CN113804938B - Optical current transformer and control method thereof - Google Patents
Optical current transformer and control method thereof Download PDFInfo
- Publication number
- CN113804938B CN113804938B CN202110936360.2A CN202110936360A CN113804938B CN 113804938 B CN113804938 B CN 113804938B CN 202110936360 A CN202110936360 A CN 202110936360A CN 113804938 B CN113804938 B CN 113804938B
- Authority
- CN
- China
- Prior art keywords
- optical
- current transformer
- coupler
- light source
- photoelectric detector
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/18—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using inductive devices, e.g. transformers
Abstract
The invention discloses an optical current transformer and a control method thereof, which can control the optical power of interference signals returned to a photoelectric detector to be kept in a certain range by introducing an adjustable optical attenuator, avoid the reduction of the measurement precision or the abnormal work of an optical current transformer system caused by the attenuation of the optical power output by a light source or the increase of the insertion loss of devices such as a polarizer, a modulator and the like, and improve the stability and the reliability of the system.
Description
Technical Field
The invention belongs to the field of photoelectric instruments, and particularly relates to an optical current transformer.
Background
The optical current transformer has the advantages of small volume, light weight, simple insulating structure, no magnetic saturation, ferromagnetic resonance, secondary open circuit and other problems, good frequency characteristic and transient characteristic, passive primary end, strong anti-interference capability, safety, environmental protection, convenient digitization and capability of adapting to the requirements of an electric power system.
The optical current transformer can be divided into a magneto-optical glass type and an all-fiber type according to the optical path structure, the all-fiber type optical current transformer utilizes optical fibers as current sensing materials, all elements of the system are formed by fusion splicing and connecting of the optical fibers, discrete elements are not needed, the structure is simple, the connection is reliable, the long-term stability is good, and the optical current transformer is the direction of key research and development of current transformer manufacturers.
At present, most researches are carried out on all-fiber optical current transformers, system optical paths of a reciprocity reflection interferometer structure of the all-fiber optical current transformers are completely symmetrical, two beams of polarized light are transmitted on two orthogonal modes of the same optical fiber all the time, most of interferences such as vibration, temperature and the like are well inhibited due to good reciprocity, and only phase shift which is in direct proportion to current and generated in an optical fiber sensing ring around a primary conductor due to Faraday magneto-optical effect is nonreciprocal, so that the optical current transformers can eliminate the interference of environmental factors such as vibration, temperature and the like, and can well detect current information. Only optical fibers at the primary end of the cable are passive, the anti-interference capacity is high, and commercial products are available at present and are applied to an extra-high voltage transmission system more and more in recent years.
One very important but weak link of the existing optical current transformer is the light source. The principle of the optical current transformer for detecting current is based on the Faraday magneto-optical effect, and a light source provides optical signals for the optical current transformer system, so that the light source is one of the bases for the normal work of the transformer. Because of its characteristics of high output power, wide spectrum width, short-time coherence and long-space coherence, the super-radiation light emitting diode (SLD) is a light source commonly used by optical current transformers. In the prior art, the output power of the SLD is generally stably controlled by two methods, namely temperature control and constant current driving. However, in terms of the level of SLD development at present, the fiber power attenuation and center wavelength drift are inevitable during long-term operation. It is generally considered that the optical current transformer adopting the closed-loop signal detection scheme is less affected by the power variation of the light source. However, early research experiments and practical operation experience show that if the power attenuation of a light source is serious (more than 50%), the error of the closed-loop optical current transformer can reach more than 1.5%, and the requirements of power transmission and transformation system statistics or protection and control application can not be met any more.
There is a report on a technique for performing closed-loop control on the optical power of an optical current transformer, that is, when detecting that the optical power of a light source decreases or the optical power received by a photodetector decreases, a driving current of the light source is automatically adjusted to increase the output power of the light source, so as to avoid the optical current transformer from working abnormally. However, practical experience shows that when the driving current of the light source increases, the optical power of the output light of the light source increases, and simultaneously the center wavelength and the spectrum of the output light change, and the precision of the optical current transformer changes due to the change of parameters such as the center wavelength, etc., and when the driving current changes excessively, the error change of the optical current transformer caused by the change of parameters may exceed 1%, and the application requirements of power transmission and transformation system statistics or protection and control of a direct current transmission system cannot be met.
Other optical devices of the optical current transformer, such as a polarizer, a modulator and the like, have the problem that insertion loss becomes large with time, and the optical device loss becomes large, so that the received light power of the detector becomes small, and the measurement accuracy of the optical current transformer is degraded or the operation is abnormal.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the invention provides an optical current transformer and a control method thereof, wherein the optical power received by a photoelectric detector of the optical current transformer is always in a linear working area of the photoelectric detector through an adjustable optical attenuator.
In order to achieve the technical purpose, the technical scheme of the invention is as follows:
an optical current transformer comprises a collecting unit, a transmission optical fiber and an optical fiber sensing ring which are connected in sequence; the optical fiber sensing ring comprises a lambda/4 wave plate, a sensing optical fiber and a reflector, wherein one end of the lambda/4 wave plate is connected with the transmission optical fiber, the other end of the lambda/4 wave plate is connected with the sensing optical fiber, and the reflector is positioned at the tail end of the sensing optical fiber; the acquisition unit includes light source, coupler, polarizer, polarization beam splitter, phase modulator, photoelectric detector and signal processor, and the output of light source is connected with the first end of the first side of coupler, and the first end of the second side of coupler is connected with transmission fiber through polarizer, polarization beam splitter and phase modulator in proper order, and the second end of the first side of coupler is connected with photoelectric detector's input, the acquisition unit still includes adjustable optical attenuator, and adjustable optical attenuator's setting mode includes following 3:
the 1 st setting mode: disposing a variable optical attenuator between an output of the light source and a first end of the first side of the coupler;
the 2 nd setting mode: arranging a variable optical attenuator between the first end of the second side of the coupler and the polarizer;
the 3 rd setting mode: disposing a variable optical attenuator at a location between a second end of the first side of the coupler and an input of the photodetector;
the signal processor is respectively electrically connected with the electric signal output end of the photoelectric detector, the driving end of the light source, the driving end of the phase modulator and the driving end of the adjustable optical attenuator.
Further, the calculation time of the average value of the output electrical signals of the photodetectors is an integral multiple of the modulation period of the optical current transformer.
Furthermore, the output power of the light source is more than or equal to 1mW.
Furthermore, the initial attenuation of the variable optical attenuator is more than or equal to 3dB.
Further, the coupler adopts a beam splitter, an optical circulator or a 2 × 2 coupler.
The method for controlling an optical current transformer according to claim 1, wherein when the average optical power received by the photodetector decreases, and the average amplitude Up of the electrical signal output after the photoelectric conversion also decreases, the signal processor determines whether Up reaches a threshold value, and if so, calculates a variation V of the electrical signal amplitude Up:
V＝(Up-U0)/U0
wherein, U0 is the initial average electrical signal amplitude of the photoelectric detector;
calculating the light attenuation A which should be introduced by the variable optical attenuator according to the variable quantity V:
A＝A0+10logV
wherein A0 is the initial attenuation of the variable optical attenuator;
then the signal processor adjusts the light attenuation of the variable optical attenuator to meet the requirement, so that the optical power received by the photoelectric detector is still the same as or similar to that before the optical power is attenuated, and the closed-loop control of the output electric signal amplitude of the photoelectric detector is realized.
The beneficial effects brought by adopting the technical scheme are as follows:
the invention provides a solution for an optical current transformer with good stability and high reliability, aiming at the problems that the error of the optical current transformer is changed due to the attenuation of the output light power of a light source, or the optical power received by a photoelectric detector of the optical current transformer is too small due to the large attenuation of the output power of the light source and the large loss of devices such as a polarizer or a modulator, and the system cannot work normally. By adding the adjustable optical attenuator into the optical current transformer system and adjusting the attenuation introduced by the adjustable optical attenuator, the optical current transformer system always works in the linear region of the photoelectric detector, closed-loop control of the received light power of the photoelectric detector is realized, the error introduced by adjusting the driving current of a light source is avoided, the error introduced by the reduction of the output power of the light source is eliminated, the error introduced by the increase of the loss of optical devices such as a polarizer and a phase modulator is also eliminated, the problem that the optical current transformer system works abnormally due to the large reduction of the light source or the excessive increase of the loss of the optical devices such as the polarizer and the phase modulator is also avoided, and the stability and reliability of the system are improved.
Drawings
Fig. 1 is a schematic structural diagram of an optical current transformer according to an embodiment;
FIG. 2 is a schematic structural diagram of an optical current transformer according to an embodiment;
FIG. 3 is a schematic structural diagram of an optical current transformer according to an embodiment;
fig. 4 is a flow chart of a control method of the present invention.
Description of reference numerals: 1-a collection unit; 2-optical fiber sensing ring; 3-a transmission fiber; 10-a light source; 11-a variable optical attenuator; 12-a coupler; 13-a polarizer; 14-a polarizing beam splitter; 15-a phase modulator; 16-a photodetector; 17-a signal processor; a 21-lambda/4 wave plate; 22-a sensing fiber; 23-a mirror; 24-primary conductor.
Detailed Description
The technical scheme of the invention is explained in detail in the following with the accompanying drawings.
Fig. 1 is a schematic structural diagram of an optical current transformer provided in this embodiment, where the optical current transformer includes an acquisition unit 1, a transmission fiber 3, and a fiber sensing loop 2.
The acquisition unit 1 and the optical fiber sensing ring 2 are connected through a transmission optical fiber 3. The collection unit 1 includes a light source 10, an adjustable optical attenuator 11, a coupler 12, a polarizer 13, a polarization beam splitter 14, a phase modulator 15, a photodetector 16, and a signal processor 17.
The coupler 12 is at least one of a beam splitter, an optical circulator and a 2 × 2 coupler. The left 2 ports of the coupler 12 are respectively a first end and a second end from top to bottom, and the right 2 ports are respectively a third end and a fourth end from top to bottom.
The light source 10 is connected to one end of the variable optical attenuator 11. The other end of the adjustable optical attenuator 11 is connected to a first end of a coupler 12. The third terminal of the coupler 12 is connected to one terminal of the polarizer 13. The other end of the polarizer 13 is connected to one end of the polarization splitter 14. The other end of the polarization beam splitter 14 is connected to one end of a phase modulator 15. The other end of the phase modulator 15 is connected to the transmission fiber 13. The above connection means include, but are not limited to, optical fiber fusion.
The optical fiber sensing ring 2 comprises a lambda/4 wave plate 21, a sensing optical fiber 22 and a reflecting mirror 23. The lambda/4 wave plate 21 is connected to the transmission fiber 3. The sensing fiber 22 is connected with the lambda/4 wave plate 21. The above connection means include, but are not limited to, optical fiber fusion. A mirror 23 is located at the end of the sensing fiber 22 and reflects the two orthogonal circularly polarized light back and along the sensing fiber 22.
The second end of the coupler 12 is connected to an optical port of the photodetector 16, including but not limited to a fiber fusion splice. The fourth end of the coupler 12 may be left free or may be connected to another photodetector (not shown in fig. 1).
The signal processor 17 is connected to an electrical signal output port of the photodetector 16. The signal processor 17 is also connected to the driving electrical port of the light source 10. The signal processor 17 is also connected to the driving electrical port of the phase modulator 15. The signal processor 17 is also connected to the driving electrical port of the variable optical attenuator 11. Optionally, the signal processor 17 further comprises a driving circuit for driving the light source 10 to emit light. Optionally, the signal processor 17 further comprises a signal generator for generating an electrical signal for driving the phase modulator 15.
The position of the variable optical attenuator 11 in this embodiment may be located between the light source 10 and the coupler 12, which corresponds to fig. 1; or between the coupler 12 and the polarizer 13, corresponding to fig. 2; and may also be located between the coupler 12 and the photodetector 16, corresponding to fig. 3.
The signal processor 17 is connected to the electrical port of the variable optical attenuator 11. Optionally, the signal processor 17 further comprises a digital control circuit and a driving circuit, and generates a suitable attenuation voltage to adjust the attenuation amount of the variable optical attenuator.
Taking the embodiment shown in fig. 1 as an example, a specific working process of the optical current transformer of the present invention is described as follows:
the driving circuit of the signal processor 17 drives the light source 10 to emit light. Light emitted from the light source 10 passes through the variable optical attenuator 11 and reaches the first end of the coupler 12, and the coupler 12 guides the light to the third end of the coupler 12. The light passes through a coupler 12 and enters a polarizer 13, producing linearly polarized light. The linearly polarized light is split by the polarizing beam splitter 14 into two incident orthogonal linearly polarized lights having the same propagation direction. Two beams of incident orthogonal linear polarized light pass through the phase modulator 15 and the transmission optical fiber 3 and reach one end of the lambda/4 wave plate 21 in the optical fiber sensing ring 2, and the other end of the lambda/4 wave plate 21 of the optical fiber sensing ring 2 outputs two orthogonal circular polarized lights. Two orthogonal circular polarized lights are transmitted along the sensing optical fiber 22 of the optical fiber sensing ring 2, and one of the two orthogonal circular polarized lights has a higher propagation speed and the other has a lower propagation speed in the sensing optical fiber 22 due to the faraday magneto-optical effect, so that a phase difference is generated. After the two orthogonal circular polarized lights are reflected by the reflector 23 at the end of the sensing fiber 22, the polarization modes of the two orthogonal circular polarized lights are exchanged due to the action of the reflector, the left-handed circular polarized light is changed into right-handed circular polarized light, and the right-handed circular polarized light is changed into left-handed circular polarized light and returns along the original path.
When the two return orthogonal circularly polarized lights return, the magnetic field direction of the primary current is not changed, and the propagation direction of the two return orthogonal circularly polarized lights is changed and the polarization state is changed, so the phase difference generated by the Faraday effect is doubled. And the two polarization beams are changed into two return orthogonal linear polarization beams after passing through the lambda/4 wave plate 21 of the optical fiber sensing ring 2 again, and the polarization directions are interchanged in the relative advancing process. When the two return orthogonal linear polarized lights return, the two return orthogonal linear polarized lights pass through the transmission optical fiber 3, the phase modulator 15 and the polarization beam splitter 14 in sequence and then are converted into combined polarized light, and the combined polarized light reaches the polarizer 13. The interference optical signal returned from the polarizer 13 is returned to the third end of the coupler 12, and then returned to the photodetector 16 through the second end of the coupler 12.
The photodetector 16 photoelectrically converts the interference light signal and outputs an electrical signal. The signal processing circuit 17 receives and demodulates the processed electrical signal to determine the measured current in the primary conductor 24 located in the fiber optic sensing loop 2.
The polarization states of the polarized light X-ray and the polarized light Y-ray output from the polarization beam splitter 14 are exchanged when the polarized light X-ray and the polarized light Y-ray return to the polarization beam splitter 14, and the optical path channels of the whole interference optical path system are reciprocal. The paths of the two beams of orthogonal polarized light are the same, and the optical path system has good reciprocity and strong anti-interference capability. The influence of environmental factors such as vibration, stress, temperature and the like on the optical current transformer can be basically eliminated.
In this embodiment, the adjustable optical attenuator 11 is introduced, and the initial operating state is: an appropriate driving current value is set for the light source 10, and simultaneously, the variable optical attenuator 11 is set to introduce a certain initial optical attenuation amount A0, so that the optical power of the interference optical signal returned to the photodetector 16 is in a linear working area of the photodetector 16, and the average amplitude of the output electrical signal of the photodetector is U0 at this time.
When the output optical power of the light source 10 decreases, or the insertion loss of the optical device such as the polarizer 13 or the modulator 15 increases, the optical power received by the photodetector 16 decreases, and the amplitude of the output electrical signal also decreases, at this time, the working process of the optical current transformer is as follows:
when the average optical power P received by the photodetector 16 decreases, and the average electrical signal amplitude Up output after photoelectric conversion also decreases, the signal processor 17 determines whether Up reaches a threshold value, and if so, calculates the variation V of the electrical signal amplitude Up:
V＝(Up-U0)/U0
calculating the optical attenuation a (in dB) that should be introduced by the variable optical attenuator 11 according to the variation V of the electrical signal:
A＝A0+10logV
then the signal processor 17 adjusts the light attenuation of the variable optical attenuator 11 to meet the requirement, so that the received optical power of the photodetector 16 still remains the same as or similar to that before the received optical power is attenuated, that is, the received optical power of the photodetector 16 and the amplitude of the output electrical signal are closed-loop controlled. The specific workflow is shown in fig. 4.
The average value of the electrical signal of the photodetector 16 is calculated by only ensuring that the calculation time is an integral multiple of the modulation period of the optical current transformer.
In order to ensure the long-term reliability of the optical current transformer, the light source 10 may have a high output light power, for example, greater than or equal to 1mW, and the initial attenuation A0 of the variable optical attenuator 11 may be set to greater than or equal to 3dB.
In this embodiment, the optical power closed-loop adjustment of the optical current transformer is realized through the variable optical attenuator 11, and the problem of precision variation of the optical current transformer caused by attenuation of the optical power output by the light source of the optical current transformer or increased loss of optical devices such as a polarizer and a modulator can be solved. The optical power closed-loop automatic adjustment of the optical current transformer of the embodiment does not need to adjust the driving current of the light source 10, and avoids the variation of the precision of the optical current transformer caused by adjusting the driving current of the light source 10. The optical current transformer of the present embodiment can maintain its stability in long-term operation. When the output power of the light source 10 is greatly reduced, or the insertion loss of optical devices such as a polarizer, a modulator and the like is increased more, the attenuation of the adjustable optical attenuator 11 is also reduced, the optical current transformer can still work normally, and the reliability of the optical current transformer is greatly improved.
The embodiments are only for illustrating the technical idea of the present invention, and the technical idea of the present invention is not limited thereto, and any modifications made on the basis of the technical scheme according to the technical idea of the present invention fall within the scope of the present invention.
Claims (6)
1. An optical current transformer, characterized by: the optical fiber sensor comprises a collection unit, a transmission optical fiber and an optical fiber sensing ring which are connected in sequence; the optical fiber sensing ring comprises a lambda/4 wave plate, a sensing optical fiber and a reflector, wherein one end of the lambda/4 wave plate is connected with the transmission optical fiber, the other end of the lambda/4 wave plate is connected with the sensing optical fiber, and the reflector is positioned at the tail end of the sensing optical fiber; the collecting unit comprises a light source, a coupler, a polarizer, a polarization splitter, a phase modulator, a photoelectric detector and a signal processor, wherein the output end of the light source is connected with the first end of the first side of the coupler, the first end of the second side of the coupler is connected with a transmission optical fiber through the polarizer, the polarization splitter and the phase modulator in sequence, the second end of the first side of the coupler is connected with the input end of the photoelectric detector, the collecting unit further comprises an adjustable optical attenuator, and the setting mode of the adjustable optical attenuator comprises the following 3 types:
the 1 st setting mode: disposing a variable optical attenuator between an output of the light source and a first end of the first side of the coupler;
the 2 nd setting mode: arranging a variable optical attenuator between the first end of the second side of the coupler and the polarizer;
the 3 rd setting mode: disposing a variable optical attenuator at a location between a second end of the first side of the coupler and an input of the photodetector;
the signal processor is respectively electrically connected with the electric signal output end of the photoelectric detector, the driving end of the light source, the driving end of the phase modulator and the driving end of the adjustable optical attenuator.
2. The optical current transformer of claim 1, wherein: the calculation time of the average value of the output electric signals of the photoelectric detector is integral multiple of the modulation period of the optical current transformer.
3. The optical current transformer of claim 1, wherein: the output power of the light source is more than or equal to 1mW.
4. The optical current transformer of claim 1, wherein: the initial attenuation of the variable optical attenuator is more than or equal to 3dB.
5. The optical current transformer of claim 1, wherein: the coupler adopts a beam splitter, an optical circulator or a 2 x 2 coupler.
6. The optical current transformer control method according to claim 1, characterized in that: when the average light power received by the photoelectric detector is reduced, the average amplitude Up of the electric signal output after photoelectric conversion is also reduced, the signal processor judges whether the Up reaches a threshold value, and if the Up reaches the threshold value, the variation V of the electric signal amplitude Up is calculated:
V＝(Up-U0)/U0
wherein, U0 is the initial average electrical signal amplitude of the photoelectric detector;
calculating the light attenuation A which should be introduced by the variable optical attenuator according to the variable quantity V:
A＝A0+10logV
wherein A0 is the initial attenuation of the variable optical attenuator;
then the signal processor adjusts the light attenuation of the variable optical attenuator to meet the requirement, so that the optical power received by the photoelectric detector is still the same as or similar to that before the optical power is attenuated, and the closed-loop control of the amplitude of the output electric signal of the photoelectric detector is realized.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110936360.2A CN113804938B (en) | 2021-08-16 | 2021-08-16 | Optical current transformer and control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110936360.2A CN113804938B (en) | 2021-08-16 | 2021-08-16 | Optical current transformer and control method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN113804938A CN113804938A (en) | 2021-12-17 |
| CN113804938B true CN113804938B (en) | 2023-02-14 |
Family
ID=78943088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110936360.2A Active CN113804938B (en) | 2021-08-16 | 2021-08-16 | Optical current transformer and control method thereof |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN113804938B (en) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003060599A2 (en) * | 2001-12-27 | 2003-07-24 | Bookham Technology Plc | An in-line waveguide photo detector |
| CN102735274B (en) * | 2012-07-06 | 2014-09-03 | 电子科技大学 | System and method for detecting weak optical fiber sensing signals |
| CN103399193B (en) * | 2013-08-05 | 2016-01-13 | 东南大学 | Based on bus current detection method and the current transformer arrangement of adjustable optical attenuator |
| CN103698571B (en) * | 2014-01-03 | 2016-06-29 | 东南大学 | There is current transformer arrangement and the bus current detection method of self energizing low-power consumption |
| CN103869134B (en) * | 2014-03-31 | 2016-08-31 | 东南大学 | A kind of current transformer and bus current detection method based on neutral net |
| CN109298425B (en) * | 2018-11-13 | 2023-12-05 | 华中光电技术研究所（中国船舶重工集团有限公司第七一七研究所） | Multifunctional laser sensing system |
| CN109932625A (en) * | 2019-04-10 | 2019-06-25 | 河北大学 | A kind of optical profile type shelf depreciation sensing device and detection method for local discharge |
| CN113138302B (en) * | 2020-01-20 | 2023-02-14 | 南京南瑞继保电气有限公司 | Optical current transformer |
-
2021
- 2021-08-16 CN CN202110936360.2A patent/CN113804938B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN113804938A (en) | 2021-12-17 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10281342B2 (en) | Faraday current and temperature sensors | |
| CN202033428U (en) | Electric field measurement device | |
| CN110057544B (en) | Automatic measuring device and method for frequency response of photoelectric conversion module | |
| CN108539569A (en) | A kind of method that ultra-narrow filters with atomic light filter and its realization | |
| CN102854360A (en) | Stability control device for transmission spectrums of optical fiber current transducer | |
| CN103900680A (en) | Device and detecting method for restraining polarization crosstalk measuring noise by the adoption of light source | |
| CN108594086A (en) | All -fiber Michelson inside transformers shelf depreciation ultrasonic signal detecting system and method | |
| CN110567594A (en) | Precision laser wavelength measuring system | |
| GB2332318A (en) | Low power output monitoring tap | |
| CN113804938B (en) | Optical current transformer and control method thereof | |
| CN106940395B (en) | Optical current transformer | |
| US5747793A (en) | Variable light source compensated optical fiber sensing system | |
| CN105157856A (en) | Device for utilizing semiconductor refractive index change to measure MeV nuclear radiation pulse time width | |
| CN111337052B (en) | Y waveguide parameter measuring instrument, measuring system and measuring method | |
| CN113138302B (en) | Optical current transformer | |
| CN205786792U (en) | A kind of all-fiber current transformator based on optical fiber temperature sensor | |
| CN111896231A (en) | Device and method for calibrating extinction ratio tester with wide-range adjustable extinction ratio | |
| CN101995569A (en) | Extinction ratio self-compensation electro-optic modulation optical pulse device | |
| CN108337046B (en) | FTTx terminal line tester | |
| CN211425818U (en) | Polarizer straight waveguide tail fiber polarization crosstalk test system | |
| CN114608631B (en) | Brillouin optical time domain reflection sensing device | |
| CN212254546U (en) | Extinction ratio tester calibrating device with wide-range adjustable extinction ratio | |
| CN114236210B (en) | Modulation frequency self-adaptive system and method for optical fiber current transformer | |
| Pappert | Ultra-wideband direction finding using a fiber optic beamforming processor | |
| CN219574218U (en) | Optical electric field sensor and electric field measuring device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |