Analysis processing system

Abstract

An analysis device 200 of the present disclosure analyzes the fluctuation of an instantaneous frequency having an intensity at a prescribed point in the longitudinal direction of an optical fiber 1, the fluctuation being measured by an OFDR measuring instrument 100 which emits light to the optical fiber 1 and measures the intensity distribution of scattered light in the optical fiber 1, and compensates for the fluctuation of the instantaneous frequency on the basis of the analysis result regarding the fluctuation of the instantaneous frequency.

Description

Analysis and Processing System

[0001] The present disclosure relates to a technique for analyzing the spectrum of backscattered light from an object to be measured.

[0002] Optical Frequency Domain Reflectometry (OFDR) is a known inspection technique for optical fibers and optical devices in field environments (e.g., in the city). OFDR can measure the distribution of optical fibers by distinguishing the light reflection positions based on time-series data (spectrogram) of the spectrum of Rayleigh backscattered light.

[0003] In such OFDRs, the spatial resolution is degraded due to fiber noise (e.g., acoustics and fiber vibrations) originating from the environment around the optical fiber, and the theoretical spatial resolution cannot be achieved, as shown in Non-Patent Document 1. This degradation of spatial resolution limits the measurement distance of the OFDR.

[0004] As described above, the measurement distance is limited not only by the noise of the OFDR measuring instrument itself but also by the fiber noise caused by the environment in which the object under test is located, making it difficult to apply OFDR to field environments. In particular, since fiber noise accumulates as the fiber length increases, there is a problem that application to long-distance measurements (for example, applications to measurements of 100 m or more) is difficult.

[0005] Y. Koshikiya, X. Fan and F. Ito, “Influence of acoustic perturbation of fibers in phase-noise compensated optical frequency domain "reflectometry", J. Lightw. Technol. , vol. 28, no. 22, pp. 3323-3328, Nov. 2010. Okamoto, Tatsuya, et al. “Deployment condition visualization of aerial optical fiber cable by distributed vibration sensing based on optical ” Journal of Lightwave Technology 39.21 (2021): 6942-6951.

[0006] In order to solve the above problem, an object of the present disclosure is to provide a technique capable of compensating for the influence of noise caused by the environment in which a device under test is placed.

[0007] To achieve the above objective, the analysis device and method disclosed herein employ a technique of analyzing fluctuations in the instantaneous frequency of intensity at a specified point in the longitudinal direction of the object being measured, and compensating for the fluctuations in the instantaneous frequency based on the analysis results.

[0008] Specifically, the analysis device disclosed herein analyzes fluctuations in the instantaneous frequency of intensity at a predetermined point in the longitudinal direction of the object being measured by a measurement device that irradiates light onto the object being measured and measures the intensity distribution of scattered light in the object being measured, and compensates for the fluctuations in the instantaneous frequency based on the analysis results of the fluctuations in the instantaneous frequency.

[0009] Furthermore, a spectrogram showing the change over time in the instantaneous frequency of the intensity at the specified point may be generated by a short-time Fourier transform, the modulation of the instantaneous frequency that caused the fluctuation may be obtained from the spectrogram, the modulation of the instantaneous frequency may be integrated over time to obtain the phase modulation of the instantaneous frequency, and the fluctuation of the instantaneous frequency may be compensated for by multiplying the intensity at the specified point by a signal of the opposite phase to the phase modulation.

[0010] More specifically, an analysis processing system according to the present disclosure includes the above-described analysis device and a measurement device that irradiates light onto an object to be measured and measures the intensity distribution of scattered light from the object to be measured.

[0011] In addition, the analysis method disclosed herein includes irradiating light onto an object to be measured, measuring the intensity distribution of scattered light in the object to be measured, analyzing fluctuations in the instantaneous frequency of the intensity at a predetermined point in the longitudinal direction of the object to be measured, and compensating for the fluctuations in the instantaneous frequency based on the analysis results of the fluctuations in the instantaneous frequency.

[0012] The above disclosures can be combined as much as possible.

[0013] According to the present disclosure, it is possible to compensate for the influence of noise caused by the environment in which the device under test is placed.

[0014] FIG. 1 is a diagram illustrating a configuration of an analysis processing system according to a first embodiment of the present disclosure. FIG. 2 is a diagram illustrating a problem of the present disclosure, showing a spectrum when fiber noise is not present. FIG. 3 is a diagram illustrating a problem of the present disclosure, showing a spectrum when fiber noise is present. FIG. 4 is a diagram illustrating spectrum broadening. FIG. 5 is a graph illustrating a beat signal. FIG. 6 is a graph illustrating a reflected light intensity distribution. FIG. 7 is a graph illustrating a beat signal at a reflection point. FIG. 7 is a graph illustrating a spectrogram. FIG. 8 is a graph illustrating beat frequency modulation. FIG. 9 is a graph illustrating phase modulation. FIG. 10 is a graph illustrating a beat signal compensated for fiber noise. FIG. 11 is a graph illustrating reflected light intensity from which fiber noise has been removed. FIG. 12 is a diagram illustrating a configuration of an analysis processing system according to a second embodiment of the present disclosure. FIG. 13 is a graph illustrating a beat signal. FIG. 14 is a graph illustrating a reflected light intensity distribution. FIG. 15 is a graph illustrating a beat signal at a reflection point. FIG. 16 is a graph illustrating a spectrogram. FIG. 17 is a graph illustrating beat frequency modulation. FIG. 18 is a graph illustrating phase modulation. FIG. 19 is a graph illustrating a beat signal compensated for fiber noise. FIG. 20 is a graph illustrating reflected light intensity from which fiber noise has been removed. FIG. 21 is a flowchart illustrating processing by an analysis device.

[0015] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the present disclosure is not limited to the embodiments shown below. These implementation examples are merely illustrative, and the present disclosure can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. Note that components with the same reference numerals in this specification and drawings indicate the same components.

[0016] First Embodiment [System Configuration] The system configuration of an analysis processing system according to a first embodiment of the present disclosure will be described with reference to Fig. 1 . The analysis processing system according to the first embodiment includes an OFDR measuring instrument 100 and an analysis device 200. The OFDR measuring instrument 100 measures the spectrum of backscattered light reflected or scattered by an optical fiber under test based on the principle of OFDR (Optical Frequency Domain Reflectometry). The analysis device 200 acquires and analyzes the spectral data obtained by the OFDR measuring instrument 100. The analysis device 200 functions as the analysis device of the present disclosure and can be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0017] The OFDR measuring instrument 100 includes a tunable light source 2 (TLS) that is a frequency swept light source, couplers 3-1 and 3-2, a circulator 4, a balanced photodetector 5 (BPD), and an analog-to-digital (AD) converter 6. The OFDR measuring instrument 100 functions as the "measurement device" in this disclosure. The analyzing device 200 includes a band-pass filter 7 (BPF).

[0018] The tunable light source 2 emits frequency-modulated light. The coupler 3-1 splits the light from the tunable light source 2 into reference light and probe light. The probe light split by the coupler 3-1 is incident on the optical fiber 1 under test via the circulator 4. The optical fiber 1 under test is an example of an "object under test." The object under test is not limited to an optical fiber and may be another optical device. The coupler 3-2 combines the signal light, which is backscattered light in the optical fiber 1 under test, with the reference light split by the coupler 3-1. The balanced photoreceiver 5 receives the interference light combined by the coupler 3-2. This interference light has a beat frequency corresponding to the difference in optical path length between the optical path of the reference light and the optical path of the probe light. The AD converter 6 converts the output signal from the balanced photoreceiver 5 into a digital signal. The analyzer 200 analyzes the digital signal from the AD converter 6.

[0019] [Analysis Principle] The analysis principle by the analysis device 200 will be described with reference to Figs. 2 to 4. As shown in Fig. 2, the wavelength-tunable light source 2 oscillates frequency-swept light whose frequency is swept at a constant sweep rate γ. Here, the optical frequency ν = γt. As shown in Fig. 2, when there is no fiber noise (e.g., acoustics or fiber vibration) due to the environment surrounding the optical fiber 1 to be measured, the delay τ １ Beat frequency f due to backscattered light from ｂｅａｔ = γτ １ A beat signal with a clean waveform can be obtained without modulation. A spectrum with a sharp peak can be obtained by subjecting the beat signal to a Fast Fourier Transform (FFT).

[0020] 3, if there is fiber noise due to the environment surrounding the optical fiber 1 under test, the backscattered light is frequency-modulated by the fiber noise. Accordingly, the beat frequency of the backscattered light is also modulated. Therefore, when the beat signal is subjected to a fast Fourier transform, a certain degree of broadening (frequency broadening) may occur in the spectrum corresponding to the reflection point.

[0021] Such broadening can be so large that it includes multiple peaks corresponding to reflection points in the absence of fiber noise, as shown in Figure 4. Figure 4 shows how spectral broadening can be measured in the absence of fiber noise. ０ From t Ｎ In other words, in the presence of fiber noise, the theoretical spatial resolution cannot be achieved without any processing.

[0022] This spectrum broadening occurs because the period of frequency modulation due to fiber noise is shorter than the measurement time of the beat signal. Specifically, if the time width of the fast Fourier transform is sufficiently shorter than the period of frequency modulation, the spectrum does not broaden even if the instantaneous frequency fluctuates over time due to fiber noise. On the other hand, if the time width of the fast Fourier transform is longer than the period of frequency modulation, the fluctuations in the instantaneous frequency broaden the spectrum.

[0023] Therefore, in the first embodiment of the present disclosure, the analysis device 200 is used to analyze the instantaneous frequency of the beat signal (fiber noise) by time-frequency analysis such as short-time Fourier transform, and the spectral broadening is compensated for.

[0024] Specifically, the analysis device 200 of the present disclosure analyzes the fluctuations in the instantaneous frequency of the intensity at a predetermined point in the longitudinal direction of the optical fiber 1 measured by the OFDR measuring instrument 100, which incidents light onto the optical fiber 1 and measures the intensity distribution of scattered light in the optical fiber 1, and compensates for the fluctuations in the instantaneous frequency based on the analysis results of the fluctuations in the instantaneous frequency.

[0025] More specifically, the analysis processing system of the present disclosure includes an analysis device 200 and an OFDR measurement device 100 that inputs light into an optical fiber 1 and measures the intensity distribution of scattered light in the optical fiber 1 .

[0026] [Analysis Processing] The analysis processing by the analysis device 200 will be described in detail with reference to Figures 5 to 12. Note that Figures 5 to 12 show measurement results obtained when fiber noise is simulated by manually shaking a bundle of optical fibers 1 under test. Below, a case where beat signals at reflection points at a predetermined distance are compensated for will be described. However, the technology disclosed herein can also be used to compensate for beat signals at reflection points at any distance.

[0027] Fig. 5 shows a beat signal obtained by OFDR measurement instrument 100. OFDR measurement instrument 100 sends this beat signal to analysis device 200. As shown in Fig. 6, analysis device 200 performs a fast Fourier transform on the beat signal to obtain a reflected light intensity distribution (spectrum). As shown in the reflected light intensity distribution, the spectrum broadens near the reflection point.

[0028] As shown in Fig. 7, the analysis device 200 uses a band-pass filter 7 to extract beat signals at reflection points from the reflected light intensity distribution. In this case, the band-pass filter 7 may extract beat signals at reflection points depending on the distance range over which fluctuation compensation is performed. In other words, the "reflection point" referred to in this disclosure may be a single point or any section including that single point. Furthermore, the "reflection point" is an example of a "predetermined point" in this disclosure.

[0029] As shown in FIG. 8 , the analysis device 200 acquires a spectrogram of the beat signal at the reflection point using a short-time Fourier transform. That is, a spectrogram showing the change in instantaneous frequency of intensity at a predetermined point over time is generated by the short-time Fourier transform. In this case, the time width of the window function of the short-time Fourier transform may be set shorter than the speed of frequency fluctuation of the fiber noise (the period of frequency modulation). Note that the analysis device 200 may be configured to extract beat signals for each point within a predetermined distance range using the band-pass filter 7, perform a short-time Fourier transform on the multiple beat signals, acquire multiple spectrograms, and then perform the following processing.

[0030] As shown in FIG. 9 , the analysis device 200 analyzes the beat frequency that gives a peak at each time in the spectrogram acquired by short-time Fourier transform (peak analysis) and calculates the beat frequency modulation due to fiber noise. That is, the instantaneous frequency modulation that caused the fluctuation is obtained from the spectrogram. As shown in FIG. 10 , the analysis device 200 time-integrates the beat frequency modulation to calculate the phase modulation due to fiber noise. That is, the instantaneous frequency modulation is time-integrated to obtain the phase modulation of the instantaneous frequency. In other words, the fluctuation in the beat frequency calculated in FIG. 9 is integrated over time to obtain a graph showing the phase change of the beat signal.

[0031] As shown in Fig. 11 , the analysis device 200 obtains a beat signal compensated for fiber noise by multiplying the beat signal at the reflection point shown in Fig. 7 by a signal that is in the opposite phase to the phase modulation shown in Fig. 10 . That is, by multiplying the intensity at a predetermined point by a signal that is in the opposite phase to the phase modulation, fluctuations in instantaneous frequency are compensated for. Here, the beat signal shown in Fig. 7 contains phase information of the fiber noise because no phase processing has been performed. Therefore, as described above, a beat signal compensated for fiber noise can be obtained by multiplying the beat signal by a signal that is in the opposite phase to the phase modulation of the fiber noise obtained by processing involving a short-time Fourier transform.

[0032] As shown in Figure 12, the analysis device 200 performs a fast Fourier transform on the beat signal after compensating for the fiber noise to obtain a reflected light intensity distribution (spectrum) from which the fiber noise has been removed. As shown in the reflected light intensity distribution, by performing the above-described process to compensate for the fiber noise, a sharp peak with reduced spectral broadening can be obtained. In other words, by compensating for the fiber noise using the method of this embodiment, degradation of spatial resolution can be compensated for, and theoretical spatial resolution can be achieved. Specifically, the spectral broadening can be reduced to approximately 625 µm (1 / 160 GHz) for 3 dB of fiber noise.

[0033] According to this embodiment, by obtaining the reflected light intensity with fiber noise removed, OFDR can be applied to long-distance measurements. For example, since it becomes possible to measure the position of a break point several kilometers away in an optical fiber line with a resolution of mm, this can be applied to checking the number of free ports of a splitter in a closure in a remote location.

[0034] Second Embodiment [System Configuration] The system configuration of an analysis processing system according to a second embodiment of the present disclosure will be described with reference to Fig. 13. The analysis processing system according to the second embodiment includes an OFDR measurement device 101 for performing relative distance measurement OFDR and an analysis device 201. The analysis device 201 functions as the analysis device of the present disclosure and can be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network.

[0035] The OFDR measuring instrument 101 includes a tunable light source 2, a coupler 3, a circulator 4, a pair of balanced optical receivers 5-1 and 5-2, an AD converter 6, an optical delay device 8, an optical 90-degree hybrid 9, and a pair of low-pass filters 10-1 and 10-2. The analyzing device 201 includes a band-pass filter 7, similar to the analyzing device 200 in the first embodiment.

[0036] The coupler 3 splits the light from the wavelength-tunable light source 2 into reference light and probe light. The probe light split by the coupler 3 is incident on the optical fiber 1 under test via a circulator 4. On the other hand, the reference light split by the coupler 3 is input to an optical delay device 8. The reference light, which has been input to the optical delay device 8 and has its delay adjusted, and the signal light, which is backscattered light in the optical fiber 1 under test, interfere in an optical 90-degree hybrid 9.

[0037] The optical 90-degree hybrid 9 generates an in-phase component I of a beat signal by combining the reference light and the signal light from the optical fiber 1 under test, and inputs this component to the balanced optical receiver 5-1. The optical 90-degree hybrid 9 also generates a quadrature component Q of a beat signal by combining the reference light, which has been phase-shifted by 90 degrees, and the signal light from the optical fiber 1 under test, and inputs this component to the balanced optical receiver 5-2.

[0038] The balanced optical receiver 5-1 acquires an analog electrical signal of the in-phase component I of the beat signal based on the input from the optical 90-degree hybrid 9, and inputs it to the AD converter 6 via a low-pass filter 10-1. The balanced optical receiver 5-2 acquires an analog electrical signal of the quadrature component Q of the beat signal based on the input from the optical 90-degree hybrid 9, and inputs it to the AD converter 6 via a low-pass filter 10-2. In this embodiment, the low-pass filters 10-1 and 10-2 are provided to acquire only predetermined frequency components, but they are not essential components and may not be provided depending on the overall length of the device under test.

[0039] The AD converter 6 converts the output signals from the balanced optical receivers 5-1 and 5-2 into digital signals. The analyzer 201 analyzes the digital signals from the AD converter 6.

[0040] In this embodiment, the reference light is delayed using the optical delay device 8, so that the reflected light distribution can be measured around a point based on the delay amount given to the reference light (see Non-Patent Document 2). In addition, by increasing the delay of the reference light, it is possible to overcome the short-distance measurement drawback of OFDR and measure a remote point.

[0041] However, as the length of the optical fiber to be measured increases, fiber noise accumulates, and therefore, in the relative distance measurement OFDR, degradation of spatial resolution due to fiber noise becomes more pronounced than in the normal OFDR.

[0042] Therefore, in the second embodiment of the present disclosure, the instantaneous frequency of the beat signal (fiber noise) is analyzed by time-frequency analysis such as short-time Fourier transform using the analysis device 201, and the spectral broadening is compensated for.

[0043] Specifically, the analysis device 201 of the present disclosure analyzes the fluctuations in the instantaneous frequency of the intensity at a predetermined point in the longitudinal direction of the optical fiber 1 measured by the OFDR measuring instrument 101, which incidents light into the optical fiber 1 and measures the intensity distribution of scattered light in the optical fiber 1, and compensates for the fluctuations in the instantaneous frequency based on the analysis results of the fluctuations in the instantaneous frequency.

[0044] More specifically, the analysis processing system of the present disclosure includes an analysis device 201 and an OFDR measurement device 101 that inputs light into the optical fiber 1 and measures the intensity distribution of scattered light in the optical fiber 1 .

[0045] [Analysis Processing] The analysis processing by the analysis device 201 will be described in detail with reference to Fig. 14 to Fig. 21. Fig. 14 to Fig. 21 show measurement results when fiber noise is simulated by shaking the bundled optical fibers 1 to be measured by hand.

[0046] Fig. 14 shows a beat signal obtained by the OFDR measuring instrument 101. The OFDR measuring instrument 101 sends the beat signal to the analyzing device 201. As shown in Fig. 15, the analyzing device 201 performs a fast Fourier transform on the beat signal to obtain a reflected light intensity distribution (spectrum). As shown in the reflected light intensity distribution, the spectrum broadens near the reflection point.

[0047] 16, the analysis device 201 uses the band-pass filter 7 to extract beat signals at reflection points from the reflected light intensity distribution. In this case, the band-pass filter 7 may extract beat signals at reflection points depending on the distance range over which fluctuation compensation is performed. In other words, the "reflection point" referred to in the present disclosure may be a single point or any section including that single point. Furthermore, the "reflection point" is an example of a "predetermined point" in the present disclosure.

[0048] As shown in FIG. 17 , the analysis device 201 uses a short-time Fourier transform to acquire a spectrogram of either the I or Q component of the beat signal at the reflection point. That is, the short-time Fourier transform generates a spectrogram showing the time-dependent change in the instantaneous frequency of the intensity at a predetermined point. In this case, the time width of the window function of the short-time Fourier transform may be set shorter than the rate of frequency fluctuation of the fiber noise (the frequency modulation period). The analysis device 201 may acquire spectrograms of both the I and Q components of the beat signal at any point extracted by the band-pass filter 7. However, since the I and Q components of the beat signal at any point are only 90 degrees out of phase with each other, the spectrograms will have the same waveform. Therefore, the object of the present disclosure can be achieved by simply acquiring a spectrogram of either the I or Q component of the beat signal as described above. Alternatively, the analysis device 201 may be configured to extract beat signals for each point within a predetermined distance range using the band-pass filter 7, perform a short-time Fourier transform on the multiple beat signals, acquire multiple spectrograms, and then perform the following processing.

[0049] As shown in Fig. 18 , the analysis device 201 analyzes the beat frequency that gives a peak at each time in the spectrogram acquired by short-time Fourier transform (peak analysis) and calculates the beat frequency modulation due to fiber noise. That is, the instantaneous frequency modulation that caused the fluctuation is obtained from the spectrogram. As shown in Fig. 19 , the analysis device 201 time-integrates the beat frequency modulation to calculate the phase modulation due to fiber noise. That is, the instantaneous frequency modulation is time-integrated to obtain the phase modulation of the instantaneous frequency. In other words, the fluctuation in the beat frequency calculated in Fig. 18 is integrated over time to obtain a graph showing the phase change of the beat signal.

[0050] As shown in Fig. 20, the analysis device 201 obtains a beat signal compensated for fiber noise by multiplying the beat signal at the reflection point shown in Fig. 16 by a signal having an opposite phase to the phase modulation shown in Fig. 19. In other words, fluctuations in instantaneous frequency are compensated for by multiplying the intensity at a predetermined point by a signal having an opposite phase to the phase modulation. Here, the beat signal shown in Fig. 16 contains phase information of the fiber noise because no phase processing has been performed. Therefore, as described above, a beat signal compensated for fiber noise can be obtained by multiplying the beat signal by a signal having an opposite phase to the phase modulation of the fiber noise obtained by processing involving a short-time Fourier transform.

[0051] As shown in Figure 21, the analyzer 201 performs a fast Fourier transform on the beat signal after compensating for the fiber noise to obtain a reflected light intensity distribution (spectrum) from which the fiber noise has been removed. As shown in the reflected light intensity distribution, by performing the above-described process to compensate for the fiber noise, a sharp peak with reduced spectral broadening can be obtained. In other words, by compensating for the fiber noise using the method of this embodiment, degradation of spatial resolution can be compensated for, and theoretical spatial resolution can be achieved. Specifically, the spectral broadening can be reduced to approximately 40 µm (2.5 THz) for 3 dB of fiber noise.

[0052] According to this embodiment, by obtaining the reflected light intensity with fiber noise removed, OFDR can be applied to long-distance measurements. For example, since it becomes possible to measure the position of a break point several kilometers away in an optical fiber line with a resolution of mm, this can be applied to checking the number of free ports of a splitter in a closure in a remote location.

[0053] (Flowchart) The flow of analysis processing by the analysis processing system of the present disclosure will be described with reference to Fig. 22. In step S1, the OFDR measuring instrument of the analysis processing system measures a beat signal using the method described in the first and second embodiments, and sends the measured beat signal to the analysis device.

[0054] In step S2, the analyzer performs a fast Fourier transform on the beat signal to obtain a reflected light intensity distribution (spectrum).

[0055] In step S3, the analyzer uses a band-pass filter to extract beat signals at the reflection points from the reflected light intensity distribution.

[0056] In step S4, the analyzer acquires a spectrogram of the beat signal at the reflection point using a short-time Fourier transform. If the OFDR measurement device is a relative distance measurement OFDR measurement device, the analyzer may acquire a spectrogram of either the I component or the Q component of the beat signal at the reflection point using a short-time Fourier transform.

[0057] In step S5, the analysis device analyzes the beat frequency that gives a peak at each time of the spectrogram acquired by short-time Fourier transform (peak analysis), and calculates the beat frequency modulation due to fiber noise.

[0058] In step S6, the analyzer integrates the beat frequency modulation over time to calculate the phase modulation due to the fiber noise.

[0059] In step S7, the analyzer multiplies the beat signal at the reflection point acquired in step S3 by a phase modulation that is opposite to the phase modulation calculated in step S6, thereby acquiring a beat signal compensated for the fiber noise.

[0060] In step S8, the analyzer performs a fast Fourier transform on the beat signal from which the fiber noise has been compensated, thereby obtaining a reflected light intensity distribution (spectrum) from which the fiber noise has been removed.

[0061] As described above, the analysis devices 200 and 201 of the present invention can be realized by a computer and a program, and the program can be recorded on a recording medium or provided via a network. The program of the present disclosure is a program for causing a computer to realize each function of the device according to the present disclosure, and is a program for causing a computer to execute each procedure of the method executed by the device according to the present disclosure.

[0062] The technology of the present disclosure can be applied to the information and communications industry.

[0063] 1: Optical fiber to be measured 2: Tunable wavelength light source 3, 3-1, 3-2: Coupler 4: Circulator 5, 5-1, 5-2: Balanced photodetector 6: AD converter 7: Bandpass filter 8: Optical delay 9: Optical 90-degree hybrid 10-1, 10-2: Lowpass filter 100, 101: OFDR measuring instrument 200, 201: Analysis device

Claims

1. An analysis device that analyzes fluctuations in instantaneous frequency of intensity at a predetermined point in the longitudinal direction of an object to be measured by a measurement device that irradiates light onto the object to be measured and measures the intensity distribution of scattered light in the object to be measured, and compensates for the fluctuations in instantaneous frequency based on the analysis results of the fluctuations in instantaneous frequency.

2. The analysis device of claim 1, which generates a spectrogram showing the change in the instantaneous frequency of the intensity at the specified point over time by short-time Fourier transform, obtains the modulation of the instantaneous frequency that caused the fluctuation from the spectrogram, obtains the phase modulation of the instantaneous frequency by time-integrating the modulation of the instantaneous frequency, and compensates for the fluctuation of the instantaneous frequency by multiplying the intensity at the specified point by a signal of the opposite phase to the phase modulation.

3. An analytical processing system comprising: the analytical device according to claim 1 or 2; and a measuring device that irradiates light onto an object to be measured and measures the intensity distribution of scattered light in the object to be measured.

4. An analysis method comprising: irradiating light onto an object to be measured, measuring the intensity distribution of scattered light in the object to be measured, analyzing fluctuations in the instantaneous frequency of the intensity at a predetermined point in the longitudinal direction of the object to be measured, and compensating for the fluctuations in the instantaneous frequency based on the analysis results of the fluctuations in the instantaneous frequency.

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