JPH05226728A - Laser-irradiation detector - Google Patents

Abstract

PURPOSE:To provide a laser-irradiation detector serving effectively as a protective means against a laser guided missile. CONSTITUTION:A laser-irradiation detector includes a half mirror 2 for receiving a laser beam from an entrance lens 1, a reflecting mirror 4 for reflecting the laser beam that has passed through the half mirror 2, and a second reflecting mirror 5 located in a distance of several millimeters from the first reflecting mirror 4 and used for reflecting the laser beam that has been reflected by the first reflecting mirror 4 and the half mirror 2 in sequence. Moreover, the detector includes a cylindrical lens 3 for receiving the laser beam from the half mirror 2 after it has been reflected from the second reflecting mirror 5, as well as the laser beam from the half mirror 2 after it has passed through the entrance lens 1, and a linear sensor made up of a plurality of light detecting elements placed in a row and straight in a light receiving direction to receive the laser beam from the cylindrical lens 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser irradiation detecting device which detects the irradiation direction of a laser by separating it from background light by utilizing the coherence of laser light.

[0002]

2. Description of the Related Art Conventionally, there are several types of anti-tank guided missiles, and the first generation method is a method in which a shooter sees both the target and the guided missile and controls the guided missile to hit the target. In the 2nd generation method, the shooter only tracks the target, and in the tracking of the guided bomb, for example, the flare behind the guided bomb is used to track with the infrared tracking device at the launch point, and the 3rd generation method irradiates the target with a laser and reflects it. There is a method in which the guided bullet tracks the wave, and a method in which the newest target is captured as an image and processed on the guided bullet to hit the target.

[0003]

The third-generation system has the highest potential, because it may be a shot-off system, but it is difficult to distinguish the target from the background, and as a hardware, it is difficult to manufacture an infrared area detector. It will take time to equip each country as soon as possible due to price issues due to difficulty. Conventionally, many first-generation system missiles have also been used, but the major difference between the first-generation system, the second-generation system, and the third-generation system is that the third-generation system uses wired guidance. It is considered that it will be used frequently as the method with the highest hit rate together in the future because it is not a commanding speed but a homing guidance that can respond to the movement of the opponent instead of commanding guidance. Therefore, it is very important and necessary to consider a defense method against this third generation method. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser irradiation detection device capable of providing effective protection means against laser-induced bullets.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a half mirror provided via an incident lens on which laser light is incident, and a laser light passing through this half mirror is reflected. A first reflecting mirror, and a second reflecting mirror provided with the laser light sequentially reflected by the first reflecting mirror and the half mirror and being separated by several mm from the first reflecting mirror; A cylindrical lens into which the laser light reflected by the second reflecting mirror and passed through the half mirror and the laser light passing through the incident lens and reflected by the half mirror are incident, and a laser passing through the cylindrical lens It is composed of a linear sensor having a plurality of light detecting elements arranged in a straight line on which light is incident, and the second reflecting mirror is separated from the first reflecting mirror by several mm. By providing Te, separated from the background light using coherence of the laser beam, and by using the cylindrical lens and the linear sensor, and detects the irradiating direction of the laser beam.

[0005]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a laser irradiation detecting apparatus according to an embodiment of the present invention, which is attached to the side surface of a tank. That is, the laser light emitted from the laser irradiator is incident on the incident lens 1, and the laser light passing through the incident lens 1 includes light reflected by the half mirror 2 and light passing through the half mirror 2. The laser light reflected by the half mirror 2 enters the cylindrical lens 3. On the other hand, the laser light transmitted through the half mirror 2 is the first
After being reflected by the reflection mirror 4, the half mirror 2 and further reflected by the second reflection mirror 5, the light passes through the half mirror 2 and enters the cylindrical lens 3. In this case, by making the distance L between the second reflection mirror 5 and the first reflection mirror 4 several millimeters apart, normal light does not cause interference, and only laser light can be caused to interfere. That is, the reason for irradiating the target with the laser beam is that the laser beam is narrow and it is easy to specify the target. The good convergence of the laser beam is because the laser light is coherent. Laser light coherence includes temporal and spatial coherence. When one laser light is divided into two and causes interference, the laser light with good coherence causes interference over a long distance. The monochromatic laser light has a coherent length of up to a meter, but the laser light used for a laser irradiator has a coherent length on the order of millimeters. If it is longer than this, there will be no problem in this method. On the other hand, ordinary light has a short length, that is, no interference occurs unless the length of the optical path is the same. In this way, the background light and the laser light can be separated by using the coherence of the laser light. In addition, in order to increase the sensitivity, a wavelength filter is set to Nd YA
It may be put in 1.6 μ of the G wavelength, but this may not be necessary for separating the background light and the laser light.

The interference fringes 10 of the laser light emitted from the laser irradiator can be formed on the focal plane of the incident lens 1, but this is made linear by the cylindrical lens 3, and a plurality of photodetection elements are arranged in a line. The received linear sensor receives the light. That is, the interference fringes 10 of the laser light have a concentric pattern with a wide center and a narrower line toward the ends. When the interference fringes 10 are arranged linearly by the cylindrical lens 3, the interference fringes 10 are wide at the center and go to the ends. A narrow band of light 11 is created. Brightness is reversed by changing the distance. Therefore, in the case of a linear sensor, if the laser light is present in the central direction, the central light detecting element has a large input, and the number of light detecting elements that receive light decreases toward the end. When this is read, it can be seen from the end which photodetecting element receives light and which photodetecting element does not receive light. That is, the direction of the laser light can be known.

Since the irradiation time of the laser light emitted from the laser irradiator is short, it is necessary to maintain the energy of the laser light. Therefore, a preamplifier 6 including an amplifying element formed for each channel corresponding to each photodetecting element is provided after each photodetecting element of the linear sensor, and the preamplifier 6 is followed by charging by, for example, a capacitor. A holding circuit 7 in which a circuit is formed for each channel is provided. That is, if the photodetector receives light, photoelectrically converts it, is amplified by the preamplifier 6 and is input to the holding circuit 7, this capacitor is charged to the highest potential. The center position detector 8 and the azimuth direction detector 9 detect the center position and the azimuth direction from the charging potential of the holding circuit 7. After the azimuth direction detector 9 detects the azimuth direction, the holding circuit 7 is discharged by the reset signal and waits for the next input.

Laser light irradiation for laser guided bullets on a tank is emitted from a laser irradiator of a vehicle on the ground, a human being or a helicopter, but if the azimuth direction of the laser light is known, if a smoke screen is set up in that direction, the laser light will be emitted. Is reflected and cannot fire effectively. Tanks can be effectively protected against laser-guided bullets by installing this laser irradiation detection device around them.

Therefore, although the object can be achieved if the azimuth direction is detected, if the accurate azimuth direction is required in consideration of the destruction of the guided bullet by the laser beam in the future, two laser irradiation detection devices should be attached at right angles. good.

[0011]

As described above, according to the present invention, the second
The reflective mirror is separated from the first reflective mirror by a few mm to separate it from the background light by using the coherence of the laser light, and the cylindrical lens and the linear sensor are used to irradiate the laser light. Can be detected.

[Brief description of drawings]

FIG. 1 is a structural explanatory view showing an embodiment of the present invention.

[Explanation of symbols]

1 ... Incident lens, 2 ... Half mirror, 3 ... Cylindrical lens, 4 ... 1st reflection mirror, 5 ... 2nd reflection mirror, 6
... Preamplifier, 7 ... Holding circuit, 8 ... Center position detector, 9
… Azimuth detector.

Claims (1)

[Claims] 1. A half mirror provided via an incident lens on which laser light is incident, a first reflecting mirror for reflecting the laser light passing through this half mirror, the first reflecting mirror, and the above A second reflection mirror, which is provided so that the laser light sequentially reflected by the half mirror is reflected and is separated from the first reflection mirror by several mm, and a laser light which is reflected by the second reflection mirror and has passed through the half mirror. And a cylindrical lens into which the laser light passing through the incident lens and reflected by the half mirror is incident, and a plurality of light detecting elements arranged in a line into which the laser light passing through the cylindrical lens is incident. A linear irradiation sensor having the laser irradiation detection device.