An electric field measurement device based on a laser probe and a signal enhancement method thereof

Abstract

The invention relates to the technical field of electric field measurement, and relates to an electric field measurement device based on a laser probe and a signal enhancement method thereof. The device comprises a laser component, a first reflector component, a second reflector component, an ultraviolet light source and a spectrometer. The laser component comprises a first laser, a second laser and a controller. The controller is used to control the time when the first laser and the second laser emit laser pulses, and there is a time interval between the laser pulses of the first laser and the second laser. The first reflector component is used to reflect the laser pulse of the first laser into an electric field. The second reflector component is used to reflect the laser pulse of the second laser to a focus corresponding to the laser pulse of the first laser. The ultraviolet light source is used to irradiate the focus in the electric field. The spectrometer is used to collect a spectral signal generated by the focus in the electric field. The invention solves the problems of limited measuring distance, insufficient signal sensitivity, low resolution and poor environmental adaptability in the prior art.

Description

Technical Field

[0001] The present invention relates to the technical field of electric field measurement, and in particular to an electric field measurement device based on a laser probe and a signal enhancement method thereof. Background Art

[0002] In UHV AC systems (such as 1100kV) and UHV DC systems (such as 800kV), excessive local electric field strength can cause problems such as corona discharge and insulation breakdown, posing a major threat to the stability and safety of the power system. This uneven distribution of local electric fields can directly lead to equipment aging, degradation of insulation performance, and even serious power accidents. Therefore, accurate measurement and analysis of local electric field distribution in UHV systems is the key to ensuring their safe operation. The current mainstream electric field measurement technology relies on physical probes such as D-dot sensors, MEMS sensors, and lithium niobate (LiNbO3, LN) sensors. D-dot sensors are mainly used for high-frequency electric field measurement, but due to their limited measurement range, it is difficult to capture micron-level electric field distribution. MEMS sensors have the advantages of compactness and high integration, but their size limits accuracy, and they are invasive measurements that interfere with electric field distribution. Lithium niobate sensors use electro-optical effects and are suitable for high-frequency electric field detection, but they still cannot meet the requirements of non-contact and long-distance measurement. Summary of the invention

[0003] The purpose of the present invention is to provide an electric field measurement device based on a laser probe and a signal enhancement method thereof to improve the above problems. In order to achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0004] On the one hand, the present application provides an electric field measurement device based on a laser probe, the device comprising a laser assembly, a first reflector assembly, a second reflector assembly, an ultraviolet light source and a spectrometer, the laser assembly comprising a first laser, a second laser and a controller, the controller being used to control the time when the first laser and the second laser emit laser pulses, and there is a time interval between the laser pulses of the first laser and the second laser; the first reflector assembly is used to reflect the laser pulse of the first laser into an electric field; the second reflector assembly is used to reflect the laser pulse of the second laser to the focus corresponding to the laser pulse of the first laser; the ultraviolet light source is used to irradiate the focus in the electric field; and the spectrometer is used to collect the spectral signal generated by the focus in the electric field.

[0005] Optionally, the first reflector assembly includes a first reflector and a focusing device, and the focusing device is arranged between the first reflector and the focal point.

[0006] Optionally, the focusing device includes a dichroic mirror and a focusing lens, the dichroic mirror is arranged between the first reflector and the focusing lens, and the focusing lens is arranged between the dichroic mirror and the focal point.

[0007] Optionally, the second reflector assembly includes a second reflector and a third reflector, the second reflector reflects the laser pulse of the second laser to the third reflector, and the third reflector reflects the laser pulse of the second laser to the focus.

[0008] Optionally, a light collecting device is provided between the collector of the spectrometer and the electric field.

[0009] Optionally, the light collecting device includes a fourth reflector, a fifth reflector and an aspheric correction lens, the fourth reflector and the fifth reflector are arranged between the collector of the spectrometer and the aspheric correction lens, the fourth reflector and the fifth reflector are arranged at intervals, and the aspheric correction lens is arranged between the fourth reflector and the electric field.

[0010] Optionally, the convex surface of the aspheric correction lens is arranged on a side close to the fourth reflecting mirror.

[0011] On the other hand, the present application provides a signal enhancement method based on a laser probe, the method comprising:

[0012] Acquire a first operation instruction, where the first operation instruction is used to control the first laser to emit a laser pulse;

[0013] After responding to the first operation instruction, acquiring delay time information and a second operation instruction, wherein the second operation instruction is used to control the second laser to emit laser pulses;

[0014] Controlling the second laser to emit laser pulses according to the delay time information and the second operation instruction;

[0015] Obtaining a third operation instruction, where the third operation instruction is used to control the ultraviolet light source to generate ultraviolet light;

[0016] After responding to the third operation instruction, the enhanced signal in the electric field is collected by using a spectrometer and the electric field is measured according to the collected result.

[0017] The beneficial effects of the present invention are:

[0018] The present invention improves the intensity and signal-to-noise ratio of the spectral signal by arranging a laser component to emit two laser pulses at an interval, then uses an ultraviolet light source to induce a pre-ionization effect in the target area, increases the free electron density of the plasma, and improves the quality of the plasma spectral signal. The enhanced signal is collected by a spectrometer to measure the electric field, effectively solving the problems of limited measurement distance, insufficient signal sensitivity, low resolution and poor environmental adaptability in the prior art, and achieving high-sensitivity and high-resolution measurement of the electric field strength of a distant target area.

[0019] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or be understood by implementing the embodiments of the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0021] Figure 1 Schematic diagram of the structure of the electric field measurement device based on the laser probe described in an embodiment of the present invention.

[0022] Markings in the figure: 1. First laser; 2. Second laser; 3. Controller; 4. Spectrometer; 5. First reflector; 6. Dichroic mirror; 7. Focusing lens; 8. Second reflector; 9. Third reflector; 10. Ultraviolet light source; 11. Electric field; 12. Focus; 13. Light collecting device; 14. Fourth reflector; 15. Fifth reflector; 16. Aspheric correction lens. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0025] Embodiment 1:

[0026] like Figure 1 As shown, this embodiment provides an electric field measurement device based on a laser probe, the device includes a laser component, a first reflector component, a second reflector component, an ultraviolet light source 10 and a spectrometer 4, the laser component includes a first laser 1, a second laser 2 and a controller 3, the controller 3 is used to control the time when the first laser 1 and the second laser 2 emit laser pulses, and there is a time interval between the laser pulses of the first laser 1 and the second laser 2; the first reflector component is used to reflect the laser pulse of the first laser 1 into the electric field 11; the second reflector component is used to reflect the laser pulse of the second laser 2 to the focus 12 corresponding to the laser pulse of the first laser 1; the ultraviolet light source 10 is used to irradiate the focus 12 in the electric field 11; the spectrometer 4 is used to collect the spectral signal generated by the focus 12 in the electric field 11, when the laser pulse is focused into the electric field, it generates extremely high energy density, the local area heats up rapidly, causing the material in the area to be instantly ionized, forming When the plasma cools, the excited atoms and ions release energy by radiation and emit characteristic spectral lines. The characteristic spectral lines of the samples under different electric field levels are collected, and it is found that the electric field linearly affects the spectral intensity of the characteristic spectral lines. Using this corresponding relationship, a regression prediction model is established using machine learning algorithms (such as BP, DT and Adaboost, etc.) to achieve the measurement of the unknown electric field. It should be noted that the first laser 1 and the second laser 2 emit laser pulses at intervals. The laser pulse of the first laser 1 is first emitted to the focus 12 in the electric field 11 for preheating. The laser pulse of the second laser 2 acts to induce breakdown to generate plasma after a time delay. Preheating the focus 12 can initially form a plasma region. This initially formed plasma region can help the laser pulse of the second laser 2 to more effectively induce breakdown, reduce the energy loss of the laser pulse, and reduce the side effects (such as excessive evaporation or ablation) caused by excessive energy at the focus 12 while enhancing the spectral signal intensity.

[0027] It is understandable that the ultraviolet light source 10 generates ultraviolet light to irradiate the plasma, which can accelerate the ionization process. Furthermore, the electric field 11 will uniformly accelerate the free electrons in the plasma. When the ultraviolet light irradiates the plasma, the free electrons generated will be accelerated by the electric field. The acceleration of electrons in the electric field not only increases their movement speed, but also increases the energy of collision between electrons and other neutral atoms or molecules, increasing the possibility of further ionization and improving the quality of the plasma spectrum signal.

[0028] In a specific embodiment of the present disclosure, the first reflector assembly includes a first reflector 5 and a focusing device, wherein the focusing device is arranged between the first reflector 5 and the focus 12, and the focusing device includes a dichroic mirror 6 and a focusing lens 7, wherein the dichroic mirror 6 is arranged between the first reflector 5 and the focusing lens 7, and the focusing lens 7 is arranged between the dichroic mirror 6 and the focus 12. In this embodiment, a high-precision adjustment platform is used to install the focusing lens 7, and the lens group can dynamically adjust the focal length to adapt to different target distances. By dynamically adjusting the focal length, the effective focusing of the laser energy on the long-distance target area is ensured, which greatly improves the measurement resolution and efficiency, and realizes the long-distance electric field 11 measurement of more than 1m.

[0029] In a specific embodiment of the present disclosure, the second reflector assembly includes a second reflector 8 and a third reflector 9, the second reflector 8 reflects the laser pulse of the second laser 2 to the third reflector 9, and the third reflector 9 reflects the laser pulse of the second laser 2 to the focus 12.

[0030] In a specific embodiment of the present disclosure, a light collecting device 13 is arranged between the collector of the spectrometer 4 and the electric field 11, and the light collecting device 13 includes a fourth reflector 14, a fifth reflector 15 and an aspheric correction lens 16. The fourth reflector 14 and the fifth reflector 15 are arranged between the collector of the spectrometer 4 and the aspheric correction lens 16, the fourth reflector 14 and the fifth reflector 15 are arranged at intervals, the aspheric correction lens 16 is arranged between the fourth reflector 14 and the electric field 11, and the convex surface of the aspheric correction lens 16 is arranged on a side close to the fourth reflector 14. The light collecting device 13 realizes efficient collection of long-distance spectral signals, breaks through the limitation of measurement distance in the prior art, realizes long-distance measurement of the electric field, and further improves the measurement accuracy.

[0031] Embodiment 2:

[0032] This embodiment provides a signal enhancement method based on a laser probe, the method comprising:

[0033] Step S1, obtaining a first operation instruction, wherein the first operation instruction is used to control the first laser 1 to emit laser pulses;

[0034] Step S2, in response to the first operation instruction, obtaining delay time information and a second operation instruction, wherein the second operation instruction is used to control the second laser 2 to emit laser pulses;

[0035] The step S2 also includes step S21, step S22, step S23, step S24, step S25 and step S26, which specifically include:

[0036] Step S21, obtaining the initialized delay time and the delay time variation;

[0037] Step S22, obtaining at least two delay time points according to the delay time variation and the initialized delay time;

[0038] Step S23, recording the signal strength information at each of the delay time points, and drawing a first curve graph according to the signal strength information at each of the delay time points, wherein the first curve graph includes a trend of signal strength changing with time delay;

[0039] Step S24, obtaining background noise;

[0040] Step S25, denoising the first curve graph according to the background noise to obtain a denoised first curve graph;

[0041] Step S26: Determine the delay time information according to the first curve graph after denoising.

[0042] In this embodiment, the first laser 1 and the second laser 2 are used to conduct experiments, the energy ratio of the two laser pulses is fixed, the experiment is repeated for each delay time point, and the corresponding spectral signal intensity information is recorded. To ensure data reliability, the background noise is recorded and the collected spectral signal is subjected to noise correction to obtain the first denoised curve graph. The variation pattern of the signal intensity is observed from the first curve graph, and the delay time point corresponding to the peak value is the optimal delay time information. If multiple peaks appear on the curve, the first or most obvious peak point can be selected as the optimal delay time based on actual application requirements to avoid interference from complex effects.

[0043] After step S26, the method further includes steps S27, S28, S29 and S210, which specifically include:

[0044] Step S27, obtaining energy ratio information of the first laser 1 and the second laser 2;

[0045] In this step, the energy ratio E1 / E2 of the two pulsed lasers is regulated by an energy controller, wherein E1 represents the energy ratio of the laser pulses of the first laser 1 , and E2 represents the energy ratio of the laser pulses of the second laser 2 .

[0046] Step S28, after determining the delay time information, recording the spectral signal intensity and signal-to-noise ratio under different energy ratio information;

[0047] In this step, after determining the optimal delay time information, the time delay is fixed, and the energy ratio of the two laser beams is gradually changed, for example, from 1:9 to 9:1 or a wider range (with a ratio step of 0.5 or 1), and the spectral signal intensity and signal-to-noise ratio under each set of energy ratios are recorded. It should be noted that multiple measurements can be performed on each energy ratio point, and the average value and standard deviation can be calculated to reduce experimental errors.

[0048] Step S29, drawing a second curve graph according to the spectral signal intensity under different energy ratio information, and drawing a third curve graph according to the spectral signal-to-noise ratio under different energy ratio information;

[0049] Step S210 , determining the energy ratio of the first laser 1 and the second laser 2 according to the second curve graph and the third curve graph.

[0050] In this step, the energy ratio E1 / E2 corresponding to the maximum signal strength is found from the second curve, and the optimal energy distribution ratio that takes into account both signal strength and signal-to-noise ratio improvement is determined in combination with the signal-to-noise ratio curve. If the intensity is inconsistent with the peak value of the signal-to-noise ratio, the ratio point with a stable signal-to-noise ratio should be selected first according to the specific application requirements.

[0051] In this embodiment, by adjusting the time delay and energy distribution of the two laser pulses, the spectral signal intensity and signal-to-noise ratio can be significantly improved, especially in a weak electric field environment, showing excellent sensitivity, thereby improving the accuracy of remote electric field 11 measurement. In addition, after determining the time delay and energy distribution of the laser assembly, it is also necessary to determine the overlap of the focal points of the two lasers to further improve the signal quality. The specific process is: 1. Path alignment: Use a beam collimator (such as a laser collimator) to adjust the propagation directions of the two laser beams so that they intersect at the target point (electric field 11 area); 2. Monitor focus overlap: Use a high-resolution beam analyzer to record the spatial distribution of the two beams of light at the target point, draw a beam superposition image, and ensure that the centers of gravity of the two beams coincide; 3. Fine-tune the beam overlap: Use a precision translation stage or tilt mirror to gradually adjust the optical paths (horizontal and vertical directions) of the two beams of light until the spots of the two beams completely overlap; 4. Data acquisition and analysis: After each adjustment, collect signal strength data; 5. Draw a curve of signal intensity versus beam overlap to find the overlapping position corresponding to the maximum signal. With the beam overlap deviation as the horizontal axis and the signal intensity as the vertical axis, find the optimal overlap parameter corresponding to the maximum signal.

[0052] Step S3, controlling the second laser 2 to emit laser pulses according to the delay time information and the second operation instruction;

[0053] Step S4, obtaining a third operation instruction, wherein the third operation instruction is used to control the ultraviolet light source 10 to generate ultraviolet light;

[0054] In this step, before emitting ultraviolet light, it is necessary to collect signal intensity data corresponding to different ultraviolet light wavelengths, signal intensity data corresponding to different time delays (the delay between the laser pulse emission time of the second laser 2 and the ultraviolet light emission of the ultraviolet light source 10), and signal intensity data corresponding to different energy densities to construct a three-dimensional relationship diagram, so as to determine the ultraviolet light wavelength, energy density and delay time of the ultraviolet light source 10, thereby further enhancing the signal and improving the accuracy of the electric field 11 measurement.

[0055] Step S5: After responding to the third operation instruction, the enhanced signal in the electric field 11 is collected by using the spectrometer 4 and the electric field 11 is measured according to the collected result.

[0056] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0057] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0059] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An electric field measuring device based on a laser probe, characterized in that: include: A laser assembly, the laser assembly comprising a first laser (1), a second laser (2) and a controller (3), the controller (3) being used to control the time at which the first laser (1) and the second laser (2) emit laser pulses, and a time interval between the laser pulses generated by the first laser (1) and the second laser (2); a first reflector assembly, the first reflector assembly being used to reflect laser pulses of the first laser (1) into an electric field (11); a second reflector assembly, the second reflector assembly being used to reflect the laser pulse of the second laser (2) to a focus (12) corresponding to the laser pulse of the first laser (1); An ultraviolet light source (10), the ultraviolet light source (10) being used to irradiate the focal point (12) in the electric field (11); A spectrometer (4) is used to collect a spectral signal generated by the focus (12) in the electric field (11).

2. The electric field measurement device based on a laser probe according to claim 1, characterized in that: The first reflector assembly comprises a first reflector (5) and a focusing device, wherein the focusing device is arranged between the first reflector (5) and the focus (12).

3. The electric field measurement device based on a laser probe according to claim 2, characterized in that: The focusing device comprises a dichroic mirror (6) and a focusing lens (7), wherein the dichroic mirror (6) is arranged between the first reflector (5) and the focusing lens (7), and the focusing lens (7) is arranged between the dichroic mirror (6) and the focal point (12).

4. The electric field measurement device based on a laser probe according to claim 1, characterized in that: The second reflector assembly comprises a second reflector (8) and a third reflector (9), wherein the second reflector (8) reflects the laser pulse of the second laser (2) to the third reflector (9), and the third reflector (9) reflects the laser pulse of the second laser (2) to the focus (12).

5. The electric field measurement device based on a laser probe according to claim 1, characterized in that: A light collecting device (13) is provided between the collector of the spectrometer (4) and the electric field (11).

6. The electric field measuring device based on a laser probe according to claim 5, characterized in that: The light collecting device (13) comprises a fourth reflecting mirror (14), a fifth reflecting mirror (15) and an aspheric correction lens (16); the fourth reflecting mirror (14) and the fifth reflecting mirror (15) are arranged between a collector of the spectrometer (4) and the aspheric correction lens (16); the fourth reflecting mirror (14) and the fifth reflecting mirror (15) are arranged at intervals; and the aspheric correction lens (16) is arranged between the fourth reflecting mirror (14) and the electric field (11).

7. The electric field measuring device based on a laser probe according to claim 6, characterized in that: The convex surface of the aspheric correction lens (16) is arranged on a side close to the fourth reflecting mirror (14).

8. A signal enhancement method based on a laser probe, characterized in that: include: Acquiring a first operating instruction, wherein the first operating instruction is used to control a first laser (1) to emit a laser pulse; After responding to the first operation instruction, acquiring delay time information and a second operation instruction, wherein the second operation instruction is used to control the second laser (2) to emit laser pulses; controlling the second laser (2) to emit laser pulses according to the delay time information and the second operation instruction; Obtaining a third operating instruction, wherein the third operating instruction is used to control the ultraviolet light source (10) to generate ultraviolet light; After responding to the third operation instruction, the enhanced signal in the electric field (11) is collected using a spectrometer (4) and the electric field (11) is measured according to the collected result.

9. The signal enhancement method based on laser probe according to claim 8, characterized in that: Get delay time information, including: Get the initial delay time and delay time change; Obtaining at least two delay time points according to the delay time variation and the initialized delay time; Recording the signal strength information at each of the delay time points, and drawing a first curve graph according to the signal strength information at each of the delay time points, wherein the first curve graph includes a trend of the signal strength changing with the time delay; Get background noise; De-noising the first curve graph according to the background noise to obtain a de-noised first curve graph; Delay time information is determined according to the first curve graph after denoising.

10. The signal enhancement method based on laser probe according to claim 9, characterized in that: After determining the delay time information according to the first curve graph after denoising, the method further includes: Acquiring energy ratio information of the first laser (1) and the second laser (2); After determining the delay time information, recording the spectral signal intensity and signal-to-noise ratio under different energy ratio information; Draw a second curve graph according to the spectral signal intensity under different energy ratio information, and draw a third curve graph according to the spectral signal-to-noise ratio under different energy ratio information; The energy ratio of the first laser (1) and the second laser (2) is determined according to the second curve graph and the third curve graph.

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