阅读说明：本技术 一种基于量子弱值放大的三分量光纤式地震加速度计 (Three-component optical fiber type seismic accelerometer based on quantum weak value amplification ) 是由 黄鲸珲 胡祥云 王广君 段雪影 于 2021-06-04 设计创作，主要内容包括：本发明提供了一种基于量子弱值放大的三分量光纤式地震加速度计,包括三个相互正交的加速度计；单个加速度计包括：量子弱测量前选择模块、偏振分束器、第一自准直透镜、量子弱测量后选择模块、平面镜、第二自准直透镜,线性速度感应光纤环、数据接受和处理模块。通过合适的选择光子态的前选择态和后选择态,然后根据广义Sagnac效应,线性速度感应光纤环把平动速度信息耦合到偏振光的相位差中,经过数据接受和处理模块得到光谱的中心波长的移动,进而得到中心波长的移动与平动速度的关系,三个单独的加速度计最终得到三个方向的线速度、加速度以及三个分量的角速度信息,本发明具有更高的信噪比、灵敏度和测量精度。(The invention provides a three-component optical fiber type seismic accelerometer based on quantum weak value amplification, which comprises three mutually orthogonal accelerometers; the single accelerometer includes: the device comprises a selection module before quantum weak measurement, a polarization beam splitter, a first auto-collimation lens, a selection module after quantum weak measurement, a plane mirror, a second auto-collimation lens, a linear velocity induction optical fiber ring and a data receiving and processing module. Through proper selection of the front selection state and the rear selection state of the photon state, then according to the generalized Sagnac effect, the linear velocity sensing optical fiber ring couples the translation velocity information into the phase difference of the polarized light, the movement of the center wavelength of the spectrum is obtained through the data receiving and processing module, and then the relation between the movement of the center wavelength and the translation velocity is obtained, and the linear velocity, the acceleration and the angular velocity information of three components in three directions are finally obtained through three independent accelerometers.)

1. A three-component optical fiber type seismic accelerometer based on quantum weak value amplification is characterized by comprising three mutually orthogonal accelerometers;

the single accelerometer includes: the device comprises a selection module (11) before quantum weak measurement, a polarization beam splitter (12), a first auto-collimation lens (13), a selection module after quantum weak measurement (14), a plane mirror (15), a second auto-collimation lens (16), a linear velocity induction optical fiber ring (17) and a data receiving and processing module (18);

the quantum weak pre-measurement selection module (11) comprises: the SLED super-radiation luminescent device comprises an SLED super-radiation luminescent light source (111), a Gaussian filter plate (112), a spectroscope (113) and a first polarizer (114);

a light source emitted by the SLED super-radiation light-emitting source (111) forms a Gaussian spectrum with a certain bandwidth after passing through the Gaussian filter (112), and then the light beam is divided into reflected light and transmitted light by the beam splitter (113);

the reflected light enters the data receiving and processing module (18), the spectrum of the reflected light is used as a reference spectrum for measuring spectrum shift, meanwhile, the transmitted light is subjected to front selection on polarized light through the first polarizing film (114), and then the polarized light is divided into polarized light V polarized along the vertical direction and polarized light H polarized along the horizontal direction through the polarization beam splitter (12);

the polarized light V polarized along the vertical direction propagates anticlockwise through the plane mirror (15), the second auto-collimation lens (16), the linear velocity induction optical fiber ring (17) and the first auto-collimation lens (13);

the polarized light H polarized along the horizontal direction is transmitted clockwise through the first autocollimation lens (13), the linear speed induction optical fiber ring (17) and the second autocollimation lens (16);

and finally, combining the two beams of polarized light into a beam of total polarized light through the polarization beam splitter (12), selecting the total polarized light through the quantum weak measurement post-selection module (14), then enabling the light beam to enter the data receiving and processing module (18), comparing a spectrum obtained after corresponding acquisition and data processing with the reference spectrum, calculating the movement of the central wavelength, and further obtaining the relation between the movement of the central wavelength and the translation speed according to a weak value amplification principle.

2. The three-component fiber optic seismic accelerometer based on quantum weak value amplification of claim 1, wherein the linear velocity sensing fiber loop (17) is wound from polarization maintaining fiber and comprises: a fixed mass (172) and a movable mass (171).

3. The three-component fiber optic seismic accelerometer based on quantum weak value amplification of claim 1, wherein the post-quantum weak measurement selection module (14) comprises a second polarizer (141).

4. The three-component fiber optic seismic accelerometer based on quantum weak value amplification of claim 1, wherein the data acceptance and processing module (18) comprises: a first spectrometer (181), a second spectrometer (182) and a data processing module (183); the first spectrometer (181) and the second spectrometer (182) are respectively electrically connected with the data processing module (183).

5. The three-component fiber seismic accelerometer based on quantum weak value amplification as claimed in claim 3, wherein the data receiving and processing module (18) is configured to sample, process and gaussian fit a spectrum in real time to obtain the movement of the center wavelength, and further obtain the relationship between the movement of the center wavelength and the translational velocity to be measured according to a weak measurement principle:

wherein, delta represents differentiation, alpha is an included angle between the polarization direction of the polarized light after passing through the first polarizer and the vertical direction, beta is an included angle between the polarization direction of the synthesized polarized light after passing through the second polarizer and the horizontal direction, Im () represents an imaginary part, i represents an imaginary unit,is the phase difference caused by the generalized Sagnac effect,c is the speed of light in vacuum, λ₀Is the wavelength of the initial spectrum in vacuum, N is the number of turns of the optical fiber ring, Delta lambda is the bandwidth of the initial spectrum, nu is the translational velocity, and L is the length of the optical fiber.

6. The three-component fiber optic seismic accelerometer based on quantum weak value amplification of claim 4, wherein the data processing module (183) comprises: ADC collector, FPGA programmable device, dynamic random access memory RAM and LCD.

7. The three-component fiber seismic accelerometer based on quantum weak point amplification of claim 1, wherein the polarization beam splitter (12), the first auto-collimating lens (13), the plane mirror (15), the second auto-collimating lens (16), and the linear velocity-sensing fiber loop (17) form a polarization-maintaining fiber loop optical path module, and the polarization-maintaining fiber loop optical path module is configured to couple translational velocity information to phase information of polarized light.

8. The three-component fiber optic seismic accelerometer based on quantum weak value amplification of claim 1, wherein the first auto-collimating lens (13) and the second auto-collimating lens (16) are used to enable connection of a free optical path with the linear velocity sensitive fiber loop (17).

Technical Field

The invention relates to the field of seismographs, in particular to a three-component optical fiber type seismic accelerometer based on quantum weak value amplification.

Background

At present, the joint observation and explanation of the ground translational motion and the ground rotational motion have important significance for the research of strong ground motion seismology, wide band seismology, seismic engineering, seismic physics, seismic instrument equipment, seismic disasters and seismic structures. Accelerometers in which translational motion is monitored and recorded can be classified in principle, mainly including piezoresistive, piezo-resistive, tunneling, resonant, optical, capacitive, and in recent years microelectronic acceleration sensors (MEMS) in large-scale applications. Compared with other accelerometers, the fiber accelerometer is widely applied to oil-gas exploration and earthquake monitoring due to the advantages of high sensitivity, wide dynamic range, strong anti-electromagnetic interference capability and the like.

In addition, with the continuous development of seismology and the continuous improvement of measurement technology, an emerging interdisciplinary discipline is created for the observation and research of the rotation motion in the ground motion, and the rotation seismology becomes a new discipline for researching the ground rotation motion caused by natural earthquakes, blasting and surrounding environment vibration. On one hand, the rotational seismology signal can be obtained through a high-precision gyroscope; on the other hand, the three-component translational motion acceleration is accurately measured, and then the corresponding three-rotation-direction angular velocities can be obtained through the finite difference principle, so that the requirement on rotational seismology research precision is met. However, the current accelerometer is not consistent with the data of the optical fiber gyroscope after partial frequency conversion, and because the measurement of the translation signal with weak intensity is not accurate, an accelerometer with higher sensitivity, high precision and stability is necessary to be designed.

Disclosure of Invention

In view of the above, the invention provides a three-component fiber seismic accelerometer based on quantum weak value amplification, in order to solve the technical problem that the measurement of a translation signal with weak intensity by the existing accelerometer is inaccurate.

In order to achieve the aim, the invention provides a three-component optical fiber type seismic accelerometer based on quantum weak value amplification, which comprises three mutually orthogonal accelerometers;

the single accelerometer includes: the system comprises a selection module before quantum weak measurement, a polarization beam splitter, a first auto-collimation lens, a selection module after quantum weak measurement, a plane mirror, a second auto-collimation lens, a linear velocity induction optical fiber ring and a data receiving and processing module;

the quantum weak pre-measurement selection module comprises: the SLED super-radiation light source, the Gaussian filter, the spectroscope and the first polaroid;

a light source emitted by the SLED super-radiation light source forms a Gaussian spectrum with a certain bandwidth after passing through the Gaussian filter, and then the beam splitter divides the light beam into reflected light and transmitted light;

the reflected light enters the data receiving and processing module, the spectrum of the reflected light is used as a reference spectrum for measuring spectrum movement, meanwhile, the transmitted light is subjected to forward selection on polarized light through the first polarizing film, and then linearly polarized light is divided into polarized light V polarized along the vertical direction and polarized light H polarized along the horizontal direction through the polarization beam splitter;

the polarized light V polarized along the vertical direction is transmitted anticlockwise through the plane mirror, the second auto-collimation lens, the linear speed induction optical fiber ring and the first auto-collimation lens;

the polarized light H polarized along the horizontal direction is transmitted clockwise through the first auto-collimation lens, the linear velocity induction optical fiber ring and the second auto-collimation lens;

and finally, combining two beams of polarized light into a beam of total polarized light through the polarization beam splitter, selecting the total polarized light through the quantum weak measurement post-selection module, then enabling the total polarized light to enter the data receiving and processing module, comparing a spectrum obtained after corresponding acquisition and data processing with the reference spectrum, calculating to obtain the movement of the central wavelength, and further obtaining the relation between the movement of the central wavelength and the translation speed according to a weak value amplification principle.

Preferably, the linear velocity sensing fiber loop is made of a polarization maintaining fiber, and comprises: a fixed mass and a movable mass.

Preferably, the post-quantum weak measurement selection module comprises a second polarizer.

Preferably, the data receiving and processing module comprises: the spectrometer comprises a first spectrometer, a second spectrometer and a data processing module, wherein the first spectrometer and the second spectrometer are respectively and electrically connected with the data processing module.

Preferably, the data receiving and processing module is configured to sample, process and gaussian fit the spectrum in real time to obtain the movement of the central wavelength, and further obtain a relationship between the movement of the central wavelength and the translation speed to be measured according to a weak measurement principle:

wherein, delta represents differentiation, alpha is an included angle between the polarization direction of the polarized light after passing through the first polarizer and the vertical direction, beta is an included angle between the polarization direction of the synthesized polarized light after passing through the second polarizer and the horizontal direction, Im () represents an imaginary part, i represents an imaginary unit,is the phase difference caused by the generalized Sagnac effect,c is the speed of light in vacuum, λ₀Is the wavelength of the initial spectrum in vacuum, N is the number of turns of the optical fiber ring, Delta lambda is the bandwidth of the initial spectrum, nu is the translational velocity, and L is the length of the optical fiber.

Preferably, the data processing module includes: ADC collector, FPGA programmable device, dynamic random access memory RAM and LCD.

Preferably, the polarization beam splitter, the first auto-collimation lens, the plane mirror, the second auto-collimation lens, and the linear velocity sensing optical fiber loop constitute a polarization maintaining optical fiber loop optical path module, and the polarization maintaining optical fiber loop optical path module is configured to couple translational velocity information to phase information of polarized light.

Preferably, the first auto-collimation lens and the second auto-collimation lens are used for realizing connection of a free light path and the linear velocity sensing optical fiber ring.

The technical scheme provided by the invention has the beneficial effects that:

1. the invention can realize high sensitivity and high precision measurement of translational linear velocity by amplifying weak value of generalized Sagnac effect of the polarization-maintaining optical fiber ring.

2. The FPGA data processing module can process the measured data in real time, and further obtains the relation between the translational acceleration and the rotation angular velocity.

3. The two spectrometers can monitor the initial spectrum and the spectrum after weak measurement in real time, and can solve the problem of unstable light power of the light source, so that the spectrum measurement based on the frequency domain has higher signal-to-noise ratio and sensitivity.

Drawings

The invention will be further described with reference to the accompanying drawings and examples, in which:

FIG. 1 is a block diagram of a three-component fiber seismic accelerometer based on quantum weak value amplification in an embodiment of the invention;

FIG. 2 is a schematic diagram of a single accelerometer based on quantum weak measurement weak value amplification in an embodiment of the invention;

the reference numbers in the figures illustrate: 11-a selection module before quantum weak measurement, 111-a SLED superradiance light source, 112-a Gaussian filter, 113-a spectroscope, 114-a first polarizing film, 12-a polarization beam splitter, 13-a first auto-collimation lens, 15-a plane mirror, 16-a second auto-collimation lens, 17-a linear velocity induction optical fiber ring, 172-a fixed mass block, 171-a movable mass block, 14-a selection module after quantum weak measurement, 141-a second polarizing film, 18-a data receiving and processing module, 181-a first spectrometer, 182-a second spectrometer and 183-a data processing module.

Detailed Description

For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

The embodiment of the invention provides a three-component optical fiber type seismic accelerometer based on quantum weak value amplification.

Referring to fig. 1 and 2, fig. 1 is a structural diagram of a three-component fiber-optic seismic accelerometer based on quantum weak value amplification in an embodiment of the present invention, where the three-component fiber-optic seismic accelerometer is mainly composed of three mutually orthogonal accelerometers, and measurement data of each accelerometer is processed by a unified data processing module.

Fig. 2 is a schematic diagram of a single accelerometer based on amplification of a quantum weak measurement weak value in an embodiment of the present invention, where fig. 2 takes an acceleration in an x-axis direction as an example, the single accelerometer based on amplification of the quantum weak value specifically includes: the system comprises a selection module 11 before quantum weak measurement, a polarization beam splitter 12, a first auto-collimation lens 13, a plane mirror 15, a second auto-collimation lens 16, a linear velocity induction optical fiber ring 17, a selection module after quantum weak measurement 14 and a data receiving and processing module 18;

wherein, the selection module 11 before the quantum weak measurement includes: the SLED super-radiation luminescent light source 111, the Gaussian filter 112, the spectroscope 113 and the first polarizer 114;

the linear velocity sensing optical fiber loop 17 includes: a fixed mass 172 and a movable mass 171;

the post-quantum weak measurement selection module 14 includes: a second polarizing plate 141;

the data acceptance and processing module 18 includes: a first spectrometer 181, a second spectrometer 182 and a data processing module 183.

The high-intensity light source emitted by the superradiation SLED superradiation light-emitting light source 111 forms a Gaussian spectrum with a certain bandwidth after passing through the Gaussian filter 112, then the light beam is divided into reflected light and transmitted light by the spectroscope 113, the reflected light enters the first spectrometer 181 and then enters the data processing module 183, the spectrum of the reflected light is used as a reference spectrum for measuring spectral movement, meanwhile, the transmitted light emitted by the spectroscope 113 is subjected to forward selection on polarized light through the first polarizing film 114, and then is divided into polarized light V polarized along the vertical direction and polarized light H polarized along the horizontal direction through the polarization beam splitter 12.

The included angle between the polarization direction of the first polarizer 114 and the vertical direction is α, and the polarized light becomes:

|φ_i＞＝sin(α)|H>+cos(α)|V>

|φ_i>corresponding to the previously selected quantum state, | H>Corresponding to the quantum state of the polarization direction in the horizontal direction, | V>Corresponding to the quantum state with polarization direction along the vertical direction.

Polarized light V polarized along the vertical direction is transmitted anticlockwise through the plane mirror 15, the second auto-collimation lens 16, the linear speed induction optical fiber ring 17 and the first auto-collimation lens 13, polarized light H polarized along the horizontal direction is transmitted clockwise through the first auto-collimation lens 13, the linear speed induction optical fiber ring 17 and the second auto-collimation lens 16, and finally two beams of polarized light are combined into one beam through the polarization beam splitter 12. This process corresponds to weak coupling in quantum weak measurements, which due to the generalized Sagnac effect causes a phase difference between clockwise and counter-clockwise propagating polarized light:

c is the speed of light in vacuum, λ₀Is the wavelength of the initial spectrum in vacuum, N is the number of turns of the fiber ring, v is the translational velocity, and L is the length of the fiber. After weak coupling and post-selection, the polarized light becomes:

|φ_f>and beta is the included angle between the polarization direction of the synthesized polarized light beam after passing through the second polaroid and the horizontal direction corresponding to the selected quantum state.

The total polarized light synthesized by the polarization beam splitter 12 is selected after passing through the second polarizer 14, and then the light beam is incident to the data receiving and processing module 18, and the spectrum obtained after corresponding acquisition and data processing is compared with the initial spectrum, and the shift of the center wavelength is calculated. The observable indicators corresponding to the invention are: a ═ H><H|-|V><V | according to the quantum weak measurement medium and weak value A_WDefinition of (1):

<φ_fφ_i>after the correspondence the probability of success is selected,<φ_f|A|φ_i>representing the expectation of a measured observable a.

A shift formula of the center wavelength of the emergent spectrum can be obtained:

where Δ λ is the bandwidth of the initial spectrum and Im () represents a function taking the imaginary part. Due to phase differenceIs a function of the translational velocity v, so that finally the shift δ λ of the central wavelength is obtained by the above formula₀Relation to translation velocity v:

the above process is based on the principle of quantum weak measurement weak value amplification: through the front selection and the back selection which are suitable for the quantum state, the translation speed is coupled into the phase of the polarized light through the linear speed induction optical fiber ring 17, and finally the relationship between the translation speed and the spectrum center wavelength movement is obtained through the weak value amplification principle.

In this embodiment, the linear velocity sensing fiber loop 17 can maintain the polarization degree of the polarized light during the transmission process of the polarized light, and the fiber loop is different from the conventional winding of the fiber loop, and the winding area of the fiber loop is nearly zero. The linear velocity sensing fiber optic ring 17 includes a fixed mass 172 and a movable mass 171. The optical fiber ring is wound on a fixed mass block 172 and a movable mass block 171, the fixed mass block 172 is fixedly connected with the whole system, the movable mass block 171 can slide left and right as shown in figure 1 to sense the translational speed, the distance between the two sliding blocks is small, the mutual friction coefficient between the two sliding blocks is small, the up-and-down movement of the two mass blocks is limited by machinery, and therefore the accelerometer along the x axis is only sensitive to the translational speed in the x direction.

In this embodiment, the data acceptance and processing module 18 includes a first spectrometer 181, a second spectrometer 182, and a data processing module 183. The first spectrometer 181 and the second spectrometer 182 convert the optical signals into electrical signals (usually voltages). The data processing module 183, as shown in fig. 1, includes a high-speed ADC collector, an FPGA programmable device, a dynamic random access memory RAM capable of storing data, and an LED capable of displaying the measurement result in real time. The FPGA programmable device can perform Gaussian fitting on the collected spectrum in real time to obtain a value of the central wavelength, so that the movement of the central wavelength and the value of the translational angular velocity are obtained. Further, the sampling time of the ADC on the spectrum can be determined according to the Nyquist sampling theorem, and the value a of the translational acceleration with a certain resolution is calculated to be d ν/dt, wherein d ν represents the variation of the speed in the dt time range, theoretically, the calculation of the acceleration is more accurate when the dt time is smaller, and the accuracy of the calculation is dependent on the sampling rate of the ADC and the data processing capacity of the FPGA.

The three-component fiber optic seismic accelerometer can measure three-component velocity and acceleration values with x-axis, y-axis and z-axis orthogonal to each other as shown in FIG. 1. Theoretical rotation vector (ω)_x,ω_y,ω_z) Can use wave fieldIs expressed in degrees of rotation. And obtaining three mutually orthogonal speeds v_x、ν_y、ν_zThe angular velocities of the three components can be further derived:

wherein the content of the first and second substances,representing the derotation of the wavefield, Δ ═ δ_x，δ_y,δ_z)，δ_x，δ_y,δ_zThe derivation of the velocity in the x-axis, y-axis and z-axis directions is shown, respectively.

When the three-component optical fiber type seismic accelerometer based on quantum weak value amplification is used for measurement, the following technologies are specifically adopted for realization:

in this embodiment, the parameters of the first polarizer 114, the second polarizer 141, and the linear velocity sensing optical fiber loop 17 may be that an angle α between the polarization direction of the first polarizer 114 and the vertical direction is 1.0rad, an angle β between the polarization direction of the second polarizer 141 and the horizontal direction is 0.01rad, the length of the linear velocity sensing optical fiber loop 17 corresponds to NL which is 5000m, and the central wavelength λ of the light source spectrum is 5000m₀＝833×10^-9m, corresponding to a gaussian spectrum width Δ λ of 80 × 10^-9And m is selected. The resolutions of the spectrums in the first spectrometer 181, the second spectrometer 182 and the DAC conversion module are all 0.2nm, and the resolution of the three-component fiber seismic accelerometer translation speed measurement based on quantum weak value amplification is 2.0 multiplied by 10^-9m/s. The above examples demonstrate the high resolution of the present invention.

The beneficial effects brought by the implementation of the invention are as follows:

1. the invention realizes the high sensitivity and high precision measurement of the translational linear velocity by amplifying the weak value of the generalized Sagnac effect of the polarization-maintaining optical fiber ring.

2. The FPGA data processing module processes the measured data in real time to further obtain the relation between the translational acceleration and the rotation angular velocity.

3. The two spectrometers of the invention monitor the initial spectrum and the spectrum after weak measurement in real time, solve the problem of unstable light power of the light source, and enable the spectrum measurement based on the frequency domain to have higher signal-to-noise ratio and sensitivity.

While the present invention has been described with reference to the embodiments shown in the drawings, the present invention is not limited to the embodiments, which are illustrative and not restrictive, and it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention as defined in the appended claims.