JPH0357433B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intruder detection device constructed using optical fiber.

[Conventional technology]

Conventionally, coherent light from a laser light source device is split into two paths using an optical splitter, etc., and is made to enter two optical fibers installed in a detection area, and then the output light from these two optical fibers is split into two paths. There is a method in which interference is caused to form interference fringes, and physical deformation or vibration of building members in the detection area is detected by the movement or change of the interference fringes. However, this method is extremely sensitive not only to physical deformation and vibration of building components, but also to physical changes other than the detection target, such as changes in ambient temperature and air turbulence. It was difficult to perform only the detection well.

Therefore, in order to eliminate the above-mentioned drawbacks, the detection section consisting of the splitter, coupler, and two optical fibers in the detection area was made of a material such as silicone resin, which has a low coefficient of thermal expansion and easily absorbs high-frequency physical vibrations. By molding and integrating the two, a detection device that does not malfunction can be obtained. That is,
In FIGS. 3 and 4, the laser light source device 2
The coherent light generated from
c, they merge in the coupler 5 and interfere, forming interference fringes. This interference fringe pattern is sent to the alarm device 5 via the optical fiber 1d. and,
Optical fibers 1b and 1 detect physical changes and vibrations caused by an intruder entering a predetermined detection area 6 including the detection unit.
movement of the interference fringe pattern based on the relative displacement of c;
Detect by change. Here, the detection section consisting of the splitter 3, the optical fibers 1b and 1c, and the coupler 5 is integrally molded with a material 13 that has a low coefficient of thermal expansion and easily absorbs high-frequency physical vibrations, such as silicone resin. It does not malfunction due to simple physical changes or changes in ambient temperature.

[Problem that the invention seeks to solve]

However, in the conventional device as described above, even if the detection part is deformed due to entry by an intruder, the pair of optical fibers 1b, 1c undergoes almost similar physical changes, so the gap between the optical fibers 1b, 1c is The relative displacement of is small. Therefore, the movement and change of the interference fringe pattern is correspondingly small, and the sensitivity remains low.

The present invention was made to solve the above-mentioned conventional problems, and uses an optical fiber that can detect minute physical changes in the detection area and can detect intruders with high sensitivity. The purpose of this study is to obtain a device for detecting invasive substances.

[Means for solving problems]

In the intruder detection device according to the present invention, one of the pair of optical fibers in the detection section is provided to cause a physical change in response to a physical change caused by an intrusion into a detection area, and the other is provided to cause a physical change in response to a physical change caused by an intrusion. The portions that cause physical changes are separated by a material that has a small coefficient of thermal expansion and easily absorbs physical vibrations, and each optical fiber is molded with the material.

[Effect]

In the present invention, when an intruder enters the detection area, a large difference occurs in the physical changes in the pair of optical fibers, and accordingly, the movement and change of the interference fringe pattern becomes large, making the detection of the intruder more sensitive. can do well. In addition, each optical fiber is molded with a material that has a low coefficient of thermal expansion and easily absorbs physical vibrations, so physical changes in each optical fiber due to physical changes other than penetration or changes in ambient temperature are suppressed. .

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

In FIGS. 1 and 2, coherent light guided from a laser light source device 2 through an optical fiber 1a is branched by a splitter 3 into an optical fiber 1b for detection and an optical fiber 1c for reference. Ru. The optical fiber 1b for detection is housed in a groove 8 provided in the inner bottom of a concave support 7 that is in direct contact with the detection area 6 and is fixed to the detection area 6 of the building member with a bolt 12 or the like. It will be laid in a circular pattern along the The detection optical fiber 1b is attached to the support 7 in this way.
After the cable is installed, it is connected to the coupler 4. Further, a container 9 is provided in the concave support 7 through a material 10 having a low coefficient of thermal expansion and easily absorbing physical vibrations, such as silicone resin, and the optical fiber 1b is molded with the material 10 and the container 9 is A reference optical fiber 1c is laid in a circle inside the optical fiber 1c.
c is connected to the coupler 4. The optical fiber 1c is also molded with the material 10. The coherent light beams are combined in the coupler 4 to form interference fringes, which are sent to the alarm device 5 via the optical fiber 1d. 11 is an outer box that protects the support body 7.

In the above-mentioned detection device, when an intruder is present in the predetermined detection area 6 including the detection part, the detection area 6
The building member 7 undergoes a physical change, and the support 7 fixed to the building member also undergoes a physical change. The optical fiber 1b installed in the groove 8 of the support 7 deforms as the support 7 deforms. At this time, the optical fiber 1c installed in the container 9 separated from the support 7 by the material 10 is difficult to deform because the material 10 easily absorbs physical changes. Therefore, since the optical fibers 1b and 1c have a significant difference in deformation, the movement and change of the interference fringes formed in the coupler 4 are large. That is, even if the physical changes in the building components are minute, the movement and changes in the interference fringes are large, resulting in extremely high sensitivity.

Note that the present invention can be applied not only to detecting an intruder but also to detecting other phenomena that cause physical deformation of building members.

〔Effect of the invention〕

As described above, the present invention includes a branching means for branching coherent light, a pair of optical fibers for passing each coherent light, and a coupling means for merging the coherent lights that have passed through both optical fibers. one of the optical fibers is arranged to cause a physical change in response to a physical change that occurs when an intruder enters a predetermined detection area including the detection part, and the other optical fiber is arranged to cause a physical change in response to a physical change that occurs when an intruder enters a predetermined detection area including the detection part; It is separated from the part that causes physical changes by a material that has a low coefficient of thermal expansion and absorbs physical vibrations, and the physical changes that occur in response to physical changes caused by an intruder entering the detection area are separated from each optical fiber. A large difference occurs in the interference pattern, and a large movement or change in the interference fringe pattern can be obtained due to minute physical deformation or vibration of a building member caused by an intruder, and the intrusion of an intruder can be detected with high sensitivity. Furthermore, each optical fiber is molded with the above-mentioned material, so it does not come into contact with the outside air and will not malfunction due to changes in ambient temperature.

[Brief explanation of drawings]

1 and 2 are a plan view and a cross-sectional view taken along the line A-A of the detection unit according to the device of the present invention, respectively, and FIGS. 3 and 4 are a block diagram and a cross-sectional view taken along the line B-B of the conventional device, respectively. It is. 1a to 1d...Optical fiber, 2...Laser light source device, 3...Brancher, 4...Coupler, 5...Alarm device, 6...Detection area, 7...Support, 8...
Groove, 9... Container, 10... Material with a small coefficient of thermal expansion and easy to absorb physical changes.

Claims (1)

[Claims] 1. A branching means that receives input coherent light and branches it into two paths, a pair of optical fibers that passes the coherent light that has been branched into two paths, and a coupling that combines the coherent light that has passed through the pair of optical fibers. A detection unit comprising a detection unit detects the intrusion of an intruder into a predetermined detection area including the detection unit, by detecting the intrusion of an intruder into a predetermined detection area including the detection unit by a change in optical interference intensity that occurs when coherent light beams merge in accordance with a physical change caused by the intrusion. In the intruder detection device for detecting an intruder, one optical fiber of the pair of optical fibers is provided so as to cause a physical change in response to a physical change due to the intrusion, and the other optical fiber is provided with a physical intruder with a small coefficient of thermal expansion. An intruder detection device using optical fibers, characterized in that a vibration-absorbing substance is used to separate the optical fibers from a part that causes physical changes due to intrusion, and the optical fibers are molded so that they do not come in contact with the outside air. .