JP2009281792A - Fbg light spectrum analyzer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speedily and accurately detect a peak wavelength by appropriately restricting the objects of peak detection operations, prior to the calculation of the peak wavelength by function approximation. <P>SOLUTION: A digital operation part 20 for finding the peak wavelength λP from sampling data (23) on rays of reflected light of a plurality of FBGs 19; holds a plurality of groups of parameters (24) including lower-limit wavelength λL, upper-limit wavelength λU, underside intensity IL, and upside intensity IU settable by an external controller 8; selects a wavelength section based on the values of the wavelength section parameters λL, λU (S12); excludes wavelengths less than the lower-limit wavelength λL (S13); performs narrowing down into the range from a maximum value up to the upside intensity IU (S14, S15); and after the objects of peak detection operations are restricted in this way, the peak wavelength λP is calculated by the function approximation (S16). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an FBG optical spectrum analyzer that uses an optical fiber in which an FBG (FiberBraggGrating) is formed. Specifically, the FBG optical spectrum analyzer is used to transmit reflected light from the FBG. The present invention relates to an FBG optical spectrum analyzer that obtains a peak wavelength from the measured sampling data by function approximation.

In order to measure a physical quantity such as temperature and strain at each position in advance by forming a plurality of FBGs on an optical fiber, an FBG optical spectrum analyzer connected to the optical fiber as a sensor is used.
Such an FBG optical spectrum analyzer includes a light transmitting means for sending light into an optical fiber formed with a plurality of FBGs, a photometric means for measuring the light quantity for each wavelength of the reflected light, and the light quantity measurement result. And a peak detection circuit for obtaining a peak wavelength from (see, for example, Patent Document 1).

In addition, the peak detection circuit is designed to obtain the peak wavelength by sampling the light intensity measurement value and performing a digital calculation, and the calculation method is targeted for data in the specified section of the optical spectrum including the peak. A method of calculating a peak wavelength by approximating a quadratic function by a least square method is known (see, for example, Patent Document 2).
Furthermore, the digital calculation unit for obtaining the spectrum center (peak wavelength) of the scattered light is configured by a programmable computer, a digital signal processor, and the like, and if necessary, a secondary storage device such as a hard disk is attached (for example, Patent Document) 3).

JP 2002-116059 A Japanese Patent Laid-Open No. 9-297090 Japanese Patent Application No. 2007-183034

The method for calculating the peak wavelength by function approximation from the sampling data of the light intensity measurement value of the FBG reflected light is not only suitable for digital computation, but also has a resolution and higher accuracy than the sampling pitch wavelength (discrete wavelength width). Since the peak wavelength can be obtained by this, it is useful for realizing a peak detection circuit together with a programmable digital circuit.
However, peak wavelength calculation by function approximation has the property that it takes time to calculate if there is a large amount of sampling data to be subjected to peak detection calculation, whereas it is difficult to maintain high accuracy if there is little sampling data to be subjected to peak detection calculation.

For this reason, when a large number of FBGs are formed in the optical fiber, if it is attempted to accurately obtain the peak wavelength for all the FBGs, the calculation may take time to be undesired compared to the photometric time. It is not suitable for applications that require high-speed processing such as observation of vibration states.
Therefore, in order to realize an FBG optical spectrum analyzer that detects peaks at high speed and with high accuracy by appropriately limiting the peak detection calculation target prior to calculating the peak wavelength by function approximation, the peak related to the sampling data of the FBG reflected light The basic technical issue is how to narrow down the detection calculation target.

Also, the FBG optical spectrum analyzer is used for various applications, and the FBG operating environment and required performance are diverse. For example, when a high-speed and high-accuracy peak detection function is given priority, simple use is given priority. There is also. In order to meet these demands alone, improvements will be made, but this will be the next technical issue.
Furthermore, since the FBG formation status in the optical fiber connected to the FBG optical spectrum analyzer is also diverse, the FBG optical spectrum analyzer that detects peaks at high speed and high accuracy can be easily adapted to various FBG formation states. Further improvement is a further technical problem.

  The FBG optical spectrum analyzer of the present invention (Solution 1) was created in order to solve such problems, and transmits light to an optical fiber in which a plurality of FBGs (fiber Bragg gratings) are formed. In the FBG optical spectrum analyzer, comprising: a means; a photometric means for measuring the light amount for each wavelength of the reflected light; and a peak detection circuit for obtaining a peak wavelength by sampling the light amount measurement value and performing a digital calculation. The digital calculation unit of the peak detection circuit holds a plurality of parameter groups including a wavelength interval parameter value, a lower intensity parameter value, and an upper intensity parameter value. Based on the wavelength interval parameter value, the light intensity measurement value Select the wavelength section to be used for peak detection calculation from the sampling data, and the light intensity in this selected section The sampling data whose constant value is lower than the lower intensity parameter value is excluded from the maximum value search target, the maximum value of the light intensity measurement value is searched from the maximum value search object, and the light intensity measurement value is within the upper intensity parameter value from this maximum value. In this case, the peak detection calculation target is narrowed down to the sampling data in which the signal is contained, and then the peak wavelength is calculated by performing function approximation on the sampling data of the peak detection calculation target.

  The FBG optical spectrum analyzing apparatus according to the present invention is (the solving means 2), the FBG optical spectrum analyzing apparatus according to the above-described solving means 1, wherein the digital operation unit replaces the lower intensity parameter value with a continuous number parameter value. In the parameter group, and instead of excluding sampling data whose light intensity measurement value falls below the lower intensity parameter value in the selected section from the maximum value search target, the continuous number parameter value continues in the selected section. A continuous rising waveform portion and a continuous falling waveform portion are searched, and a maximum value search target is narrowed down to sampling data belonging between both waveform portions.

  Further, the FBG optical spectrum analyzer of the present invention (Solution means 3) is the FBG optical spectrum analyzer of the above-mentioned solution means 1, wherein the digital operation unit includes a continuous number parameter value in the parameter group, After limiting the maximum value search target based on the lower strength parameter value, prior to searching for the maximum value, a continuous rising waveform portion that continues for the maximum number search value at this point and the continuous number of parameter values and continuous The maximum value search target is further limited by searching the descending waveform portion and narrowing down the maximum value search target to the sampling data belonging between both waveform portions.

  The FBG optical spectrum analyzing apparatus according to the present invention (solving means 4) is the FBG optical spectrum analyzing apparatus according to the above-mentioned solving means 2 and 3, wherein the digital operation unit is included in a plurality of consecutive parameters included in the parameter group. Instead of the number parameter value, one common continuous number parameter value is held, and when searching for the continuous rising waveform portion and the continuous falling waveform portion, the common continuous number parameter value is substituted for the continuous number parameter value for any wavelength section. The number parameter value is used.

  The FBG optical spectrum analyzing apparatus according to the present invention is (the solving means 5), the FBG optical spectrum analyzing apparatus according to the above-described solving means 1 to 4, wherein the digital operation unit is a common lower intensity parameter separately from the parameter group. In addition to the peak detection means for calculating a peak wavelength by selecting a wavelength section based on the wavelength section parameter value for the sampling data of the light quantity measurement value and calculating a peak wavelength, the light quantity With respect to the sampling data of the measured value, the peak detection calculation target is determined by removing the sampling data whose light intensity measurement value is lower than the common lower intensity parameter value from the maximum value search target without selecting the wavelength section based on the wavelength section parameter value. It also includes other peak detection means for calculating the peak wavelength by performing function approximation after limiting, Characterized in that it can now select perform any of the peak detecting means.

  Also, the FBG optical spectrum analyzer of the present invention (solving means 6) is the FBG optical spectrum analyzing apparatus of the above-mentioned solving means 1 to 5, wherein all or part of the parameter values can be set from the outside. It is characterized by becoming.

  In such an FBG optical spectrum analyzer of the present invention (Solution 1), the digital calculation unit limits the sampling data to be subjected to peak detection calculation prior to the calculation of the peak wavelength by function approximation. Different types of processing are performed in multiple stages. Specifically, selection of a wavelength section based on the wavelength section parameter value, data exclusion based on the lower intensity parameter value, and data narrowing based on the maximum value and the upper intensity parameter value are performed. Since the peak wavelength at the time of forming the FBG is specified, only one peak waveform corresponding to each FBG is included in the selected section by selecting the wavelength section. And since the tail part of the peak waveform is removed by data exclusion based on the lower intensity parameter value, the maximum value that should be near the peak is efficiently searched, and by narrowing down the data based on the maximum value and the upper intensity parameter value, Sampling data to be subjected to peak detection calculation is quickly and accurately limited.

In this way, since the peak detection calculation target is appropriately limited prior to the peak wavelength calculation by function approximation, the peak is detected at high speed and with high accuracy.
In addition, since a plurality of parameter groups are held using the parameter values such as the wavelength section, the lower intensity, and the upper intensity as parameter groups, one parameter group is assigned to each FBG, and the parameters corresponding to the characteristics of each FBG. By setting the value to the corresponding parameter group, it is possible to easily and appropriately limit the peak detection calculation target.
Therefore, according to the present invention, it is possible to realize an FBG optical spectrum analyzer that detects a peak at high speed and with high accuracy, and a basic technical problem is solved.

  In the FBG optical spectrum analyzer of the present invention (solution 2), instead of excluding data based on the lower intensity parameter value, the maximum value search target is between the continuous rising waveform portion and the continuous falling waveform portion. Therefore, even if noise that expresses a large value sporadically or sporadically appears on the FBG light spectrum when it deviates from the monotonic slope waveform portion such as continuous rise or fall, even if it enters the sampling data. Such a noise component is removed from the maximum value search target.

As a result, even when noise exceeding the peak value occurs, it can be accurately excluded if it is single or sporadic, so that it can avoid undesired influence on the subsequent maximum value search, Even if the maximum value search is employed in order to limit the peak detection calculation target at high speed, the accuracy is maintained high.
Therefore, according to the present invention, it is possible to realize an FBG optical spectrum analyzer that detects a peak at high speed and with high accuracy even when used in a situation where single or sporadic noise is generated.

Furthermore, in the FBG optical spectrum analyzer of the present invention (Solution means 3), after selecting the wavelength section, prior to the maximum value search, in addition to the exclusion of the maximum value search target based on the lower intensity parameter value, the continuous increase The search for the maximum value search target between the waveform portion and the continuously falling waveform portion is also performed. Therefore, the advantages of both can be enjoyed simultaneously.
Therefore, according to the present invention, it is possible to realize an FBG optical spectrum analyzer that detects a peak at a higher speed and with higher accuracy even when used in a situation where single or sporadic noise is generated.

In the FBG optical spectrum analyzer of the present invention (solution 4), since one common continuous number parameter value is shared for peak detection of a plurality of FBGs, the continuous number parameter value is determined for each FBG. Also, the parameter value can be easily determined. On the other hand, the occurrence of single or sporadic noise often shows a similar tendency across the entire optical fiber, and it is unlikely to vary greatly between individual FBGs. Even if the values are made common, there is no inconvenience when a very high accuracy is not required such as preliminary measurement.
Therefore, according to the present invention, it is possible to easily realize an FBG optical spectrum analyzer that detects a peak at high speed and with high accuracy even when used in a situation where single or sporadic noise occurs.

In the FBG optical spectrum analyzer of the present invention (solution 5), the above-mentioned peak detection means for detecting a peak at high speed and high accuracy using a plurality of parameter groups, and a small number of common parameter values are used. Thus, it is possible to selectively use other peak detection means that can detect peaks easily. For example, when checking the operation after setting the apparatus or operating in a favorable environment, the apparatus can be operated simply and quickly by determining a small number of parameter values and selectively executing other peak detection means. On the other hand, when preparing for actual operation or long-term operation of the apparatus, it is possible to detect a peak with high speed and high accuracy by selecting and executing the above-described peak detecting means after determining a plurality of parameter groups corresponding to a plurality of FBGs.
Therefore, according to the present invention, an FBG optical spectrum analyzer suitable for various applications can be realized by selecting a high-speed and high-accuracy peak detection function and simple use, and in addition to basic technical problems. The following technical problem is solved.

  In the FBG optical spectrum analyzer of the present invention (solution 6), the parameter value can be set from the outside, so that the parameter value can be easily set or changed. For this reason, for example, FBG light that detects peaks at high speed and with high accuracy by, for example, providing an external control device with various combinations of parameter values reflecting FBG formation conditions and selecting and setting appropriate parameters. The spectrum analyzer can be easily adapted to various FBG formation states. As a result, according to the present invention, the above-described further technical problems are solved in addition to the basic technical problems.

With respect to such an FBG optical spectrum analyzer of the present invention, specific modes for carrying out this will be described with reference to the following Examples 1 to 5.
The embodiment 1 shown in FIGS. 1 and 2 embodies the above-described solving means 1 and 6 (claims 1 and 6 as originally filed), and the embodiment 2 shown in FIG. Means 2 and 6 (claims 2 and 6 at the beginning of the application) are embodied, and the third embodiment shown in FIG. 4 is the solution means 3 and 6 (claims 3 and 6 at the beginning of the application) described above. The embodiment 4 shown in FIG. 5 is an embodiment of the above-described solving means 4 and 6 (claims 4 and 6 as originally filed), and is shown in FIGS. Example 5 embodies the above-described solving means 5 and 6 (claims 5 and 6 as originally filed).

  A specific configuration of the FBG optical spectrum analyzer according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1A is an overall block diagram of an optical fiber 18 and an external control device 8 connected to an FBG optical spectrum analyzer 10, and FIG. 1B is a block diagram of a digital computing unit 20 of the FBG optical spectrum analyzer 10. is there.

The FBG optical spectrum analyzer 10 of this embodiment (see FIG. 1A) measures the reflected light while transmitting light from one end to an optical fiber 18 in which a large number of FBGs 19 such as a plurality of, for example, 10 are formed, and determines the peak wavelength. One end of the optical fiber 18 can be connected by the optical connector 17 so that transmission / reception with respect to the optical fiber 18 is possible.
Further, the FBG optical spectrum analyzer 10 further performs data processing outside the apparatus 10 for controlling the operation or setting parameter values from the outside, or for the optical spectrum data obtained by photometry and the peak wavelength of the detection result. The external control device 8 having a desired additional function can be connected as necessary, for example, when displaying or displaying the screen.

  Further, the FBG optical spectrum analyzer 10 includes a broadband light source 11 made of, for example, an ASE light source as a light transmitting means for sending light to the optical fiber 18, and a broadband light source 11 as a photometric means for measuring the amount of light for each wavelength of the reflected light. Photoelectric conversion comprising an optical branching device 12 inserted in a light transmission line extending to the optical connector 17, a wavelength tunable filter 13 connected to the branching line, and a photodiode (PD) connected to the output side, for example. And a container 14. Of course, a peak detection circuit 15 for obtaining the peak wavelength from the light amount measurement result output from the photoelectric converter 14 is also provided. It is sufficient that such hardware follows the conventional technology (see, for example, Patent Document 1), and the wavelength sweep may be performed on the light transmission side as usual.

  The peak detection circuit 15 (see FIG. 1A) includes an A / D converter 16 that performs analog-to-digital conversion with a cycle time of 1 μs, for example, in order to sample and digitize a light intensity measurement value, and its sampling data (optical spectrum). ) Is input and digital calculation is performed to obtain a peak wavelength (spectrum center of reflected light). The digital arithmetic unit 20 is composed of a programmable arithmetic circuit such as a microprocessor system (MPU), for example, and also includes an internal memory or an external memory having a sufficient capacity as storage means for accumulating and holding sampling data and the like (for example, Patent Documents). 2 and 3).

  An input program 21, a communication program 22, and a peak detection program 26 are installed in the digital calculation unit 20 (see FIG. 1B), and an input data area 23 and a parameter area 24 are stored in the memory of the digital calculation unit 20. And an output data area 25 are allocated. The input data area 23 holds sampling data (light spectrum / light spectrum) of the light quantity I measured at each wavelength λ in the sweep range of the wavelength tunable filter 13, and can hold, for example, a set of sampling data. A one-dimensional array is reserved. Although only one such array may be used, in this example, in order to improve the processing speed, the array is used for writing and waiting so that data update by the input program 21 and data processing by the peak detection program 26 can be executed in parallel. About three are reserved for reading and reading.

  The input program 21 fetches sampling data from the A / D converter 16 in synchronization with the wavelength sweep of the wavelength tunable filter 13, writes it in the input data area 23, and stores it in three arrays. Of these, writing is performed. When a set of sampling data has been accumulated in the array for writing, the array for writing is switched to the array for standby, and the array for standby is switched to the array for writing. Let When the sampling data is requested from the peak detection program 26, if the unprocessed data is accumulated and held in the standby array, the address of the array for standby is waited for immediately after the data storage is completed otherwise. Is passed to the peak detection program 26. Such an input program 21 can reliably supply the latest data to the peak detection program 26 with a minimum waiting time.

  The communication program 22 writes the parameter value in the corresponding part of the parameter area 24 when it is transmitted by an appropriate message from the external control device 8 regardless of one or many parameter values to be initialized or reset. It has become. When a result output instruction is received from the peak detection program 26, a group of peak wavelengths .lambda.P held in the output data area 25 is read out, and these values are collectively or subdivided with an appropriate message for external control. The data is transmitted to the device 8. Communication between the digital arithmetic unit 20 and the external control device 8 may be one-to-one communication using a dedicated cable, or may be network communication using a wired LAN or a wireless LAN.

  In the parameter area 24, for example, a two-dimensional array is secured in order to hold a plurality of parameter groups with a parameter group including a wavelength section parameter value, a lower intensity parameter value, and an upper intensity parameter value as a unit. In this example, in each parameter group, the lower limit wavelength λL and the upper limit wavelength λU are adopted as the wavelength interval parameters, the lower intensity IL is adopted as the lower intensity parameter, and the upper intensity IU is adopted as the upper intensity parameter. ing. The number of parameter groups secured in the parameter area 24 is equal to or greater than the number of FBGs 19 formed or formed on the optical fiber 18.

  In the output data area 25, for example, a one-dimensional array is secured in order to temporarily store the peak wavelength λP detected from the sampling data until the transmission to the external control device 8 is completed. Although the arrangement may be small for occasional transmission or subdivision transmission, in this example, batch transmission is adopted, so that the output data is stored so that all peak wavelengths λP detected from a set of sampling data can be retained. The size of the array secured in the region 25 is equal to or greater than the number of FBGs 19 formed or formed on the optical fiber 18.

  The peak detection program 26 requests sampling data from the input program 21 (step S11), detects all the peak wavelengths λp of the FBG 19 of the optical fiber 18 from the passed sampling data (steps S12 to S17), and then results An output instruction is issued to the communication program 22 (step S18). This series of calculation processing is repeated, and each time a new set of sampling data is supplied from the input data area 23, the peak wavelengths λp of all the FBGs 19 are successively detected and stored in the output data area 25. After that, it is transmitted to the external control device 8.

All the peak wavelengths λ P of the FBG 19 of the optical fiber 18 are detected from a set of sampling data (steps S12 to S17). A wavelength section is selected as a part of the sampling data, and the peak wavelength λ P is selected from the selected section. One detection processing (steps S12 to S16) is performed by the number of parameter groups set in the parameter area 24, more specifically, a pair of lower limit wavelength λL and upper limit wavelength λU set as wavelength section parameters. By repeating as many times as the number of data (step S17), it can be achieved.
Details of the calculation processing (steps S12 to S16) for detecting one peak wavelength λp from the wavelength section selection will be exemplified in the following description of the operation.

  The usage and operation of the FBG optical spectrum analyzer of the first embodiment will be described with reference to the drawings. 1B is a flowchart showing the processing contents of the peak detection program 26, FIG. 2A is an example of formation of the FBG 19 in the optical fiber 18, and FIG. 1B is an example of sampling data and parameters. It is. FIGS. 2C to 2E are examples of sampling data including one peak waveform, and show a data processing process at the time of peak detection.

Prior to the use of the FBG optical spectrum analyzer 10, the optical fiber 18 used together with the FBG optical spectrum analyzer 10 is connected by the optical connector 17 so that light can be transmitted and received (see FIG. 2A).
The FBG 19 formed in the optical fiber 18 includes FBGa having a peak wavelength (spectrum center wavelength of reflected light) of 1535 nm, FBGb of 1540 nm, and FBGc of 1545 nm at a standard temperature and in an undistorted state. To do. In other FBGs 19, the peak wavelengths are appropriately shifted so that the peak waveforms do not overlap.

  In this case, prior to use of the FBG optical spectrum analyzer 10, a parameter group is also set in the parameter area 24 of the digital arithmetic unit 20 via the external control device 8. The parameter group is set for one FBG 19 (see FIG. 2B). Among the many FBGs 19, for example, FBGa, a lower limit wavelength λL and an upper limit wavelength λU that define an FBGa section including 1535 nm on the wavelength λ axis, and a lower intensity IL to exclude an extra tail part of the peak waveform, Four values are set with the upper intensity IU to narrow down the calculation target data in the vicinity of the peak.

  Similarly, for the FBGb, four values of the lower limit wavelength λL and the upper limit wavelength λU for defining the FBGb section including 1540 nm, the lower intensity IL for excluding the tail portion, and the upper intensity IU for narrowing the peak vicinity are set as separate groups. For FBGc, four values of lower limit wavelength λL and upper limit wavelength λU for defining the FBGc section including 1545 nm, lower intensity IL for excluding the tail portion, and upper intensity IU for narrowing the peak vicinity are set in another group. Is done. Similarly, for the other parameter groups, four values of a lower limit wavelength λL, an upper limit wavelength λU, a lower intensity IL, and an upper intensity IU related to the corresponding FBG 19 are set.

  In setting these parameter values λL, λU, IL, and IU, first, for example, a lower limit wavelength λL is determined by subtracting a constant value from the design value of the peak wavelength at the time of forming the FBG 19, and the constant value is added to the same design value. A simple determination method is used in which the upper limit wavelength λU is determined, the lower intensity IL is determined by multiplying the output intensity of the broadband light source 11 at the same design value by a fixed value, and the upper intensity IU is determined by simply adopting a fixed value. However, if there is time to observe the optical spectrum of the actually sampled data, or if you can refer to the situation of the installation site or past measurement results, the characteristics of each FBG 19 obtained by that will be reflected. It is preferable to determine each parameter value λL, λU, IL, IU while adjusting it.

  When the setting of the parameter group in the parameter area 24 is completed for all the FBGs 19, the FBG optical spectrum analyzer 10 is activated. Then, each time the wavelength is swept by the wavelength tunable filter 13, the light amount for each wavelength of the reflected light is measured by the photoelectric converter 14 or the like, and the measured light amount is sampled by the A / D converter 16, and a new set is obtained. The sampling data is taken into the input data area 23 by the input program 21 (see FIG. 2B). Then, when it is provided to the processing of the peak detection program 26 in response to the data request (step S11 in FIG. 1), the peak wavelength λ P from the set of sampling data becomes the number of FBGs 19 formed in the optical fiber 18, that is, in the parameter region 24. Only the set number of parameter groups is detected (steps S12 to S17). The calculation process (steps S12 to S16) for detecting one peak wavelength .lambda.P for one parameter group is repeated for the set number of parameter groups (step S17).

  The calculation process (steps S12 to S16) for detecting one peak wavelength λp will be described in detail. One parameter group is selected in order, and based on the parameter values λL, λU, IL, and IU included in the parameter group. Thus, the search for the peak waveform and the calculation of the peak wavelength are performed. Specifically, the wavelength section belonging to both wavelengths λL and λU as a wavelength section used for peak detection calculation from sampling data based on the lower limit wavelength λL and the upper limit wavelength λU, which are wavelength section parameter values, by the peak detection program 26. Is selected (step S12, see FIG. 2 (c)), and sampling data in which the light quantity measurement value I falls below the lower intensity IL in this selection section is excluded from the maximum value search target (FIG. 1, step S13, FIG. 2 ( c)).

  Further, the maximum value IP of the light quantity measurement value I is searched from the sampling data portion remaining at the maximum value search target at this time (see step S14 in FIG. 1, FIG. 2 (d)), and this maximum value IP is included there. The peak detection calculation target is narrowed down to the sampling data in which the light quantity measurement value I is within the upper intensity IU from (see step S15 in FIG. 1, FIG. 2D). When the number of sampling data to be subjected to the peak detection calculation is sufficiently limited by such repeated limiting processing, a function approximation is performed on the sampling data to be subjected to the peak detection calculation, and the peak wavelength λp is calculated and output to the output data area 25. It is written (see step S16 in FIG. 1, FIG. 2E). The calculation of peak wavelength calculation by function approximation may be performed by approximation of the quadratic function by the least square method described above (see Patent Document 2), or may be another known calculation method. Since the calculation target data is sufficiently narrowed down, it is performed at high speed while maintaining high accuracy.

  A specific configuration of the FBG optical spectrum analyzer according to the second embodiment of the present invention will be described with reference to the drawings. 3A is a block diagram of the digital operation unit 30, and FIG. 3B is an example of sampling data including one peak waveform.

  This FBG optical spectrum analyzer is different from that of the first embodiment described above (see FIG. 3A) in that the digital operation unit 20 is replaced with a digital operation unit 30. The difference from the calculation unit 20 is that the lower intensity IL is lost for each parameter group set in the parameter area 24, and instead a continuous number CN (continuous number parameter value) is entered, and a peak detection program 26 is a partly modified peak detection program 36. The difference between the peak detection program 36 and the peak detection program 26 is that there is no calculation process (step S13) for removing sampling data whose light intensity measurement value I is below the lower intensity IL in the selected section from the maximum value search target. The continuous limitation process (step S33) is performed at the same timing.

  In this continuous limiting process (see FIG. 3B), from the lower limit wavelength λL side to the upper limit wavelength λU side for the range belonging to the selected section between the lower limit wavelength λL and the upper limit wavelength λU in the sampling data. First, a continuously rising waveform portion that continues for the continuous number CN or more is searched, and then a continuous falling waveform portion that continues for the continuous number CN or more is searched. Then, the maximum value search target is narrowed down to only the sampling data belonging to a small interval between the waveform portions, that is, the wavelength CL to the wavelength CU. The left side portion (lower limit wavelength λL to wavelength CL) and the right side portion (wavelength CU to upper limit wavelength λU) are excluded from the maximum value search target.

  In this case, even if an inappropriate maximum value 37 exceeding the appropriate maximum value 38 belonging to the peak waveform appears outside the peak waveform, if it is single or sporadic, it is accurately determined from the maximum value search target. Excluded. Therefore, in the maximum value search (step S14) following the continuous limiting process (step S33), the appropriate maximum value 38 is searched instead of the inappropriate maximum value 37 as the maximum value IP of the light quantity measurement values I. It will be. Thereafter, the peak detection calculation target is narrowed down based on the maximum value IP and the upper intensity IU (step S15), and the peak wavelength λP is calculated after the number of sampling data of the peak detection calculation target is sufficiently limited ( Step S16), even if the calculation of peak wavelength calculation is based on function approximation, it is performed at high speed with high accuracy.

  A specific configuration of the FBG optical spectrum analyzer according to the third embodiment of the present invention will be described with reference to the drawings. 4A is a block diagram of the digital operation unit 40, and FIG. 4B is an example of sampling data including one peak waveform.

This FBG optical spectrum analyzer is different from those of the first and second embodiments described above (see FIG. 4A) in that the digital arithmetic units 20 and 30 are replaced with the digital arithmetic unit 40. The unit 40 is different from the digital arithmetic units 20 and 30 in that each parameter group set in the parameter area 24 includes five values of a lower limit wavelength λL, an upper limit wavelength λU, a lower intensity IL, a continuous number CN, and an upper intensity IU. This is a point where a value is entered and a point where the peak detection programs 26 and 36 are partially remodeled to become a peak detection program 46.
The difference between the peak detection program 46 and the peak detection programs 26 and 36 is that, after the wavelength section selection process (step S12), the lower intensity limiting process (step S13) and the continuous limiting process (step S33). ) Are performed in that order, and then the above-described maximum value search (step S14) is performed.

  In this case (see FIG. 4B), after a wavelength section belonging to the lower limit wavelength λL and the upper limit wavelength λU is selected as the wavelength section used for peak detection calculation from the sampling data (step S12), the light quantity in this selected section Sampling data whose measured value I is below the lower intensity IL is excluded from the maximum value search target (step S13). Then, with respect to the sampling data portion remaining as the maximum value search target at this time point, a continuous rising waveform portion that continues for the continuous number CN or more is searched from the lower limit wavelength λL side to the upper limit wavelength λU side, and then continues for the continuous number CN or more. A continuously descending waveform portion is searched, the maximum value search object is narrowed down to only sampling data belonging to a small section of the wavelength CL to the wavelength CU between both waveform portions, and the outer portions (λL to CL, CU to λU) are It is excluded from the maximum value search target (step S33).

  In this case as well, even if an inappropriate maximum value 37 exceeding the appropriate maximum value 38 belonging to the peak waveform appears outside the peak waveform, if it is single or sporadic, continuous limiting processing (step S33). ) Is accurately excluded from the maximum value search target. In addition, since the maximum value search target that is also the target of the continuous limiting process is limited by the lower intensity limiting (step S13) prior to the continuous limiting process, the continuous limiting process (step S33) is also the maximum value searching process (step S14). ) Is also done quickly and accurately. Therefore, the subsequent upper intensity limiting process (step S15) and the calculation of peak wavelength calculation by function approximation (step S16) are performed at high speed with high accuracy.

  The FBG optical spectrum analyzer of the present invention whose block diagram is shown in FIG. 5 is different from that of the third embodiment described above in that the digital operation unit 40 is replaced with the digital operation unit 50. The digital calculation unit 50 is different from the digital calculation unit 40 in that there is no continuous number CN for each parameter group set in the parameter area 24, and the lower limit wavelength λL, the upper limit wavelength λU, the lower intensity IL, and the upper intensity IU. And a point where the parameter area 54 is secured in the memory and the common continuous number CA for monotonic slope partial search is held as a common continuous number parameter, and peak detection The program 46 is partly modified to become a peak detection program 56.

The difference between the peak detection program 56 and the peak detection program 46 is that the continuous limiting process (step S33) referring to the continuous number CN is changed to the continuous limiting process (step S53) referring to the common continuous number CA. .
In this continuous limiting process (step S53), for the sampling data portion remaining as the maximum value search target, a continuous rising waveform portion that continues from the lower limit wavelength λL side to the upper limit wavelength λU side for the common continuous number CA or more is searched first. A continuous descending waveform portion continuing for the common continuous number CA or more is searched, the maximum value search target is narrowed down only to sampling data belonging to a small section between both waveform portions, and the outer portion is excluded from the maximum value search target.

In this case, parameter values are set not only in the parameter area 24 but also in the parameter area 54 via the external control device 8 prior to use of the apparatus, but the parameters in the parameter area 54 are only a single common continuous number CA. .
Then, in the continuous limitation process (step S53) for selecting wavelength sections for sampling data, the same common continuous number CA is used when any wavelength section is selected.
Thus, since the common continuous number CA is shared by many FBGs 19 for peak detection, it is easier to determine the corresponding parameter value than to determine the continuous number CN for each FBG. As described above, there is no problem even if the continuous number CN is unified into the common continuous number CA.

  A specific configuration of the FBG optical spectrum analyzer according to the fifth embodiment of the present invention will be described with reference to the drawings. FIG. 6 is a block diagram of the digital calculation unit 60.

  This FBG optical spectrum analyzer (FIG. 6) is different from that of the third embodiment (FIG. 4) described above in that the digital operation unit 40 is replaced with a digital operation unit 60. The difference from the calculation unit 40 is that a parameter area 64 is additionally secured in the memory, and there is a common lower strength IB (common lower strength parameter), a common continuous number CA (common continuous number parameter), and a common upper strength IA ( The common upper intensity parameter) is set, the peak detection program 66 is additionally installed, and the communication program 22 is expanded to become the communication program 62.

  The parameter region 24 in which the parameter group including the parameter values λL, λU, IL, CN, and IU is held more than the number of FBGs 19 is secured in memory, and the wavelength interval parameter λL for the sampling data of the light quantity measurement value I The fact that the peak detection program 46 for calculating the peak wavelength λ P by performing the function approximation after selecting the wavelength section based on λ U is installed is inherited from the digital calculation unit 40 as it is. The input program 21, the sampling data holding input data area 23, and the output data area 25 holding many peak wavelengths .lambda.P are also taken over as they are.

The common lower intensity IB for exclusion of the skirt portion set in the parameter area 64, the common continuous number CA for monotone slope search, and the common upper intensity IA for narrowing the peak vicinity are one by one, both of which are externally controlled. It is set via the device 8. When the setting from the outside is omitted, default values are set for the common continuous number CA and the common upper strength IA.
The peak detection program 66 is another peak detection means added separately from the peak detection program 46. In short, the wavelength section based on the wavelength section parameters λL and λU is not selected for the sampling data of the light quantity measurement value I. The peak wavelength is calculated by performing function approximation after limiting the peak detection calculation target by excluding the sampling data whose light intensity measurement value I is lower than the common lower intensity IB from the maximum value search target.

  Specifically, a data request process S61 similar to the above-described process S11, a lower intensity limiting process S62 having a different data range and reference parameter from the above-described process S13, and a series of reference parameters different from the above-described process S33. A limiting process S63, a maximum value search process S64 similar to the above-described process S14, an upper-side intensity limiting process S65 having a different reference parameter from the above-described process S15, a peak wavelength calculation process S66 similar to the above-described process S16, An end determination process S67, which is different from the above-described process S17, and a result output process S68 similar to the above-described process S18 are performed. The detailed contents of each calculation process will be described later when the operation is described.

  In addition to the function of the communication program 22 described above, the communication program 62 also exhibits a command relay function of receiving only a selection instruction from the external control device 8 and executing only one of the peak detection programs 46 and 66. ing. When the peak detection program 46 is selected, only the selection instruction Sa is enabled and the peak detection program 46 is executed, but the peak detection program 66 is stopped, and when the peak detection program 66 is selected, only the selection instruction Sb is enabled. The peak detection program 66 is executed, but the peak detection program 46 is stopped.

  With respect to the FBG optical spectrum analyzer of the fifth embodiment, the operation when the peak detection program 66 is selected and executed will be described with reference to the drawings. FIGS. 7A to 7C are examples of sampling data including a plurality of peak waveforms, and show a data processing process when the first peak is detected. FIGS. 8A to 8C are examples of sampling data including a plurality of peak waveforms, and show a data processing process at the time of detecting the second peak. Further, FIGS. 9A to 9C are examples of sampling data including a plurality of peak waveforms, and show a data processing process when the third peak is detected.

  When a data request is issued from the peak detection program 66 to the input program 21 (step S61), and a new set of sampling data is provided to the processing of the peak detection program 66 accordingly, the light intensity measurement value in the entire sampling data is obtained. Sampling data in which I is lower than the lower intensity IL is excluded from the maximum value search target (see step S62 in FIG. 6, FIG. 7A). Then, every time one peak waveform is detected by the continuous limiting process (S63), the peak wavelength λp is set to one by the maximum value searching process (S64), the upper intensity limiting process (S65), and the peak wavelength calculating process (S66). Is calculated. This peak waveform detection and peak wavelength calculation are repeated while shifting the wavelength region from the short wavelength side to the long wavelength side, and are performed for all wavelengths of the sampling data (step S67).

  More specifically, for the sampling data having no bottom portion, from the short wavelength side to the long wavelength side, first, a continuously rising waveform portion that continues over the common continuous number CA is searched, and then a continuous falling waveform portion that continues over the common continuous number CA. Search is performed (see step S63 in FIG. 6, FIG. 7A). Then, the maximum value IP is searched from the sampling data belonging to the small section between the two waveform portions (see step S64 in FIG. 6, FIG. 7A). In addition, the peak detection calculation target is narrowed down to sampling data including the maximum value IP and within which the light quantity measurement value I is within the common upper intensity IA (see step S65 in FIG. 6 and FIG. 7B). Then, function approximation is performed on the sampling data to be subjected to peak detection calculation, and the peak wavelength λ P is calculated and written in the output data area 25 (see step S66 in FIG. 6, FIG. 7C).

  Thus, the first peak is detected and its peak wavelength λp is obtained. Then, for sampling data that has not yet been searched, a continuous rising waveform portion and a continuous falling waveform portion that continue over the common continuous number CA from the short wavelength side to the long wavelength side are searched, and the maximum value is obtained from the small interval between the two waveforms. IP is searched (see FIG. 8 (a)), the peak detection calculation target is narrowed within the common upper intensity IA from this maximum value IP (see FIG. 8 (b)), and then the peak wavelength λP is calculated by function approximation. And written in the output data area 25 (see FIG. 8C). In this way, the second peak is also detected and its peak wavelength λp is obtained. Then, the same processing is repeated to detect the third peak and obtain the peak wavelength λ P (see FIGS. 9A to 9C). Further, the same processing is repeated for all wavelengths of the sampling data, and all peak wavelengths λP are obtained.

  A usage mode of the FBG optical spectrum analyzer of the fifth embodiment will be described. This FBG optical spectrum analyzer can select which of the peak detection programs 46 and 66 is to be executed by the digital arithmetic unit 60 and designate it via the external control device 8, and is used when only the peak detection program 46 is executed. Prior to this, parameter values λL, λU, IL, CN, and IU are set in the parameter area 24 by the number of FBGs 19 as described above. When only the peak detection program 66 is executed, the common lower intensity IB, the common continuous number CA and the common upper intensity IA are set one by one in the parameter area 64 via the external control device 8 before use. The continuous number CA and the common upper strength IA need not be set if they are the default values. In any case, since the number of parameters is small, determination and setting are easy.

  When the peak detection programs 46 and 66 are switched and executed, parameter values must be set in the parameter area 24 and the parameter area 64 prior to use. In most cases, peak detection with a light parameter setting burden is performed. When the program 66 is preceded and a large number of parameter values are prepared, the peak detection program 46 is switched thereafter, so that the FBG optical spectrum analyzer can be quickly operated as long as the common lower intensity IB is initially determined. Thereafter, while using the FBG optical spectrum analyzer, program switching and parameter updating can be appropriately performed to improve measurement accuracy.

  For example, even if the FBG optical spectrum analyzer and the optical fiber 18 are carried into the field, the optical fiber 18 is rarely finally installed without a test, and the operation of the apparatus is checked before the installation. Such an operation check is performed by temporarily placing the optical fiber 18 in a relatively good environment. Therefore, at that stage, the peak detection program 66 is selected and executed. If the surrounding environment of the optical fiber 18 is good, the sampling data is clear and the noise is small. Therefore, even if a small number of parameter values are shared, all peak wavelengths λp can be accurately obtained. The parameter values λL, λU, IL, CN, and IU are determined while confirming the operation of the apparatus.

  When the operation is confirmed, the optical fiber 18 is also installed at the final destination, and the parameter values λL, λU, IL, CN, and IU are further determined. When the parameter values λL, λU, IL, CN, and IU have been determined for all FBGs 19, they are set in the parameter area 24 of the digital arithmetic unit 60, and then the peak detection program 66 is stopped to detect the peak. The program 46 is executed. Then, even if the sampling data becomes obscure or noise increases due to the severe environment of the optical fiber 18 installation location, etc., if the data deterioration is not extreme, it corresponds to all FBG19 The obtained peak wavelength λp is required at high speed with high accuracy.

  In addition, by observing the optical spectrum of the actually sampled data, the characteristics of each FBG 19 are reassessed, and the parameter area so that the individual parameter values λL, λU, IL, CN, IU are finely adjusted according to the grasped contents. The corresponding part of the 24 parameter groups may be reset. By doing so, the performance of the FBG optical spectrum analyzer can be improved by a simple operation of updating parameters while using the FBG optical spectrum analyzer.

[Others]
In the above embodiment, the continuous limiting process prior to the maximum value search is performed from the short wavelength side to the long wavelength side, but the continuous limiting process may be performed from the long wavelength side to the short wavelength side.

The structure of the FBG optical spectrum analyzer is shown about Example 1 of this invention, (a) is a whole block diagram, (b) is a block diagram of a digital calculating part. (A) is a formation example of FBG, (b) is an example of sampling data and each parameter. (C) to (e) are examples of sampling data including one peak waveform, and show a data processing process at the time of peak detection. In the second embodiment of the present invention, the structure of the FBG optical spectrum analyzer is shown, (a) is a block diagram of a digital operation unit, and (b) is an example of sampling data including one peak waveform. FIG. 5 shows the structure of an FBG optical spectrum analyzer for Example 3 of the present invention, where (a) is a block diagram of a digital operation unit, and (b) is an example of sampling data including one peak waveform. It is a block diagram of the digital calculating part of the FBG optical spectrum analyzer about Example 4 of this invention. It is a block diagram of the digital calculating part of the FBG optical spectrum analyzer about Example 5 of this invention. (A) to (c) are examples of sampling data including a plurality of peak waveforms, and show a data processing process at the time of detecting the first peak. (A) to (c) are examples of sampling data including a plurality of peak waveforms, and show a data processing process at the time of detecting the second peak. (A) to (c) are examples of sampling data including a plurality of peak waveforms, and show a data processing process at the time of detecting the third peak.

Explanation of symbols

8 ... External control device,
10 ... FBG optical spectrum analyzer,
11 ... Broadband light source, 12 ... Optical splitter
13 ... Variable wavelength filter, 14 ... Photoelectric converter (PD),
15 ... Peak detection circuit, 16 ... A / D converter,
17 ... Optical connector, 18 ... Optical fiber,
19 ... FBG (FiberBraggGrating)
20: Digital operation unit (MPU),
21 ... Input program, 22 ... Communication program,
23 ... Input data area, 24 ... Parameter area,
25 ... Output data area, 26 ... Peak detection program,
30: Digital calculation unit, 36: Peak detection program,
37 ... Inappropriate maximum value, 38 ... Appropriate maximum value,
40: Digital calculation unit, 46: Peak detection program,
50: Digital arithmetic unit,
54 ... parameter region, 56 ... peak detection program,
60 ... Digital operation unit, 62 ... Communication program,
64: Parameter area, 66: Peak detection program

Claims (6)

  A light transmitting means for sending light to an optical fiber formed with a plurality of FBGs (fiber Bragg gratings), a light measuring means for measuring the amount of light for each wavelength of the reflected light, and performing digital computation by sampling the light amount measurement value In the FBG optical spectrum analyzer having a peak detection circuit for obtaining a peak wavelength, the digital calculation unit of the peak detection circuit includes a parameter group including a wavelength section parameter value, a lower intensity parameter value, and an upper intensity parameter value. A plurality of wavelength sections are selected and a wavelength section to be used for peak detection calculation is selected from the sampling data of the light quantity measurement value based on the wavelength section parameter value, and the light quantity measurement value falls below the lower intensity parameter value in the selected section. Remove the data from the maximum value search target, and from this maximum value search target The maximum value of the quantity measurement value is searched, the peak detection calculation target is narrowed down to the sampling data whose light intensity measurement value is within the upper intensity parameter value from this maximum value, and then the function approximation to the sampling data of the peak detection calculation target is performed. An FBG optical spectrum analyzer characterized in that it performs the calculation of the peak wavelength.   The digital calculation unit includes a continuous number parameter value in the parameter group instead of the lower intensity parameter value, and searches for the maximum value of sampling data whose light intensity measurement value is lower than the lower intensity parameter value in the selected section. Instead of being excluded from the target, a search is made for a continuous rising waveform portion and a continuous falling waveform portion that continue for the continuous number parameter value or more in the selected section, and the maximum value search target is narrowed down to sampling data belonging between both waveform portions. The FBG optical spectrum analyzer according to claim 1, wherein   The digital arithmetic unit also includes a continuous number parameter value in the parameter group, and after limiting the maximum value search target based on the lower strength parameter value, before searching for the maximum value, at this time The maximum value search target is further reduced by searching for the continuously rising waveform portion and the continuous falling waveform portion that continue for the continuous number of parameter values or more and narrowing down the maximum value search target to the sampling data belonging between the two waveform portions. 2. The FBG optical spectrum analyzing apparatus according to claim 1, wherein the FBG optical spectrum analyzing apparatus is limited.   The digital operation unit holds one common continuous number parameter value instead of a plurality of continuous number parameter values included in the parameter group, and searches for the continuous rising waveform portion and the continuous falling waveform portion. 4. The FBG optical spectrum analyzer according to claim 2, wherein the common continuous number parameter value is used instead of the continuous number parameter value for any wavelength section.   The digital operation unit holds a common lower intensity parameter value separately from the parameter group, and performs function approximation after selecting a wavelength section based on the wavelength section parameter value for the sampling data of the light quantity measurement value. In addition to the peak detecting means that performs the calculation of the peak wavelength, the light intensity measurement value is set to the common lower intensity parameter value without selecting the wavelength interval based on the wavelength interval parameter value for the sampling data of the light intensity measurement value. It is also equipped with other peak detection means for calculating the peak wavelength by limiting the peak detection calculation target by excluding lower sampling data from the maximum value search target, and either of the peak detection means 5. The FBG according to claim 1, wherein the FBG can be selected and executed. Spectrum analyzer.   6. The FBG optical spectrum analyzing apparatus according to claim 1, wherein all or part of the parameter values can be set from the outside.

Images