Integrated low-noise optical fiber very-low-frequency vector sensor

Abstract

The invention discloses an integrated low-noise optical fiber very-low-frequency vector sensor, and belongs to the technical field of optical fiber vector hydrophones, the sensor comprises a mass block, the six surfaces of the mass block in the X-axis direction, the Y-axis direction and the Z-axis direction are respectively provided with an elastic cylinder, the outer end part of each elastic cylinder is connected with a piezoelectric actuator, and the piezoelectric actuator is connected with the mass block. Piezoelectric actuator signal lines are arranged on the piezoelectric actuators, limiting blocks are connected to the outer ends of the piezoelectric actuators, and the limiting blocks are installed on the sensor fixing assembly through fixing nuts; the X-axis direction, the Y-axis direction and the Z-axis direction of the mass block are respectively provided with a Michelson interferometer which is wound on the elastic cylinder and the piezoelectric actuator in the same direction. The integrated low-noise optical fiber very-low-frequency vector sensor is simple in structure, low in manufacturing cost, good in sensitivity, high in precision and capable of adapting to various severe environments, drifting can be accurately eliminated, the low-frequency performance of the optical fiber vector sensor is improved, and the frequency band is widened.

Description

Technical Field

[0001] The invention relates to the technical field of optical fiber vector hydrophones, and in particular to an integrated low-noise optical fiber very low frequency vector sensor. Background Art

[0002] In the prior art, fiber optic vector sensors are widely used in vibration monitoring, underwater acoustic detection and precision measurement because they can sense the amplitude and directionality of signals at the same time. As a classic design of fiber optic vector sensors, the push-pull structure generates a directional response through two sets of symmetrical sensing units to effectively amplify the target signal, and is a common solution for achieving high-sensitivity detection. However, in the measurement of very low frequency signals, due to the influence of optical fiber thermal noise and light source frequency noise, the low-frequency performance of fiber optic sensors is poor, and the low-frequency phase noise is at a relatively high level. This creates a technical bottleneck. When measuring very low frequency signals of the order of hundreds of seconds, the low-frequency noise of the fiber optic sensor is too high, causing the target signal to be submerged, seriously affecting the measurement accuracy. How to reduce the low-frequency noise of the fiber optic sensor is a current research difficulty in fiber optic sensors. Summary of the invention

[0003] The purpose of the present invention is to provide an integrated low-noise fiber optic very low frequency vector sensor with a simple structure, low manufacturing cost, good sensitivity, high precision and the ability to adapt to various harsh environments. It can accurately eliminate drift, improve the low-frequency performance of the fiber optic vector sensor, and widen the frequency band.

[0004] To achieve the above-mentioned purpose, the present invention provides an integrated low-noise fiber-optic very low frequency vector sensor, comprising a mass block, wherein six surfaces of the mass block in the X-axis, Y-axis and Z-axis directions are installed with elastic cylinders, the outer end of each of the elastic cylinders is connected to a piezoelectric driver, the piezoelectric driver is provided with a piezoelectric driver signal line, the outer end of the piezoelectric driver is connected to a limit block, and the limit blocks are installed on a sensor fixing assembly through a fixing nut; the X-axis, Y-axis and Z-axis directions of the mass block are respectively provided with Michelson interferometers on the elastic cylinder and the piezoelectric driver wound in the same direction.

[0005] Preferably, a boss corresponding to the elastic column is provided on the mass block.

[0006] Preferably, the main body of the mass block is a cubic structure and each edge is chamfered.

[0007] Preferably, the Michelson interferometer includes a coupler installed at the chamfer of the mass block, and the two optical fibers of the coupler are respectively and evenly and tightly wound on the elastic cylinder and the piezoelectric driver on both sides in the same direction, and the ends of the optical fibers are connected to Faraday rotators wound on the piezoelectric driver.

[0008] Preferably, the sensor fixing assembly includes a first fixing ring and a second fixing ring which are vertically connected to each other.

[0009] Therefore, the beneficial effects of the integrated low-noise optical fiber very low frequency vector sensor used in the present invention are as follows: (1) Low production cost and simple structure.

[0010] (2) Good sensitivity, high precision and able to adapt to various harsh environments.

[0011] (3) The piezoelectric driver is integrated into the fiber optic vector sensor as a feedback device to accurately eliminate drift, improve the low-frequency performance of the fiber optic vector sensor, widen the frequency band, and achieve a large dynamic range within a small linear motion area to meet the needs of very low frequency signal monitoring.

[0012] (4) The introduction of feedback will improve the dynamic range, resolution and signal-to-noise ratio of the fiber optic vector sensor.

[0013] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the overall structure of an embodiment of an integrated low-noise optical fiber very low frequency vector sensor of the present invention; Figure 2 It is a structural schematic diagram of a mass block of an embodiment of an integrated low-noise optical fiber very low frequency vector sensor of the present invention.

[0015] Reference numerals 1. First fixing ring; 2. Piezoelectric driver signal line; 3. Piezoelectric driver; 4. Elastic cylinder; 5. Second fixing ring; 6. Limit block; 7. Fixing nut; 8. Coupler; 9. Mass block; 10. Faraday rotator. DETAILED DESCRIPTION

[0016] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0017] Unless otherwise defined, the technical terms or scientific terms used in the present invention should be understood by people with ordinary skills in the field to which the present invention belongs. The words "first", "second" and similar words used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. "Include" or "comprise" and similar words mean that the elements or objects appearing before the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. "Connect" or "connected" and similar words are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. "Up", "down", "left", "right" and the like are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0018] Embodiment 1 like Figure 1 As shown, the present invention provides an integrated low-noise fiber-optic very low frequency vector sensor, including a mass block 9, and elastic cylinders 4 are installed on the six surfaces of the mass block 9 in the X-axis, Y-axis, and Z-axis directions to form six axes X+, Y+, Z+, X-, Y-, and Z-. The outer end of each elastic cylinder 4 is connected to a piezoelectric driver 3, and each piezoelectric driver 3 is provided with a piezoelectric driver signal line 2 for connecting with an external device.

[0019] The outer ends of the piezoelectric driver 3 are connected to the limit blocks 6, and the limit blocks 6 are installed on the sensor fixing assembly through the fixing nuts 7 to fix the sensor structure. The sensor fixing assembly includes a first fixing ring 1 and a second fixing ring 5 connected vertically to each other, and each elastic column 4 and the piezoelectric driver 3 can be fixed in the X-axis, Y-axis, and Z-axis directions. In this way, the piezoelectric driver 3 is integrated with the optical fiber vector hydrophone, thereby accurately eliminating drift and meeting the very low frequency signal monitoring requirements.

[0020] Elastic cylinders 4 and Michelson interferometers on the piezoelectric driver 3 are respectively arranged on the X-axis, Y-axis, and Z-axis directions of the mass block 9. Figure 2 As shown, in this embodiment, a boss corresponding to the elastic column 4 is provided on the mass block 9, which is convenient for positioning the elastic column 4 during the manufacturing process. The main body of the mass block 9 is a cubic structure and each edge is chamfered, which is convenient for installing the Michelson interferometer.

[0021] The Michelson interferometer includes a coupler 8 installed at the chamfer of the mass block 9, and the two optical fibers of the coupler 8 are respectively and evenly and tightly wound on the elastic cylinder 4 and the piezoelectric driver 3 on both sides in the same direction. There are three Michelson interferometers in total, which are respectively and evenly and tightly wound on the elastic cylinder 4 and the piezoelectric driver 3 in the X+, X-, Y+, Y-, Z+, and Z- directions. The end of each optical fiber is connected to a Faraday rotator 10 wound on the piezoelectric driver 3.

[0022] The sensor is made as follows: (1) The elastic column 4 and the mass block 9 are assembled with sealant to form the basic structure of the vector hydrophone.

[0023] (2) The piezoelectric driver 3 is placed on the elastic column 4 of the push-pull structure, and the piezoelectric driver 3 is buckled into the elastic column 4.

[0024] (3) The Michelson interferometer is uniformly and tightly wound around the elastic cylinder 4 and the piezoelectric actuator 3 in the same direction.

[0025] (4) The whole is placed in the sensor fixing assembly, and the piezoelectric driver 3 is connected to the demodulation circuit to complete the assembly.

[0026] Working principle: When the fiber optic vector hydrophone is acted upon by an acceleration vector parallel to the axial direction of the elastic cylinder 4, due to the inertia of the mass block 9, the elastic cylinder 4 will be compressed or stretched in the axial direction, resulting in radial expansion or contraction of the cylinder, which in turn causes the optical fiber wound on the elastic cylinder 4 to stretch or shorten, resulting in a phase change. Due to the influence of noise factors such as the frequency noise of the light source, a voltage signal is applied to the piezoelectric ceramic of the piezoelectric driver 3. The piezoelectric ceramic can produce a small deformation according to the applied voltage, and the voltage signal drives the piezoelectric ceramic to deform in real time to adjust the dynamic characteristics of the system, thereby accurately eliminating drift and achieving stable control.

[0027] Therefore, the present invention adopts the above-mentioned integrated low-noise optical fiber very low frequency vector sensor, which has a simple structure, low manufacturing cost, good sensitivity, high precision and can adapt to various harsh environments. It can accurately eliminate drift, improve the low-frequency performance of the optical fiber vector sensor, and widen the frequency band.

[0028] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. An integrated low-noise optical fiber very low frequency vector sensor, characterized in that: It includes a mass block, six surfaces of the mass block in the X-axis, Y-axis and Z-axis directions are installed with elastic cylinders, the outer end of each of the elastic cylinders is connected to a piezoelectric driver, the piezoelectric driver is provided with a piezoelectric driver signal line, the outer end of the piezoelectric driver is connected to a limit block, and the limit blocks are installed on the sensor fixing component through a fixing nut; the X-axis, Y-axis and Z-axis directions of the mass block are respectively provided with Michelson interferometers on the elastic cylinder and the piezoelectric driver wound in the same direction.

2. The integrated low-noise optical fiber very low frequency vector sensor according to claim 1, characterized in that: The mass block is provided with a boss corresponding to the elastic column.

3. The integrated low-noise optical fiber very low frequency vector sensor according to claim 1, characterized in that: The main body of the mass block is a cubic structure and each edge is chamfered.

4. The integrated low-noise optical fiber very low frequency vector sensor according to claim 1, characterized in that: The Michelson interferometer includes a coupler installed at the chamfer of the mass block, and two optical fibers of the coupler are respectively and evenly and tightly wound on the elastic cylinder and the piezoelectric driver on both sides in the same direction, and the ends of the optical fibers are connected to Faraday rotators wound on the piezoelectric driver.

5. The integrated low-noise optical fiber very low frequency vector sensor according to claim 1, characterized in that: The sensor fixing assembly includes a first fixing ring and a second fixing ring which are vertically connected to each other.

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