JP2009031040A - Brillouin scattering measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Brillouin scattering measuring device capable of measuring in a wide domain with a resolution of 1 m or less, and being automated easily, even if an optical fiber to be measured is changed. <P>SOLUTION: This Brillouin scattering measuring device has a light source 20 of laser light; a modulation means 21 for changing periodically the wavelength of the laser light; a branch part 23 for branching the laser light; a frequency conversion means 24 for converting the frequency of laser light on one branched side; a lead-out means 26 constituted so that a light wave outputted from the frequency conversion means enters one end of the optical fiber 25 to be measured, and that laser light on the other branched side enters the other end of the optical fiber to be measured, and provided between the branch part and the other end of the optical fiber to be measured, for leading out a light wave emitted from the other end of the optical fiber to be measured to a part other than the branch part; and a photodetector 27 for detecting the light wave led out of the lead-out means. In the device, a pulse conversion means 22 for pulsing continuous light with an integer-fold period of a period of the modulation means is provided between the light source and the branch part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

The present invention relates to blanking Lil Ann scattering measuring apparatus, in particular, for measuring by the incidence of two laser beams of different wavelengths in the optical fiber to be measured from different directions, the blanking Lil Ann scattering caused during the it relates to blanking Lil Anne scattering measurement device.

  Conventionally, an optical fiber is used to measure a physical quantity distribution such as temperature and strain of an environment in which the optical fiber is installed. Such physical quantity measurement methods using optical fibers include: maintenance and management of optical communication paths, maintenance and management of large-scale structures such as dams and dikes, and materials and structures that have self-diagnosis functions for defects and failures (smart It is used for material structure.

As a method of measuring the distribution of such spatial distortion and temperature in the environment in which the optical fiber is installed, those using blanking Lil Ann scattering phenomenon in the optical fiber is known. The Bed Lil Ann scattering phenomenon, the pass by two light waves of different frequencies in the optical fiber, a phenomenon with a high frequency of light to a low frequency of light, the power of the light travels through the acoustic wave in the optical fiber Means.

In addition, the frequency difference at which the moving power is maximum depends on the refractive index in the optical fiber and the velocity of the acoustic wave, which depends on the temperature around the optical fiber and the strain applied to the optical fiber. by moving power by Lil Ann scattering to identify where maximum frequency difference becomes and movement has occurred, it is possible to measure the temperature and strain distribution in the optical fiber laid space.

In Patent Document 1, as a measurement method using a blanking Lil Ann scattering, a second frequency-modulated by a first continuous oscillation light and the predetermined modulation frequency equal to the modulation frequency that is frequency-modulated at a predetermined modulation frequency A device using continuous wave light is described. In particular, the first continuous wave light is incident from one end face of the optical fiber to be measured, the center frequency of the second continuous wave light is frequency-shifted, and the second frequency is shifted by the frequency shift. Light emitted from the one end face or the other end face of the optical fiber to be measured by making the oscillation light enter from the other end face of the optical fiber to be measured and changing the frequency shift amount of the center frequency of the second continuous wave light by measuring the power, the optical fiber to be measured, as characterized by measuring the blanking Lil Ann gain spectrum in said first and second phase synchronization and increases the correlation value position of frequency modulation of the continuous wave light Yes.
Japanese Patent No. 3667132

  Specifically, as shown in FIG. 1, the laser light emitted from the semiconductor laser 1 driven by the signal generation circuit 2 is branched into two by an optical branching unit 3. One of the branched laser beams is shifted in the center frequency of the laser beam by the light intensity modulator 5 driven by the microwave generator 4 in accordance with the frequency of the microwave. The frequency-shifted laser light is incident from one end of the measured optical fiber 6 as probe light L1. The probe light uses a sideband on the low frequency side generated by the light intensity modulator 5.

  The other branched laser beam is incident from the other end of the measured optical fiber 6 as pump light L2. If necessary, an optical delay device 7 is interposed to adjust the timing at which the laser light L2 enters the optical fiber 6 to be measured.

  The probe light emitted from the optical fiber 6 to be measured is led to the photodetector side by an optical branching device 8 such as a circulator, and the frequency of the probe light L1 (corresponding to the above-described low frequency sideband) by the optical wavelength filter 9. The light wave having the frequency of the light wave is separated and transmitted, and the light intensity of the light wave is detected by the photodetector 10.

Patent Document 2 discloses the following optical fiber characteristic measuring device. A light source that emits laser light, an incident means that makes a part of the laser light emitted from the light source incident as a probe light of continuous light from one end of the optical fiber to be measured, and a part of the laser light emitted from the light source A pulse modulator that pulses the remainder of the optical fiber to be measured and enters as pump light from the other end of the optical fiber to be measured, and is set to the optical fiber to be measured among light emitted from the other end of the optical fiber to be measured An optical fiber comprising: a timing adjuster that allows only light from the vicinity of a measurement point to pass; and a detector that detects light that has passed through the timing adjuster and measures characteristics of the optical fiber to be measured. It is a characteristic measuring device.
Japanese Patent No. 3607930

  Specifically, as shown in FIG. 2, the laser light emitted from the semiconductor laser 1 driven by the signal generation circuit 2 is branched into two by an optical branching unit 3. One of the branched laser beams is shifted in the center frequency of the laser beam by the light intensity modulator 5 driven by the microwave generator 4 corresponding to the frequency of the microwave, as in FIG. The frequency-shifted laser light is incident from one end of the measured optical fiber 6 as probe light L1.

  The other branched laser beam is incident from the other end of the measured optical fiber 6 as pump light L2. The laser beam L2 is pulsed by the pulse modulator 11.

  The probe light emitted from the optical fiber to be measured 6 is led out to the optical detector side by the optical branching unit 8 and enters the timing adjuster 12 that allows only light from the vicinity of the measurement point set in the optical fiber to be measured 6 to pass. Is done. The light wave having passed through the timing adjuster 12 is selected by the optical wavelength filter 9 as the light wave having the frequency of the probe light L 1, and the light intensity of the light wave that has passed through the optical wavelength filter 9 is detected by the photodetector 10.

However, in the measurement method of Patent Document 1, since the first and second continuous lights are periodically frequency-modulated, a correlation peak is exhibited at a periodic point of about 10 to 50 m. Therefore, even when measuring the blanking Lil Ann scattering, so that the measuring the plurality of periodic points simultaneously. In order to solve this problem, it is necessary to limit the measurement distance to the period of the correlation peak, that is, 10-50 m or less.

  In the measurement method of Patent Document 2, the above limitation can be removed by a pulse modulator and a timing adjuster. However, in this method, it is necessary to adjust the timing each time the measurement sample is changed, and the measurement work becomes complicated and automatic adjustment is difficult.

An object of the present invention is to solve is to solve the problems as described above, can measure the blanking Lil Ann scattering of the measured optical fiber at 1m or less resolution, yet measurable over a wide area, the to provide a blanking Lil Ann scattering measuring apparatus that can be measured for the optical fiber to easily automated be replaced.

In order to solve the above problems, in the invention according to claim 1, a light source that emits laser light, a modulation unit that periodically changes the wavelength of the laser light, and a branch that branches the laser light emitted from the light source. Part, a frequency converting means for converting the frequency of one branched laser light, and a light wave output from the frequency converting means is incident on one end of the optical fiber to be measured, and the other branched laser light is An optical fiber to be measured configured to be incident on the other end of the optical fiber for measurement; and provided between the branch portion and the other end of the optical fiber for measurement. and deriving means for deriving the light waves emitted from the end other than the branch portion, the blanking Lil Ann scattering measuring apparatus having a photodetector for detecting light waves derived from the electrically detecting means, the period of the modulation means continuous light Pulse with an integer multiple of Pulse converting means for, characterized in that provided between the light source and the branch unit.

In the invention according to claim 2, the light source that emits the laser light, the modulation means that periodically changes the wavelength of the laser light, the branching unit that branches the laser light emitted from the light source, and one of the branched light sources Frequency conversion means for converting the frequency of the laser light, and a light wave output from the frequency conversion means is incident on one end of the optical fiber for measurement, and the other branched laser light is supplied to the optical fiber for measurement. An optical fiber to be measured configured to be incident on the other end; and a light wave emitted from the other end of the optical fiber to be measured provided between the branch portion and the other end of the optical fiber to be measured. and deriving means for deriving a non-branching portion, the blanking Lil Ann scattering measuring apparatus having a photodetector for detecting light waves derived from the electrically detecting means, pulsed continuous light at an integer multiple of the period of the cycle of the modulation means The pulse conversion means to It is provided between the branching section and one end of the optical fiber to be measured and between the branching section and the derivation means, and has synchronization control means for synchronizing both pulse conversion means. .

In the invention according to claim 3, two light sources that emit laser light, modulation means that periodically changes the wavelength of the laser light, and frequency conversion that converts the frequency of the laser light emitted from one of the light sources. And a light wave output from the frequency converting means is incident on one end of the optical fiber for measurement, and a laser beam emitted from the other of the light sources is incident on the other end of the optical fiber for measurement Provided between the configured optical fiber to be measured, the other light source, and the other end of the optical fiber to be measured, and the light wave emitted from the other end of the optical fiber to be measured other than the other light source and deriving means for deriving, in blanking Lil Ann scattering measuring apparatus having a photodetector for detecting light waves derived from the electrically detecting means, the pulse converter pulsing the continuous light by an integer multiple of the period of the period of modulation means Means for the one light source Provided both between and between said other light source and the conductor detecting means and one end of 該被 measuring optical fiber, characterized by having a synchronization control means for synchronizing the pulse converter means both.

The invention according to claim 4, in blanking Lil Ann scattering measuring apparatus according to any one of claims 1 to 3, wherein the frequency conversion means, characterized by using the SSB optical modulators.

The invention according to claim 5, in blanking Lil Ann scattering measuring apparatus according to any one of claims 1 to 4,該Bu Lil Ann scattering measuring apparatus, distortion of該被measuring optical fiber is arranged structures It is the distortion measuring device for measuring the above.

According to the first aspect of the present invention, a light source that emits laser light, a modulation unit that periodically changes the wavelength of the laser light, a branching unit that branches the laser light emitted from the light source, and one of the branched light sources Frequency conversion means for converting the frequency of the laser light, and a light wave output from the frequency conversion means is incident on one end of the optical fiber for measurement, and the other branched laser light is supplied to the optical fiber for measurement. An optical fiber to be measured configured to be incident on the other end; and a light wave emitted from the other end of the optical fiber to be measured provided between the branch portion and the other end of the optical fiber to be measured. and deriving means for deriving a non-branching portion, the blanking Lil Ann scattering measuring apparatus having a photodetector for detecting light waves derived from the electrically detecting means, pulsed continuous light at an integer multiple of the period of the cycle of the modulation means Pulse conversion means By providing between the light source and the branch portion, it is possible to perform periodic intensity modulation in synchronization with the probe light and the pump light, and the measurement target position can be measured over a wide area. Can be changed with a resolution of 1 m or less. Moreover, since there is no need to use a conventional timing adjuster, adjustment between the pulse modulator and the timing adjuster is not required even if the optical fiber to be measured is changed, and can be easily automated. it is possible to provide a blanking Lil Anne scattering measurement device.

According to the invention of claim 2, a light source that emits laser light, a modulation unit that periodically changes the wavelength of the laser light, a branching unit that branches the laser light emitted from the light source, and one of the branched light sources Frequency conversion means for converting the frequency of the laser light, and a light wave output from the frequency conversion means is incident on one end of the optical fiber for measurement, and the other branched laser light is supplied to the optical fiber for measurement. An optical fiber to be measured configured to be incident on the other end; and a light wave emitted from the other end of the optical fiber to be measured provided between the branch portion and the other end of the optical fiber to be measured. and deriving means for deriving a non-branching portion, the blanking Lil Ann scattering measuring apparatus having a photodetector for detecting light waves derived from the electrically detecting means, pulsed continuous light at an integer multiple of the period of the cycle of the modulation means Pulse conversion means The probe light is provided between both the branch part and one end of the optical fiber to be measured and between the branch part and the derivation means, and has synchronization control means for synchronizing both pulse conversion means. It is possible to perform periodic intensity modulation in synchronization with the pump light and to change the measurement target position with a resolution of 1 m or less while being able to measure over a wide area. Further, it is possible to provide in the same manner as in the invention according to claim 1, easily blanking Lil Ann scattering measuring apparatus that can be automated.

According to the invention of claim 3, two light sources that emit laser light, modulation means that periodically changes the wavelength of the laser light, and frequency conversion that converts the frequency of the laser light emitted from one of the light sources And a light wave output from the frequency converting means is incident on one end of the optical fiber for measurement, and a laser beam emitted from the other of the light sources is incident on the other end of the optical fiber for measurement Provided between the configured optical fiber to be measured, the other light source, and the other end of the optical fiber to be measured, and derives the light wave emitted from the other end of the optical fiber to be measured to other than the branching portion and deriving means for, in blanking Lil Ann scattering measuring apparatus having a photodetector for detecting light waves derived from the electrically detecting means, the pulse conversion means for pulsing an integral multiple of the period of the period of modulation means continuous light With one of the light sources Provided between both ends of the optical fiber to be measured and between the other light source and the derivation means, and having synchronization control means for synchronizing both pulse conversion means, the probe light and the pump light The periodic intensity modulation can be performed in synchronization with each other, and the measurement target position can be changed with a resolution of 1 m or less. Further, it is possible to provide in the same manner as in the invention according to claim 1 or 2, readily Bed Lil Ann scattering measuring apparatus that can be automated.

The invention according to claim 4, in blanking Lil Ann scattering measuring apparatus according to any one of claims 1 to 3, wherein the frequency conversion means for using the SSB optical modulators, whereas one of the probe light or the pump light It is possible to easily shift the frequency.

The invention according to claim 5, in blanking Lil Ann scattering measuring apparatus according to any one of claims 1 to 4,該Bu Lil Ann scattering measuring apparatus, distortion of該被measuring optical fiber is arranged structures Therefore, the strain of the structure can be measured with higher accuracy.

Hereinafter, the present invention will be described in detail using preferred examples.
Figure 3 is a diagram showing a first embodiment of the probe drill en scattering measuring apparatus of the present invention.
A semiconductor laser 20 is used as a light source that emits laser light. A signal having a predetermined frequency f1 is input to the semiconductor laser 20 from a signal generator 21, which is a modulation means for periodically changing the wavelength of the laser light, and the laser light frequency-modulated at the predetermined frequency f1 from the semiconductor laser 20. Is emitted.

More specifically, as shown in FIG. 6, when the wavelength when the semiconductor laser 20 is driven by a direct current is λ ₀ , the laser beam b emitted from the semiconductor laser 20 when driven at a predetermined frequency f1 is The wavelength fluctuates in the range of λ ₀ ± Δλ ₁ and the fluctuation period becomes 1 / f1.

  The laser light is converted into a predetermined cycle T1 (usually, T1 = N / f1, N is a natural number by the pulse converter 22 which is a pulse conversion unit. That is, the laser beam has a cycle which is an integral multiple of the modulation cycle by the modulation unit. )). The laser beam converted into a pulse shape is branched into two laser beams by an optical branching device 23 constituting a branching unit.

One of the branched laser lights is modulated by the specific frequency f2 by the frequency converting means 24 for converting the frequency, and the center frequency of the laser light is shifted by a predetermined amount. Specifically, as shown in FIG. 6, the center wavelength has a predetermined wavelength shift amount (± Δλ ₂ , where Δλ ₂ = C / f2, C so that the laser beam b becomes the laser beam c. Shift by the speed of light.)

As the frequency conversion means 24, an SSB optical modulator can be used. A microwave having a frequency f2 is input to the SSB optical modulator by a microwave generator, and a sideband having a center wavelength of λ ₀ ± Δλ ₂ is obtained. The light wave which has is generated. When the light wave that has passed through the frequency converting means is used as the probe light, the sideband on the low frequency side of λ ₀ + Δλ ₂ is used. Further, when used as pump light, a sideband on the high frequency side of λ ₀ −Δλ ₂ is used. In the following, the laser light emitted from the frequency converting means will be described mainly using an example of using the sideband on the low frequency side. However, if the sideband on the high frequency side is used, the optical splitter 23 in FIG. Frequency conversion means is disposed between the optical branching device 26, between the optical branching device 32 and the optical branching device 38 in FIG. 4, and between the semiconductor laser 46 and the optical branching device 49 in FIG.

  The light wave output from the frequency converting means 24 enters one end of the optical fiber 25 to be measured as the probe light L1. The other branched laser beam is configured to enter the other end of the optical fiber 25 to be measured as pump light L2.

By the probe light and pumping light intersect, blanking Lil Ann scattering including information such as spatial distortion and temperature in the environment being disposed optical fiber to be measured is generated, the light energy of the pump light probe light Move power to.

In the present invention, since the both pulsed also probe light is also the pump light using a pulse converter 22, even inside of the measuring optical fiber having a wide area, the following resolution 1 m, blanking Lil It is possible to specify the location where unscattering occurs.

Specifically, when the probe light L1 and the pump light L2 before being pulsed are incident on the optical fiber for measurement (region of length L), as shown in FIG. position the frequency difference between the pumping light does not fluctuate periodically appear, blanking Lil Ann scattering phenomenon at a portion corresponding to a node of the speak standing wave is generated. In FIG. 7A, the vertical axis represents the fluctuation amplitude of the frequency difference between the pump light and the probe light. 0 is a point where the two light waves branched from the branching section 3 join again with the same optical path length (hereinafter referred to as an intermediate point), and a standing wave node is always generated at the intermediate point. .., N + 1,... Shown in FIG. 7A indicate the number of nodes counted from the intermediate point. n is a natural number. The optical fiber for measurement is a region indicated by a range L. In FIG. 7A, the optical fiber for measurement is blocked at the positions of four nodes (n to n + 3) of the standing wave generated in the optical fiber for measurement. so that the Lil Anne scattering is measured.

When the center wavelength λ ₀ of the semiconductor laser is 1550 nm and the driving frequency f 1 of the semiconductor laser is 3 MHz, Δλ 1 is about 0.04 nm. Next, the wavelength shift amount Δλ2 when a modulation frequency of 10.5 GHz is applied to the frequency converter is about 0.08 nm. Since both the probe light and the pump light fluctuate periodically at 3 MHz, the distance between the nodes of the standing wave is about 30 m (assuming that the center refractive index of the optical fiber to be measured is n = 1.457) It becomes.

  Next, when the driving frequency f1 is changed, for example, by about 10% (from 0.3 MHz, 3 MHz to 2.7 MHz), the interval between the nodes is about 10% (3 m), which extends conversely. FIG. 7B shows this state, and the first node is moved by X1 by adjusting the driving frequency f1. When attention is paid to the n-th node, Xn (= X1 × n) moves. In other words, when X1 = 3 m and n = 16, Xn = 48 m, and f1 is continuously changed between 3 MHz and 2.7 MHz, and the n-th node has a continuous range of about 50 m. It is possible to move on.

  For this reason, it is possible to easily realize a resolution of 1 m or less simply by reducing the amount of change in the drive frequency f1. As another method for increasing the resolution, the interval between the nodes of the standing wave can be set narrower as the drive frequency f1 is increased, so that the resolution can be increased. For example, when the driving frequency f1 is increased 10 times, the node interval becomes 1/10 (about 3 m).

Incidentally, as shown in FIG. 7A, since there are a plurality of nodes inside the optical fiber to be measured, even if the probe light emitted from the optical fiber is simply observed, It becomes possible to measure the total of the probe Lil Anne scattering in a plurality of positions. For this reason, it is impossible to specify which part the phenomenon is. To avoid this, in Patent Document 2, by adjusting the incident timing of the probe light injected into the pulsing and the photodetector of the pump light by the pulse modulator, a position blanking Lil Ann scattering phenomenon occurs I have identified.

However, in the method of Patent Document 2, it is necessary to adjust the pulse modulator and the timing adjuster every time the optical fiber to be measured changes, making the adjustment work complicated and making measurement automation difficult. .
In the present invention, this problem is solved by using the pulse converter 22 described above. That is, when both the probe light and the pump light are pulsed at a predetermined cycle T1 (T1 = N / f1, N is a natural number), as shown in FIG. 7C or FIG. Only this phenomenon can be extracted. Specifically, in a predetermined cycle T1 obtained by dividing the drive frequency f1, for example, when N = 2, a node that is a multiple of 2 is selected as shown in FIG. 7C, and when N = 4, FIG. As shown in (d), a node that is a multiple of 4 is selected.

Thus, by adjusting the number of nodes to be selected, one node can be measured in the optical fiber to be measured as shown in FIG. by moving the section by changing the driving frequency f1 as described above, it is possible to measure the blanking Lil Ann scattered extensively over and high resolution through the optical fiber to be measured.

  In order to measure the probe light L1 emitted from the optical fiber for measurement 25, it is provided between the optical splitter 23 and the other end of the optical fiber for measurement 25, and is emitted from the other end of the optical fiber for measurement. Deriving means 26 for deriving the probe light L1 other than the optical splitter 23 is provided. As the derivation means, an optical branching device 26 such as a circulator can be used.

  The probe light L1 derived by the optical splitter 26 is input to the photodetector 27, and the light intensity of the probe light is measured. In addition, in order to measure the wavelength light which concerns on probe light correctly, it is also possible to arrange | position a wavelength filter in the front | former stage of the photodetector 27 as needed.

  In the first embodiment according to the present invention, the optical branching device 23, the frequency converter, the optical fiber to be measured, and the optical branching device 26, in the loop in which the light wave formed by the optical branching device 26 propagates, It is necessary to adjust the waveguide length of an optical fiber or the like used for forming the loop so that the two branched light waves meet again (intermediate point) in the loop so as not to be located in the fiber 25 to be measured. This is because the place where the branched light waves meet again does not change even if the pulse period is changed, so if there is such a place in the optical fiber under measurement, the measurement always includes the state of the optical fiber at that place. This is because the result is observed.

In the present invention, only by adjusting the period T1 and the signal generator 21 of the pulse converter 22, it will be able to more specifically the measurement target position in the fiber under test, measuring the blanking Lil Ann scattering phenomena for a wide range since it becomes possible to, it is possible to provide a blanking Lil Ann scattering measuring apparatus automated.

Figure 4 is a diagram showing a second embodiment of the probe drill en scattering measuring apparatus according to the present invention.
The difference from the first embodiment is that the pulse converter arranged in the previous stage of the optical branching device 23 is arranged in the subsequent stage of the optical branching device 32 and that each of the branching by the optical branching device 32 is performed. A plurality of pulse converters are used for pulsing light waves, and both pulse converters are controlled synchronously.

The pulse converters 33 and 36 are provided with a synchronization control means 37 for generating pulses of the same frequency and adjusting the timing of generating the pulses.
By generating a pulse of the same frequency, as in the case of the first embodiment, by changing the period of the pulse, a specific node of the standing wave generated in the optical fiber for measurement can be changed. In addition, by adjusting the drive frequency f1, it is possible to measure a wide range and easily adjust the measurement resolution.

  Further, in FIG. 3, it is necessary to measure the adjacent node by changing the modulation frequency f1 greatly, but by adjusting the pulse generation timing of the pulse converters 33 and 36, as shown in FIG. For example, the adjustment can be performed as if the midpoint 0 is shifted to the position of the numeral 1, which makes it possible to select a node at an adjacent location. FIG. 7 shows a state where the predetermined period T1 of the pulse converter is 2 / f1.

Figure 5 is a diagram showing a third embodiment of the probe drill en scattering measuring apparatus according to the present invention.
The difference from the second embodiment is that the laser light source is composed of two semiconductor lasers 40 and 46.

When the semiconductor lasers 40 and 46 are driven at the same predetermined frequency, it is necessary to shift the frequency of the probe light L1 or the pump light L2 using the frequency converter 43 as shown in FIG. However, when driving at a different frequency, the frequency converter 43 becomes unnecessary.
Further, when the semiconductor lasers are driven at the same predetermined frequency, the signal generators 41 and 45 can be shared by only one of them.

Bed Lil Ann scattering measuring apparatus of the present invention, the optical fiber under test as described above, by the inside buried optical fiber, such as the structure, as the strain measuring apparatus for measuring the internal strain of the structure It can be used. Further, Bed Lil Ann scattering because it also affects the temperature change of the optical fiber, it can be also used as a temperature distribution measuring device of the internals.

According to the present invention, over a wide area, and can measure the blanking Lil Ann scattering of the measured optical fiber in the following resolution 1 m, moreover, can easily be automated even replaced is optical fiber under test it becomes possible to provide a blanking Lil Anne scattering measurement device.

It is a schematic diagram of a conventional blanking Lil Ann scattering measuring apparatus. It is a schematic view of another conventional blanking Lil Ann scattering measuring apparatus. The first embodiment of the probe drill en scattering measuring apparatus according to the present invention is a schematic diagram showing. A second embodiment of the probe drill en scattering measuring apparatus according to the present invention is a schematic diagram showing. It is a schematic diagram showing a third embodiment of the probe drill en scattering measuring apparatus according to the present invention. It is a figure which shows the mode of the wavelength fluctuation of probe light and pump light. Is a diagram showing the measurement principle of the probe drill en scattering measuring apparatus according to the present invention.

Explanation of symbols

1, 20, 30, 40, 46 Semiconductor laser 2, 21, 31, 41, 45 Signal generator 3, 23, 32 Optical splitter 4 Microwave generator 5 Optical intensity modulator 6, 25, 35, 44 Optical fiber 7 Optical delay device 8, 26, 38, 49 Optical branching device (derivation means)
9 Optical wavelength filter 10, 27, 39, 50 Photo detector 11 Pulse modulator 12 Timing adjuster 22, 33, 36, 42, 47 Pulse converter 24, 34, 43 Frequency converter 37, 48 Synchronization control means

Claims (5)

A light source that emits laser light;
Modulation means for periodically changing the wavelength of the laser beam;
A branching section for branching the laser beam emitted from the light source;
A frequency conversion means for converting the frequency of one of the branched laser beams;
The light wave output from the frequency converting means is incident on one end of the optical fiber to be measured, and the other branched laser beam is incident on the other end of the optical fiber for measurement. Optical fiber,
A derivation means provided between the branch portion and the other end of the optical fiber for measurement, and for deriving a light wave emitted from the other end of the optical fiber for measurement to other than the branch portion;
In a Brillouin scattering measurement apparatus having a photodetector for detecting a light wave derived from the deriving means,
An apparatus for measuring Brillouin scattering, characterized in that pulse conversion means for pulsing continuous light at a period that is an integral multiple of the period of the modulation means is provided between the light source and the branching section. A light source that emits laser light;
Modulation means for periodically changing the wavelength of the laser beam;
A branching section for branching the laser beam emitted from the light source;
A frequency conversion means for converting the frequency of one of the branched laser beams;
The light wave output from the frequency converting means is incident on one end of the optical fiber to be measured, and the other branched laser beam is incident on the other end of the optical fiber for measurement. Optical fiber,
A derivation means provided between the branch portion and the other end of the optical fiber for measurement, and for deriving a light wave emitted from the other end of the optical fiber for measurement to other than the branch portion;
In a Brillouin scattering measurement apparatus having a photodetector for detecting a light wave derived from the deriving means,
Pulse conversion means for pulsing continuous light at a period that is an integral multiple of the period of the modulation means, both between the branching section and one end of the optical fiber to be measured and between the branching section and the deriving means Provided in
A Brillouin scattering measurement apparatus comprising synchronization control means for synchronizing both pulse conversion means. Two light sources that emit laser light;
Modulation means for periodically changing the wavelength of the laser beam;
Frequency conversion means for converting the frequency of laser light emitted from one of the light sources;
The light wave output from the frequency converter is incident on one end of the optical fiber for measurement, and the laser beam emitted from the other of the light sources is incident on the other end of the optical fiber for measurement. An optical fiber for measurement;
A derivation means that is provided between the other light source and the other end of the optical fiber to be measured, and derives a light wave emitted from the other end of the optical fiber to be measured, other than the other light source;
In a Brillouin scattering measurement apparatus having a photodetector for detecting a light wave derived from the deriving means,
Pulse conversion means for pulsing continuous light at a period that is an integral multiple of the period of the modulation means, between the one light source and one end of the optical fiber to be measured, and between the other light source and the lead-out means In both
A Brillouin scattering measurement apparatus comprising synchronization control means for synchronizing both pulse conversion means.   4. The bullian scattering measurement apparatus according to claim 1, wherein the frequency conversion means uses an SSB optical modulator.   5. The bullian scattering measurement device according to claim 1, wherein the bullian scattering measurement device is a strain measuring device for measuring strain of a structure in which the optical fiber for measurement is arranged. A characteristic Burrian scattering measurement device.

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