JP2012184953A - Sensing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a measurement precision without reducing the intensity of light from a light source of which the route is changed even when performing measurements at a plurality of positions over a long distance.SOLUTION: As detection units 128-139 for measuring external factors in performing oscillation observation, for example, various detection means can be used. Furthermore, optical circulators 106a-106l are provided not to split light like a conventional photo-coupler but to change an output destination of light. Therefore, even if the number of optical circulators 106a-106l is increased, the intensity of light of which the output destination is to be changed by each of the optical circulators 106a-106l is prevented from being reduced.

Description

  The present invention relates to a sensing system using an optical fiber, an optical fiber applied optical component, or the like, and more particularly to a sensing system suitable for measurement that performs vibration observation, temperature observation, water level observation, velocity observation, acceleration observation, strain observation, and the like.

  Conventionally, various sensing systems suitable for measurement that perform, for example, vibration observation, temperature observation, water level observation, velocity observation, acceleration observation, strain observation, etc. have been proposed by using optical fibers or optical fiber applied optical components. .

  For example, an optical accelerometer using an optical fiber sensor having an FBG (Fiber Bragg Grating) as disclosed in Patent Document 1 is known as an apparatus that performs acceleration observation.

  In this optical accelerometer, a plurality of optical couplers are connected via a first optical fiber to a wavelength measuring instrument that incorporates a light source and measures a reflected wavelength, and further a second optical fiber is connected to each optical coupler. The path from each optical coupler is branched, and an optical accelerometer having a sensor FBG is connected to the tip of the branched second optical fiber.

  In such an optical accelerometer, the light from the light source of the wavelength measuring instrument is transmitted through the first optical fiber, branched by each optical coupler, and reaches each optical accelerometer. When acceleration is applied to any of the optical accelerometers, the wavelength of reflected light from the sensor FBG used in the optical accelerometer changes, and the reflected light returns to the wavelength measuring instrument. Thus, the wavelength of the changed light is measured, the acceleration is calculated, and the position where the wavelength of the reflected light is changed is specified.

JP 2005-30796 A

  As described above, in the optical accelerometer in Patent Document 1, the wavelength of the changed light is measured by the wavelength measuring device, so that it is possible to recognize that there is vibration and distortion at a specific position, and the change in acceleration. Can be measured.

  However, in such an optical accelerometer, the wavelength change of the reflected light from the sensor FBG is observed to observe the vibration and specify the position where the vibration is generated. Therefore, the sensor used for each optical accelerometer However, there was a problem that it was limited to FBG.

  Also, the light from the light source of the wavelength measuring device is branched to the second optical fiber side by each optical coupler on the first optical fiber because the light source of the wavelength measuring device is single. As the number of optical couplers increases, there is also a problem that the intensity of light branched by each optical coupler decreases.

  In addition, if measurement is performed at multiple locations over a long distance, it will be necessary to install optical accelerometers at multiple locations, which will naturally increase the number of optical couplers. When the intensity of light branched by the coupler is further reduced, the intensity of reflected light from the sensor FBG located far from the light source among the sensors FBG of each optical accelerometer is significantly reduced. Therefore, it is predicted that the position where the vibration has occurred cannot be specified, and there is a problem that the measurement accuracy deteriorates.

  The present invention has been made in view of such a situation, and even when measuring a plurality of locations over a long distance, without reducing the intensity of light from a light source whose course is changed. An object of the present invention is to provide a sensing system capable of improving measurement accuracy.

The sensing system of the present invention corresponds to a light source that emits light having different wavelengths, a plurality of light output destination changing means for changing the output destination of light from the light source, and these light output destination changing means. A plurality of specific wavelength reflecting means for reflecting light of a specific wavelength whose output destination has been changed by the output destination changing means, and the light reflected by these specific wavelength reflecting means is propagated corresponding to these specific wavelength reflecting means. A plurality of optical fibers, a plurality of external factor change detecting means provided at the ends of these optical fibers, which change the characteristics of the light propagated by the optical fiber according to external factors, and the detection of these external factor changes And a reflected light observation means for observing a change in the characteristic of the light reflected from the means.
In the sensing system of the present invention, the output destinations of light from light sources that emit light having different wavelengths are changed by a plurality of light output destination changing means, and these light output destination changing means correspond to these light output destination changing means. The light of a specific wavelength output from the light is reflected by a plurality of specific wavelength reflection means, and the light reflected by the specific wavelength reflection means is propagated by each optical fiber, and a plurality of light provided at the tips of these optical fibers. The external factor change detection means changes the characteristics of the light propagated by the optical fiber according to the external factor, and the reflected light observation means observes the change in the characteristics of the reflected light from the external factor change detection means. Is done.
That is, in the present invention, since the light source emits light having different wavelengths, for example, external factor change detection means for measuring external factors when performing vibration observation, temperature observation, water level observation, speed observation, acceleration observation, strain observation, etc. Various detection means can be used.
In addition, the light output destination changing means in the present invention does not branch the light as in the conventional optical coupler, but changes the light output destination. The intensity of each light whose output destination is changed by the output destination changing means does not decrease.

  According to the sensing system of the present invention, various detection means are used as external factor change detection means for measuring external factors when performing vibration observation, temperature observation, water level observation, speed observation, acceleration observation, strain observation, and the like. In addition, since the light output destination changing means does not split the light as in the conventional optical coupler, but changes the light output destination, the light intensity is greatly reduced by changing the light output destination. In practical use, a decrease in light intensity does not become a problem, so even if the number of light output destination changing means increases, the intensity of each light whose output destination is changed by each light output destination changing means decreases. Therefore, even when a plurality of points are measured over a long distance, the measurement accuracy can be increased without reducing the intensity of light from the light source whose course is changed.

It is a figure for demonstrating 1st Embodiment of the sensing system of this invention. It is a figure for demonstrating the specific structural example of the detection part of FIG. It is a figure for demonstrating 2nd Embodiment at the time of changing the structure of the sensing system of FIG. It is a figure for demonstrating 3rd Embodiment at the time of changing the structure of the sensing system of FIG.

Details of the embodiment of the present invention will be described below.
(First embodiment)
FIG. 1 is a diagram for explaining an embodiment of the sensing system of the present invention, and FIG. 2 is a diagram for explaining a specific configuration example of the detection unit of FIG. The following sensing systems are suitable for measurements such as vibration observation, temperature observation, water level observation, velocity observation, acceleration observation, strain observation, etc., and any sensing system that observes changes in light characteristics can be used. Although the application is not limited, for the sake of easy understanding of the description, for example, it is assumed that vibration observation is performed.

  The sensing system shown in FIG. 1 includes a measurement unit 1 and a measurement unit 2 that are connected by an optical fiber 300. The measuring unit 1 includes laser diodes 101 to 103, a wavelength multiplexing coupler 104, an optical amplifier 105, an optical circulator 106, an optical amplifier 107, a wavelength separation coupler 108, photodetectors 109 to 111, AD converters 112 to 114, a data processing device. 115.

  The laser diodes 101 to 103 are light sources and emit light having predetermined wavelengths (λ1 to λn), respectively. Here, the predetermined wavelengths (λ1 to λn) are adjusted to the characteristics of FBGs 116 to 127 described later.

  The wavelength combining coupler 104 combines wavelengths (λ1 to λn) of light emitted from the laser diodes 101 to 103. The optical amplifier 105 amplifies the light from the wavelength multiplexing coupler 104 to a predetermined level.

  The optical circulator 106 outputs the light amplified by the optical amplifier 105 to the measurement unit 2 side via the optical fiber 300, and outputs the reflected light from the optical fiber 300 to the optical amplifier 107 side via the optical fiber 301. Or Here, the optical circulator 106 has a plurality of ports (terminals). For example, if the optical circulator 106 has three ports (terminals), the light input to the first port is, for example, the second port. The light is output only to the port, light input to the second port is output only to the third port, and light input to the third port is output only to the first port.

  The optical amplifier 107 amplifies the reflected light from the respective measurement units 2 via the optical fiber 301 to a predetermined level. The wavelength separation coupler 108 separates the reflected light amplified to a predetermined level by the optical amplifier 107 into respective wavelengths (λ1 to λn).

  The photodetectors 109 to 111 take out the light of each wavelength (λ1 to λn) separated by the wavelength separation coupler 108 as an electrical signal (analog signal). The AD converters 112 to 114 convert electric signals (analog signals) from the photodetectors 109 to 111 into digital signals. The data processor 115 accumulates each digital signal from the AD converters 112 to 114 and converts it into a predetermined data expression format.

  The measurement unit 2 includes optical circulators 106a to 106l, FBG (Fiber Bragg Grating Sensor) 116 to 127, and detection units 128 to 139. In FIG. 1, each measurement unit 2 includes four optical circulators 106 a to 106 d, 106 e to 106 h, 106 i to 106 l, FBGs 116 to 127, and detection units 128 to 139. For example, the optical circulators 106 a to 106 l, the FBGs 116 to 127, and the detection units 128 to 139 may be configured by one, two, or three, respectively. Of course, it may be composed of more than one.

  Like the optical circulator 106, the optical circulators 106a to 106l have a plurality of ports (terminals). For example, assuming that the optical circulators 106a to 106l have three ports (terminals), the first port, for example, The light input to the second port is output only to the second port, the light input to the second port is output only to the third port, and the light input to the third port is output only to the first port. It has the following characteristics.

  The FBGs 116 to 127 have a characteristic of reflecting only light having the same wavelength as the respective predetermined wavelengths (λ1 to λn) from the laser diodes 101 to 103 which are the light sources described above. That is, for example, the FBG 116 reflects only light having the wavelength (λ1) from the laser diode 101, the FBG 117 reflects only light having the wavelength (λ2) from the laser diode 102, and the FBG 127 reflects the wavelength (λn) from the laser diode 103. It reflects only the light.

  Here, the FBGs 116 to 127 have a characteristic of reflecting only light having a specific wavelength (λ1 to λn) called a Bragg wavelength proportional to the refractive index modulation period. In the FBGs 116 to 127, the Bragg wavelength changes when strain is applied in the longitudinal direction or the temperature changes. The amount of change varies linearly with changes in strain, temperature, etc. applied to the FBG.

  The detection units 128 to 139 constitute a sensor that detects vibration and causes a change in the wavelength or intensity of light by the detected vibration.

  Here, an example of the configuration of the detection units 128 to 139 will be described with reference to FIGS. Since all the configurations of the detection units 128 to 139 are the same, the detection unit 128 will be described as a representative in FIG.

  First, as shown in FIG. 2A, the detection unit 128 is attached to an arbitrary measurement object 400. The detection unit 128 includes an FBG 200 provided on the distal end side of the optical fiber 302, a pulley 201 that holds a posture extending in a vertical direction so that the optical fiber 302 does not bend, and a vibration transmission pulley that transmits vibration to the optical fiber 302. 202.

  The FBG 200 reflects only light having the same wavelength as the FBG 116 shown in FIG. One end of a support bar 204 is connected to the vibration transmission pulley 202. A weight 205 biased upward by a spring 206 is connected to the other end of the support bar 204. In the figure, reference numeral 209a is a bracket for fixing the vibration transmission pulley 202 to the measurement object 400, reference numeral 209b is a bracket for fixing the pulley 201 to the measurement object 400, and reference numeral 209c is a front end side of the optical fiber 302. A bracket fixed to the measurement object 400.

  In such a detection unit 128, when the measurement object 400 vibrates, the weight 205 biased upward by the spring 206 vibrates in the direction of the arrow, and rotates the support bar 204 in the direction of the arrow. That is, a vibration meter is constituted by the weight 205 urged upward by the spring 206 and the support bar 204. At this time, one end of the support rod 204 transmits vibration to the optical fiber 302 via the vibration transmission pulley 202, whereby vibration is transmitted to the FBG 200 in the form of expansion and contraction in the arrow direction. Thereby, a change occurs in the wavelength of the reflected light from the FBG 200, and the detection unit 128 configured to change the reflected light in conjunction with the vibration is configured.

  2B, one end side of the leaf spring 208 is attached to the measurement object 400, and the weight 205 urged upward by the spring 206 is connected to the other end side of the leaf spring 208. ing. In addition, an attached diaphragm 207 provided at the tip of the optical fiber 302 is attached to one end side of the leaf spring 208.

  In such a detection unit 128, when the measurement object 400 vibrates, the weight 205 urged upward by the spring 206 vibrates, and the leaf spring 208 vibrates in the direction of the arrow. That is, the vibration meter is constituted by the weight 205 urged upward by the spring 206 and the leaf spring 208. At this time, a change occurs in the intensity of the reflected light from the diaphragm 207 forming the optical interferometer, and the detection unit 128 is configured such that the intensity of the reflected light changes in conjunction with the vibration.

  Next, vibration measurement in the sensing system will be described. First, the laser diodes 101 to 103 of the measuring unit 1 are driven, and light is output from each of the laser diodes 101 to 103. At this time, light having a wavelength of λ1 is output from the laser diode 101, light having a wavelength of λ2 is output from the laser diode 102, and light having a wavelength of λn is output from the laser diode 103. These wavelengths (λ1 to λn) are matched to the characteristics of the FBGs 116 to 127 as described above.

  The respective lights output from the laser diodes 101 to 103 are combined by the wavelength combining coupler 104, amplified to a predetermined level by the optical amplifier 105, and output to the optical fiber 300 via the optical circulator 106. The light output from the optical circulator 106 passes through all the optical circulators 106a to 106l of the measurement unit 2 and propagates to the end.

  Here, the FBG 116 reflects light having a wavelength of λ1 and enters the detection unit 128 side through the optical fiber 302 from the optical circulator 106a. Similarly, the FBG 117 reflects light having a wavelength of λ2, and enters the detection unit 129 side through the optical fiber 302 from the optical circulator 106b. In the same manner, similarly, each of the FBGs 118 to 127 reflects light having a wavelength of λ3 to λn, and enters the detection units 130 to 139 via the optical fiber 302 from the optical circulators 106c to 106l.

  Here, for example, if the detection unit 128 of the measurement unit 2 has the configuration shown in FIG. 2A, the weight 205 biased upward by the spring 206 is vibrated in the direction of the arrow due to the measurement object 400 vibrating. By rotating the support rod 204 in the direction of the arrow, the one end side of the support rod 204 transmits the vibration to the optical fiber 302 via the vibration transmission pulley 202, and the FBG 200 is expanded and contracted in the direction of the arrow. Reportedly. Thereby, a change occurs in the wavelength of the reflected light from the FBG 200 in conjunction with the vibration of the measurement object 400. This phenomenon is the same in the other detection units 129 to 139 of the measurement unit 2.

  For example, if the detection unit 128 of the measurement unit 2 has the configuration shown in FIG. 2B, the weight 205 urged upward by the spring 206 vibrates when the measurement object 400 vibrates, The leaf spring 208 is vibrated in the direction of the arrow. At this time, the intensity of the reflected light from the diaphragm 207 changes, and the intensity of the reflected light changes in conjunction with the vibration of the measurement object 400. This phenomenon is the same in the other detection units 129 to 139 of the measurement unit 2.

  And when the reflected light from each detection part 128 returns to the measurement part 1 via the optical circulators 106a-106l and the optical fiber 300, it will be branched to the optical fiber 301 side by the optical circulator 106 of the measurement part 1, and the optical amplifier 107 Is amplified to a predetermined level and output.

  The reflected light amplified to a predetermined level by the optical amplifier 107 is separated into the respective wavelengths (λ1 to λn) by the wavelength separation coupler 108 and the respective wavelengths (λ1 to λn) separated by the photodetectors 109 to 111. Light is extracted as an electrical signal (analog signal). Then, each digital signal from the AD converters 112 to 114 is accumulated by the data processing device 115 and converted into a predetermined data expression format.

  Here, when the reflected light from each measurement unit 2 changes in the wavelength of the reflected light from the FBG 200 in conjunction with the vibration of the measurement object 400 described with reference to FIG. Assuming that the data expression format is represented by, for example, a light spectrum, it is possible to observe the spectra of the reflection wavelengths of λ1 to λn. Further, if the data expression format by the data processing device 115 is expressed by, for example, light intensity, it is possible to observe changes in the intensity of the reflected wavelengths of λ1 to λn.

  In this case, it is assumed that each measurement unit 2 has the configuration shown in FIG. 2A, and when a distortion linked to the vibration of the measurement object 400 occurs in the FBG 200 of any measurement unit 2, the reflected wavelength shifts to the short wavelength side. Therefore, the reflection wavelength is different from that of the corresponding FBG 116. At this time, since the amount of light reflected by the FBG 200 of the measurement unit 2 is reduced, if the data representation format by the data processing device 115 is represented by, for example, a light spectrum, it is confirmed that vibration has occurred from the light spectrum. It becomes possible.

  Further, it is assumed that each measurement unit 2 has the configuration of FIG. 2B, and the intensity of reflected light from any one of the measurement units 2 changes in conjunction with the vibration of the measurement object 400, and the data processing device 115. If the data expression format is expressed by, for example, light intensity, it is possible to confirm that vibration has occurred from the change in the light intensity.

  As described above, in the first embodiment, light from the laser diodes 101 to 103 that are a plurality of light sources that emit light having different wavelengths is combined by the wavelength combining coupler 104 that is a combining unit, and the wavelength combining coupler is used. The output destination of the light from 104 is changed by optical circulators 106a to 106l which are a plurality of optical output destination changing means, and corresponds to these optical circulators 106a to 106l, and a specific wavelength output from these optical circulators 106a to 106l Are reflected by the FBGs 116 to 127 that are a plurality of specific wavelength reflecting means, and the lights reflected by these FBGs 116 to 127 are propagated by the plurality of optical fibers 302 to correspond to these FBGs 116 to 127. Detection that is a plurality of external factor change detection means provided at the tip of the fiber 302 128 to 139 changes the characteristics of the light propagated by the optical fiber 302 in accordance with external factors, and the reflected light from these detection units 128 to 139 is changed for each wavelength by the wavelength separation coupler 108 which is a wavelength separation means. The light of each wavelength (λ1 to λn) separated by the wavelength separation coupler 108 is taken out as an electrical signal by a plurality of photodetectors 109 to 111, and the light from these photodetectors 109 to 111 is extracted. When the signals are converted into digital signals by the AD converters 112 to 114, the respective digital signals from the AD converters 112 to 114 are accumulated by the data processing device 115 as reflected light observation means and converted into a predetermined data expression format. Is done.

  That is, in the first embodiment, since a plurality of laser diodes 101 to 103 are provided to emit light having different wavelengths (λ1 to λn), for example, an external factor change for measuring an external factor when performing vibration observation The detection units 128 to 139 that are detection means are not limited to conventional FBGs, but various detection means such as a vibrometer as shown in FIG. Detection means can be used.

  Further, the optical circulators 106a to 106l serving as the optical output destination changing means in the first embodiment are not for splitting the light as in the conventional optical coupler but for changing the output destination of the optical circulator 106a. Even if .about.106 l increases, the intensity of each light whose output destination is changed by each of the optical circulators 106a to 106l does not decrease.

  For this reason, for example, various detection means can be used as the detection units 128 to 139 for measuring external factors when performing vibration observation, and the optical circulators 106a to 106l are similar to conventional optical couplers. Since the output destination of light is not changed but the output destination of light is changed, the intensity of each light whose output destination is changed by each of the optical circulators 106a to 106l decreases even if the number of optical circulators 106a to 106l increases. Therefore, even when a plurality of points are measured over a long distance, the measurement accuracy is improved without reducing the intensity of light from the laser diodes 101 to 103 whose path is changed. Can do.

(Second Embodiment)
FIG. 3 is a diagram showing a second embodiment when the configuration of the sensing system of FIG. 1 is changed. Note that, in the drawings shown below, the same reference numerals are given to portions common to those in FIG.

  In the second embodiment, each of the plurality of photodetectors 109 to 111 and AD converters 112 to 114 shown in FIG. 1 is a single photodetector 109 and AD converter 112, and the photodetector 109 and the wavelength separation coupler 108 are 1 is different from the sensing system of FIG. 1 only in that a high-speed optical switch 140 is provided.

  In such a configuration, as in the first embodiment, when the reflected light from each detection unit 128 returns to the measurement unit 1 via the optical circulators 106a to 106l and the optical fiber 300, the optical circulator 106 of the measurement unit 1 is used. Is branched to the optical fiber 301 side, amplified to a predetermined level by the optical amplifier 107 and output.

  The reflected light amplified to a predetermined level by the optical amplifier 107 is separated into the respective wavelengths (λ1 to λn) by the wavelength separation coupler 108. Here, the respective wavelengths (λ1 to λn) are separated by the high-speed optical switch 140. ) So as to be sequentially output to the photodetector 109.

  That is, the switching by the high-speed optical switch 140 is performed according to the time difference when the reflected light from each of the detection units 128 to 139 returns, for example, so that the photodetector 109 is provided for each wavelength (λ1 to λn) of the reflected light. It is possible to output sequentially.

  As a result, the high-speed optical switch 140 outputs reflected light of only the wavelength (λ1) to the photodetector 109, and the high-speed optical switch 141 outputs reflected light of only the wavelength (λ2) to the photodetector 110. In 142, reflected light having only a wavelength (λn) is output to the photodetector 111.

  Then, light of each wavelength (λ1 to λn) sequentially output by the switching of the high-speed optical switch 140 is extracted as an electrical signal (analog signal) by the photodetector 109, converted into a digital signal by the AD converter 112, and data When the signals are sequentially output to the processing device 115, the digital signals sequentially output from the AD converter 112 by the data processing device 115 are accumulated and converted into a predetermined data expression format as described above.

  As described above, in the second embodiment, the plurality of photodetectors 109 to 111 and the AD converters 112 to 114 shown in FIG. Since the high-speed optical switch 140 is provided between the separation coupler 108, the high-speed optical switch 140 performs switching so that the reflected light is sequentially output to the photodetector 109 for each wavelength (λ1 to λn). Therefore, even if each of the photodetectors 109 to 111 and the AD converters 112 to 114 is a single one, the path is changed when measuring a plurality of locations over a long distance, as in the first embodiment. Measurement accuracy can be increased without reducing the intensity of light from the laser diodes 101-103.

(Third embodiment)
FIG. 4 is a diagram showing a third embodiment when the configuration of the sensing system of FIG. 1 is changed. Note that, in the drawings shown below, the same reference numerals are given to portions common to those in FIG.

  In the third embodiment, high-speed optical switches 140 to 142 are provided between the photodetectors 109 to 111 and the wavelength separation coupler 108 shown in FIG. 1 so as to correspond to the respective photodetectors 109 to 111. Only, the configuration is different from the sensing system of FIG.

  In such a configuration, as in the first embodiment, when the reflected light from each detection unit 128 returns to the measurement unit 1 via the optical circulators 106a to 106l and the optical fiber 300, the optical circulator 106 of the measurement unit 1 is used. Is branched to the optical fiber 301 side, amplified to a predetermined level by the optical amplifier 107 and output.

  The reflected light amplified to a predetermined level by the optical amplifier 107 is separated into the respective wavelengths (λ1 to λn) by the wavelength separation coupler 108. Here, the respective photodetectors are respectively detected by the high-speed optical switches 140 to 142. Only wavelengths (λ1 to λn) corresponding to 109 to 111 are switched so as to be output to the respective photodetectors 109 to 111.

  That is, the high-speed optical switch 140 outputs only the reflected light of the wavelength (λ1) to the photodetector 109, and the high-speed optical switch 141 outputs the reflected light of only the wavelength (λ2) to the photodetector 110. Then, the reflected light having only the wavelength (λn) is output to the photodetector 111.

  Here, similarly to the second embodiment, switching by the high-speed optical switch 140 is performed according to a time difference when the reflected light from each of the detection units 128 to 139 returns, for example, so that each of the photodetectors 109 to 109 is switched. Only wavelengths (λ1 to λn) corresponding to 111 can be output to the respective photodetectors 109 to 111.

  Then, light of each wavelength (λ1 to λn) sequentially output by the switching of the high-speed optical switch 140 is extracted as an electrical signal (analog signal) by the photodetector 109, converted into a digital signal by the AD converter 112, and data When the signals are sequentially output to the processing device 115, the digital signals sequentially output from the AD converter 112 by the data processing device 115 are accumulated and converted into a predetermined data expression format as described above.

  Thus, in the third embodiment, the high-speed optical switches 140 to 142 are provided between the photodetectors 109 to 111 and the wavelength separation coupler 108 shown in FIG. Therefore, the high-speed optical switches 140 to 142 are switched so that only the wavelengths (λ1 to λn) corresponding to the photodetectors 109 to 111 are output to the photodetectors 109 to 111, respectively. In the case where the high-speed optical switches 140 to 142 and the photodetectors 109 to 111 are made to correspond to each other, even when the measurement is performed at a plurality of locations over a long distance, the course is the same as in the first embodiment. Measurement accuracy can be improved without reducing the intensity of light from the laser diodes 101 to 103 to be changed.

  In the first to third embodiments described above, a case where a plurality of laser diodes 101 to 103 as light sources are provided for each wavelength has been described. However, the present invention is not limited to this example, and the output is uniform over a wide band. It may be configured to selectively output light of a predetermined wavelength using an ASE (Amplified Spontaneous Emission) light source that emits spontaneous emission light, or to output light of a predetermined wavelength using a variable wavelength LD light source. .

  In the first and third embodiments described above, a case has been described where a plurality of photodetectors 109 to 111 and AD converters 112 to 114 are provided for each wavelength. However, the present invention is not limited to this example, and the second embodiment. As described above, even if the photodetectors 109 to 111 and the AD converters 112 to 114 are configured by extracting only predetermined wavelengths (λ1 to λn) by switching by the high-speed optical switch 140, Good.

  In the first to third embodiments described above, the digital signal sequentially output from the AD converter 112 or the AD converters 112 to 114 is accumulated by the data processing device 115 and converted into a predetermined data expression format. Although described as an example, the present invention is not limited to this example, and reflected light may be observed using an optical spectrum analyzer, an optical power meter, or the like.

  In the first to third embodiments described above, the sensing system in each embodiment has been described as performing vibration observation, for example. However, the present invention is not limited to this, and temperature observation, water level observation, speed observation, acceleration Of course, the present invention may be applied to other measurements for observation, strain observation, and the like.

101-103 Laser diode 104 Wavelength multiplexing coupler 105 Optical amplifier 106 Optical circulator 106a-106l Optical circulator 107 Optical amplifier 108 Wavelength separation coupler 112-114 AD converter 115 Data processing device 116-127 FBG
128 to 139 Detectors 140 to 142 High-speed optical switch 201 pulley 202 vibration transmission pulley 204 support rod 205 weight 206 spring 207 diaphragm 208 leaf spring 300 to 301 optical fiber 400 object to be measured

Claims (1)

Light sources that emit light of different wavelengths;
A plurality of light output destination changing means for changing the output destination of light from the light source;
Corresponding to these light output destination changing means, a plurality of specific wavelength reflecting means for reflecting the light of the specific wavelength whose output destination has been changed by these light output destination changing means,
A plurality of optical fibers corresponding to these specific wavelength reflecting means and propagating the light reflected by these specific wavelength reflecting means;
A plurality of external factor change detection means provided at the ends of these optical fibers, which change the characteristics of light propagated by the optical fiber according to external factors;
A sensing system comprising: reflected light observation means for observing changes in the characteristics of light reflected from the external factor change detection means.

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