Multi-channel self-adaptive optical fiber ring testing method

Abstract

A multi-channel self-adaptive optical fiber ring testing method comprises the steps that temperature excitation is applied to an optical fiber ring through a high-low temperature box, light emitted by a light source is divided into multiple paths of light beams through a coupler, and the multiple paths of light beams are transmitted to a multi-path light wave coupling and modulating device; two beams of light which are oppositely transmitted in the optical fiber ring traverse the whole ring and then return to the Y waveguide to form an interference light signal, the interference light signal is transmitted to the photoelectric detector through the coupler to be subjected to photoelectric conversion to form an electric signal, and the electric signal is demodulated by the modulation-demodulation circuit to obtain zero offset signal output of the optical fiber ring gyroscope test system. According to the invention, multiple specifications of optical fiber rings can multiplex one set of test hardware, manual correction is not needed, the degree of dependence of large-scale and batch optical fiber ring performance test on the number of the test hardware is greatly relieved, the test result can be directly displayed, whether the tested optical fiber ring is qualified or not is clear at a glance, and the test efficiency is improved. And the test method and system are suitable for the performance test of the optical fiber ring of the interference type optical fiber gyroscope with various precision levels.

Description

Technical Field

[0001] The invention patent belongs to the technical field of fiber optic gyroscope performance testing and relates to a multi-channel adaptive fiber optic ring testing method. Background Art

[0002] Since there are many types of fiber optic rings, and fiber optic rings with different structures, lengths and winding methods have different transmission loss characteristics, the existing fiber optic ring testing system is not compatible with fiber optic rings of various models and specifications. For example, the test systems mentioned in CN208269933U "A fiber optic gyroscope sensitive ring testing system" and CN208140877U "A fiber optic gyroscope detection circuit testing system" require manual modification of system parameters or replacement of the adapted system when testing fiber optic rings of different specifications.

[0003] How to test and calibrate the zero-bias static parameters of multiple fiber optic rings at all temperatures at one time, and to perform adaptive testing on fiber optic rings of different specifications, and to significantly improve the testing efficiency of the fiber optic rings while ensuring the test accuracy are the technical problems that need to be overcome. Summary of the invention

[0004] The technical problem to be solved by the patent of this invention is to provide a multi-channel adaptive fiber optic ring testing method, which can test and calibrate the zero-bias static parameters of multiple fiber optic rings at all temperatures at one time, and can perform adaptive testing on fiber optic rings of different specifications without the need for manual adjustment devices, thereby greatly improving the fiber optic ring testing efficiency while ensuring the test accuracy.

[0005] In order to solve the above technical problems, the technical solution adopted by the patent of the present invention is: a multi-channel adaptive optical fiber ring testing method, including a testing system, the testing system includes a high and low temperature box and a computer electrically connected to the testing chassis; the testing chassis is connected to the pigtail of the optical fiber ring to be tested placed in the high and low temperature box; The testing steps include: S1, placing multiple optical fiber rings to be tested in a high and low temperature box in sequence, with the pigtails of the optical fiber rings extending out of the box and connected to the pigtails of the optical path components on the mainboard of the test system by fusion splicing; S2, applying temperature excitation to the optical fiber ring through a high and low temperature box, the light emitted by the light source is divided into multiple light beams through a coupler, and transmitted to the multi-channel light wave coupling and modulation device respectively; S3, the two beams of light that are transmitted in opposite directions in the optical fiber ring traverse the entire ring and return to the Y waveguide to form an interference light signal. The interference light signal is transmitted to the photodetector through the coupler for photoelectric conversion to form an electrical signal. The electrical signal is demodulated by the modulation and demodulation circuit to obtain the zero bias signal output of the optical fiber ring gyroscope test system.

[0006] In S2, the light beam is transmitted to the multi-way coupler. After the output of the coupler, it is polarized by the polarizer in the Y waveguide and then polarized and split by the Y waveguide of the optical fiber ring to be tested, forming multiple beams of light that are transmitted in opposite directions in the optical fiber ring.

[0007] In S3, the obtained gyro bias signal is transmitted to the host computer and plotted into a curve, and the bias stability is calculated by taking the standard deviation of the obtained gyro bias signal output through the calculation module.

[0008] In S3, the level of the fiber optic ring determines the accuracy of the gyro. The gyro accuracy is characterized by the zero bias stability index. The principle for judging the quality of the fiber optic ring is 1° / h for low-precision gyro, 0.01° / h for medium-precision gyro, and 0.001° / h for high-precision gyro.

[0009] In S2, the output power of the light source cannot exceed the saturation power of the photodetector.

[0010] In S2, the light source power is determined by the output signal of the light source driving circuit, and the light intensity can be increased without being saturated.

[0011] In S3, the electrical signal emitted by the photodetector is processed by the voltage detection circuit; the voltage detection circuit performs DC bias, amplification and filtering on the electrical signal output by the photodetector, and the processed signal is transmitted to the AD for conversion into a digital signal.

[0012] In S3, the digital signal is transmitted to the data processing logic chip of the modulation and demodulation circuit for logical judgment; the judgment is based on sampling the AD digital signal input value within a period of time, taking its peak-to-peak value, and if it exceeds the set threshold range, a feedback signal is sent to the light source driving circuit to perform light source driving voltage control, so that the optical power output by the light source is always within a set range.

[0013] In S3, the light source driving circuit includes a DA conversion chip, a power management circuit, a light source and a temperature control circuit which are electrically connected in sequence to the DA conversion chip; the DA conversion chip includes a digital signal input terminal and an analog signal output terminal, and the digital signal input terminal is connected to a digital processing logic chip.

[0014] In S3, the power management circuit includes a voltage input terminal, a voltage regulating controlled terminal, and a load terminal; the voltage regulating controlled terminal of the power management circuit is connected to the analog signal output terminal of the DA conversion chip, and its load terminal is connected to the light source; the voltage regulation signal of the digital processing logic chip is received through the DA conversion chip, and the voltage regulation signal is converted into an analog signal and output to the voltage regulating controlled terminal, and the voltage regulating controlled terminal converts the voltage into a current signal and outputs it to the load terminal, thereby driving the adjustment of the brightness of the light source.

[0015] The main beneficial effects of the present invention are mainly reflected in: The zero-bias static parameters of multiple fiber optic rings can be tested and calibrated at all temperatures at one time; adaptive testing can be performed on fiber optic rings of different specifications without the need for manual adjustment of the device; the fiber optic ring testing efficiency is greatly improved while ensuring the test accuracy.

[0016] A set of test hardware can be used to multiplex fiber optic rings of various specifications without manual calibration, which greatly alleviates the dependence of large-scale and batch fiber optic ring performance testing on the number of test hardware. The test results can be directly displayed, and it is clear at a glance whether the tested fiber optic ring is qualified. In addition, the test method and system are suitable for interferometric fiber optic gyroscope fiber optic ring performance testing at various accuracy levels. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0018] Figure 1 It is a schematic diagram of the structure of the test system of the present invention.

[0019] Figure 2 Flow chart of the test system of the present invention.

[0020] Figure 3 This is a voltage detection circuit diagram of the present invention.

[0021] Figure 4 It is a curve diagram of the gyro zero bias signal output of the present invention.

[0022] Figure 5 This is a light source driving circuit diagram of the present invention.

[0023] In the figure: test chassis 1; high and low temperature box 2; computer 3; optical fiber ring 20 to be tested; light source 111; modulation device 113; photodetector 1131; light source driving circuit 121; modulation and demodulation circuit 122; voltage detection circuit 123; power management circuit 1211; digital processing logic chip 1221; digital processing logic chip 1221. DETAILED DESCRIPTION

[0024] like Figure 1~Figure 5 A multi-channel adaptive optical fiber ring test method includes a test system, the test system includes a test chassis 1 electrically connected to a high and low temperature box 2 and a computer 3; the test chassis 1 is connected to the pigtail of the optical fiber ring to be tested placed in the high and low temperature box 2; Example N optical fiber rings 20 to be tested are placed in the high and low temperature box 2 in sequence, and the pigtails of the optical fiber rings extend out of the box and are fused and connected with the pigtails of the optical path components on the mainboard of the test system.

[0025] Temperature excitation is applied to the fiber ring through a high and low temperature box, and the light emitted by the light source is divided into N light beams through a 1*N coupler and transmitted to the N light wave coupling and modulation devices 113. Taking one of the light paths as an example, the light beam is transmitted to the 2x2 coupler, and after the output of the coupler, it is polarized by the polarizer in the Y waveguide and then polarized and split by the Y waveguide of the fiber ring to be tested, forming two beams of light that are transmitted in opposite directions in the fiber ring.

[0026] After the two beams of light transmitted in opposite directions in the optical fiber ring traverse the entire ring, they return to the Y waveguide to form an interference light signal. The interference light signal is transmitted to the photodetector 1131 through the coupler for photoelectric conversion to form an electrical signal. The electrical signal is demodulated by the modulation and demodulation circuit 122 to obtain the zero bias signal output of the optical fiber ring gyroscope test system to complete the test of the optical fiber ring.

[0027] The obtained gyro zero bias signal output is transmitted to the host computer and plotted into a curve, and the zero bias stability is calculated by taking the standard deviation of the obtained gyro zero bias signal output through the calculation module.

[0028] Fiber optic ring quality determination method: Since the level of the fiber optic ring determines the accuracy of the gyro, the accuracy of the gyro is characterized by the zero bias stability index, such as 1° / h for low-precision gyros, 0.01° / h for medium-precision gyros, and 0.001° / h for high-precision gyros. Zero bias stability is calculated by taking the standard deviation of the gyro zero bias output signal. Therefore, if the zero bias stability value is calculated by taking the standard deviation of the tested gyro zero bias signal output and is higher than the accuracy value required by the gyro, the fiber optic ring is unqualified. If it is lower than the accuracy value required by the gyro, the fiber optic ring is qualified. The zero bias stability is calculated by taking the standard deviation of the gyro zero bias signal output obtained by the calculation module. The gyro zero bias signal output curve and the zero bias stability value can be directly displayed on the upper computer display, and the tester can see at a glance whether the fiber optic ring is qualified.

[0029] The pain point of the existing technology is that during the test of the optical fiber ring test system, the power of the light source is controlled by the light source driving circuit. The electrical signal output by the photodetector is as follows: Figure 4 As shown, it is a typical comb signal. The high-frequency spike signal is an interference noise signal, and the amplitude of the high-frequency spike signal is also much larger than the amplitude of the low-frequency effective signal. In the design process of the demodulation circuit, there is a large contradiction in the filtering design between the high-frequency spike signal and the low-frequency effective signal. When the optical signal exceeds the saturation power of the photodetector, the high-frequency spike signal is further broadened, affecting the sampling of the low-frequency effective signal. At the same time, it will also cause the high-frequency spike signal to be distorted and coupled into the low-frequency effective signal, further affecting the sampling of the low-frequency effective signal. Therefore, the output power of the light source cannot exceed the saturation power of the photodetector. Furthermore, since the light source power is determined by the output signal of the light source driving circuit, which is fixed in the design stage, according to the FOG signal-to-noise ratio formula , from this formula, we can know that to improve the FOG test accuracy, the larger the light intensity signal I0, the better. In summary, this requires increasing the light intensity as much as possible while not saturating it. However, when measuring optical fibers of different specifications, due to the different characteristic parameters of the optical fiber ring, or even the same specification of optical fiber, due to the existence of uncontrollable factors such as fusion splicing and optical device pigtail length, in the actual test process, for different tested optical fiber ring systems, it is necessary to manually change the light source drive circuit to adjust the light source power. This not only destroys the integrity of the entire test system hardware, but also affects the test efficiency.

[0030] The solution is that the electrical signal sent by the photodetector 1131 is processed by the voltage detection circuit 123. Figure 3 As shown, the voltage detection circuit 123 performs DC bias, amplification and filtering on the electrical signal output by the photodetector, and transmits the processed signal to the AD to convert it into a digital signal. The digital signal is transmitted to the data processing logic chip of the modulation and demodulation circuit 122 for logical judgment. The judgment is based on sampling the input value of the AD digital signal within a period of time, taking its peak-to-peak value, and if it exceeds the set threshold range, a feedback signal is sent to the light source driving circuit 121 to perform light source driving voltage regulation control, so that the light power output by the light source is always within a suitable range.

[0031] The principle of light source driving voltage regulation to control the output power of the light source is as follows Figure 5 As shown. The fiber optic gyro light source 111 is usually an SLD light source, which is current driven. The digital-to-analog conversion chip includes a digital signal input terminal and an analog signal output terminal, and the digital signal input terminal is connected to the digital processing logic chip 1221; the power management circuit 1211 includes a voltage input terminal, that is, a constant voltage source, a voltage regulating controlled terminal, and a load terminal. The voltage regulating controlled terminal of the power management circuit is connected to the analog signal output terminal of the DA conversion chip, and the light source 111 is connected to its load terminal. The voltage regulation signal of the digital processing logic chip 1221 is received by the DA conversion chip, and the voltage regulation signal is converted into an analog signal and output to the voltage regulating controlled terminal. The voltage regulating controlled terminal converts the voltage into a current signal and outputs it to the load terminal, thereby driving the adjustment of the brightness of the light source.

[0032] In the above method, a set of test hardware can be used for multiple fiber optic rings of various specifications without manual calibration, which greatly alleviates the dependence of large-scale and batch fiber optic ring performance testing on the number of test hardware. The test results can be directly displayed, and it is clear at a glance whether the tested fiber optic ring is qualified. In addition, the test method and system are suitable for interferometric fiber optic gyroscope fiber optic ring performance testing at various accuracy levels.

[0033] The above-mentioned embodiments are only preferred technical solutions of the present invention and should not be regarded as limitations on the present invention. The embodiments and features in the embodiments in this application can be combined with each other in any way without conflict. The protection scope of the present invention should be the technical solutions recorded in the claims, including the equivalent replacement solutions of the technical features in the technical solutions recorded in the claims. That is, equivalent replacement improvements within this scope are also within the protection scope of the present invention.

Claims

1. A multi-channel adaptive optical fiber ring testing method, characterized in that: The test system comprises a test case (1), a high and low temperature box (2) and a computer (3) which are electrically connected to the test case (1); The test box (1) is connected to the pigtail of the optical fiber ring to be tested which is placed in the high and low temperature box (2); The testing steps include: S1, placing a plurality of optical fiber rings (20) to be tested in sequence in a high and low temperature box (2), wherein the tail fibers of the optical fiber rings extend out of the box and are fused and connected to the tail fibers of the optical path device on the main board of the test system; S2, applying temperature excitation to the optical fiber ring through a high and low temperature box, and the light emitted by the light source is divided into multiple light beams through a coupler and transmitted to the multiple light wave coupling and modulation device (113) respectively; S3, after two beams of light transmitted in opposite directions in the optical fiber ring traverse the entire ring, they return to the Y waveguide to form an interference light signal, which is transmitted to the photoelectric detector (1131) through the coupler for photoelectric conversion to form an electrical signal, which is demodulated by the modulation and demodulation circuit (122) to obtain the zero bias signal output of the optical fiber ring gyroscope test system.

2. The multi-channel adaptive fiber ring testing method according to claim 1, characterized in that: In S2, the light beam is transmitted to the multi-way coupler. After the output of the coupler, it is polarized by the polarizer in the Y waveguide and then polarized and split by the Y waveguide of the optical fiber ring to be tested, forming multiple beams of light that are transmitted in opposite directions in the optical fiber ring.

3. The multi-channel adaptive fiber ring testing method according to claim 1, characterized in that: In S3, the obtained gyro bias signal is transmitted to the host computer and plotted into a curve, and the bias stability is calculated by taking the standard deviation of the obtained gyro bias signal output through the calculation module.

4. The multi-channel adaptive optical fiber ring testing method according to claim 3 is characterized in that: In S3, the level of the fiber optic ring determines the accuracy of the gyro. The gyro accuracy is characterized by the zero bias stability index. The principle for judging the quality of the fiber optic ring is 1° / h for low-precision gyro, 0.01° / h for medium-precision gyro, and 0.001° / h for high-precision gyro.

5. The multi-channel adaptive fiber ring testing method according to claim 1, characterized in that: In S2, the output power of the light source cannot exceed the saturation power of the photodetector.

6. The multi-channel adaptive fiber ring testing method according to claim 5, characterized in that: In S2, the light source power is determined by the output signal of the light source driving circuit, and the light intensity can be increased without being saturated.

7. The multi-channel adaptive fiber ring testing method according to claim 6, characterized in that: In S3, the electrical signal emitted by the photodetector (1131) is processed by the voltage detection circuit (123); the voltage detection circuit (123) performs DC biasing, amplification and filtering on the electrical signal output by the photodetector, and transmits the processed signal to the AD for conversion into a digital signal.

8. The multi-channel adaptive fiber ring testing method according to claim 7, characterized in that: In S3, the digital signal is transmitted to the data processing logic chip of the modulation and demodulation circuit (122) for logic judgment; The judgment is based on sampling the AD digital signal input value within a period of time and taking its peak-to-peak value. If it exceeds the set threshold range, a feedback signal is sent to the light source driving circuit (121) to perform light source driving voltage regulation control, so that the light power output by the light source is always within a set range.

9. The multi-channel adaptive fiber ring testing method according to claim 6, characterized in that: In S3, the light source driving circuit (121) comprises a DA conversion chip, a power management circuit (1211), a light source (111), and a temperature control circuit, which are electrically connected in sequence to the DA conversion chip; the DA conversion chip comprises a digital signal input terminal and an analog signal output terminal, and the digital signal input terminal is connected to the digital processing logic chip (1221).

10. The multi-channel adaptive fiber ring testing method according to claim 9, characterized in that: In S3, the power management circuit (1211) comprises a voltage input terminal, a voltage regulating controlled terminal, and a load terminal; the voltage regulating controlled terminal of the power management circuit is connected to the analog signal output terminal of the DA conversion chip, and its load terminal is connected to the light source (111); the DA conversion chip receives the voltage regulation signal of the digital processing logic chip (1221), and converts the voltage regulation signal into an analog signal and outputs it to the voltage regulating controlled terminal; the voltage regulating controlled terminal converts the voltage into a current signal and outputs it to the load terminal, thereby driving the adjustment of the brightness of the light source.

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