Long-distance crop growth situation detection system based on ultraviolet Raman

Abstract

The invention discloses a long-distance crop growth situation detection system based on ultraviolet Raman, which comprises a laser, a signal transmission system, a spectrometer, a digital delay generator, an oscilloscope and a computer, and is characterized in that the signal transmission system mainly comprises a reflector, a dichroic sheet, a negative lens, a Cassegrain telescope, a lens, a pinhole diaphragm, an optical filter and an optical fiber; a pulse laser signal generated by the laser is transmitted through the signal transmission system and is focused on the surface of a sample to be detected to generate a Raman or fluorescence signal, and the Raman or fluorescence signal is collected and transmitted to the spectrograph; the spectrograph is used for carrying out dispersion light splitting on the received signal, converting a light signal into an electric signal and transmitting the electric signal to the oscilloscope and the computer so as to obtain a Raman signal of the to-be-detected sample; and the digital delay generator performs time sequence control. By designing light paths, the light receiving and transmitting paths are coaxial; the problem of collection time control in ultraviolet light long-distance Raman detection is solved; and a fluorescence detection technology is realized.

Description

Technical Field

[0001] The invention relates to a crop growth situation detection technology, and in particular to a long-distance crop growth situation detection system based on ultraviolet Raman. Background Art

[0002] Related technical explanation:

[0003] Fluorescence spectrum:

[0004] When a substance absorbs incident light, the energy of the photon is transferred to the substance molecule. After the molecule is excited, the electron transitions from a lower energy level to a higher energy level. The molecule in this excited state is called an electronic excited state molecule. The molecule in the excited state is unstable, and it may return to the ground state through the decay process of radiative transition and non-radiative transition. The decay process of radiative transition is accompanied by the emission of photons, that is, fluorescence. Fluorescence is a photoluminescence phenomenon. Due to the selective absorption of light by molecules, incident light of different wavelengths has different excitation efficiencies. This process will be completed within 3 to 8 ns, and the spectrum formed is the fluorescence spectrum. Due to the differences in the molecular structures of different substances, their respective fluorescence spectrum characteristics are also different. Plants are good fluorescent emitting substances because they contain chlorophyll, so when they are excited, they will form a fluorescence spectrum of a special band, thereby identifying substances.

[0005] Raman spectroscopy:

[0006] Raman spectroscopy is an active spectral testing technology used to analyze lattice and molecular vibration, rotation modes and other specific low-frequency modes. The sample is excited by laser, which irradiates the molecule and interacts with the molecular bond or electron cloud of the molecule to produce inelastic light scattering. The energy / frequency of the incident laser changes, generating a Raman spectrum corresponding to the molecular structure.

[0007] Raman spectroscopy technology is widely used in various fields such as chemistry, physics, biology, medicine, industrial and agricultural production, etc. due to its characteristics of rapid, repeatable, non-contact, non-destructive material detection and no need for sample processing.

[0008] Remote detection:

[0009] There are many demands for dangerous goods detection in modern battlefields, industrial production, social security and daily life, such as biological and chemical agents / explosives in modern battlefields, dangerous gas / chemical leakage in industrial production processes, explosives / toxic substances in various important occasions in the field of social security (airports, stations, conference halls, etc.), and expired and spoiled objects / toxic foods in daily life. Effective new detection technologies and instruments are urgently needed. Although various X-ray security scanners, dangerous gas leak detectors, explosive detectors based on ion mobility spectroscopy, THz security scanners and other new security inspection technologies have been developed, there is still a lack of effective detection methods and equipment for on-site detection of some dangerous goods (explosives, biological and chemical agents, industrial dangerous goods leakage) and spoiled foods beyond a safe distance.

[0010] Non-contact detection is the advantage of Raman and fluorescence spectroscopy technology. For long distances and harsh and dangerous environments, Raman and fluorescence spectroscopy technology can play a huge role, using optical means to detect long-distance materials to avoid harm to testers.

[0011] UV:

[0012] Currently, the common excitation light sources for Raman spectroscopy are near-infrared and visible light lasers. Not only are their Raman spectra overlapped with the fluorescence spectra, which reduces the detection signal-to-noise ratio and sensitivity, affecting the accurate identification of substances, but the samples being tested need to avoid the influence of ambient light and can only be measured in a laboratory or a detection dark box.

[0013] Compared with near-infrared and visible light, ultraviolet Raman detection has its advantages:

[0014] (1) Strong UV Raman signal: The scattering intensity of the Raman spectrum is proportional to the fourth power of the incident laser frequency. Therefore, compared with near-infrared and visible light, the wavelength of ultraviolet light is smaller and the signal intensity of ultraviolet Raman is greater. Under the same Raman signal conditions, ultraviolet Raman spectroscopy requires less laser power than visible light and near-infrared.

[0015] (2) Less affected by environmental interference: Due to interference from sunlight and other surrounding light sources, near-infrared and visible light Raman spectroscopy detection requires that the object be sampled and placed in a test box or performed at night. Due to the absorption and scattering of the atmospheric ozone layer, ground radiation in the day-blind ultraviolet band is almost extinct, and the ultraviolet component of daily light sources is very low. Therefore, day-blind ultraviolet laser Raman spectroscopy detection is less affected by the surrounding stray light, and Raman spectra can be remotely measured in the natural environment outdoors during the day.

[0016] (3) Easy to separate from fluorescence: Laser irradiation will produce Raman light and fluorescence. Usually, the Raman spectrum has a Raman shift of about 200 to 4000 cm-1, and the fluorescence spectrum is stronger at 280 to 370 nm. Using ultraviolet laser excitation with a shorter wavelength is expected to separate the Raman and fluorescence spectra in the spectrum, which is conducive to the analysis of Raman spectra. When the laser wavelength is below 250nm, the fluorescence spectrum is between the ultraviolet region and 400nm, and the Raman spectrum can be completely separated from the fluorescence spectrum.

[0017] Prior art 1:

[0018] Fluorescence spectroscopy has the advantages of high sensitivity, good selectivity and non-destructiveness. It is a simple and effective method for qualitative and quantitative analysis of target substances. Traditional fluorescence spectroscopy analysis can analyze the fluorescence spectral characteristics of the sample through the original spectrum obtained by the collection, and establish the relationship between the fluorescence spectral characteristics and the material characteristics through its spectral characteristics, so as to analyze and obtain the corresponding prediction model for subsequent research and application.

[0019] Disadvantages of prior art 1:

[0020] However, traditional fluorescence spectroscopy technology is difficult to use for detection objects with complex components or detection objects that do not have fluorescence effects. When the components of the detection object are complex, the original spectra obtained are intricate and difficult to obtain the useful information needed for the test by directly analyzing the original spectra of the samples or preprocessing them with simple algorithms, so as to build a predictive model. Detection objects that do not have fluorescence effects lack the most basic conditions for traditional fluorescence spectroscopy analysis, and it is impossible to further obtain the fluorescence spectra of the detection objects.

[0021] Prior art 2:

[0022] Visible Raman spectroscopy telemetry technology:

[0023] In 2020, Sandford et al. from the University of Hawaii used a compact, portable remote Raman system consisting of a 532nm (Nd:YAG) pulsed laser, a 3in diameter lens, a small spectrometer, and a miniature image-intensified charge-coupled device (mini-ICCD). The system was able to detect water (H2O), water ice (H2O-ice), carbon dioxide ice, hydrous minerals, organic matter, nitrates, and an amino acid from a distance of 122m under natural light conditions. This is also the compact remote Raman detection system with the farthest detection capability currently available. The development of this unique, compact, portable remote Raman system is suitable for a range of solar system exploration missions, including fixed landers for ocean worlds and lunar exploration, as they can clearly detect compounds indicative of life and the resources needed for further human exploration.

[0024] Disadvantages of the second prior art:

[0025] When visible light is used as the excitation light source for Raman, the Raman signal is weak and has high requirements on the environment, requiring a darkroom detection environment.

[0026] Existing technology three:

[0027] Near infrared close range:

[0028] Zhuoli Hanguang has developed a variety of Raman spectrometer products. Zhuoli Hanguang's handheld Raman spectrometer FinderEdge uses a near-infrared 785nm laser and can be used for on-site detection of drugs and precursor chemicals. The test sample needs to be made into liquid or powder and placed in a test bottle and placed on the test head for detection.

[0029] Disadvantages of the prior art three:

[0030] It can only measure the Raman spectrum of materials at close range, and the entire optical path is in a black box. It has high requirements on the detection environment, and the test samples need to be processed into liquid or powder in advance.

[0031] In view of this, the present invention is proposed. Summary of the invention

[0032] The purpose of the present invention is to provide a long-distance crop growth status detection system based on ultraviolet Raman to solve the above-mentioned technical problems existing in the prior art.

[0033] The objective of the present invention is achieved through the following technical solutions:

[0034] The ultraviolet Raman-based long-distance crop growth status detection system of the present invention comprises a laser, a signal transmission system, a spectrometer, a digital delay generator, an oscilloscope and a computer, wherein the signal transmission system mainly comprises a reflector, a dichroic film, a negative lens, a Cassegrain telescope, a lens, a pinhole aperture, a filter and an optical fiber;

[0035] The pulsed laser signal generated by the laser is transmitted through the signal transmission system, and is focused on the surface of the sample to be tested through the reflector, dichroic plate, negative lens, Cassegrain telescope and 500mm lens in sequence to generate Raman or fluorescence signals, which are then collected and transmitted to the spectrometer through a 100mm lens, a pinhole diaphragm, a filter and an optical fiber;

[0036] The spectrometer performs dispersion and spectroscopy on the received signal, converts the optical signal into an electrical signal, and transmits the electrical signal to an oscilloscope and a computer to obtain the Raman signal of the sample to be tested;

[0037] The digital delay generator performs timing control, generates a high-level signal, controls the laser to generate pulsed laser, and controls the signal receiving time of the echelle grating spectrometer by adjusting the delay time of the signal between different channels in the timing control;

[0038] The oscilloscope is used to observe the signals generated in the timing control so as to adjust the parameters of the timing control and realize the timing control of the system;

[0039] The entire system is operated and controlled by a computer, which further analyzes and processes the acquired spectral signals.

[0040] Compared with the prior art, the ultraviolet Raman-based long-distance crop growth status detection system provided by the present invention realizes coaxial light transmission and receiving paths by designing the optical path; solves the problem of controlling the collection time in ultraviolet light long-distance Raman detection; and realizes fluorescence detection technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 Schematic diagram of the overall system design of an embodiment of the present invention.

[0042] Figure 2 Schematic diagram of timing control according to an embodiment of the present invention.

[0043] Figure 3 Schematic diagram of Raman and fluorescence spectra (Laser Line is the laser emission source) according to an embodiment of the present invention.

[0044] Figure 4 Schematic diagram of an RC Cassegrain telescope according to an embodiment of the present invention.

[0045] Figure 5 1 is a comparison chart of Raman and fluorescence generation and duration according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, not all of the embodiments, which does not constitute a limitation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0047] First, the terms that may be used in this article are explained as follows:

[0048] The term “and / or” means that either or both of them can be realized at the same time. For example, X and / or Y means both “X” or “Y” and “X and Y”.

[0049] The terms "include", "comprises", "contains", "has" or other descriptions with similar semantics should be interpreted as non-exclusive inclusion. For example, including certain technical feature elements (such as raw materials, components, ingredients, carriers, dosage forms, materials, dimensions, parts, components, mechanisms, devices, steps, procedures, methods, reaction conditions, processing conditions, parameters, algorithms, signals, data, products or products, etc.) should be interpreted as including not only certain technical feature elements explicitly listed, but also other technical feature elements known in the art that are not explicitly listed.

[0050] The term "consisting of..." means excluding any technical feature elements not explicitly listed. If this term is used in a claim, it will make the claim closed, so that it does not contain technical feature elements other than the technical feature elements explicitly listed, except for the conventional impurities related to them. If this term only appears in a clause of a claim, it only limits the elements explicitly listed in the clause, and the elements recorded in other clauses are not excluded from the overall claim.

[0051] Unless otherwise specified or limited, the terms "installed", "connected", "connected", "fixed" and the like 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this article can be understood according to specific circumstances.

[0052] The orientation or position relationship indicated by terms such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", etc. are based on the orientation or position relationship shown in the drawings and are only for the convenience and simplification of description, and do not explicitly or implicitly indicate that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation of this document.

[0053] The contents not described in detail in the examples of the present invention belong to the prior art known to professionals in the field. If no specific conditions are specified in the examples of the present invention, the conditions are carried out according to the conventional conditions in the field or the conditions recommended by the manufacturer. If the manufacturer is not specified in the reagents or instruments used in the examples of the present invention, they are all conventional products that can be purchased commercially.

[0054] The ultraviolet Raman-based long-distance crop growth situation detection system of the present invention is characterized in that it includes a laser, a signal transmission system, a spectrometer, a digital delay generator, an oscilloscope and a computer, wherein the signal transmission system mainly includes a reflector, a dichroic plate, a negative lens, a Cassegrain telescope, a lens, a pinhole diaphragm, a filter, and an optical fiber;

[0055] The pulsed laser signal generated by the laser is transmitted through the signal transmission system, and is focused on the surface of the sample to be tested through the reflector, dichroic plate, negative lens, Cassegrain telescope and 500mm lens in sequence to generate Raman or fluorescence signals, which are then collected and transmitted to the spectrometer through a 100mm lens, a pinhole diaphragm, a filter and an optical fiber;

[0056] The spectrometer performs dispersion and spectroscopy on the received signal, converts the optical signal into an electrical signal, and transmits the electrical signal to an oscilloscope and a computer to obtain the Raman signal of the sample to be tested;

[0057] The digital delay generator performs timing control, generates a high-level signal, controls the laser to generate pulsed laser, and controls the signal receiving time of the echelle grating spectrometer by adjusting the delay time of the signal between different channels in the timing control;

[0058] The oscilloscope is used to observe the signals generated in the timing control so as to adjust the parameters of the timing control and realize the timing control of the system;

[0059] The entire system is operated and controlled by a computer, which further analyzes and processes the acquired spectral signals.

[0060] 2. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1, characterized in that the method for timing control of the digital delay generator comprises:

[0061] A digital delay generator is used to perform timing control on two independent devices, the laser and the spectrometer. On the one hand, it provides a timing signal for the generation of laser pulse laser, and on the other hand, it provides a suitable trigger signal for the spectrometer to receive Raman or fluorescence signals.

[0062] 3. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1 or 2 is characterized in that the laser sampling Nd:YAG laser is used to generate pulsed lasers with higher energy and power density, and the laser interacts with distant materials to produce inelastic reflection to generate Raman or fluorescence signals, wherein the Raman measurement laser wavelength is preferably 266nm or 355nm.

[0063] 4. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1 or 2, characterized in that the digital delay generator uses Stanford's DG645 digital delay generator for timing control.

[0064] 5. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1 or 2, characterized in that the spectrometer adopts a medium-step grating spectrometer.

[0065] In summary, the ultraviolet Raman-based long-distance crop growth status detection system of the embodiment of the present invention realizes coaxial light transmission and receiving paths by designing the optical path; solves the problem of controlling the acquisition time in ultraviolet light long-distance Raman detection; and realizes fluorescence detection technology.

[0066] In order to more clearly demonstrate the technical solution and technical effects provided by the present invention, the embodiments of the present invention are described in detail with specific embodiments below.

[0067] Example 1

[0068] like Figure 1 As shown:

[0069] 1. Overall system design plan;

[0070] It is mainly composed of Nd:YAG laser, signal transmission system, echelle spectrometer, digital delay generator, oscilloscope and computer. Among them:

[0071] Nd:YAG laser can generate pulsed laser with high energy and power density. The laser interacts with distant materials and produces Raman or fluorescence signals by inelastic reflection. The Raman measurement laser wavelength is preferably 266nm, because 266nm has higher requirements on laser equipment, and 355nm is also acceptable.

[0072] The signal transmission system mainly includes:

[0073] Reflectors, dichroic filters, negative lenses, Cassegrain telescopes, lenses, pinhole diaphragms, filters, and optical fibers. The signal transmission system transmits the pulsed laser signal generated by the laser and focuses it on the surface of the sample to be tested, generating Raman or fluorescence signals, which are then collected and transmitted to the spectrometer;

[0074] The spectrometer performs dispersion and spectroscopy on the received signal and converts the optical signal into an electrical signal to obtain the Raman signal of the sample to be tested. The integration time of the spectrometer used for the Raman signal must be in the nanosecond level.

[0075] The digital delay generator performs timing control, can generate high-level signals, control the laser to generate pulsed lasers, and can control the signal receiving time of the spectrometer by adjusting the delay time of signals between different channels in the timing control;

[0076] The oscilloscope is used to observe the signals generated in the timing control so as to adjust the parameters of the timing control and realize the timing control of the system.

[0077] The entire system is operated and controlled by a computer, which further analyzes and processes the spectral signals obtained by the spectrometer.

[0078] 2. Timing control scheme:

[0079] The DG645 digital delay generator from Stanford was used for timing control.

[0080] Timing control scheme such as Figure 2 As shown:

[0081] This system uses a digital delay generator to perform timing control on two independent devices, the laser and the spectrometer. On the one hand, it provides a timing signal for the generation of laser pulses, and on the other hand, it provides a suitable trigger signal for the spectrometer to receive Raman or fluorescence signals.

[0082] 3. Beneficial effects brought by the technical solution of the present invention:

[0083] 1) Strong UV Raman signal:

[0084] The relationship between the scattering intensity of Raman spectroscopy and the incident laser can be expressed by the following formula, where I s It represents the intensity of Raman scattered light, k is the proportionality coefficient, V is the volume of the sample acted on by the laser, and I0 represents the intensity of the incident light.

[0085] I s =kv 4 nV0

[0086] The scattering intensity of Raman spectroscopy is proportional to the fourth power of the incident laser frequency. Therefore, compared with near-infrared and visible light, the wavelength of ultraviolet light is smaller and the signal intensity of ultraviolet Raman is greater. Under the same Raman signal conditions, ultraviolet Raman spectroscopy requires less laser power than visible light and near-infrared.

[0087] 2) Less affected by environmental interference:

[0088] Due to interference from sunlight and other surrounding light sources, near-infrared and visible light Raman spectroscopy detection requires the object to be sampled and placed in a test box or performed at night. Due to the absorption and scattering of the atmospheric ozone layer, ground radiation in the day-blind ultraviolet band is almost extinct, and the ultraviolet component of daily light sources is very low. Therefore, day-blind ultraviolet laser Raman spectroscopy detection is little affected by the surrounding stray light, and the Raman spectrum can be remotely measured in the natural environment outdoors during the day.

[0089] 3) Easy to separate from fluorescence:

[0090] Laser irradiation will produce Raman light and fluorescence. Usually, the Raman spectrum has a Raman shift of about 200 to 4000 cm-1, and the fluorescence spectrum is stronger at 280 to 370 nm. The use of ultraviolet laser excitation with a shorter wavelength is expected to separate the Raman and fluorescence spectra in the spectrum, which is beneficial to the analysis of Raman spectra. When the laser wavelength is below 250nm, the fluorescence spectrum is between the ultraviolet region and 400nm, and the Raman spectrum can be completely separated from the fluorescence spectrum.

[0091] like Figure 3 The figure shows a schematic diagram of Raman and fluorescence spectra (Laser Line is the laser emission source).

[0092] 4) Long-distance detection:

[0093] Different from the existing short-range detection of 1-2 cm, the present invention will realize long-range Raman detection of 3m, 6m, and 10m.

[0094] In the design of the light-receiving and light-emitting circuit, the present invention adopts a two-piece RC Cassegrain telescope. Figure 4 As shown in the figure, the telescope system is a reflective structure, and both the primary mirror and the secondary mirror are curved reflectors. Compared with the traditional Cassegrain telescope, this system has a wider field of view and can better correct coma, thereby improving the imaging quality. The focal length of the telescope system is 2400mm. In order to adjust the measurement distance of the remote LIBS detection system, a position-adjustable negative lens is added behind the primary mirror. The combination of this lens and the RC telescope can adjust the focal length of the system. By adjusting the distance between the negative lens and the RC Cassegrain telescope, the laser can be focused on samples to be tested at different distances, and the focal length can be continuously adjusted, so that LIBS signals can be measured for samples to be tested at different distances. In addition, a position-adjustable focusing mirror is equipped in front of the secondary mirror, which can adjust the focal length of the system, focus the laser on the sample to be tested, and collect the Raman signal generated by the excitation.

[0095] 5) Detection time:

[0096] Raman spectroscopy is produced due to inelastic collisions. According to relevant information, this process occurs tens of picoseconds after the laser irradiates the material.

[0097] When the incident light from the laser source is scattered by molecules, the intensity of the fluorescence spectrum generated is 10-3 of the incident light intensity, while the intensity of the scattered Raman spectrum is about 10-9 times the incident light intensity. However, in terms of time, the time from when the material is irradiated by the laser to when the induced spectrum appears is called the spectrum response time. The response time of the fluorescence spectrum is 10-11s and the response time of the Raman spectrum is 10-13s.

[0098] Comparison of Raman and fluorescence generation and duration Figure 5 shown.

[0099] The time scale effect eliminates the influence of fluorescence background. Raman scattering and fluorescence background signals have different response characteristics on the time scale. Raman spectroscopy occurs at the moment when the laser acts on the material, which is generally less than 2ns, while the fluorescence generation time is as long as 50ns. Therefore, the Raman scattering spectrum and fluorescence spectrum signals can be effectively separated by precise time series acquisition [41,42]. The use of time-gated technology can effectively reduce fluorescence interference during Raman detection.

[0100] Taking into account the flight time of the laser, the detection start time is calculated, and the appropriate signal reception time and exposure integration time are selected.

[0101] 6) Combination of Raman technology and fluorescence technology:

[0102] Fluorescence technology only works well for objects with fluorescence effects. For crops without fluorescence effects or with more complex compositions, Raman technology can be used as a supplement to achieve information complementarity between Raman and fluorescence technology in crop detection, thus broadening the application scenarios.

[0103] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the present invention 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. The information disclosed in the background technology section of this article is only intended to deepen the understanding of the overall background technology of the present invention, and should not be regarded as an admission or in any form that the information constitutes prior art known to those skilled in the art.

Claims

1. A long-distance crop growth status detection system based on ultraviolet Raman, characterized in that: It includes a laser, a signal transmission system, a spectrometer, a digital delay generator, an oscilloscope and a computer, wherein the signal transmission system mainly includes a reflector, a dichroic plate, a negative lens, a Cassegrain telescope, a lens, a pinhole diaphragm, a filter and an optical fiber; The pulsed laser signal generated by the laser is transmitted through the signal transmission system, and is focused on the surface of the sample to be tested through the reflector, dichroic plate, negative lens, Cassegrain telescope and 500mm lens in sequence to generate Raman or fluorescence signals, which are then collected and transmitted to the spectrometer through a 100mm lens, a pinhole diaphragm, a filter and an optical fiber; The spectrometer performs dispersion and spectroscopy on the received signal, converts the optical signal into an electrical signal, and transmits the electrical signal to an oscilloscope and a computer to obtain the Raman signal of the sample to be tested; The digital delay generator performs timing control, generates a high-level signal, controls the laser to generate pulsed laser, and controls the signal receiving time of the echelle grating spectrometer by adjusting the delay time of the signal between different channels in the timing control; The oscilloscope is used to observe the signals generated in the timing control so as to adjust the parameters of the timing control and realize the timing control of the system; The entire system is operated and controlled by a computer, which further analyzes and processes the acquired spectral signals.

2. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1, characterized in that: The method for the digital delay generator to perform timing control comprises: A digital delay generator is used to perform timing control on two independent devices, the laser and the spectrometer. On the one hand, it provides a timing signal for the generation of laser pulse laser, and on the other hand, it provides a suitable trigger signal for the spectrometer to receive Raman or fluorescence signals.

3. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1 or 2, characterized in that: The laser sampling Nd:YAG laser is used to generate pulsed laser with higher energy and power density. The laser interacts with distant matter and generates Raman or fluorescence signals by inelastic reflection. The Raman measurement laser wavelength is preferably 266nm or 355nm.

4. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1 or 2, characterized in that: The digital delay generator uses Stanford's DG645 digital delay generator for timing control.

5. The ultraviolet Raman-based long-distance crop growth status detection system according to claim 1 or 2, characterized in that: The spectrometer adopts an echelle grating spectrometer.

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