CN115839711B - Optical fiber gyroscope - Google Patents
Optical fiber gyroscope Download PDFInfo
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- CN115839711B CN115839711B CN202310127656.9A CN202310127656A CN115839711B CN 115839711 B CN115839711 B CN 115839711B CN 202310127656 A CN202310127656 A CN 202310127656A CN 115839711 B CN115839711 B CN 115839711B
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Abstract
The embodiment of the invention discloses an optical fiber gyroscope, which comprises a light source, an isolator, a polarizer, a coupler, a directional coupling waveguide, an optical fiber ring and a first photoelectric detector and a second photoelectric detector, wherein the first photoelectric detector and the second photoelectric detector are respectively used for receiving reciprocal interference signals and nonreciprocal interference signals output by the coupler; the light source, the isolator, the polarizer and the coupler are sequentially coupled, the port of the directional coupling waveguide is sequentially coupled with the second end of the coupler, the second photoelectric detector and the second end of the optical fiber loop at the first end of the optical fiber loop, and the third end of the coupler is connected with the first photoelectric detector; the light source output beam is transmitted in one direction through the isolator to transmit the polarized light beam to the polarizer, and is transmitted to the optical fiber ring through the coupler and the directional coupling waveguide to interfere. When the input is at a large angular speed or at a large impact, the output energy is detected and compensated through the energy distribution of the directional coupling waveguide ports in different proportions, so that the problem that the output is inaccurate or locked at a fixed value is solved, and the precision requirement is ensured.
Description
Technical Field
The invention relates to the technical field of optical gyroscopes, in particular to an optical fiber gyroscope.
Background
The ultra-high precision optical fiber gyroscope is used as a high-precision sensor, can support long-endurance high-precision optical fiber inertial navigation to realize long-time autonomous secret navigation, and has great strategic significance.
The long-time zero bias stability of the ultra-high precision fiber optic gyroscope reported at present improves the precision of the gyroscope by increasing the length of the optical fiber and the diameter of the optical fiber ring, and a long-fiber large-size optical fiber ring design is generally adopted, however, when the ultra-high precision fiber optic gyroscope adopts the long-fiber large-diameter design, the maximum measurement range of the gyroscope is reduced linearly.
Currently, outputting a fixed value when the maximum measurement range is exceeded, i.e. not responding to an input exceeding the measurement range; or a cross-stripe modulation method is adopted, namely when the input angular velocity is relatively high, the gyroscope works in a phase modulation interval of + -n pi with zero as the center, and the correct gyroscope output is obtained. Meanwhile, as the intensity energy detection of each level of interference fringes and the distinction difficulty of adjacent fringes are large in the closed-loop fiber optic gyroscope, the inaccuracy of the cross-fringe detection can cause the inaccuracy of the output of the gyroscope during the large dynamic input.
Disclosure of Invention
The embodiment of the invention provides an optical fiber gyroscope, which detects the optical energy of a directional coupling waveguide port by utilizing different coupling distribution proportions of the optical energy of the directional coupling waveguide input/output port under different input rotation speeds of the gyroscope, thereby compensating the external input in real time, especially the real-time compensation during the large dynamic and large impact input, ensuring the precision requirement of the ultra-high precision optical fiber gyroscope during the large dynamic and large impact input, improving the dynamic range and the impact resistance of the ultra-high precision optical fiber gyroscope and expanding the application range of the ultra-high precision optical fiber gyroscope.
According to an aspect of the present invention, there is provided an optical fiber gyroscope, specifically including a light source, an isolator, a polarizer, a coupler, a directional coupling waveguide, an optical fiber ring, a first photodetector and a second photodetector;
the output end of the light source is coupled with the input end of the isolator, the output end of the isolator is coupled with the input end of the polarizer, the output end of the polarizer is coupled with the first end of the coupler, the second end of the coupler is coupled with the first end of the directional coupling waveguide, the third end of the coupler is connected with the first photoelectric detector, the second end of the directional coupling waveguide is connected with the second photoelectric detector, the third end of the directional coupling waveguide is coupled with the first end of the optical fiber ring, and the fourth end of the directional coupling waveguide is coupled with the second end of the optical fiber ring;
the light beam emitted by the light source is transmitted unidirectionally through the isolator and then is incident to the polarizer, is transmitted through the polarizer and then is converted into a polarized light beam, and the polarized light beam is transmitted to the optical fiber ring through the coupler and the directional coupling waveguide to interfere;
the first photoelectric detector is used for receiving the reciprocal interference signal output by the coupler;
the second photodetector is used for receiving the nonreciprocal interference signal output by the directional coupling waveguide.
Optionally, the optical fiber gyroscope specifically further includes a data processing unit, where the data processing unit is configured to output a measurement result according to a signal of the first photodetector when the external interference is smaller than a preset threshold, and calculate and compensate an error according to signals of the first photodetector and the second photodetector when the external interference is greater than or equal to the preset threshold, and then output the measurement result.
Optionally, the preset threshold comprises an external dynamic condition of 200 °/s and an external impact condition comprising an impact 80G within 5 ms.
Optionally, the isolator comprises a fiber optic isolator, the polarizer comprises a fiber optic polarizer, and the coupler comprises a fiber optic coupler;
the output end of the light source is connected with the input end of the optical fiber isolator, and the optical fiber isolator, the optical fiber polarizer and the optical fiber coupler are sequentially connected.
Optionally, the optical fibers used for the fiber optic coupler and the fiber optic ring are polarization maintaining fibers.
Optionally, the first photodetector and the second photodetector each include a polarization maintaining fiber, the first photodetector is connected to the third end of the fiber coupler through the polarization maintaining fiber, and the second photodetector is connected to the directional coupling waveguide through the polarization maintaining fiber.
Optionally, the reciprocal interference signal is formed by interference of a first optical path and a second optical path, and the transmission process of the first optical path includes: the light beam output by the second end of the coupler sequentially passes through the first end and the third end of the directional coupling waveguide and then enters the optical fiber ring, and the light beam output from the optical fiber ring sequentially passes through the fourth end and the first end of the directional coupling waveguide and then enters the coupler and is output to the first photoelectric detector from the third end of the coupler; the transmission process of the second optical path comprises the following steps: the light beam output by the second end of the coupler sequentially passes through the first end and the fourth end of the directional coupling waveguide and then enters the optical fiber ring, and the light beam output from the optical fiber ring sequentially passes through the third end and the first end of the directional coupling waveguide and then enters the coupler and is output to the first photoelectric detector from the third end of the coupler;
the nonreciprocal interference signal is formed by interference of a third optical path and a fourth optical path, and the transmission process of the third optical path comprises the following steps: the light beam output by the second end of the coupler sequentially passes through the first end and the third end of the directional coupling waveguide and then enters the optical fiber ring, and the light beam output from the optical fiber ring sequentially passes through the fourth end and the second end of the directional coupling waveguide and then is output to the second photoelectric detector; the transmission process of the fourth optical path comprises the following steps: the light beam output by the second end of the coupler sequentially passes through the first end and the fourth end of the directional coupling waveguide and then enters the optical fiber ring, and the light beam output from the optical fiber ring sequentially passes through the third end and the second end of the directional coupling waveguide and then is output to the second photoelectric detector.
Optionally, the fiber length of the fiber optic loop is greater than or equal to 10km and the diameter of the fiber optic loop is greater than or equal to 210mm.
Optionally, the light beam emitted by the light source is spontaneous radiation light in the c+l band.
Optionally, the spectral width of the light beam emitted by the light source is greater than or equal to 30nm.
The optical fiber gyroscope provided by the embodiment of the invention comprises a light source, an isolator, a polarizer, a coupler, a directional coupling waveguide, an optical fiber ring, a first photoelectric detector and a second photoelectric detector; the light beam emitted by the light source is transmitted unidirectionally through the isolator and then is incident to the polarizer, is transmitted through the polarizer and then is converted into a polarized light beam, and the polarized light beam is transmitted to the optical fiber ring through the coupler and the directional coupling waveguide to interfere; receiving a reciprocal interference signal output by the coupler through a first photoelectric detector; receiving the nonreciprocal interference signal output by the directional coupling waveguide through a second photoelectric detector; and detecting the output energy of the port and performing compensation output through the difference of the energy distribution proportion of the port of the directional coupling waveguide when the directional coupling waveguide is input at a large angular speed or large impact. The problem that the fixed value output or the output is inaccurate when the ultra-high precision optical fiber gyro inputs at a large angular speed or a large impact is solved, so that the precision requirement of the ultra-high precision optical fiber gyro is ensured.
It should be understood that the description in this section is not intended to identify key or critical features of the embodiments of the invention or to delineate the scope of the invention. Other features of the present invention will become apparent from the description that follows.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is apparent that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a fiber optic gyroscope according to an embodiment of the present invention;
FIG. 2 is a diagram of the light propagation process of a directional coupling waveguide in an embodiment of the present invention;
FIG. 3 shows the intensity I and the angular velocity of sensitivity without modulation
Is a functional relationship diagram of (2);
FIG. 4 shows the intensity I and the angular velocity of sensitivity when the modulation signal is applied
Is a functional relationship diagram of (2);
fig. 5 is a signal processing method according to an embodiment of the invention.
The device comprises a 1-light source, a 2-isolator, a 3-polarizer, a 4-coupler, a 5-directional coupling waveguide, a 6-optical fiber ring, a 7-first photoelectric detector and an 8-second photoelectric detector, wherein the first light source is connected with the 2-isolator; a 10-AD converter; the system comprises 11-FPGA modem logic, 12-FPGA compensation logic, 13-DA converter, 14-amplifier and 15-output data processing module.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and the claims of the present invention and the above figures are used for distinguishing between similar objects and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used may be interchanged where appropriate such that the embodiments of the invention described herein may be implemented in sequences other than those illustrated or otherwise described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.
Fig. 1 is a schematic structural diagram of an optical fiber gyroscope provided in an embodiment of the present invention, referring to fig. 1, the optical fiber gyroscope specifically includes a light source 1, an isolator 2, a polarizer 3, a coupler 4, a directional coupling waveguide 5, an optical fiber ring 6, a first photodetector 7 and a second photodetector 8;
the output end of the light source 1 is coupled with the input end of the isolator 2, the output end of the isolator 2 is coupled with the input end of the polarizer 3, the output end of the polarizer 3 is coupled with the first end of the coupler 4, the second end of the coupler 4 is coupled with the first end of the directional coupling waveguide 5, the third end of the coupler 4 is connected with the first photodetector 7, the second end of the directional coupling waveguide 5 is connected with the second photodetector 8, the third end of the directional coupling waveguide 5 is coupled with the first end of the optical fiber loop 6, and the fourth end of the directional coupling waveguide 5 is coupled with the second end of the optical fiber loop 6;
the light beam emitted by the light source 1 is transmitted unidirectionally through the isolator 2 and then is incident to the polarizer 3, is transmitted through the polarizer 3 and then is converted into a polarized light beam, and the polarized light beam is transmitted to the optical fiber ring 6 through the coupler 4 and the directional coupling waveguide 5 to interfere;
the first photoelectric detector 7 is used for receiving the reciprocal interference signal output by the coupler;
the second photodetector 8 is arranged to receive the nonreciprocal interference signal output by the directional coupling waveguide.
The light source 1 includes, but is not limited to, a narrow light source, a wide light source and an ultra-wide light source, such as an ultra-wide spectrum c+l light source, capable of generating ultra-wide spectrum spontaneous emission ASE light covering a c+l band (1530nm to 1625 nm); optionally, the spectral width of the light beam emitted by the light source is greater than or equal to 30nm. Wherein the spectral widths transmitted and acted by other device isolators, polarizers, couplers, directional coupling waveguides, optical fiber loops, first photodetectors and second photodetectors included in the fiber optic gyroscope should include greater than or equal to 30nm. The isolator 2 comprises, but is not limited to, a linear optical isolator, such as an optical fiber isolator, and is used for conducting optical signals in the direction from the ultra-wide spectrum C+L light source to the optical fiber polarizer in a unidirectional manner, isolating return optical signals input by the polarization maintaining coupler through the optical fiber polarizer, and ensuring the stability of the ultra-wide spectrum light source; the polarizer 3 includes, but is not limited to, a nicol prism and a polarizer, for example, the optical fiber polarizer converts the optical signal output by the optical fiber isolator into polarized light, ensures that the ultra-high precision optical fiber gyroscope is a full polarization-preserving optical path, and suppresses polarization-related noise; coupler 4 includes, but is not limited to, a waveguide dual-hole directional coupler, a dual-branch directional coupler, and a directional coupler such as a polarization maintaining fiber coupler, coupling polarized light output from a fiber polarizer into a directional coupling waveguide, and coupling an interference light signal returned from the directional coupling waveguide into a polarization maintaining fiber photodetector; the directional coupling waveguide 5 utilizes the light energy coupling distribution proportion of the input/output port at different external input rotation speeds, if the reciprocal interference signals (the optical paths of the two interference signals are the same) are output, the reciprocal interference signals return to the polarization maintaining fiber coupler and are finally subjected to photoelectric conversion by the first photoelectric detector 7, and if the non-reciprocal interference signals (the optical paths of the two interference signals are different) are output, the second photoelectric detector 8 is subjected to photoelectric conversion; the optical fiber ring 6 can be a long optical fiber large-size optical fiber ring, realizes a sensitive loop for Sagnac phase shift detection, and is formed by winding full polarization maintaining optical fibers; the first photodetector 7 may be a polarization maintaining fiber photodetector for detecting a reciprocal interference signal output by the polarization maintaining fiber coupler; the second photodetector 8 may be a polarization maintaining fiber photodetector for detecting a non-reciprocal interference signal directly output from the directional coupling waveguide.
It can be understood that the light beam emitted from the light source 1 is transmitted unidirectionally through the isolator 2 and then is incident to the polarizer 3, is transmitted through the polarizer 3 and then is converted into a polarized light beam, the polarized light beam is transmitted to the optical fiber ring 6 through the coupler 4 and the directional coupling waveguide 5 to interfere, a reciprocal interference signal and a non-reciprocal interference signal are generated, and the returned two light signals are respectively transmitted to the first photoelectric detector 7 and the second photoelectric detector 8 through the directional coupling waveguide 5.
The ultra-wide spectrum C+L light source emits a wide spectrum light signal, the light signal sequentially transmits the optical fiber isolator, the optical fiber polarizer and the polarization maintaining optical fiber coupler and then enters the directional coupling waveguide, the light signal is split into two bundles of light through the directional coupling waveguide and then transmits a long optical fiber large-size optical fiber ring, the two bundles of light returned by the optical fiber ring are transmitted to the polarization maintaining optical fiber coupler and the polarization maintaining optical fiber photoelectric detector through the directional coupling waveguide, and the light signal transmitted to the polarization maintaining optical fiber coupler is coupled into the polarization maintaining optical fiber detector.
Optionally, the optical fiber gyroscope specifically further includes a data processing unit, where the data processing unit is configured to output a measurement result according to a signal of the first photodetector when the external interference is smaller than a preset threshold, and calculate and compensate an error according to signals of the first photodetector and the second photodetector when the external interference is greater than or equal to the preset threshold, and then output the measurement result.
When the external interference is greater than or equal to a preset threshold, the input is considered as large dynamic and large impact input, and in order to ensure the precision requirement of the optical fiber gyroscope under the condition, the measurement result is output after the signal calculation and the error compensation are needed.
Optionally, the preset threshold comprises an external dynamic condition of 200 °/s and an external impact condition comprising an impact 80G within 5 ms.
Wherein, the maximum value of the external dynamic condition is 200 DEG/s, the applicable external impact condition comprises 5ms internal impact 80G, and the maximum dynamic value of the fiber-optic gyroscope is 20 DEG/s.
Optionally, the isolator comprises a fiber optic isolator, the polarizer comprises a fiber optic polarizer, and the coupler comprises a fiber optic coupler;
the output end of the light source is connected with the input end of the optical fiber isolator, and the optical fiber isolator, the optical fiber polarizer and the optical fiber coupler are sequentially connected.
The output end of the light source is connected with the input end of the optical fiber isolator, the output end of the optical fiber isolator is connected with the input end of the optical fiber polarizer, and the output end of the optical fiber polarizer is connected with the input end of the optical fiber coupler.
Optionally, the optical fibers used for the fiber optic coupler and the fiber optic ring are polarization maintaining fibers.
The optical fibers used by the optical fiber coupler and the optical fiber ring are polarization maintaining optical fibers, and the polarization maintaining optical fibers are matched with the optical fiber coupler and the optical fiber ring respectively.
Optionally, the first photodetector and the second photodetector each include a polarization maintaining fiber, the first photodetector is connected to the third end of the fiber coupler through the polarization maintaining fiber, and the second photodetector is connected to the directional coupling waveguide through the polarization maintaining fiber.
Wherein, the polarization maintaining optical fibers included in the first photoelectric detector and the second photoelectric detector are matched with the connected detectors.
It can be understood that the reciprocal interference signal output by the coupler is transmitted to the optical fiber coupler by the first photoelectric detector through the polarization maintaining optical fiber and is coupled in by the third end; the nonreciprocal interference signal output by the directional coupling waveguide is received by the second photodetector through the polarization maintaining fiber.
Fig. 2 is a diagram of an optical propagation process of a directional coupling waveguide according to an embodiment of the present invention, referring to fig. 2 in conjunction with fig. 1, where a) of fig. 2 is a first transmission process diagram of a reciprocal interference signal, and b) of fig. 2 is a second transmission process diagram of the reciprocal interference signal. Optionally, the reciprocal interference signal is formed by interference of a first optical path (clockwise optical path) and a second optical path (counterclockwise optical path), and the transmission process of the first optical path includes: the light beam output by the second end of the coupler 4 sequentially passes through the first end (1) and the third end (3) of the directional coupling waveguide 5 and then enters the optical fiber ring 6, the light beam output from the optical fiber ring 6 sequentially passes through the fourth end (4) and the first end (1) of the directional coupling waveguide 5 and then enters the coupler 4, and the light beam is output from the third end of the coupler 4 to the first photoelectric detector 7, and the light path is subjected to a primary coupling process; the transmission process of the second optical path comprises the following steps: the light beam output by the second end of the coupler 4 sequentially passes through the first end (1) and the fourth end (4) of the directional coupling waveguide 5 and then enters the optical fiber ring 6, the light beam output from the optical fiber ring 6 sequentially passes through the third end (3) and the first end (1) of the directional coupling waveguide 5 and then enters the coupler 4, the light beam is output from the third end (3) of the coupler 4 to the first photoelectric detector 7, and the light path passes through a primary coupling process;
with continued reference to fig. 2 in conjunction with fig. 1, fig. 2 c) is a first transmission process diagram of the non-reciprocal interference signal and fig. 2 d) is a second transmission process diagram of the non-reciprocal interference signal. The nonreciprocal interference signal is formed by interference of a third optical path (clockwise optical path) and a fourth optical path (anticlockwise optical path), and the transmission process of the third optical path comprises: the light beam output by the second end of the coupler 4 sequentially passes through the first end (1) and the third end (3) of the directional coupling waveguide 5 and then enters the optical fiber ring 6, the light beam output from the optical fiber ring 6 sequentially passes through the fourth end (4) and the second end (2) of the directional coupling waveguide 5 and then is output to the second photodetector 8, and the optical path has no coupling process; the transmission process of the fourth optical path comprises the following steps: the light beam output by the second end of the coupler 4 sequentially passes through the first end (1) and the fourth end (4) of the directional coupling waveguide 5 and then enters the optical fiber ring 6, the light beam output from the optical fiber ring 6 sequentially passes through the third end (3) and the second end (2) of the directional coupling waveguide 5 and then is output to the second photodetector 8, and the light path passes through the coupling process twice.
The first transmission process of the reciprocal interference signal is the transmission process of the reciprocal clockwise optical path, the second transmission process of the reciprocal interference signal is the transmission process of the reciprocal anticlockwise optical path, the first transmission process of the non-reciprocal interference signal is the transmission process of the non-reciprocal clockwise optical path, and the second transmission process of the non-reciprocal interference signal is the transmission process of the non-reciprocal anticlockwise optical path.
It can be understood that the transmission process of the reciprocal clockwise optical path is that the optical signal input by the polarization maintaining optical fiber coupler enters the optical fiber ring from the third end through the directional coupling waveguide by the first end of the directional coupling waveguide, enters the directional coupling waveguide from the fourth end of the directional coupling waveguide by the output of the optical fiber ring, and is output by the first end of the directional coupling waveguide; the transmission process of the reciprocal anticlockwise light path is that the light signal input by the polarization maintaining fiber coupler is coupled through the directional coupling waveguide at the first end and then output by the fourth end to enter the fiber ring, and output by the fiber ring enters the directional coupling waveguide from the third end of the directional coupling waveguide and output by the first end of the directional coupling waveguide; the reciprocity interference signal light path ensures the light path reciprocity of the closed-loop fiber-optic gyroscope, solves the problem of nonreciprocal noise caused by nonreciprocal light path, and realizes the detection of the gyroscope on the external input rotating speed. The transmission process of the nonreciprocal clockwise optical path is that an optical signal input by the polarization maintaining optical fiber coupler enters an optical fiber ring from a third end through a directional coupling waveguide by a first end of the directional coupling waveguide, enters the directional coupling waveguide from a fourth end of the directional coupling waveguide by an output of the optical fiber ring, and is output from a second end of the directional coupling waveguide; the transmission process of the nonreciprocal anticlockwise light path is that an optical signal input by the polarization maintaining optical fiber coupler passes through the directional coupling waveguide coupler from the first end of the directional coupling waveguide and then is output by the fourth end to enter the optical fiber ring, the output of the optical fiber ring enters the directional coupling waveguide from the third end of the directional coupling waveguide, the output of the optical fiber ring is output by the second end of the directional coupling waveguide after being coupled, and the nonreciprocal interference signal light path can be used for detecting the optical signal generated by the optical fiber gyroscope during large dynamic impact through the second photoelectric detector, so that the detection and compensation of a large dynamic range are realized.
It is worth noting that the transmission process of the reciprocal interference signal has only one coupling process, and the transmission process of the non-reciprocal interference signal can have no coupling process or two coupling processes.
Based on this, FIG. 3 shows the intensity I and the angular velocity of sensitivity without modulation
Wherein the light intensity I is the ordinate axis, the sensitivity angular velocity +.>
When the optical fiber gyroscope is not added with a modulation signal, the signal received by the first end of the first photoelectric detector is as shown in the figure3, the light intensity I and the sensitive angular velocity of the first end of the directional coupling waveguide>
In a cosine function relation, the rotating speed direction can not be distinguished near 0; FIG. 4 shows the intensity I and the sensitivity of the angular velocity when a modulated signal is applied>
Wherein the light intensity I is the ordinate axis, the sensitivity angular velocity +.>
When the optical fiber gyro is added with a modulation signal for the coordinate transverse axis, the signal received by the first end of the first photoelectric detector is shown as a solid line in the graph of fig. 4, and the light intensity I and the sensitive angular velocity of the first end of the directional coupling waveguide are +.>
The rotational speed direction can be effectively distinguished near 0 in a sine function relation. When the optical fiber gyro works at 0 position in a closed loop, the light intensity I and the sensitive angular velocity +.>
The relation is that the signal received by the second photodetector is shown by the broken line in the graph of FIG. 4, and the light intensity I and the sensitive angular velocity of the third end of the directional coupling waveguide are +.>
In a sinusoidal functional relationship. Especially when the fiber-optic gyroscope receives large dynamic and large impact input, the fiber-optic gyroscope cannot stably work close to the 0 position in a closed loop, and the third end of the directional coupling waveguide obtains the maximum light energy; and when the input of the maximum dynamic measurement range of the fiber-optic gyroscope is not exceeded, the gyroscope stably works near 0 bit, and the third end of the directional coupling waveguide does not have optical energy output.
It is noted that when the optical fiber loop return optical phase difference approaches zero (when the optical fiber gyroscope is static or the closed loop 0 bit works), optical energy is output from the first end of the directional coupling waveguide, when the optical fiber gyroscope is subjected to a large dynamic angular velocity or a large impact, the optical fiber loop return optical phase difference approaches 180 degrees, optical energy is output from the second end of the directional coupling waveguide, and the sum of the energy output from the first end and the second end is unchanged, namely, the sum of the total energy converted by the first photoelectric detector and the second photoelectric detector is unchanged.
Optionally, the fiber length of the fiber optic loop is greater than or equal to 10km and the diameter of the fiber optic loop is greater than or equal to 210mm.
FIG. 5 is a diagram of a signal processing method according to an embodiment of the present invention, referring to FIG. 5 in combination with FIG. 4, when the input angular rate of the fiber optic gyroscope is input within the dynamic range, the first photodetector 7 photoelectrically converts the sensitive reciprocal interference angular rate, converts the converted reciprocal interference angular rate into a digital signal by the AD converter 10, and then modulates and demodulates the digital signal by the FPGA modulation/demodulation logic 11 to demodulate the angular rate
And generating additional feedback +.>
A signal and a modulated signal. Additional feedback->
The signal and the modulated signal are converted by the DA converter 13, amplified by the amplifier 14 and input to the directional coupling waveguide 5, and the directional coupling waveguide 5 generates a signal with an angular rate +.>
Additional feedback equal in magnitude and opposite in sign +.>
The phase difference is counteracted, so that the gyro stably works at the 0 working point position in a closed loop. Demodulation angular Rate->
And the compensation signal is transmitted to an output data processing module 15 for processing, and the processed output is the output of the fiber-optic gyroscope. At this time, the second photodetector 8 has no optical energy because the fiber-optic gyroscope is stably closed-loop operated at the 0 operating point position. />
The fiber optic gyroscope is in large dynamic state and impactWhen inputting, the second photodetector 8 receives the light energy signal, after the photoelectric conversion is completed, the light energy signal is converted into a digital signal by the AD converter 10, and then the digital signal is passed through the FPGA compensation logic 12 to be resolved, so that the input angular velocity and the impact at the moment can be resolved, namely
And (3) compensating the value, and delivering the value to an output data processing module 15 for processing, wherein the output is the output of the fiber optic gyroscope.
For example, as shown by the dashed line in fig. 4, the second end of the directional coupling waveguide is a sine function in the range of [ -pi, +pi ], and the linear fitting can be simply performed, that is, the greater the angular velocity of the input exceeding the maximum dynamic range of the gyro, the greater the optical energy of the second photodetector, and the greater the digital quantity after AD conversion, which is implemented as follows:
assuming a maximum dynamic range of 20 DEG/s for the fiber optic gyroscope, a required usage range is 200 DEG/s.
S1: placing the fiber optic gyroscope on a speed turntable, wherein the rotating speeds of the turntable are respectively set as follows: 40 °/s, ±60 °/s, ±80 °/s, ±100 °/s, ±120 °/s, ±140 °/s, ±160 °/s, ±180 °/s, ±200 °/s, collecting an FPGA output value of the second photodetector;
s2: placing the fiber optic gyroscope on a speed turntable, wherein the rotating speeds of the turntable are respectively set as follows: collecting FPGA output values of the first photoelectric detector, wherein the FPGA output values are +/-0 degree/s, +/-0.1 degree/s, +/-0.2 degree/s, +/-1 degree/s, +/-2 degree/s, +/-5 degree/s, +/-10 degree/s and +/-20 degree/s;
s3: and establishing a fitting curve of all the rotating speeds, calculating scale performance indexes such as asymmetry, nonlinearity and the like of the gyro scale according to the curve, and enabling the scale performance indexes to meet the use requirements, wherein the fitting curve is established.
The invention provides an optical fiber gyroscope, which comprises a light source, an isolator, a polarizer, a coupler, a directional coupling waveguide, an optical fiber ring, a first photoelectric detector and a second photoelectric detector, wherein the first photoelectric detector and the second photoelectric detector are respectively used for receiving reciprocal interference signals and nonreciprocal interference signals output by the coupler; the light source, the isolator, the polarizer and the first end of the coupler are sequentially coupled, the port of the directional coupling waveguide is sequentially coupled with the second end of the coupler, the second photoelectric detector and the second end of the optical fiber loop at the first end of the optical fiber loop, and the third end of the coupler is connected with the first photoelectric detector; the light source output beam is transmitted in one direction through the isolator to transmit the polarized light beam to the polarizer, and is transmitted to the optical fiber ring through the coupler and the directional coupling waveguide to interfere. By utilizing the fact that the light energy coupling distribution proportion of the directional coupling waveguide port is different under different input rotating speeds of the gyroscope, the light energy of the directional coupling waveguide port is detected, external input can be compensated in real time, particularly, when large dynamic and large impact input is carried out, the precision requirement of the ultra-high precision optical fiber gyroscope on the large dynamic and large impact input is guaranteed, meanwhile, the dynamic range and the shock resistance of the optical fiber gyroscope are improved, and the application range is expanded.
The above embodiments do not limit the scope of the present invention. It will be apparent to those skilled in the art that various modifications, combinations, sub-combinations and alternatives are possible, depending on design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of the present invention.
Claims (9)
1. The optical fiber gyroscope is characterized by comprising a light source, an isolator, a polarizer, a coupler, a directional coupling waveguide, an optical fiber ring, a first photoelectric detector and a second photoelectric detector;
the output end of the light source is coupled with the input end of the isolator, the output end of the isolator is coupled with the input end of the polarizer, the output end of the polarizer is coupled with the first end of the coupler, the second end of the coupler is coupled with the first end of the directional coupling waveguide, the third end of the coupler is connected with the first photodetector, the second end of the directional coupling waveguide is connected with the second photodetector, the third end of the directional coupling waveguide is coupled with the first end of the optical fiber loop, and the fourth end of the directional coupling waveguide is coupled with the second end of the optical fiber loop;
the light beam emitted by the light source is transmitted in one direction through the isolator and then enters the polarizer, is transmitted through the polarizer and then is converted into a polarized light beam, and the polarized light beam is transmitted to the optical fiber ring through the coupler and the directional coupling waveguide to interfere; the directional coupling waveguide utilizes the light energy coupling distribution proportion of the input/output port at different external input rotation speeds;
the first photoelectric detector is used for receiving the reciprocal interference signal output by the coupler;
the second photoelectric detector is used for receiving the nonreciprocal interference signals output by the directional coupling waveguide;
the system further comprises a data processing unit, wherein the data processing unit is used for outputting a measurement result according to the signal of the first photoelectric detector when the external interference is smaller than a preset threshold value, and outputting the measurement result after calculating and compensating errors according to the signals of the first photoelectric detector and the second photoelectric detector when the external interference is larger than or equal to the preset threshold value.
2. The fiber optic gyroscope of claim 1, wherein the preset threshold includes an external dynamic condition and an external shock condition, the external dynamic condition being 200 °/s, the external shock condition including a 5ms internal shock 80G.
3. The fiber optic gyroscope of claim 1, wherein the isolator comprises a fiber optic isolator, the polarizer comprises a fiber optic polarizer, and the coupler comprises a fiber optic coupler;
the output end of the light source is connected with the input end of the optical fiber isolator, and the optical fiber isolator, the optical fiber polarizer and the optical fiber coupler are sequentially connected.
4. A fiber optic gyroscope according to claim 3, wherein the optical fibers used for the fiber optic coupler and the fiber optic loop are polarization maintaining fibers.
5. The fiber optic gyroscope of claim 4, wherein the first photodetector and the second photodetector each comprise a polarization maintaining fiber, the first photodetector being connected to the third end of the fiber optic coupler by the polarization maintaining fiber, the second photodetector being connected to the directional coupling waveguide by the polarization maintaining fiber.
6. The fiber optic gyroscope of claim 1, wherein the reciprocal interference signal is formed by interference of a first optical path and a second optical path, the transmission of the first optical path comprising: the light beam output by the second end of the coupler sequentially passes through the first end and the third end of the directional coupling waveguide and then enters the optical fiber ring, the light beam output from the optical fiber ring sequentially passes through the fourth end and the first end of the directional coupling waveguide and then enters the coupler, and the light beam is output from the third end of the coupler to the first photoelectric detector; the transmission process of the second optical path comprises the following steps: the light beam output by the second end of the coupler sequentially passes through the first end and the fourth end of the directional coupling waveguide and then enters the optical fiber ring, the light beam output from the optical fiber ring sequentially passes through the third end and the first end of the directional coupling waveguide and then enters the coupler, and the light beam is output from the third end of the coupler to the first photoelectric detector;
the nonreciprocal interference signal is formed by interference of a third optical path and a fourth optical path, and the transmission process of the third optical path comprises the following steps: the light beam output by the second end of the coupler sequentially passes through the first end and the third end of the directional coupling waveguide and then enters the optical fiber ring, and the light beam output from the optical fiber ring sequentially passes through the fourth end and the second end of the directional coupling waveguide and then is output to the second photoelectric detector; the transmission process of the fourth optical path comprises the following steps: the light beam output by the second end of the coupler sequentially passes through the first end and the fourth end of the directional coupling waveguide and then enters the optical fiber ring, and the light beam output from the optical fiber ring sequentially passes through the third end and the second end of the directional coupling waveguide and then is output to the second photoelectric detector.
7. The fiber optic gyroscope of claim 1, wherein the fiber optic loop has a fiber length greater than or equal to 10km and a diameter greater than or equal to 210mm.
8. The fiber optic gyroscope of claim 1, wherein the light beam emitted from the light source is spontaneous emission light in the c+l band.
9. The fiber optic gyroscope of claim 8, wherein the spectral width of the light beam emitted by the light source is greater than or equal to 30nm.
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