JP2008164242A - Infrared ray detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an infrared ray detector improving detection accuracy of a target by facilitating discrimination of infrared radiation from a target rocket plume and infrared radiation from the background. <P>SOLUTION: The infrared ray detector is provided with a detection signal generating circuit 10 having a narrowband infrared ray transmitting filter 11b having a transmitting characteristic conforming to a typical infrared radiation characteristic radiated by the target rocket plume, and a broadband infrared ray transmitting filter 11a transmitting infrared radiation of high temperature gas of the rocket plume, and separately generating a narrowband passing electric signal after passing through the narrowband infrared ray transmitting filter 11b, and a broadband passing electric signal after passing through the broadband infrared ray transmitting filter 11a on the basis of infrared rays radiated from the target rocket plume. It is also provided with a target extraction calculation circuit 20 generating a target extraction image from a subtraction signal or an integration signal between the narrowband passing electric signal and the broadband passing electric signal separately generated by the detection signal generating circuit 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an infrared detection device that detects a target by discriminating infrared rays emitted from a target rocket plume from infrared radiation or reflected light from ground features or clouds as a background.

  By analyzing the infrared spectral intensity emitted by the target rocket plume, an infrared search and tracking device that examines how much spectral characteristics of the target aerodynamic heating, exhaust port and exhaust gas are included, and determines its aspect angle Yes (see, for example, Patent Document 1).

JP 2004-162942 A

However, the prior art has the following problems.
In the conventional detection method based on the integral intensity in the target wide wavelength band, the infrared radiation emitted from the target rocket plume is the integral intensity of the infrared radiation or reflected light from the ground features and clouds in the background. Or the difference in the shape of the infrared image is small. Therefore, it is difficult to discriminate infrared radiation from the ground or background immediately after launch from the infrared radiation emitted from the target rocket plume to be detected.

  The present invention has been made in order to solve the above-described problems, and an infrared detection apparatus that facilitates discrimination between infrared radiation from a target rocket plume and infrared radiation from a background to improve target detection accuracy. The purpose is to obtain.

  An infrared detector according to the present invention includes a narrowband infrared transmission filter having a transmission characteristic that matches a characteristic spectral infrared emission characteristic emitted by a target rocket plume, and a broadband infrared that transmits infrared radiation of a high temperature gas from the rocket plume. A narrow-band electrical signal after passing through the narrow-band infrared transmission filter and a broadband-pass electrical signal after passing through the broadband infrared transmission filter based on infrared radiation emitted from the target rocket plume. A detection signal generation circuit for generating and generating a target extraction image from a difference signal or product signal of a narrow band pass electric signal and a wide band pass electric signal separated and generated by the detection signal generation circuit. It is provided.

  According to the present invention, the characteristic spectral infrared radiation characteristics emitted by the target rocket plume are extracted using a narrow-band infrared transmission filter, so that the infrared radiation from the target rocket plume and the infrared radiation from the background are extracted. It is possible to obtain an infrared detection device that facilitates discrimination from the above and improves target detection accuracy.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of an infrared detection apparatus according to Embodiment 1 of the present invention. This infrared detection apparatus includes a detection signal generation circuit 10 and a target extraction calculation circuit 20. Further, the detection signal generation circuit 10 includes a filter plate 11 equipped with a broadband infrared transmission filter 11a and a narrowband infrared transmission filter 11b, an optical system 12, an infrared detector 13, and a signal separation circuit 14. .

Next, a specific operation of the infrared detecting apparatus having such a configuration will be described.
FIG. 2 is a diagram illustrating a captured image 31 captured by the infrared detection device according to Embodiment 1 of the present invention. The captured image 31 shown in FIG. 2 includes a target rocket. Further, FIG. 2 shows a state in which the rocket plume 32 is burning.

  FIG. 3 is a diagram showing the spectral radiation characteristic 33 corresponding to the captured image 31 of FIG. 2 in the first embodiment of the present invention. The spectral radiation characteristic 33 includes an infrared spectral radiation characteristic 33a radiated from the background reflecting sunlight above the sky and an infrared spectral radiation characteristic 33b radiated from the target rocket plume 32. .

  FIG. 4 individually shows the two spectral radiation characteristics 33a and 33b in the first embodiment of the present invention. The infrared spectral radiation characteristic 33b radiated from the target rocket plume 32 includes radiation of high-temperature carbon dioxide or nitrogen oxide in a wavelength band of 4.0 to 4.5 μm.

  Accordingly, if the infrared spectral radiation characteristic 33b radiated from the target rocket plume 32 is extracted from the spectral radiation characteristic 33 and a captured image is generated by using the subsequent electrical signal, the target rocket plume 32 is obtained. A desired image that has been discriminated can be obtained. In the present invention, in order to obtain such a desired image, a filter having two types of spectral transmission characteristics is utilized, and details thereof will be described below.

  FIG. 5 is a diagram showing the spectral transmission characteristics of the broadband infrared transmission filter 11a and the narrowband infrared transmission filter 11b according to Embodiment 1 of the present invention. FIG. 5A shows the spectral transmission characteristics of the broadband infrared transmission filter 11a, which transmits infrared rays having a wavelength range of 3 to 5 μm.

  As such a broadband infrared transmission filter 11a, for example, by applying dielectric thin film processing to a substrate material having transmission characteristics in a wavelength range longer than 1 to 2 μm and shorter than 6 to 7 μm, such as Si or Ge. A filter with improved transmittance in a wavelength region of ˜5 μm can be applied.

  On the other hand, FIG.5 (b) has shown the spectral transmission characteristic of the narrowband infrared transmission filter 11b, and selectively permeate | transmits the infrared rays of a wavelength range of 4-4.5 micrometers. As such a narrow band infrared transmission filter 11b, for example, a high refractive index dielectric material on the surface of a substrate material having transmission characteristics in a wavelength range longer than 1 to 2 μm and shorter than 6 to 7 μm, such as Si or Ge. By alternately forming a thin film and a low-refractive-index dielectric material thin film in multiple layers, it is possible to apply a filter that transmits light with a high transmittance only in the wavelength region of 4 to 4.5 μm.

  FIG. 6 is a diagram showing the infrared spectral characteristics that have passed through each of the broadband infrared transmission filter 11a and the narrowband infrared transmission filter 11b in the first embodiment of the present invention. FIG. 6A shows the infrared spectral characteristics from the target and background that have passed through the broadband infrared transmission filter 11a.

  The broadband infrared transmission filter 11a having improved transmittance in the wavelength region of 3 to 5 μm can transmit infrared radiation of the hot gas of the rocket plume 32, and can obtain infrared spectral characteristics from the target and the background. However, the infrared radiation from the target is buried in the radiation from the background, making it difficult to distinguish it from the infrared radiation from the target.

  On the other hand, FIG. 6B shows infrared spectral characteristics from the target and the background that have passed through the narrow-band infrared transmission filter 11b. The narrow-band infrared transmission filter 11b that transmits only in the wavelength range of 4 to 4.5 μm with high transmittance has a transmission characteristic that matches the characteristic spectral emission characteristic emitted by the target rocket plume.

  Specifically, as shown in FIG. 4B, the narrow-band infrared transmission filter 11b has a wavelength band of 4.0 to 4.5 μm, which is a characteristic of infrared radiation from the target rocket plume. Only high temperature carbon dioxide or nitrogen oxide radiation is allowed to pass through. As a result, infrared radiation from the background is suppressed and discrimination of the target rocket plume from the background is facilitated.

  As shown in FIG. 1, the broadband infrared transmission filter 11a and the narrowband infrared transmission filter 11b are mounted on the filter plate 11. Then, by rotating the filter plate 11 at a constant speed in the infrared detection device, the optical system 12 alternately transmits the infrared rays transmitted through the broadband infrared transmission filter 11a and the narrowband infrared transmission filter 11b onto the infrared detector 13. It can be combined with light. The infrared detector 13 photoelectrically converts the input infrared signal and outputs it.

  Further, the signal separation circuit 14 outputs the output signal from the infrared detector 13 based on the rotation synchronization signal of the filter plate 11, the broadband passing infrared signal passing through the broadband infrared transmission filter 11 a, and the narrowband infrared transmission filter 11 b. It is a signal separation circuit that separates a narrow-band passing infrared signal to pass.

  Through such a series of operations, the detection signal generation circuit 10 finally has the wideband passing electric signal after passing through the wideband infrared transmitting filter 11a and the narrowband passing electric signal after passing through the narrowband infrared transmitting filter 11b. Signals can be generated separately.

  Next, the target extraction calculation circuit 20 generates a target extraction image from the difference signal or product signal between the narrow band pass electric signal and the wide band pass electric signal separated and generated by the detection signal generation circuit 10. FIG. 7 is a diagram showing an image processed by the target extraction calculation circuit 20 according to the first embodiment of the present invention.

  More specifically, FIG. 7A is a captured image by a broadband passing electric signal after passing through the broadband infrared transmission filter 11a. FIG. 7B is a captured image by a narrow-band passing electric signal after passing through the narrow-band infrared transmission filter 11b. Further, FIG. 7C is generated by a difference signal or product signal between the wide-band electrical signal corresponding to the image of FIG. 7A and the narrow-band electrical signal corresponding to the image of FIG. This is a target extraction image.

  In this way, the target extraction image generated by the target extraction arithmetic circuit 20 can discriminate and display the rocket plume that is buried in the background data and difficult to discriminate in FIG. It is possible to detect early when the rocket plume is burning.

  Further, after the target rocket plume is combusted, the infrared radiation characteristic due to the hot gas disappears, and as shown in FIG. 7D, the target image disappears from the captured image by the narrow-band passing electric signal, The rocket plume cannot be detected. However, at this stage, the target has reached a high altitude and the background is a low-temperature sky, so that the signal that has passed through the broadband infrared transmission filter 11a has a signal strength that stands out from the low-temperature background. Therefore, the target rocket can be discriminated and maintained from the target extraction image as shown in FIG.

  As described above, according to the first embodiment, by using the narrow-band infrared transmission filter that can extract the characteristic spectral infrared radiation characteristic emitted by the target rocket plume, during the combustion of the target rocket plume. Therefore, it is possible to obtain an infrared detecting device that can distinguish the infrared radiation from the background and detect the target at an early stage.

Embodiment 2. FIG.
In the second embodiment, an infrared detection device in which the configuration of the detection signal generation circuit 10 is different from that of the first embodiment will be described. FIG. 8 is a configuration diagram of the infrared detection apparatus according to Embodiment 2 of the present invention. This infrared detection apparatus includes a detection signal generation circuit 10 and a target extraction calculation circuit 20.

  Further, the detection signal generation circuit 10 includes an optical system 12, an optical path separator 15, a broadband infrared transmission filter 11a, a narrowband infrared transmission filter 11b, a broadband infrared detector 13a, and a narrowband infrared detector 13b. It consists of.

  In the first embodiment, the wide band electric signal and the narrow band electric signal are separated and generated by the function of the signal separation circuit 14 synchronized with the constant speed rotation of the filter plate 11. On the other hand, in the second embodiment, the optical path separator 15 is used to separate and generate the wide band electric signal and the narrow band electric signal.

  The optical system 12 according to the second embodiment collects and images infrared light emitted from the target on the optical path separator 15. Then, the optical path separator 15 divides the infrared light focused by the optical system 12 into two optical paths (that is, an optical path for wideband processing and an optical path for narrowband processing).

  A broadband infrared transmission filter 11a and a broadband infrared detector 13a are provided in the optical path for broadband processing. As described in the first embodiment, the broadband infrared transmission filter 11a with improved transmittance in the wavelength region of 3 to 5 μm can transmit the infrared radiation of the high-temperature gas of the rocket plume 32. Infrared spectral characteristics from the background can be obtained.

  Further, the broadband infrared detector 13a detects infrared radiation that has passed through the broadband infrared transmission filter 11a and photoelectrically converts it to generate a broadband passing electric signal.

  On the other hand, a narrowband infrared transmission filter 11b and a narrowband infrared detector 13b are provided in the optical path for narrowband processing. As described in the first embodiment, the narrow-band infrared transmission filter 11b that transmits only in the wavelength range of 4 to 4.5 μm with high transmittance matches the characteristic spectral radiation characteristic emitted by the target rocket plume. Transmission characteristics.

  Specifically, as shown in FIG. 4B, the narrow-band infrared transmission filter 11b has a wavelength band of 4.0 to 4.5 μm, which is a characteristic of infrared radiation from the target rocket plume. Only high temperature carbon dioxide or nitrogen oxide radiation is allowed to pass through. As a result, infrared radiation from the background is suppressed and discrimination of the target rocket plume from the background is facilitated.

  Further, the narrowband infrared detector 13b detects the infrared radiation that has passed through the narrowband infrared transmission filter 11b and performs photoelectric conversion to generate a narrowband electrical signal.

  Through such a series of operations, the detection signal generation circuit 10 finally has the wideband passing electric signal after passing through the wideband infrared transmitting filter 11a and the narrowband passing electric signal after passing through the narrowband infrared transmitting filter 11b. Signals can be generated separately.

  The operation of the target extraction calculation circuit 20 that is a subsequent stage of the detection signal generation circuit 10 is the same as that of the first embodiment.

  As described above, according to the second embodiment, it is possible to extract a characteristic spectral infrared radiation characteristic emitted by the target rocket plume even by a detection signal generation circuit having a configuration different from that of the first embodiment. By using the infrared transmission filter, it is possible to obtain an infrared detection device that enables discrimination from infrared radiation from the background while the target rocket plume is burning, and can detect the target early.

It is a block diagram of the infrared rays detection apparatus in Embodiment 1 of this invention. It is the figure which showed the captured image taken in by the infrared rays detection apparatus in Embodiment 1 of this invention. It is the figure which showed the spectral radiation characteristic corresponding to the captured image of FIG. 2 in Embodiment 1 of this invention. The two spectral radiation characteristics in Embodiment 1 of this invention are shown separately. It is the figure which showed the spectral transmission characteristic of the wideband infrared transmission filter and the narrowband infrared transmission filter in Embodiment 1 of this invention. It is the figure which showed the infrared spectral characteristic which each passed each of the broadband infrared transmission filter and narrowband infrared transmission filter in Embodiment 1 of this invention. It is the figure which showed the image processed by the target extraction calculating circuit in Embodiment 1 of this invention. It is a block diagram of the infrared rays detection apparatus in Embodiment 2 of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Detection signal generation circuit, 11 Filter board, 11a Broadband infrared transmission filter, 11b Narrowband infrared transmission filter, 12 Optical system, 13 Infrared detector, 13a Broadband infrared detector, 13b Narrowband infrared detector, 14 Signal separation Circuit, 15 optical path separator, 20 target extraction calculation circuit, 31 captured image, 32 rocket plume.

Claims (3)

A narrowband infrared transmission filter having transmission characteristics that match the characteristic spectral infrared emission characteristics emitted by the target rocket plume, and a broadband infrared transmission filter that transmits infrared radiation of the hot gas of the rocket plume, Based on the infrared rays radiated from the target rocket plume, a narrow-band electrical signal after passing through the narrow-band infrared transmission filter and a wide-band electrical signal after passing through the broadband infrared transmission filter are separately generated. A detection signal generation circuit;
A target extraction operation circuit that generates a target extraction image from a difference signal or product signal between the narrowband electrical signal and the broadband electrical signal separated and generated by the detection signal generation circuit; Detection device. The infrared detection device according to claim 1,
The detection signal generation circuit includes:
A filter plate on which the narrowband infrared transmission filter and the broadband infrared transmission filter are mounted;
An optical system for focusing and imaging infrared radiation from the target obtained via the filter plate;
An infrared detector that detects infrared radiation that has passed through the optical system and outputs an electrical signal after photoelectric conversion;
Narrow-band passing electrical signal photoelectrically converted by the infrared detector through the narrow-band infrared transmission filter and the optical system, and photoelectric conversion by the infrared detector through the broadband infrared transmission filter and the optical system An infrared detection apparatus comprising: a signal separation circuit that separates and generates a wide-band passing electric signal. The infrared detection device according to claim 1,
The detection signal generation circuit includes:
An optical system for focusing and imaging infrared rays emitted from the target rocket plume;
An optical path separator that divides the infrared light focused by the optical system into two optical paths;
From one of the optical paths divided by the optical path separator, an infrared detector for narrowband that generates the narrowband pass electrical signal by detecting and photoelectrically converting infrared radiation that has passed through the narrowband infrared transmission filter, and
A broadband infrared detector that detects the infrared radiation that has passed through the broadband infrared transmission filter from the other optical path divided by the optical path separator and photoelectrically converts the infrared radiation to generate the broadband passing electrical signal. Infrared detector characterized by.

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