possible to obtain an apparatus for determining the degree of threat to the target device.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of an infrared search and tracking apparatus according to Embodiment 1 of the present invention.
FIG. 2 is a diagram showing the main infrared radiation source of an air target .
FIG. 3 is a spectral infrared intensity characteristic of the front and exhaust of an aircraft target.
FIG. 4 is a spectral intensity characteristic of an aircraft target exhaust gas.
FIG. 5 is a relationship of spectral spectrum intensity according to an observation aspect angle of an aircraft target.
FIG. 6 is a relationship between an observation aspect angle of an aircraft target and an output signal corresponding to a wavelength band.
FIG. 7 is a functional block diagram of an infrared search and tracking device according to Embodiment 1 of the present invention.
FIG. 8 is a functional block diagram of an infrared search and tracking device according to Embodiment 1 of the present invention.
FIG. 9 is a functional block diagram of the infrared search and tracking device according to the first embodiment of the present invention.
FIG. 10 is a functional block diagram of an infrared search and tracking device according to Embodiment 1 of the present invention.
[Explanation of symbols]
1 Infrared condensing optical system ,
2 A first dichroic mirror for wavelength 3-5 μm band / wavelength 8-12 μm band separation ,
3 wavelength 3-5 μm band sensor , 4 wavelength 8-12 μm band sensor ,
The signal strength comparing circuit when 5 the infrared wavelength around 3~4μm band around / wavelength 4~5μm band around / wavelength 8~12μm band was converted into an electric signal,
6 Second dichroic mirror for wavelength 3-4 μm band / wavelength 4-5 μm band separation ,
7 reference light sources,
8 Aerodynamically heated infrared radiation source for aircraft targets ,
9 Aircraft target exhaust infrared radiation source ,
10 Aircraft target exhaust gas infrared radiation source ,
11 Spectral luminance characteristics of aerodynamic infrared radiation source for aircraft targets ,
12 Spectral luminance characteristics of the aircraft target exhaust port ,
13 aircraft target spectral intensity characteristic of the exhaust port of the (relative value),
14 Wavelength 3-5μm band / wavelength 3-4μm band / wavelength 4-5μm band transmission film
Rotating disk with built- in
15 wavelength 3-4 μm band signal / wavelength 4-5 μm band signal / signal strength comparison circuit ,
16 Wavelength 3-5 μm band spectral intensity meter .

Claims

A first sensor that receives infrared light in a 3 to 4 μm band emitted from an exhaust port of the airframe ;
A second sensor that receives infrared light in a 4 to 5 m band emitted from exhaust gas discharged from the exhaust port ;
A third sensor that receives infrared light in an 8 to 12 μm band emitted from the front of the body of the body ;
A signal strength comparison circuit for comparing sensor outputs of the first, second, and third sensors,
The infrared search and tracking device, wherein the signal intensity comparison circuit acquires an aspect angle of the aircraft based on the comparison result .

The signal strength comparison circuit includes:
The first sensor output> the second sensor output> the third sensor output;
It is determined that the aircraft is being observed from directly behind when
The first sensor output≈the second sensor output> the third sensor output,
It is determined that the aircraft is observed obliquely from the rear when
The first sensor output≈0 and the second sensor output> the third sensor output,
It is determined that the aircraft is observed obliquely from the front when
The first sensor output≈0, the second sensor output≈0, and the third sensor output> 0,
The infrared search and tracking device according to claim 1, wherein the aspect angle of the airframe is acquired by determining that the airframe is being observed from the front when the relationship is satisfied.

A condensing optical system for condensing infrared rays;
A first dichroic mirror that separates infrared light collected by the condensing optical system into a 3 to 5 μm band and an 8 to 12 μm band;
A second die lock mirror that separates the 3-5 μm band infrared light separated by the first die lock mirror into a 3-4 μm band and a 4-5 μm band,
The first sensor receives infrared light of 3 to 4 μm band separated by the second dylock mirror,
The second sensor receives infrared light in a 4 to 5 μm band separated by the second dylock mirror,
2. The infrared search and tracking device according to claim 1, wherein the third sensor receives infrared light in an 8 to 12 μm band separated by the first dichroic mirror. 3.

A condensing optical system for condensing infrared rays;
A first dichroic mirror that separates infrared light collected by the condensing optical system into a 3 to 5 μm band and an 8 to 12 μm band;
Provided with a filter that selectively transmits the 3 to 4 μm band and the 4 to 5 μm band, the infrared rays in the 3 to 5 μm band separated by the first dichroic mirror into the 3 to 4 μm band and the 4 to 5 μm band A rotating disk to be separated,
The first sensor receives infrared light of 3 to 4 μm band separated by the rotating disk,
The second sensor receives infrared light in a 4 to 5 μm band separated by the rotating disk,
2. The infrared search and tracking device according to claim 1, wherein the third sensor receives infrared light in an 8 to 12 μm band separated by the first dichroic mirror. 3.