JPS5939856B2 - infrared night vision device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an infrared night vision device that detects infrared rays from a target object while scanning it, displays the detection output as an image, and monitors the target object at night, for example.

Figure 1 shows a conventional optical scanning type infrared night vision device, published by the University of Tokyo in 1973, published by Ka2uhiko Atsu.
``MEDICAL THERMOGRAPHY'' written by nll
”, page 116, the infrared rays emitted from the target object 1 are focused by a condensing system consisting of a primary mirror 2 and a secondary mirror 3, reflected by a reflecting mirror 4, and sent to an infrared detector 5. is incident on the detection surface.

The incident infrared rays are converted into electrical signals by the infrared detector 5, amplified by the video amplifier 6, and the display cathode ray tube 9 is brightly modulated by the amplified output. On the other hand, the secondary mirror 3 also serves as a scanning mirror, and is rotated at high speed by the scanning mechanism section T.
For example, the target object 1 is vibrated in the elevation direction at a rate of about once every 100 rotations, and while the target object 1 is facing the rotating target object 1 side.
horizontally scanned, and vertically scanned by vibration in the elevation direction. That is, as shown in FIG. 2A, the picture elements 10 are sequentially scanned in the direction of the arrows, and the surface scanning of the entire visual field 11 is completed. Therefore, a deflection signal synchronized with the rotation and vibration of the scanning mechanism section T is generated by a deflection signal generator 8, and these signals are applied to the XY-axis deflection coils of the display cathode ray tube 9. Therefore, an object image 12 is displayed on the display cathode ray tube 9 in accordance with the amount of infrared radiation. In this way, the difference in the amount of infrared radiation of a target object can be detected and captured as an image to monitor the object. The amount of infrared radiation W of an object is determined by the emissivity ε and absolute temperature T of the object, and is expressed as w=εKT'' (where is the Stefan Boltzmann constant).

When the target object is not a heating element, the object is influenced by the ambient temperature and maintains a constant temperature that is approximately the same as the ambient temperature. When such an object is imaged with an infrared night vision device, the temperature of the object is almost constant, so the emissivity ε of the object surface is
The difference in the amount of radiated infrared rays due to the difference in is projected. As shown in FIG. 2B, within the field of view 13, the difference in emissivity ε, ε2, ε3 of each part is displayed. When the temperature surrounding the object becomes low and the amount of infrared radiation from the object decreases, or when the difference in emissivity of the object is small, the difference in the amount of infrared radiation is buried in the noise of the detection device and difficult to image. becomes. The purpose of the present invention is to extend the limitations of such conventional devices to an even lower level. In other words, it is an infrared night vision system that emphasizes the emissivity difference and enables imaging of low-temperature objects with small emissivity differences. The goal is to provide equipment.

According to this invention, in the optical scanning type infrared night vision device,
In synchronization with the scanning, in a state slightly advanced from this, for example, while projecting infrared rays onto the detection surface of the target object at a pixel position that has advanced by at least one pixel in the scanning direction, the projection point is set on the detection surface. to scan in two dimensions.

Therefore, the reception scanning of the infrared rays emitted from the object is performed after the projection of the infrared rays, and the amount of the infrared rays radiated increases in accordance with the projected infrared rays. For example, as shown in FIG. 3, when the object 16 has a high emissivity part 17 and a low emissivity part 18, the picture elements 14 arranged on the detection surface are sequentially scanned in the direction of the arrow to create an image. However, an infrared ray with a wavelength of around 10μ, at which an object near room temperature emits maximum radiation, is projected onto a portion 15 corresponding to the next step of the picture element 14, that is, a portion 15 that is advanced by one pixel in the scanning direction. The projection point is scanned in synchronization with the scanning of picture elements on the detection surface of the target object. In other words, the light receiving condensing system scans and images the detection surface of the target object immediately after the infrared projection is performed. In a general opaque object, the emissivity is almost equal to the absorption rate, and the sum of the reflectance and absorption rate is 1. Therefore, the projected infrared rays are well absorbed in the object's surface portion where the absorption rate is high, and the projected infrared rays are well reflected and absorbed in the object surface portion where the absorption rate is low and therefore the reflectance is high. Therefore, the temperature rise is large in the surface area where the absorption rate is high. This local temperature increase is transferred to the low temperature part of the object by heat conduction inside the object, and the temperature of the object is gradually equalized, but only slowly over time. Therefore, immediately after infrared radiation is emitted, a portion with a high absorption rate has a high temperature and a high emissivity, so it emits a large amount of infrared rays. On the other hand, the portion with low absorption rate has a low temperature and low emissivity, so the amount of infrared rays radiated is small. Additionally, the overall surface temperature is rising due to infrared radiation. Therefore, if this is detected and visualized, the effect of emphasizing the emissivity difference on the object's surface will be added, and the emissivity difference on the surface of low-temperature objects and small objects, which was previously impossible, can be visualized, and the object's emissivity difference will be enhanced. It becomes possible to monitor details. FIG. 4 shows an embodiment of the infrared night vision device of the present invention, and parts corresponding to those in FIG.
In this invention, an infrared projector 20 is provided, and the infrared rays from this are reflected by a plane scanning mirror 22 in a scanning section 21, and the reflected light is projected onto the detection surface of the target object 1, and the movement of the plane scanning mirror 22 causes the reflected light to be projected onto the detection surface of the target object 1. Therefore, the reflected light travels on the object, for example, in the third direction.
As shown in the figure, one picture element is sequentially scanned two-dimensionally.

The infrared light to be used is wavelength 10, which has good transmittance in the atmosphere.
A value in the vicinity of μ is preferable, and the use of a CO2 laser device or the like is effective. On the other hand, a secondary mirror 3 that receives infrared rays emitted from the target object 1 is provided, and the secondary mirror 3 is rotated at high speed by the scanning mechanism 7, and is rotated in the elevation direction at a rate of about once every 100 rotations. It is structured so that it vibrates. Therefore, during the rotation, the secondary mirror 3 horizontally scans the infrared irradiation surface of the target object 1 while facing the target object 1,
Vertical scanning is performed by vibration in the vertical direction. The scanning of this plane scanning mirror 22 is synchronized with the scanning of the secondary mirror 3, but as shown in FIG.
The scan of the projection point of the infrared projector 20 on the detection surface of the target proboscis by the plane scanning mirror 22 is selected to be advanced by the number of picture elements. Therefore, an image corresponding to the amount of infrared radiation from the pixel portion of the detection surface of the target object immediately after the infrared radiation is projected is displayed on the scanning type display, for example, the display cathode ray tube 9.
In this way, the device of the present invention utilizes the infrared radiation from the object surface immediately after the infrared rays are projected, so the amount of infrared rays radiated from the object surface increases and the emissivity difference is emphasized. Since small emissivity differences can be imaged, objects can be monitored in detail and sufficiently at night, and the effect is extremely large in practical terms.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional optical scanning type infrared night vision device, Fig. 2 is an explanatory diagram of its operation, Fig. 3 is an explanatory diagram of the operation of the infrared night vision device of the present invention, and Fig. 4 is an infrared ray of the present invention. FIG. 2 is a block diagram showing an embodiment of a night vision device. 1. Target object, 2, 3: condensing system, 5: photodetector, 7: scanning mechanism section, 8: deflection signal generator, 9: display cathode ray tube, 20: infrared projector, 22: scanning mechanism section.

Claims (1)

[Claims] 1. While two-dimensionally scanning a radiation point of radiated infrared rays emitted from a target object with respect to a detection surface of the target object, sequentially detecting and scanning radiated infrared rays from each pixel portion of the detection surface as a display signal, An infrared night vision device that displays the target object as an image based on the obtained display signal includes a projector that projects infrared rays onto the detection surface of the object, and a projector that is synchronized with the projection by the projector and that , the detection scanning is performed with a delay of a predetermined time within the duration of the infrared radiation effect from the detection surface due to the infrared projection, which is determined by the properties of the detection surface of the target object, such as reflectance, absorption rate, etc. a scanning means for scanning a display surface in synchronization with the detection scan of the radiation infrared rays, optically displaying each scanning point in accordance with the display signal, and displaying an image of the target object on the display surface; An infrared night vision device having a scanning display.