CN115839711A - Optical fiber gyroscope - Google Patents
Optical fiber gyroscope Download PDFInfo
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- CN115839711A CN115839711A CN202310127656.9A CN202310127656A CN115839711A CN 115839711 A CN115839711 A CN 115839711A CN 202310127656 A CN202310127656 A CN 202310127656A CN 115839711 A CN115839711 A CN 115839711A
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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, 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 non-reciprocal interference signals output by the coupler; the light source, the isolator, the polarizer and the coupler are coupled in sequence, a port of the directional coupling waveguide is coupled with the second end of the coupler, the second photoelectric detector and the second end of the first end of the optical fiber ring in sequence, 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 and the transmission polarizer to output polarized light beam, and then is transmitted to the optical fiber ring through the coupler and the directional coupling waveguide to generate interference. When the input is carried out at a large angular velocity or large impact, the output energy is detected and compensated through energy distribution of different proportions of the directional coupling waveguide port, and the problem of inaccurate output or constant value locking is solved, so that 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 covert navigation, and has great strategic significance.
The long-time zero-bias stability of the currently reported ultrahigh-precision optical fiber gyroscope 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 is generally adopted for design, however, when the ultrahigh-precision optical fiber gyroscope adopts the long-fiber large-diameter design, the maximum measurement range of the gyroscope is reduced linearly.
Currently, a fixed value is output when the maximum measurement range is exceeded, namely, the input exceeding the measurement range is not responded; or a cross-fringe modulation method is adopted, namely when the input angular velocity is larger, the gyroscope works in a phase modulation interval of +/-n pi with zero as the center, and correct gyroscope output is obtained. Meanwhile, because the difficulty of detecting the light intensity energy of each level of interference fringes and distinguishing adjacent fringes in the closed-loop fiber-optic gyroscope is high, the cross-fringe detection has inaccuracy, which can cause the inaccuracy of the output of the gyroscope during large dynamic input.
Disclosure of Invention
The embodiment of the invention provides an optical fiber gyroscope, which detects optical energy at a directional coupling waveguide port by utilizing different optical energy coupling distribution proportions of the directional coupling waveguide input and output ports at different input rotating speeds of the gyroscope, so as to compensate external input in real time, particularly compensate in real time during large-dynamic and large-impact input, ensure the precision requirements of the ultrahigh-precision optical fiber gyroscope on large-dynamic and large-impact input, improve the dynamic range and the impact resistance of the ultrahigh-precision optical fiber gyroscope, and expand the application range of the ultrahigh-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 loop, 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 in one direction by the isolator and then enters the polarizer, the light beam is transmitted by the polarizer and then is converted into a polarized light beam, and the polarized light beam is transmitted to the optical fiber ring for interference by the coupler and the directional coupling waveguide;
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 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 output the measurement result after calculating and compensating 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.
Optionally, the preset threshold comprises an external dynamic condition and an external impact condition, the external dynamic condition is 200 °/s, and the external impact condition comprises 80G impact within 5 ms.
Optionally, the isolator comprises a fiber isolator, the polarizer comprises a fiber polarizer, and the coupler comprises a fiber 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 coupler and the fiber loop are polarization maintaining fibers.
Optionally, the first photodetector and the second photodetector both 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, the light beam output by 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 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, the light beam output by 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 to the first photoelectric detector from the third end of the coupler;
the nonreciprocal interference signal is formed by the 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 beams output by the second end of the coupler enter the optical fiber loop after sequentially passing through the first end and the third end of the directional coupling waveguide, and the light beams output by the optical fiber loop are output to the second photoelectric detector after sequentially passing through the fourth end and the second end of the directional coupling waveguide; the transmission process of the fourth optical path comprises the following steps: and the light beams output from the optical fiber ring sequentially pass through the third end and the second end of the directional coupling waveguide and are output to the second photoelectric detector.
Optionally, the optical fiber length of the optical fiber loop is greater than or equal to 10km, and the diameter of the optical fiber loop is greater than or equal to 210mm.
Optionally, the light beam emitted by the light source is spontaneous emission light in a 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 in one direction by the isolator and then enters the polarizer, the light beam is transmitted by the polarizer and then is converted into a polarized light beam, and the polarized light beam is transmitted to the optical fiber ring for interference by the coupler and the directional coupling waveguide; receiving the reciprocal interference signal output by the coupler through a first photoelectric detector; receiving a non-reciprocal interference signal output by the directional coupling waveguide through a second photoelectric detector; when the directional coupling waveguide is input at a large angular speed or large impact, the energy output by the port is detected and compensated and output is carried out according to different energy distribution proportions of the ports of the directional coupling waveguide. The problem that fixed value output or output is inaccurate when the ultrahigh-precision fiber-optic gyroscope is input at a large angular speed or large impact is solved, and therefore the precision requirement of the ultrahigh-precision fiber-optic gyroscope is guaranteed.
It should be understood that the statements in this section do not necessarily identify key or critical features of the embodiments of the present invention, nor do they necessarily limit the scope of the invention. Other features of the present invention will become apparent from the following description.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an optical fiber gyroscope according to an embodiment of the present invention;
FIG. 2 is a diagram illustrating the light propagation process of a directionally coupled waveguide in an embodiment of the present invention;
FIG. 3 shows the intensity I and the sensitive angular velocity without modulation signal
A functional relationship diagram of (1);
FIG. 4 shows the intensity I and the sensitive angular velocity when the modulation signal is applied
A functional relationship diagram of (1);
fig. 5 is a diagram of a signal processing method according to an embodiment of the invention.
The device comprises a light source 1, a 2-isolator, a 3-polarizer, a 4-coupler, a 5-directional coupling waveguide, an optical fiber ring 6, a first photoelectric detector 7 and a second photoelectric detector 8, wherein the light source is connected with the optical fiber ring 6; a 10-AD converter; 11-FPGA modulation and demodulation logic, 12-FPGA compensation logic, 13-DA converters, 14-amplifiers and 15-output data processing modules.
Detailed Description
In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or 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 according to an embodiment of the present invention, and 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 loop 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 photoelectric detector 7, the second end of the directional coupling waveguide 5 is connected with the second photoelectric detector 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 in one direction by the isolator 2 and then enters the polarizer 3, the light beam is transmitted by 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 generate interference;
the first photoelectric detector 7 is used for receiving the reciprocal interference signal output by the coupler;
the second photodetector 8 is used for receiving 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, and can generate ultra-wide spectrum spontaneous emission ASE light covering C + L wave bands (1530 nm to 1625 nm); optionally, the spectral width of the light beam emitted by the light source is greater than or equal to 30nm. The spectral widths transmitted and acted by other devices, such as an isolator, a polarizer, a coupler, a directional coupling waveguide, an optical fiber ring, the first photoelectric detector and the second photoelectric detector, included in the optical fiber gyroscope are more than or equal to 30nm. The isolator 2 includes but is not limited to a line type optical isolator, such as an optical fiber isolator, and unidirectionally conducts an optical signal in a direction from the ultra-wide spectrum C + L light source to the optical fiber polarizer, and isolates a return optical signal input by the polarization maintaining coupler through the optical fiber polarizer, so as to ensure the stability of the ultra-wide spectrum light source; the polarizer 3 includes but is not limited to a Nicol prism and a polaroid, such as an optical fiber polarizer, converts an optical signal output by the optical fiber isolator into polarized light, ensures that the ultra-high precision optical fiber gyroscope is a full polarization-maintaining optical path, and inhibits polarization-related noise; the coupler 4 includes but is not limited to a waveguide double-hole directional coupler, a double-branch directional coupler and a directional coupler such as a polarization-maintaining fiber coupler, couples polarized light output by a fiber polarizer into a directional coupling waveguide, and couples interference optical signals returned by 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 rotating speeds, if reciprocal interference signals are output (the optical paths of two interference signals are the same), the reciprocal interference signals are returned to the polarization-maintaining fiber coupler and are subjected to photoelectric conversion by the first photoelectric detector 7 finally, and if nonreciprocal interference signals are output (the optical paths of two interference signals are different), the photoelectric conversion is performed by the second photoelectric detector 8; the optical fiber loop 6 can be a long optical fiber large-size optical fiber loop, realizes a sensitive loop of Sagnac phase shift detection, and is formed by winding a fully polarization-maintaining optical fiber; the first photodetector 7 may be a polarization maintaining fiber photodetector for detecting the reciprocal interference signal outputted by the polarization maintaining fiber coupler; the second photodetector 8 may be a polarization maintaining fiber photodetector for detecting the non-reciprocal interference signal directly output by the directional coupling waveguide.
It can be understood that light beams emitted by the light source 1 are transmitted in one direction by the isolator 2 and then enter the polarizer 3, the light beams are transmitted by the polarizer 3 and then converted into polarized light beams, the polarized light beams are transmitted to the optical fiber ring 6 through the coupler 4 and the directional coupling waveguide 5 to generate interference, so as to generate a reciprocal interference signal and a non-reciprocal interference signal, and two returned light signals are transmitted to the first photodetector 7 and the second photodetector 8 through the directional coupling waveguide 5 respectively.
Illustratively, an ultra-wide spectrum C + L light source emits a wide spectrum light signal, the light signal is sequentially transmitted to a fiber isolator, a fiber polarizer and a polarization maintaining fiber coupler and then enters a directional coupling waveguide, the light signal is split into two beams by the directional coupling waveguide and then is transmitted to a long-fiber large-size fiber ring, the two beams of light returned by the fiber ring are transmitted to the polarization maintaining fiber coupler and a polarization maintaining fiber photoelectric detector by the directional coupling waveguide, and the light signal transmitted to the polarization maintaining fiber coupler is coupled to the polarization maintaining fiber photoelectric 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 output the measurement result after calculating and compensating 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.
When the external interference is greater than or equal to the preset threshold, the large dynamic and large impact input is considered, and in order to ensure the precision requirement of the optical fiber gyroscope under the condition, the signal calculation is needed, the error is compensated, and then the measurement result is output.
Optionally, the preset threshold comprises an external dynamic condition of 200 °/s and an external impact condition comprising 80G impact within 5 ms.
The maximum value of the external dynamic condition is 200 DEG/s, the applicable external impact condition comprises 80G impact within 5ms, and the maximum dynamic value of the fiber-optic gyroscope is 20 DEG/s.
Optionally, the isolator comprises a fiber isolator, the polarizer comprises a fiber polarizer, and the coupler comprises a fiber 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 coupler and the fiber loop are polarization maintaining fibers.
The optical fibers used by the optical fiber coupler and the optical fiber ring are polarization maintaining optical fibers which are respectively matched with the optical fiber coupler and the optical fiber ring.
Optionally, the first photodetector and the second photodetector both 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.
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 photodetector through the polarization-maintaining optical fiber and is coupled in from the third end; and the nonreciprocal interference signal output by the directional coupling waveguide is received by the second photoelectric detector through the polarization-maintaining optical fiber.
Fig. 2 is a diagram of an optical propagation process of a directional coupling waveguide according to an embodiment of the present invention, and referring to fig. 2 in conjunction with fig. 1, a) of fig. 2 is a diagram of a first transmission process of a reciprocal interference signal, and b) of fig. 2 is a diagram of a second transmission process 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: light beams output by the second end of the coupler 4 sequentially pass through the first end (1) and the third end (3) of the directional coupling waveguide 5 and then enter the optical fiber ring 6, light beams output from the optical fiber ring 6 sequentially pass through the fourth end (4) and the first end (1) of the directional coupling waveguide 5 and then enter the coupler 4, the light beams are output to the first photoelectric detector 7 from the third end of the coupler 4, and the light path passes through a primary coupling process; the transmission process of the second optical path comprises the following steps: light beams output by the second end of the coupler 4 sequentially pass through the first end (1) and the fourth end (4) of the directional coupling waveguide 5 and then enter the optical fiber ring 6, light beams output from the optical fiber ring 6 sequentially pass through the third end (3) and the first end (1) of the directional coupling waveguide 5 and then enter the coupler 4, the light beams are output to the first photoelectric detector 7 from the third end (3) of the coupler 4, and a light path passes through a primary coupling process;
with continuing reference to fig. 2 in conjunction with fig. 1, fig. 2 c) is a diagram of a first transmission process of the non-reciprocal interference signal, and fig. 2 d) is a diagram of a second transmission process of the non-reciprocal interference signal. The nonreciprocal interference signal is formed by the interference of a third optical path (a clockwise optical path) and a fourth optical path (a counterclockwise optical path), and the transmission process of the third optical path comprises the following steps: light beams output by the second end of the coupler 4 sequentially pass through the first end (1) and the third end (3) of the directional coupling waveguide 5 and then enter the optical fiber ring 6, the light beams output from the optical fiber ring 6 sequentially pass through the fourth end (4) and the second end (2) of the directional coupling waveguide 5 and are output to the second photoelectric detector 8, and the optical path has no coupling process; the transmission process of the fourth optical path comprises the following steps: light beams output by the second end of the coupler 4 enter the optical fiber ring 6 after sequentially passing through the first end (1) and the fourth end (4) of the directional coupling waveguide 5, the light beams output from the optical fiber ring 6 are output to the second photoelectric detector 8 after sequentially passing through the third end (3) and the second end (2) of the directional coupling waveguide 5, and the light paths are subjected to two coupling processes.
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 counterclockwise 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 counterclockwise optical path.
It can be understood that, in the transmission process of the reciprocal clockwise optical path, the optical signal input by the polarization-maintaining fiber coupler passes through the first end of the directional coupling waveguide, is output from the third end through the directional coupling waveguide, enters the fiber ring, is output from the fiber ring, enters the directional coupling waveguide from the fourth end of the directional coupling waveguide, and is output from the first end of the directional coupling waveguide; the transmission process of the reciprocal counterclockwise optical path is that an optical signal input by the polarization-maintaining optical fiber coupler is coupled through the directional coupling waveguide by the first end of the directional coupling waveguide, then is output from the fourth end to enter the optical fiber ring, is output from the optical fiber ring, enters the directional coupling waveguide by the third end of the directional coupling waveguide, and is output by the first end of the directional coupling waveguide; the reciprocity interference signal light path ensures the reciprocity of the closed-loop fiber-optic gyroscope light path, solves the nonreciprocal noise caused by nonreciprocal light path, and realizes the detection of the gyroscope to 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 passes through the first end of the directional coupling waveguide, is output from the third end through the directional coupling waveguide, enters the optical fiber ring, is output from the optical fiber ring, enters the directional coupling waveguide from the fourth end of the directional coupling waveguide, and is output from the second end of the directional coupling waveguide; the transmission process of the nonreciprocal counterclockwise optical path is that an optical signal input by the polarization-maintaining optical fiber coupler passes through the directional coupling waveguide coupler through the first end of the directional coupling waveguide and then is output from the fourth end to enter the optical fiber ring, the optical signal is output from the optical fiber ring and enters the directional coupling waveguide through the third end of the directional coupling waveguide, the optical signal is output from the second end after being coupled by the directional coupling waveguide, and the nonreciprocal interference signal optical path can be used for detecting an 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 should be noted that the transmission process of the reciprocal interference signal only has a coupling process, and the transmission process of the non-reciprocal interference signal may have no coupling process or two coupling processes.
Based on this, FIG. 3 shows the intensity I and the sensitive angular velocity without modulation signal
In which the light intensity I is the ordinate axis of the coordinate and the sensitive angular speed ≥ is present>
The horizontal axis of the coordinate is, when the fiber optic gyroscope is not added with the modulation signal, the signal received by the first end of the first photoelectric detector is as shown in fig. 3, and the light intensity I and the sensitive angular velocity ^ are directionally coupled with the first end of the waveguide>
A cosine function relationship is formed, and the rotating speed direction can not be distinguished near 0; FIG. 4 shows the light intensity I and the sensitive angular velocity->
In which the light intensity I is the ordinate axis of the coordinate and the sensitive angular speed ≥ is present>
When the fiber-optic gyroscope adds a modulation signal, the signal received by the first end of the first photoelectric detector is shown as a solid line in fig. 4, and the light intensity I and the sensitive angular velocity ^ are greater than or equal to the light intensity I and the sensitive angular velocity at the first end of the directional coupling waveguide>
The rotating speed direction can be effectively distinguished near 0 by a sine function relationship. When the fiber-optic gyroscope works at the 0 position in a closed loop mode, the light intensity I and the sensitive angular speed->
In relation to this, the signal received by the second photodetector is, as indicated by the dashed line in FIG. 4, directionally coupled to the light intensity I and the sensitive angular velocity->
Is in a sine function relationship. Especially when the fiber optic gyroscope is subjected to large dynamic and large impact input, the fiber optic gyroscope cannot stably work close to the 0 position, and the third end of the directional coupling waveguide obtains maximum light energy; when the input is not beyond the maximum dynamic measurement range of the fiber-optic gyroscope, the gyroscope stably works near the 0 position, and no optical energy is output from the third end of the directional coupling waveguide.
It is worth noting that when the phase difference of the return light of the optical fiber loop tends to zero (when the optical fiber gyroscope is in a static state or works at a 0-position of a closed loop), the optical energy is output from the first end of the directional coupling waveguide, and when the phase difference of the return light of the optical fiber loop tends to 180 degrees when the optical fiber gyroscope is subjected to a large dynamic angular velocity or a large impact, the sum of the energies output by the first end and the second end is not changed, that is, the sum of the total energies converted by the first photodetector and the second photodetector is not changed.
Optionally, the optical fiber length of the optical fiber loop is greater than or equal to 10km, and the diameter of the optical fiber 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 in the dynamic range, the first photodetector 7 performs photoelectric conversion on the sensed reciprocal interference angular rate, the converted reciprocal interference angular rate is converted into a digital signal by the AD converter 10, and the digital signal is modulated and demodulated by the FPGA modulation and 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 fed to the directional coupling waveguide 5, and the directional coupling waveguide 5 generates a signal which is equal to the angular rate->
Additional feedback of equal magnitude and opposite sign>
And offsetting the phase difference to ensure that the gyroscope stably works at the working point position of 0 in a closed loop mode. Demodulated angular rate->
And the compensation signal is processed by the output data processing module 15, and the processed output is the output of the fiber-optic gyroscope. At this time, the second photodetector 8 has no light energy because the fiber-optic gyroscope works at the 0 working point position in a stable closed loop. />
When the optical fiber gyroscope is in a large dynamic state and is in impact input, the second photoelectric detector 8 receives an optical energy signal, after photoelectric conversion is completed, the optical energy signal is converted into a digital signal by the AD converter 10, the digital signal is subjected to calculation by the FPGA compensation logic 12, and the input angular velocity and the impact magnitude at the moment can be calculated, namely
And (4) compensating the value, and processing the value by an output data processing module 15, wherein the output is the output of the fiber optic gyroscope.
Illustratively, a solution method in the FPAG compensation logic may be that, as shown by a dotted line in fig. 4, the second end of the directional coupling waveguide is a sine function in the range of [ -pi, + pi ], and a linear fitting may be simply performed, that is, the larger the angular velocity of the input exceeding the maximum dynamic range of the gyroscope is, the larger the optical energy of the second photodetector is, the larger the digital quantity after AD conversion is, and the following steps are performed:
assuming the maximum dynamic range of the fiber-optic gyroscope to be 20/s, the required range of use is 200/s.
S1: the fiber-optic gyroscope is placed on a rate turntable, and the rotating speeds of the turntable are respectively set as: +/-40 °/s, +/-60 °/s, +/-80 °/s, +/-100 °/s, +/-120 °/s, +/-140 °/s, +/-160 °/s, +/-180 °/s, +/-200 °/s, and the FPGA output value of the second photoelectric detector is collected;
s2: the fiber-optic gyroscope is placed on a rate turntable, and the rotating speeds of the turntable are respectively set as: plus or minus 0 degree/s, plus or minus 0.1 degree/s, plus or minus 0.2 degree/s, plus or minus 0.5 degree/s, plus or minus 1 degree/s, plus or minus 2 degree/s, plus or minus 5 degree/s, plus or minus 10 degree/s, plus or minus 20 degree/s, and collecting the FPGA output value of the first photoelectric detector;
s3: and establishing a fitting curve of all the rotating speeds, and calculating scale performance indexes such as asymmetry, nonlinearity and the like of the scale of the gyroscope according to the curve, wherein the scale performance indexes meet the use requirement, and the fitting curve is established.
The invention provides an optical fiber gyroscope which specifically 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 which are respectively used for receiving reciprocal and non-reciprocal 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 first end of the optical fiber ring, 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 and the transmission polarizer to output polarized light beam, and then is transmitted to the optical fiber ring through the coupler and the directional coupling waveguide to generate interference. By utilizing different light energy coupling distribution proportions of the directional coupling waveguide port at different input rotating speeds of the gyroscope, the light energy of the directional coupling waveguide port is detected and external input, particularly real-time compensation during large-dynamic and large-impact input is realized, so that the precision requirements of the ultrahigh-precision fiber optic gyroscope on large-dynamic and large-impact input are met, meanwhile, the dynamic range and the impact resistance of the fiber optic gyroscope are improved, and the application range is expanded.
The above-described embodiments should not be construed as limiting the scope of the invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may be made in accordance with design requirements and other factors. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. An 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;
an output end of the light source is coupled with an input end of the isolator, an output end of the isolator is coupled with an input end of the polarizer, an output end of the polarizer is coupled with a first end of the coupler, a second end of the coupler is coupled with a first end of the directional coupling waveguide, a third end of the coupler is connected with the first photodetector, a second end of the directional coupling waveguide is connected with the second photodetector, a third end of the directional coupling waveguide is coupled with a first end of the optical fiber loop, and a fourth end of the directional coupling waveguide is coupled with a second end of the optical fiber loop;
the light beam emitted by the light source is transmitted in a single direction by the isolator and then enters the polarizer, the light beam is transmitted by the polarizer and then is converted into a polarized light beam, and the polarized light beam is transmitted to the optical fiber ring for interference by the coupler and the directional coupling waveguide;
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 signal output by the directional coupling waveguide.
2. The optical fiber gyroscope according to claim 1, further comprising a data processing unit configured to output a measurement result based on the signal of the first photodetector when the external disturbance is smaller than a preset threshold, and to output a measurement result after calculating and compensating an error based on the signals of the first photodetector and the second photodetector when the external disturbance is greater than or equal to the preset threshold.
3. The fiber optic gyroscope of claim 2, wherein the preset threshold comprises an external dynamic condition and an external impact condition, the external dynamic condition being 200 °/s, the external impact condition comprising an 80G impact in 5 ms.
4. The fiber optic gyroscope of claim 1, wherein the isolator comprises a fiber isolator, the polarizer comprises a fiber polarizer, and the coupler comprises a fiber 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.
5. The fiber optic gyroscope of claim 4, wherein the optical fibers used for the fiber coupler and the fiber loop are polarization maintaining fibers.
6. The fiber optic gyroscope of claim 5, wherein the first photodetector and the second photodetector each comprise a polarization maintaining fiber, the first photodetector connected to the third end of the fiber coupler through the polarization maintaining fiber, the second photodetector connected to the directionally coupled waveguide through the polarization maintaining fiber.
7. The optical fiber gyroscope of claim 1, wherein 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 comprises: 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 by 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 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 beams output by the second end of the coupler sequentially pass through the first end and the fourth end of the directional coupling waveguide and then enter the optical fiber loop, the light beams output by the optical fiber loop sequentially pass through the third end and the first end of the directional coupling waveguide and then enter the coupler, and the light beams are 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 beams output by the second end of the coupler enter the optical fiber ring after sequentially passing through the first end and the third end of the directional coupling waveguide, and the light beams output by the optical fiber ring are sequentially output to the second photoelectric detector after sequentially passing through the fourth end and the second end of the directional coupling waveguide; the transmission process of the fourth optical path comprises the following steps: and the light beams output by the second end of the coupler enter the optical fiber ring after sequentially passing through the first end and the fourth end of the directional coupling waveguide, and the light beams output by the optical fiber ring sequentially pass through the third end and the second end of the directional coupling waveguide and are output to the second photoelectric detector.
8. The fiber optic gyroscope of claim 1, wherein the fiber length of the fiber loop is greater than or equal to 10km and the diameter of the fiber loop is greater than or equal to 210mm.
9. The optical fiber gyroscope of claim 1, wherein the light beam emitted by the light source is spontaneous emission light in a C + L band.
10. The fiber optic gyroscope of claim 9, wherein the spectral width of the light beam emitted by the light source is greater than or equal to 30nm.
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