A small, high-precision fiber optic angular acceleration measurement device

Abstract

This invention discloses a small, high-precision fiber optic angular acceleration measurement device. The light source module is connected to a fiber optic circulator via a polarizer, and the fiber optic circulator is connected to an optical modulator via a fiber optic coupler. The optical modulator is connected to a polarization-maintaining fiber optic ring, used to split the linearly polarized light into two counter-propagating beams that enter the polarization-maintaining fiber optic ring, and to receive the interference signal returned from the polarization-maintaining fiber optic ring and input it into the fiber optic coupler. The fiber optic coupler splits the interference signal into two outputs: one path enters a first photodetector via the fiber optic circulator, and the other path enters a second photodetector. The first photodetector converts the received optical signal into an electrical signal and inputs it into a first digital signal acquisition processor. The second photodetector converts the received optical signal into an electrical signal and inputs it into a second digital signal acquisition processor. The first and second digital signal acquisition processors respectively acquire and process the input signals and input them into a data processing unit to calculate the angular acceleration value.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of angular acceleration measurement, and particularly relates to a small high-precision optical fiber angular acceleration measurement device with a fiber coupler non-reciprocal end demodulation. BACKGROUND

[0002] Angular acceleration is an important parameter of sensitive carrier rotation relative to inertial space, and plays an important role in dynamics control, and is widely used in aerospace and earthquake monitoring fields. However, so far, a small angular accelerometer with high precision and wide band response is still an important sensor which is difficult to develop.

[0003] The fiber Sagnac effect is a physical effect that light produces interference in a fiber ring. A bundle of light emitted by the same light source is decomposed into two bundles, which are made to circulate in the same fiber loop in opposite directions for one round and then meet to produce interference. If the fiber ring around the normal of the plane occurs rotation, the phases of the two lights emitted from the interferometer will no longer be consistent, but will produce a phase related to the rotation speed, thereby causing the movement of the interference fringes. The phase movement is the fiber Sagnac phase shift, and its expression is: S

[0004]

[0005] Wherein, λ is the wavelength of light, L is the length of the fiber ring, D is the area of the fiber ring, c is the speed of light in vacuum, and Ω is the rotation angular velocity.

[0006] The sensor for measuring angular velocity based on the fiber Sagnac effect is called fiber gyroscope, which has the advantages of no mechanical structure, high precision, high reliability and long service life. The interference signal of the fiber gyroscope is:

[0007] I=I0[1+cos(φ S +Δφ(t))] Formula (2)

[0008] Wherein, I is the output light intensity, I0 is the incident light intensity, φ S is the phase movement, and Δφ(t) is the phase additional value. The angular velocity measurement value Ω(t) can be restored by demodulating the interference signal.

[0009] The dual-polarization fiber Sagnac interferometer can transmit the light signal using two polarization channels of the fiber, and can demodulate two independent angular velocity results after interference. The angular velocity output value is delayed, and the angular acceleration value with a flattened response in the full frequency band range can be output by differentiating the two angular velocities. SUMMARY

[0010] ​In view of the problems in the prior art, the present application aims to provide a high-precision optical fiber angular acceleration measuring device. Based on the realization of angular velocity measurement by the optical fiber Sagnac interferometer, the present application adopts the non-reciprocal end of the optical fiber coupler to demodulate the angular velocity, combines it with the angular velocity of the reciprocal end to realize high-precision measurement of angular acceleration, and has the advantages of high sensitivity, wide frequency band response and strong environmental adaptability; the optical fiber coupler is a 2x1 optical fiber coupler or a 2x2 optical fiber coupler.

[0011] The technical scheme of the present application is as follows:

[0012] A small high-precision optical fiber angular acceleration measuring device, characterized in that it comprises a light source module 1, a polarizer 2, a first digital signal acquisition processor 3, a second digital signal acquisition processor 6, a first photoelectric detector 4, a second photoelectric detector 7, an optical fiber circulator 5, an optical fiber coupler 8, an optical modulator 9, a polarization maintaining optical fiber ring 10 and a data processing unit.

[0013] The light source module 1 is connected with the optical fiber circulator 5 through the polarizer 2, and is used to input the output light into the optical fiber circulator 5 after changing it into linearly polarized light through the polarizer 2.

[0014] The optical fiber circulator 5 is connected with the optical modulator 9 through the optical fiber coupler 8, and is used to input the linearly polarized light into the optical modulator 9 through the optical fiber coupler 8.

[0015] The optical modulator 9 is connected with the polarization maintaining optical fiber ring 10, and is used to divide the linearly polarized light into two counter-propagating beams entering the polarization maintaining optical fiber ring 10, and receive the interference signal returned from the polarization maintaining optical fiber ring 10 and input it into the optical fiber coupler 8.

[0016] The optical fiber coupler 8 divides the interference signal into two outputs, one of which enters the first photoelectric detector 4 through the optical fiber circulator 5, and the other enters the second photoelectric detector 7.

[0017] The first photoelectric detector 4 converts the received optical signal into an electrical signal and inputs it into the first digital signal acquisition processor 3; the second photoelectric detector 7 converts the received optical signal into an electrical signal and inputs it into the second digital signal acquisition processor 6.

[0018] The first digital signal acquisition processor 3 and the second digital signal acquisition processor 6 respectively collect and process the input signals and input them into the data processing unit.

[0019] The data processing unit is used to calculate the angular acceleration value according to the two received signals.

[0020] Further, the data processing unit comprises a first ARM processor 11, a second ARM processor 12 and a third ARM processor 13; the first ARM processor 11 is connected with the first digital signal acquisition processor 3, and is used for calculating the angular velocity Ω1(t) according to the signal output by the first digital signal acquisition processor 3 and sending the angular velocity Ω1(t) to the third ARM processor 13; the second ARM processor 12 is connected with the second digital signal acquisition processor 6, and is used for calculating the angular velocity Ω2(t) according to the signal output by the second digital signal acquisition processor 6 and sending the angular velocity Ω2(t) to the third ARM processor 13; the third ARM processor 13 calculates the angular acceleration value α(t) according to the angular velocities Ω1(t) and Ω2(t).

[0021] Further, the angular acceleration value α(t) is calculated according to the angular velocities Ω1(t) and Ω2(t). Wherein, Ω1(ω) is the frequency domain signal of Ω1(t), Ω2(ω) is the frequency domain signal of Ω2(t), and τ is a set time delay.

[0022] Further, the polarization maintaining optical fiber ring 10 is a quadrupole symmetrically wound optical fiber ring.

[0023] Further, the optical path part composed of the light source module 1, the polarizer 2, the first digital signal acquisition processor 3, the second digital signal acquisition processor 6, the first photoelectric detector 4, the second photoelectric detector 7, the optical fiber ring 5, the optical fiber coupler 8 and the optical modulator 9 is packaged as an optical path unit 15 and placed in a cylindrical structure; the polarization maintaining optical fiber ring 10 is wound outside the cylindrical structure, and the circuit module 14 is connected with the optical path unit 15, and is used for powering the power units in the optical path unit 15.

[0024] Further, the polarization maintaining optical fiber radius of the polarization maintaining optical fiber ring 10 is 80 microns.

[0025] Further, the diameter of the polarization maintaining optical fiber ring 10 is 3 cm, and the ring height is 2 cm.

[0026] Further, the optical fiber length of the polarization maintaining optical fiber used by the polarization maintaining optical fiber ring 10 is less than 500 m.

[0027] Further, the optical fiber coupler 8 is a 2×1 optical fiber coupler.

[0028] Further, the optical fiber coupler 8 is a 2×2 optical fiber coupler.

[0029] The advantages of the present application are as follows:

[0030] The application is based on a fiber-optic angular acceleration measuring device with 2*1 fiber-optic coupler non-reciprocal end demodulation, which can realize high sensitivity detection of angular acceleration in a small size, thereby producing a small angular accelerometer with high precision, wide band response, strong environmental adaptability, low price and other advantages. The implementation of the application will provide a theoretical basis and technical support for the development of small high-precision angular accelerometers, promote their application in many fields such as inertial navigation, planetary earthquake monitoring and satellite high attitude jitter, and has great social application value and high economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is an optical path diagram for angular acceleration sensing demodulation of the application.

[0032] Figure 2 It is a signal processing diagram of the application.

[0033] Figure 3 It is a packaging structure diagram of a small high-precision fiber-optic angular accelerometer.

[0034] The figure mark: 1-light source module, 2-polarizer, 3-first digital signal acquisition processor, 4-first photoelectric detector, 5-fiber-optic circulator, 6-second digital signal acquisition processor, 7-second photoelectric detector, 8-fiber-optic coupler, 9-optical modulator, 10-polarization maintaining fiber ring, 11-ARM processor, 12-second ARM processor, 13-third ARM processor, 14-circuit module, 15-optical path unit. DETAILED DESCRIPTION

[0035] The application will be further described in detail below in combination with the drawings, and the examples are only used to explain the application, not to limit the scope of the application.

[0036] The application relates to a small high-precision fiber-optic angular acceleration measuring device based on fiber-optic coupler non-reciprocal end demodulation, wherein the fiber-optic coupler is a 2*1 fiber-optic coupler or a 2*2 fiber-optic coupler; taking the 2*1 fiber-optic coupler as an example, the structural diagram of the device is as shown in the figure. Figure 1The device is based on a minimum mutual heterostructure fiber Sagnac interferometer optical sensing system, including a light source module 1, a polarizer 2, a first digital signal acquisition processor (DSP) 3 and a second digital signal acquisition processor 6, a first photoelectric detector 4 and a second photoelectric detector 7, a fiber ring 5, a 2x1 fiber coupler 8, an optical modulator (MIOC) 9, and a polarization maintaining fiber ring 10. The entire optical path system is designed with polarization maintaining fiber, so the specific working principle is as follows: the light emitted by the light source module 1 becomes linearly polarized light through the polarizer 2, and then enters the fiber ring 5. The fiber ring 5 has directionality for the transmission of the entering light, and the light will enter the 2x2 coupler 8 and will not enter the first photoelectric detector 4. The light from the 2x1 fiber coupler 8 will enter the optical modulator 9, and then be divided into two paths to enter the polarization maintaining fiber ring 10. When the fiber ring rotates, it will modulate the phase of the light transmitted therein, and then produce interference in the optical modulator 9. The light from the optical modulator 9 again enters the 2x1 fiber coupler 8, and then is divided into two paths, one of which enters the first photoelectric detector 4 through the fiber ring 5, and the other of which directly enters the second photoelectric detector 7. The two photoelectric detectors convert the optical signal into an electrical signal, which is then processed by the DSP.

[0037] After collecting two light signals, the phase shift φ caused by the angular motion of the fiber ring can be calculated s (t), and the angular velocity value Ω(t) can be restored:

[0038]

[0039] Two angular velocities Ω1(t) and Ω2(t) can be demodulated by the two photoelectric detectors of the angular acceleration sensing system. The angular acceleration value can be calculated by time domain differentiation on one of the two paths with a delay τ. The angular acceleration can be represented as:

[0040]

[0041] where α(t) is the angular acceleration, t is the time, τ is the delay parameter, which is determined according to the specific use scenario, Ω1(ω) is the frequency domain signal corresponding to Ω1(t), and Ω2(ω) is the frequency domain signal corresponding to Ω2(t). Since the formula does not contain the frequency parameter, the demodulated angular acceleration will not decrease in sensitivity with increasing frequency, and has a flat angular acceleration response in a wide frequency range.

[0042] Figure 2 The signal processing diagram is shown in FIG. 11, wherein the first digital signal acquisition processor 3 and the second digital signal acquisition processor 6 transmit the converted signals to the first ARM processor 11 and the second ARM processor 12, the two ARM processors demodulate two angular velocities, and then the third ARM processor 13 demodulates the final angular acceleration.

[0043] Figure 3 The packaging structure diagram of the small high-precision fiber optic angular accelerometer includes a small ASE light source optical path unit 15 and a circuit module 14, and a fiber ring 10; the fiber ring 10 (a polarization maintaining fiber with a radius of less than 80 microns) adopts a fiber ring wound in a four-pole symmetrical manner. When packaged, the light source module 1, the polarizer 2, the first digital signal acquisition processor 3, the second digital signal acquisition processor 6, the first photoelectric detector 4, the second photoelectric detector 7, the fiber ring 5, the fiber coupler 8, and the optical modulator 9 are packaged into an optical path unit 15 and placed in a cylindrical structure; the polarization maintaining fiber ring 10 is wound outside the cylindrical structure, and the circuit module 14 is connected with the optical path unit 15 and used to supply power for the power units in the optical path unit 15. Due to the consideration of miniaturization and price, the fiber length is considered to be less than 500 m, so the diameter and height of the wound fiber ring are relatively small. The diameter of the fiber ring is less than 3 cm, and the height of the ring is less than 2 cm.

[0044] Although the specific embodiments of the present application are disclosed for the purpose of illustrating the present application, the purpose is to help understand the content of the present application and to implement the same, those skilled in the art can understand that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present application and the appended claims. Therefore, the present application should not be limited to the disclosed content of the best mode, and the scope of the present application claimed is defined by the scope of the claims.

Claims

1. A small high-precision fiber-optic angular acceleration measuring device, characterized in that, The application relates to a kind of optical fiber angular acceleration sensor, including light source module (1), polarizer (2), first digital signal acquisition processor (3), second digital signal acquisition processor (6), first photoelectric detector (4), second photoelectric detector (7), optical fiber circulator (5), optical fiber coupler (8), optical modulator (9), polarization maintaining optical fiber ring (10) and data processing unit; The light source module (1) is connected with the optical fiber circulator (5) through the polarizer (2), and is used for inputting the output light into the optical fiber circulator (5) after changing the output light into linearly polarized light through the polarizer (2). The optical fiber circulator (5) is connected with the optical modulator (9) through the optical fiber coupler (8), and is used for inputting the linearly polarized light into the optical modulator (9) through the optical fiber coupler (8). The optical modulator (9) is connected with the polarization maintaining optical fiber ring (10), and is used for dividing the linearly polarized light into two light beams propagating in opposite directions into the polarization maintaining optical fiber ring (10), and receiving interference signals returned from the polarization maintaining optical fiber ring (10) and inputting the interference signals into the optical fiber coupler (8). The optical fiber coupler (8) divides the interference signals into two paths, one path enters the first photoelectric detector (4) through the optical fiber circulator (5), and the other path enters the second photoelectric detector (7). The first photoelectric detector (4) converts the received optical signals into electrical signals and inputs the electrical signals into the first digital signal acquisition processor (3); and the second photoelectric detector (7) converts the received optical signals into electrical signals and inputs the electrical signals into the second digital signal acquisition processor (6). The first digital signal acquisition processor (3) and the second digital signal acquisition processor (6) respectively acquire and process the input signals and input the processed signals into the data processing unit. The data processing unit is used for calculating an angular acceleration value according to the two received signals.

2. The small high-precision fiber-optic angular acceleration measurement device according to claim 1, characterized in that, The data processing unit includes a first ARM processor (11), a second ARM processor (12) and a third ARM processor (13); the first ARM processor (11) is connected with the first digital signal acquisition processor (3), is used for calculating an angular velocity omega1(t) according to the signal output by the first digital signal acquisition processor (3) and sending the angular velocity omega1(t) to the third ARM processor (13); the second ARM processor (12) is connected with the second digital signal acquisition processor (6), is used for calculating an angular velocity omega2(t) according to the signal output by the second digital signal acquisition processor (6) and sending the angular velocity omega2(t) to the third ARM processor (13); and the third ARM processor (13) calculates an angular acceleration value alpha(t) according to the angular velocities omega1(t) and omega2(t).

3. The small high-precision fiber-optic angular acceleration measuring device according to claim 1 or 2, characterized in that, The polarization maintaining optical fiber ring (10) is a four-pole symmetrical winding optical fiber ring.

4. The small high-precision fiber-optic angular acceleration measuring device according to claim 1 or 2, characterized in that, The light source module (1), the polarizer (2), the first digital signal acquisition processor (3), the second digital signal acquisition processor (6), the first photoelectric detector (4), the second photoelectric detector (7), the optical fiber circulator (5), the optical fiber coupler (8), and the optical modulator (9) are packaged into a light path unit (15) and placed in a cylindrical structure; the polarization maintaining optical fiber ring (10) is wound outside the cylindrical structure; the circuit module (14) is connected with the light path unit (15) and is used for supplying power for the power units in the light path unit (15).

5. The small high-precision fiber-optic angular acceleration measurement device according to claim 4, characterized in that The polarization maintaining optical fiber radius of the polarization maintaining optical fiber ring (10) is 80 microns.

6. The small high-precision fiber-optic angular acceleration measurement device according to claim 5, characterized in that The diameter of the polarization maintaining optical fiber ring (10) is 3 cm, and the ring height is 2 cm.

7. The small high-precision fiber-optic angular acceleration measurement device according to claim 6, characterized in that The optical fiber length of the polarization maintaining optical fiber used in the polarization maintaining optical fiber ring (10) is less than 500 m.

8. The small high-precision fiber-optic angular acceleration measuring device according to claim 1, characterized in that, The optical fiber coupler (8) is a 2×1 optical fiber coupler.

9. The small high-precision fiber-optic angular acceleration measuring device according to claim 1, characterized in that, The optical fiber coupler (8) is a 2×2 optical fiber coupler.

Images