JP2006234587A - Electromagnetic wave imaging system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electromagnetic wave imaging system capable of acquiring an image or a picture of an object domain without damaging a fine appearance or an external appearance, and without interference of precaution caused by an invader or the like. <P>SOLUTION: This electromagnetic wave imaging system has an electromagnetic wave generation source 1, an irradiation device 2 for irradiating the object domain with an electromagnetic wave 5, an imaging means 3 for imaging the electromagnetic wave 5, and a detection means 4 for detecting an imaged electromagnetic wave 5 image. The electromagnetic wave generation source 1, the irradiation device 2, the imaging means 3 and the detection means 4 are installed inside a structure or an obstacle, or on an spot invisible from the object domain by being interrupted by the structure or the obstacle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an electromagnetic wave imaging system that irradiates an electromagnetic wave in a detection area, for example, and obtains an image or video of an object in the detection area from a transmitted wave or a reflected wave, and particularly, a frequency of about 30 GHz to 30 THz. The so-called millimeter wave to terahertz wave is used for a system for obtaining an image or video in a target area using an electromagnetic wave in a frequency domain called a terahertz wave.

Conventionally, various types of sensors such as an infrared sensor, an ultrasonic sensor, a radio wave sensor and the like have been proposed as a security sensor for detecting a human body for the purpose of crime prevention, and some of them have been put into practical use. In addition, surveillance cameras that obtain images and videos using visible light or infrared light are used.

There are various types of radio wave sensors. For example, a system is disclosed that detects a human body that has entered a detection area by radiating millimeter waves in the detection area, installing a reflective object in the detection area, and detecting a reflected wave from the reflective object. (See Patent Document 1). Use existing structures as reflective objects, embed reflective objects in walls and ground, and embed millimeter-wave radiation sources in walls and ground without damaging aesthetics and appearance. Can do.

In recent years, a technique using so-called terahertz waves has attracted attention. Spectral analysis and imaging using terahertz waves are expected to be industrially applicable. For example, in the application field of terahertz waves, a technique for imaging as a safe fluoroscopic inspection apparatus replacing X-rays has been proposed.

Terahertz waves are transmissive and have a resolution of about 1 mm when used for imaging. Various methods have been proposed (see Patent Document 2).
JP 2002-228744 JP Japanese Patent Laid-Open No. 2001-50908

However, Patent Document 1 can detect the size and position of an object that has entered the detection area, but cannot obtain an image or video of the intruding object.

In addition, with a surveillance camera using visible light or infrared light, an image or video of an object that has entered the detection area can be obtained, but the appearance and appearance are impaired. Means to disguise surveillance cameras as streetlights have also been proposed and put into practical use, but if they are trained intruders, they can see the disguise and interfere with monitoring.

In view of the above problems, the electromagnetic wave imaging system of the present invention forms an electromagnetic wave by imaging an electromagnetic wave generation source such as a terahertz wave radiation source, an irradiation means such as a terahertz wave illumination optical system for irradiating the electromagnetic wave to a target region, and the like. Imaging means such as a terahertz wave imaging optical system, and detection means such as a terahertz wave imaging element for detecting the image of the formed electromagnetic wave, the electromagnetic wave generation source, the irradiation means, the imaging means, and the detection The means is characterized in that it is installed inside the structure or obstacle, or at a place that is blocked by the structure or obstacle and cannot be seen from the target area.

For example, these means are embedded in a wall, ceiling, or floor, or in the ground, or in furniture, or in a pole, installed in a place that cannot be seen from the target area, or on a wall, ceiling, floor, or ground. It may be installed in a place where it cannot be seen from the target area. In this way, it is possible to embed in the wall and ceiling of the detection area, the interior of the furniture, or install it in the adjacent room of the detection area, without damaging the beauty and appearance, and preventing the intruder from obstructing the monitoring. Images and videos in the area can be obtained.

According to the present invention described above, there is an effect that it is possible to obtain an image and a video of the target area without being detrimental to the beauty and appearance, and without being disturbed by an intruder or the like, and can perform a warning of the detection area. is there.

Hereinafter, examples for clarifying embodiments of an electromagnetic wave imaging system according to the present invention will be described with reference to the drawings.

In the electromagnetic wave imaging system of the embodiment, as shown in FIG. 1, the terahertz wave radiation source 1 and the terahertz wave illumination optical system 2 are embedded in a part of the wall surface 7 of the detection area, and the terahertz wave imaging optical system 3 and The terahertz imaging device 4 is embedded. The terahertz wave 5 radiated from the terahertz wave radiation source 1 is changed to a terahertz wave having a sufficiently large cross-sectional area so that an image capable of identifying the target region can be obtained by the terahertz wave illumination optical system 2. And the light is condensed on the terahertz wave imaging device 4 by the terahertz wave imaging optical system 3. The terahertz wave 5 has a property of transmitting through a wall or the like and has a resolution of about 1 mm, so that an image / video of the object 6 that has entered the detection area can be obtained. As a method of obtaining an image / video, there is a method of picking up a reflected wave as shown in FIG. 2 in addition to a method using a transmitted wave as shown in FIG. 1. Either method may be used.

When the transmitted wave is used, an image of the object 6 that has entered the detection area is obtained as a shadow picture by the terahertz wave imaging device 4. When the reflected wave is used, an image of the object 6 that has entered the detection area is obtained like an ordinary camera using scattered light from the object 6.

For the terahertz radiation source 1, for example, a known means for applying a voltage to a dipole antenna (so-called photoconductive antenna) formed on low-temperature grown gallium arsenide and irradiating a femtosecond laser is used. Further, a means for irradiating a non-linear crystal such as indium phosphorus or zinc telluride with a femtosecond laser may be used, or a method using parametric oscillation may be used.

For the terahertz wave illumination optical system 2 and the terahertz wave imaging optical system 3, for example, a combination of one or more paraboloidal mirrors and spherical mirrors is used. Alternatively, a lens using a dielectric (for example, high-resistance silicon or white polyethylene) that has low absorption and dispersion with respect to terahertz waves may be used.

For the terahertz wave imaging element 4, a known method using zinc telluride or a method in which photoconductive antennas are arrayed is used. However, terahertz detection means other than this method may be two-dimensionally used. good.

For the wall surfaces 7 and 7 ′, it is preferable to use a dielectric that has low absorption and dispersion with respect to terahertz waves. Further, the terahertz wave radiation source 1, the terahertz wave illumination optical system 2, the terahertz wave imaging optical system 3, and the terahertz wave imaging element 4 may be installed in an adjacent room or the like without being embedded in a wall.

In addition, as shown in FIG. 3, a wide detection area can be set by installing a plurality of terahertz radiation sources 1 and illumination optical systems 2. When a plurality of images are used, a wide range of images can be easily obtained. In this case, the entire image may be formed by connecting the image portions with the terahertz wave imaging device 4 on the detection side.

Further, the terahertz wave radiation source 1, the terahertz wave illumination optical system 2, the terahertz wave imaging optical system 3, and the terahertz wave imaging element 4 are installed in a place other than a wall (for example, in a ceiling or a cage). Also good.

It is a figure which shows the Example of the transmission-type terahertz imaging system embedded in the wall. It is a figure which shows the Example of the reflection type terahertz imaging system embedded in the wall. It is a figure which shows the Example of the multiple type | mold terahertz imaging system embedded in the wall.

Explanation of symbols

1 Terahertz radiation source (electromagnetic wave source)
2 Terahertz illumination optics (irradiation means)
3 Terahertz imaging optical system (imaging means)
4 Terahertz imaging device (detection means)
5 Terahertz wave (electromagnetic wave)
6 Intruder (object in the target area)
7,7 'wall

Claims (3)

An electromagnetic wave generation source, an irradiation means for irradiating the target area with the electromagnetic wave, an imaging means for imaging the electromagnetic wave, and a detection means for detecting an image of the formed electromagnetic wave, An electromagnetic wave imaging system in which a source, an irradiating unit, an imaging unit, and a detecting unit are installed inside a structure or an obstacle, or at a place that is blocked by the structure or an obstacle and cannot be seen from a target area. 2. The part according to claim 1, wherein the electromagnetic wave generation source, the irradiation unit, the imaging unit, and the detection unit are embedded in a wall, a ceiling, a floor, a ground, a furnishing product, or a utility pole, and are not visible from a target region. An electromagnetic imaging system characterized by being installed in 2. The part according to claim 1, wherein the electromagnetic wave generation source, the irradiation unit, the imaging unit, and the detection unit are obstructed by a wall, a ceiling, a floor, a ground, a furnishing product, or a utility pole, and are not visible from a target area. An electromagnetic imaging system characterized by being installed in

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