JPH0492523A - Detecting sensor for contact information - Google Patents

Abstract

PURPOSE:To detect the contact information with no mechanical force applied by providing the light shielding mechanisms which work based on the contact information between the optical branching devices and mirrors provided at plural areas of an optical fiber. CONSTITUTION:The optical branching device 4 and the mirrors 5 which reflect the branched beams and then apply again these beams into the devices 4 are provided at plural areas of an optical fiber 2 connected to an OTDR(optical time domain reflectometer) central unit 1. Then the light shielding mechanisms 7-10 which work based on the contact information are provided between the devices 4 and the mirrors 5 respectively. The light intensity is reduced in steps when the optical pulses are branched by the devices 4. However a peak part having the high light intensity is produced at an area where the branched light is reflected. Then a fact whether the contact information is changed or not can be detected. Then the contact information can be detected without applying the mechanical power to the fiber 2 through the device 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a contact information detection sensor using 0TDR technology.

[Conventional technology]

Conventionally, 0TDR (Optlcal Tlme Doma) is a technology for detecting contact information at multiple points.
In Reflectometer), the following has been developed.

First, regarding 0TDR, it is used for measuring optical fiber loss distribution and investigating fault points, etc. It includes a sensor section made of an optical fiber, a measuring section connected to one end of the optical fiber, and a measuring section consisting of a laser light source, light receiving circuit, etc. Consists of a computer processing section.

Then, by inputting a light pulse from a laser light source into an optical fiber and measuring the delay time of the backscattered light (the time from when the light pulse is input until the backscattered light returns to the input end), The transmission loss of the optical fiber at each position is determined by determining the position where scattered light (usually Leh scattered light is used) and detecting the intensity of the backscattered light.

Therefore, if the optical fiber is configured to be subjected to factors that increase transmission loss, such as bending and pressure strain, based on the contact information, it becomes possible to detect the contact information from changes in the loss.

[Problem to be solved by the invention]

However, in the above conventional technology, mechanical forces such as bending and pressure strain are applied to the optical fiber, making it difficult to guarantee the long-term performance of the optical fiber. There was a problem that the detection part became large.

[Means to solve the problem]

Therefore, the present invention has been made to solve the above problems, and it provides a sensor that detects contact information by using 0TDR technology and without applying mechanical force that causes deterioration of optical fibers. It is something.

That is, the sensor of the present invention includes an optical splitter and a mirror that reflects the branched light branched by the optical splitter and introduces it into the optical splitter again at a plurality of locations on the optical fiber connected to the 0TDR solid device. between this optical splitter and the mirror,
It is characterized by the provision of a light shielding mechanism that operates based on contact information.

Further, as the above-mentioned light shielding mechanism, a liquid crystal element is provided between the optical branching device and the mirror and is connected to a power supply section and is opened and closed based on contact information, thereby electrically controlling the branched light.

Further, as another light shielding mechanism, a two-stage polarizing plate that is movable based on contact information can be provided between the optical splitter and the mirror to mechanically control the branched light.

Furthermore, when the liquid crystal element is used, it may be connected to a power source and a reed switch that opens and closes using magnetic force, and branched light may be controlled by contact information extracted as magnetic force.

〔Example〕

The present invention will be explained below based on the embodiments shown in FIGS. 1 to 3, 5, and 6. Note that the same reference numerals in each figure indicate the same parts.

(Example 1) Figure 1 is a schematic diagram showing the overall configuration of the sensor of the present invention.
Detectors 3 are provided at multiple locations on the optical fiber 2 connected to the DR solid device 1. This 0TDR solid device 1 is similar to the conventional one, and includes a measuring section and a processing section, and measures the delay time and light intensity of backscattered light. Although the detection section 3 has the configuration shown in FIGS. 3, 5, and 6, the basic principle common to each aspect will first be explained using FIG. 2.

As shown in the figure, a light pulse (incident light) propagating through an optical fiber is split into two directions by an optical splitter 4. The branching ratio of this optical splitter 4 is set to A: (1-A). For example, if A = 0.99, most of the light is guided to the next optical fiber side, and 1/100 of the light is guided to the next optical fiber side. Only the light is guided to the mirror 5 side (branched light). The light guided to this mirror 5 is reflected here, enters the optical splitter 4 again, and then returns to the 0TDR solid device 1 via the optical fiber 2 (
.

Therefore, if the amount of light from the optical splitter 4 to the mirror 5 is controlled in relation to the contact information, 0TDR solid device 1
By performing the IQ ff1ll of the light intensity, it is possible to detect contact information. Incidentally, even if the mirror 5 is not particularly installed, a similar waveform can be obtained by the Fresnel reflected light from the end face of the optical fiber, and the end face can also be mirror-treated (
Silver vapor deposition, etc.) may also be used.

Next, regarding the means for controlling the amount of light reaching the mirror 5 from the optical splitter 4, a detection section shown in FIG. 3 that electrically performs this will be described. As shown in the figure, the optical fiber 2 is provided with an optical splitter 4 equipped with a rod lens 6, and the incident light is split into two directions by the optical splitter 4, one being sent to the next optical fiber, The other is led to the mirror side. This mirror 5
is for reflecting the branched light and guiding the light to the optical splitter 4 again. A liquid crystal element 7 is arranged between this and the optical splitter 4, and a liquid crystal element 7 is arranged between the liquid crystal element 7 and the optical splitter 4. is provided with an antireflection film 8. The liquid crystal element 7 adjusts the amount of light reaching the mirror 5 from the light splitter 4 by changing the amount of transmitted light due to changes in its turbidity or polarization, and the antireflection film 8 is used to prevent reflection from the liquid crystal surface. It is. Since the amount of light transmitted through the liquid crystal element 7 is changed electrically, the liquid crystal element 7 is connected to a power supply section 9 including a battery, and this power supply section 9 is further connected to a contact input terminal IO. Therefore,
By inputting contact information, a potential is applied to the liquid crystal element 7 via the power supply section 9, and the amount of transmitted light can be changed. In this example, the entire detection section is wrapped in mold I+ for mechanical protection, but the power supply section 9 can also be attached externally.

When contact information is detected using such a detection unit, for example, if the liquid crystal element 7 transmits all branched light, the mirror 5
On the other hand, if there is no total (transmission), no reflection will occur. Therefore, if you observe the light intensity with an 0TDR solid device, you will get a graph like the one shown in Figure 4. The light intensity decreases step by step at the point where the branched light is branched, but if the branched light is reflected, a strong peak of light intensity is created at that point, and it is possible to detect whether or not there is a change in the contact point information.

(Embodiment 2) Next, a description will be given of a detection unit shown in FIG. 5 that uses a polarizing plate 12 instead of the liquid crystal element 7 to mechanically control the amount of light reaching the mirror from the optical splitter.

As shown in the figure, there are two stages of polarizing plates I2 between the mirror 5 and the optical splitter 4, and between the polarizing plate +2 (upper stage) and the optical splitter 4, there is an antireflection film 8 similar to that in Example 1. is located. The polarizing plate 12 transmits only one of the two orthogonal polarized components of light, and the lower polarizing plate of the two stages has two orthogonal polarized components.
It is made by joining two polarizing plates together. One of these two polarizing plates transmits the same polarized component as the upper polarizing plate, and the other has a different polarization component, and by moving it in the horizontal direction based on the contact information, it becomes the same as the upper polarizing plate. The scene from the light splitter to the mirror is controlled redundantly.

(Third Embodiment) Furthermore, FIG. 6 shows a detection section using a liquid crystal element as in the first embodiment for a different deafness.

This eliminates the contact input terminal as shown in Figure 1, and includes a liquid crystal element 7, a power supply section 9, and a reed switch 1 that opens and closes using magnetic force.
3 are connected, and the contact information is extracted as a change in the magnetic force of the magnet 14, and the reed switch 13 is opened and closed from outside the detection part without contact, thereby controlling the amount of light from the optical splitter to the mirror.

In addition, in both Examples 2 and 3, the connection with the 0TDR solid device, the mold of the detection part, and the method of detecting contact information are the same as in Example 1.

〔Effect of the invention〕

As explained above, according to the present invention, a distributed contact information detection system can be constructed using an optical splitter without applying mechanical force to the optical fiber.

Further, by completely molding the detection section itself, the external environment can be prevented from affecting the detection section, and furthermore, an explosion-proof structure can be achieved.

Therefore, it can be effectively used to detect openings and closings over a wide range of areas, such as detecting the opening and closing of manholes, opening and closing of doors, opening and closing of valves in pipelines, and detecting the alarm output of fire alarms.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the overall configuration of the sensor of the present invention, FIG. 2 is an explanatory diagram showing the basic principle of the sensor detection section of the present invention, and FIG. 3, FIG. 5, and FIG. 6 are respective detection sections with different aspects. Configuration diagram,
FIG. 4 shows a graph when light intensity is measured using the 0TDR main unit. 1...0TDR solid device, 2...optical fiber, 3...
...Detection unit, 4...Optical branch KA, 5...Mirror
6... Mouth, drain, 7... Liquid crystal element, 8... Antireflection film, 9... Power supply section, 10... Contact input terminal,
11...Mold, 12...Polarizing plate, +3...Reed switch, +4...Magnet. Nazu dazzling〉 3 figure 7 (liquid crystal +-1) arithmetic calculation base 6 figure 13 (reet sui 7)

Claims (4)

[Claims] (1) An optical splitter is installed at multiple locations on the optical fiber connected to the OTDR central device, and a mirror is installed to reflect the branched light branched by the optical splitter and introduce it back into the optical splitter. A contact information detection sensor characterized in that a light shielding mechanism that operates based on contact information is provided between the container and the mirror. (2) The contact information detection sensor according to claim (1), further comprising a liquid crystal element connected to a power source that can be opened and closed based on contact information, provided between the optical splitter and the mirror. (3) Claim (1) characterized in that a two-stage polarizing plate that is movable based on contact information is provided between the optical splitter and the mirror.
) Contact information detection sensor described. (4) The contact information detection sensor according to claim (1), further comprising a liquid crystal element connected to a power source and a reed switch that can be opened and closed by magnetic force, between the optical splitter and the mirror.