Radar system for simultaneously detecting visibility and wind field

Abstract

The utility model relates to a radar system for simultaneously detecting visibility and a wind field, and the system comprises a laser emission unit which is used for emitting laser with a first wavelength and laser with a second wavelength to the atmosphere; the optical receiving unit is used for receiving a first wavelength laser echo signal and a second wavelength laser echo signal which are scattered by the atmosphere and contain atmosphere information; the detector is used for respectively converting the first wavelength laser echo signal and the second wavelength laser echo signal received by the optical receiving unit into a first electric signal and a second electric signal; the data acquisition module is used for acquiring a first electric signal and a second electric signal of the detector; and the upper computer is connected with the laser emission unit and the data acquisition module. According to the utility model, two atmospheric elements of visibility and an atmospheric wind field can be monitored simultaneously and synchronously.

Description

Technical Field

[0001] This utility model relates to the field of lidar technology, and in particular to a radar system for simultaneously detecting visibility and wind field. Background Technology

[0002] Visibility conditions and wind field information have always been closely related to flight activities, road traffic, and port / shipping. Low visibility, fog, sea fog, and low-level wind shear can easily trigger numerous sea, land, and air traffic accidents, causing severe casualties, property damage, and environmental pollution. Therefore, developing an atmospheric visibility monitoring and early warning system project is crucial to overcome the limitations of existing visibility meters and traffic meteorological stations. This system will establish continuous, dynamic, point-to-line, area-to-area, and network-based synchronous monitoring of visibility and wind field factors, improving and enhancing the capabilities of existing traffic meteorology, environmental meteorology, and military meteorological services, as well as the accuracy of automatic forecasts under complex weather conditions. This is of great significance for disaster prevention and mitigation.

[0003] Currently, both domestically and internationally, technologies such as visibility meters, nautical charts, anemometers, and satellites are mainly used to monitor traffic "killers" such as low visibility, fog, wind shear, and low-altitude jet streams. However, these technologies are insufficient to meet the monitoring and early warning needs of large-scale horizontal or slant-path low visibility, the path and area affected by fog patches and sea fog, the formation and dissipation process of fog patches and sea fog, low-altitude wind shear, and airport wakes. Utility Model Content

[0004] Based on this, the purpose of this utility model is to provide a radar system for simultaneous detection of visibility and wind field, so as to realize the simultaneous and synchronous monitoring of two atmospheric elements, visibility and atmospheric wind field.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] This utility model provides a radar system for simultaneously detecting visibility and wind field, which includes:

[0007] A laser emitting unit, which is used to emit a first wavelength laser and a second wavelength laser into the atmosphere;

[0008] An optical receiving unit is used to receive a first-wavelength laser echo signal and a second-wavelength laser echo signal containing atmospheric information, which are scattered by the atmosphere.

[0009] The detector is used to convert the first wavelength laser echo signal and the second wavelength laser echo signal received by the optical receiving unit into a first electrical signal and a second electrical signal, respectively.

[0010] The data acquisition module is used to acquire the first electrical signal and the second electrical signal of the detector; and

[0011] The host computer is connected to the laser emitting unit and the data acquisition module.

[0012] This invention simultaneously emits a first-wavelength laser and a second-wavelength laser into the atmosphere and receives the first-wavelength laser echo signal and the second-wavelength laser echo signal containing atmospheric information scattered by the atmosphere. The atmospheric wind speed and direction are obtained by inversion based on the first-wavelength laser echo signal, and the visibility is obtained by inversion based on the second-wavelength laser echo signal, thereby realizing the simultaneous and synchronous monitoring of two atmospheric elements: visibility and atmospheric wind field.

[0013] As a further improvement of the above-mentioned solution of this utility model, the laser emitting unit includes a first laser and a first collimator. The first laser is used to emit a first wavelength laser and communicate with the host computer. The first wavelength laser is collimated by the first collimator and then emitted into the atmosphere.

[0014] As a further improvement of the above-mentioned solution of this utility model, the laser emitting unit further includes a second laser, a first reflector, a second reflector and an electric adjustment frame. The first reflector and the second reflector are arranged opposite to each other. The second reflector is mounted on the electric adjustment frame and the electric adjustment frame is controlled and driven by the host computer to rotate the second reflector. The second laser is used to emit a second wavelength laser and is connected to the host computer for communication. The second wavelength laser passes through the first reflector and the second reflector in sequence and is emitted into the atmosphere.

[0015] As a further improvement to the above-mentioned solution of this utility model, the first wavelength laser is a 1550nm laser and the second wavelength laser is a 1064nm laser.

[0016] As a further improvement of the above-mentioned solution of this utility model, the optical receiving unit includes a dichroic filter, a secondary mirror, and a primary mirror arranged in sequence; the first wavelength laser echo signal passes through the primary mirror and the secondary mirror in sequence and reaches the dichroic filter, is reflected by the dichroic filter to the first collimator, and then returns to the first laser by the first collimator; the first wavelength laser emitted by the first laser is collimated by the first collimator and reaches the dichroic filter, is reflected by the dichroic filter to the secondary mirror, and is then expanded by the secondary mirror and the primary mirror before being emitted into the atmosphere.

[0017] As a further improvement to the above-mentioned solution of this utility model, the detector includes a photoelectric balance detector, which is communicatively connected to the host computer; the first laser transmits a first wavelength laser echo signal to the photoelectric balance detector, which converts the first wavelength laser echo signal into a first electrical signal.

[0018] As a further improvement to the above-mentioned solution of this utility model, the optical receiving unit further includes an eyepiece and a second collimator. The second collimator, eyepiece, dichroic filter, secondary mirror, and primary mirror are arranged in sequence. The second wavelength laser echo signal passes through the primary mirror and secondary mirror in sequence, then passes through the dichroic filter to reach the eyepiece, and is received by the second collimator after being collimated by the eyepiece.

[0019] As a further improvement of the above-mentioned solution of this utility model, the detector includes a single-photon detector, which is communicatively connected to the host computer; the single-photon detector is connected to a second collimator through an optical fiber, the second collimator couples the received second-wavelength laser echo signal to the optical fiber and transmits it to the single-photon detector, and the single-photon detector converts the second-wavelength laser echo signal into a second electrical signal.

[0020] As a further improvement to the above-mentioned solution of this utility model, the diameter of the primary mirror is 110mm and the focal length is 260mm; the diameter of the secondary mirror is 12.5mm and the focal length is -10mm.

[0021] As a further improvement to the above-mentioned solution of this utility model, the dichroic filter is used to reflect light beams in the 1180nm-1550nm band and transmit light beams in the 400nm-1180nm band.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This utility model synchronously emits a first wavelength laser and a second wavelength laser into the atmosphere and receives the first wavelength laser echo signal and the second wavelength laser echo signal containing atmospheric information scattered by the atmosphere. The atmospheric wind speed and wind direction are obtained by inversion based on the first wavelength laser echo signal, and the visibility is obtained by inversion based on the second wavelength laser echo signal, thereby realizing the simultaneous and synchronous monitoring of two atmospheric elements: visibility and atmospheric wind field.

[0024] 2. This utility model uses only one primary mirror to receive echo signal light from two wavelengths. By setting a dichroic filter, the first wavelength laser echo signal is reflected and the second wavelength laser echo signal is transmitted. The receiving channels of the first wavelength laser echo signal and the second wavelength laser echo signal do not interfere with each other.

[0025] 3. In this utility model, the first laser, the first collimator, the dichroic separator, the secondary mirror, and the primary mirror constitute a wind field monitoring system, which adopts a coaxial transceiver structure; while the primary mirror, the secondary mirror, the dichroic separator, the eyepiece, the second collimator, the optical fiber, and the single-photon detector constitute a visibility receiving system. The second reflector is driven to rotate by an electric adjustment frame controlled by a host computer, thereby determining the optimal emission direction of the second wavelength laser. The stability of the optical path of the entire system is ensured by the automatic collimation method of the light spot. Attached Figure Description

[0026] Figure 1 An optical path diagram of a radar system for simultaneous detection of visibility and wind field proposed in this embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the structure of a radar system for simultaneously detecting visibility and wind field, as proposed in an embodiment of this utility model.

[0028] Reference numerals in the attached figures: 1. Radar main body; 11. First laser; 12. First collimator; 13. Second laser; 14. First reflector; 15. Second reflector; 16. Electric adjustment frame; 17. Dichroic separator; 18. Secondary mirror; 19. Primary mirror; 110. Eyepiece; 111. Second collimator; 112. Optical fiber; 113. Single-photon detector; 114. Photoelectric balance detector; 2. Host computer; 3. Pan-tilt unit. Detailed Implementation

[0029] To facilitate understanding of this invention, a more comprehensive description of the invention will be provided below with reference to specific embodiments. However, this invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to enable a more thorough and complete understanding of the disclosure of this invention.

[0030] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0031] Reference Figure 1 , Figure 2 This embodiment proposes a radar system for simultaneously detecting visibility and wind field, including a radar body 1, a data acquisition module, and a host computer 2, and may also include a fork-arm gimbal 3. The data acquisition module uses a data acquisition card, which is integrated into the host computer 2.

[0032] The radar body 1 includes a laser emitting unit, an optical receiving unit, and a detector. The laser emitting unit is used to emit a first-wavelength laser and a second-wavelength laser into the atmosphere; the optical receiving unit is used to receive the first-wavelength laser echo signal and the second-wavelength laser echo signal containing atmospheric information scattered by the atmosphere; the detector is used to convert the first-wavelength laser echo signal and the second-wavelength laser echo signal received by the optical receiving unit into a first electrical signal and a second electrical signal, respectively.

[0033] In this embodiment, the laser emitting unit includes a first laser 11, a first collimator 12, a second laser 13, a first reflector 14, a second reflector 15, and an electric adjustment frame 16.

[0034] The first laser 11 is communicatively connected to the host computer 2, and is controlled by the host computer 2 to emit a first wavelength laser. In this embodiment, the laser wavelength emitted by the first laser 11 is 1550nm. The first collimator 12 is used to collimate the 1550nm laser emitted by the first laser 11, and the collimated laser wavelength is 4.6mm.

[0035] The second laser 13 is communicatively connected to the host computer 2, and is controlled by the host computer 2 to emit a second wavelength laser. In this embodiment, the laser wavelength emitted by the second laser 13 is 1064nm. The first reflector 14 and the second reflector 15 are arranged opposite to each other, and the second reflector 15 is mounted on the electric adjustment frame 16. The 1064nm laser passes through the first reflector 14 and the second reflector 15 in sequence before being emitted into the atmosphere. In this embodiment, the electric adjustment frame 16 is controlled by the host computer 2, which drives the second reflector 15 to rotate, thereby changing the emission direction of the second wavelength laser. In this embodiment, both the first reflector 14 and the second reflector 15 use Thorlabs BB2-E03, with a reflectivity greater than 99%. In this embodiment, the frequency of the second laser 13 is 3000Hz, the single pulse energy is 500uJ, and the beam-expanding spot diameter is 10mm.

[0036] In this embodiment, the optical receiving unit includes a dichroic filter 17, a secondary mirror 18, a primary mirror 19, an eyepiece 110, and a second collimator 111. The detector includes a photoelectric balanced detector 114 and a single-photon detector 113, which are communicatively connected to the data acquisition card. The primary mirror 19, secondary mirror 18, dichroic filter 17, eyepiece 110, and second collimator 111 are arranged sequentially, and the second collimator 111 is connected to the single-photon detector 113 via an optical fiber 112.

[0037] In this embodiment, the primary mirror 19 is a convex lens with a diameter of 110 mm and a focal length of 260 mm; the secondary mirror 18 is a concave lens with a diameter of 12.5 mm and a focal length of -10 mm; the primary mirror 19 and the secondary mirror 18 together form a telescope. The dichroic separator 17 is positioned at 45° relative to the optical axis of the telescope, reflecting light beams in the 1180 nm-1550 nm band and transmitting light beams in the 400 nm-1180 nm band. In this embodiment, the eyepiece 110 has a diameter of 1 inch and a focal length of 40 mm.

[0038] The primary mirror 19, secondary mirror 18, and dichroic separator 17 form the first receiving channel. The echo signal of the 1550nm laser scattered by the atmosphere passes through the primary mirror 19 and secondary mirror 18 and reaches the dichroic separator 17. It is reflected by the dichroic separator 17 to the first collimator 12, and then returned by the first collimator 12 to the first laser 11. The first laser 11 is equipped with a circulator to distinguish between reflected and received signal light. The first laser 11 transmits the 1550nm laser echo signal to the photoelectric balance detector 114. The photoelectric balance detector 114 converts the first wavelength laser echo signal into a first electrical signal. The host computer 2 controls the data acquisition card to acquire the first electrical signal output by the photoelectric balance detector 114 and obtains the wind field (including atmospheric wind speed and wind direction) based on the first electrical signal. In this embodiment, wind field measurement adopts the coherent detection principle in existing technology. A 1550nm frequency-stabilized laser is used as the illumination beam. The Doppler frequency shift of the particles is obtained by mixing the 1550nm laser echo signal reflected back by aerosol particles through a coherent detection system. The velocity and direction of aerosol particles in the direction of 1550nm laser emission are calculated, i.e., radial wind speed and wind direction. By switching the emission direction of the 1550nm frequency-stabilized laser to point to the east, west, south, and north directions respectively, the radial wind speed and wind direction in the four directions can be obtained. The horizontal wind speed and wind direction, and the vertical wind speed and wind direction are derived from the four radial wind speed and wind direction. The wind speed and wind direction information corresponding to each height are obtained according to the time distance gate.

[0039] In addition, the secondary mirror 18 and the primary mirror 19 form a beam expanding system, which can expand the 1550nm laser beam by 26 times. The 1550nm laser emitted by the first laser 11 is collimated by the first collimator 12, reflected by the dichroic dichroic filter 17, and then expanded by the secondary mirror 18 and the primary mirror 19 before being emitted into the atmosphere.

[0040] The primary mirror 19, secondary mirror 18, dichroic separator 17, eyepiece 110, and second collimator 111 form the second receiving channel. The primary mirror 19 and secondary mirror 18 receive the Mie scattering echo signal from atmospheric aerosols. Unlike the first receiving channel, due to wavelength chromatic aberration, the echo signal of the 1064nm laser converges. The eyepiece 110 collimates the 1064nm laser echo signal, which is then received by the second collimator 111 and coupled to the optical fiber 112 for transmission to the single-photon detector 113. The single-photon detector 113 converts the second-wavelength laser echo signal into a second electrical signal. The host computer 2 controls the data acquisition card to acquire the second electrical signal output by the single-photon detector 113 and retrieves the visibility based on the second electrical signal. In this embodiment, the atmospheric extinction coefficient is obtained using the known Fermald method. αMeteorological optical range (MOR) refers to the distance required for the luminous flux of a parallel beam of light emitted by an incandescent lamp at a color temperature of 2700K to decrease to 5% of its original value after absorption and scattering by the atmosphere. MOR is the physical definition of visibility. In practical applications, considering the obstruction of lidar, the lidar detects the corresponding quantile of visibility data within a single period. This data is used as the dominant visibility measurement by the lidar. Using Koschmieder's law (defined at a contrast threshold of 5% and a wavelength of 550nm), the relationship between visibility and extinction coefficient is as follows: V = -ln(0.05) / α = 3 / α ,in V For meteorological visibility, α Extinction coefficient, visibility V Based on the extinction coefficient α When the laser wavelength λ used is not equal to 550nm, it is necessary to determine the extinction coefficient measured by the lidar. α After wavelength correction and empirical adjustments, the visibility calculation formula is as follows:

[0041]

[0042] in, q Correction coefficient ，q The value of is related to the type of aerosol.

[0043] The electric adjustment frame 16 is controlled by the host computer 2 to drive the second reflector 15 to rotate, thereby changing the emission direction of the second wavelength laser. This allows the second wavelength laser beam to scan systematically, maximizing the intensity of the second wavelength laser echo signal scattered by the high-altitude atmosphere. This determines the optimal direction of the emitted beam, ensuring that the laser radar's transmitting and receiving optical axes are parallel. The host computer 2 controls the electric adjustment frame 16 to scan in both east-west and north-south directions. Simultaneously, the single-photon detector 113 and data acquisition card collect the number of photons in the echo signal. The data acquisition card and the host computer 2 are connected via network communication, and the echo signal intensity within a specified altitude range is fed back to the host computer 2. At the specified altitude, when the emitted beam fully enters the field of view of the receiving telescope and the echo signal reaches its maximum, the host computer 2 controls the electric adjustment frame 16 to drive the second reflector to the optimal position based on the maximum echo signal intensity.

[0044] In this embodiment, combined with Figure 2 The radar body 1 is mounted on the fork-arm gimbal 3. By using the fork-arm gimbal 3, it can realize 3D scanning detection function (DBS, VAD, PPI, RHI and CAPPI) and can switch between multiple working modes such as vertical detection and horizontal detection.

[0045] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0046] The embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A radar system for simultaneously detecting visibility and wind field, characterized in that, It includes: A laser emitting unit, which is used to emit a first wavelength laser and a second wavelength laser into the atmosphere; An optical receiving unit is used to receive a first-wavelength laser echo signal and a second-wavelength laser echo signal containing atmospheric information, which are scattered by the atmosphere. The detector is used to convert the first wavelength laser echo signal and the second wavelength laser echo signal received by the optical receiving unit into a first electrical signal and a second electrical signal, respectively. The data acquisition module is used to acquire the first electrical signal and the second electrical signal of the detector; and The host computer is connected to the laser emitting unit and the data acquisition module.

2. The radar system for simultaneous detection of visibility and wind field according to claim 1, characterized in that, The laser emitting unit includes a first laser and a first collimator. The first laser is used to emit a first wavelength laser and communicate with the host computer. The first wavelength laser is collimated by the first collimator and then emitted into the atmosphere.

3. The radar system for simultaneous detection of visibility and wind field according to claim 1, characterized in that, The laser emitting unit also includes a second laser, a first reflector, a second reflector, and an electric adjustment frame. The first reflector and the second reflector are arranged opposite to each other. The second reflector is mounted on the electric adjustment frame, and the electric adjustment frame is controlled and driven by the host computer to rotate the second reflector. The second laser is used to emit a second wavelength laser and is connected to the host computer for communication. The second wavelength laser passes through the first reflector and the second reflector in sequence before being emitted into the atmosphere.

4. The radar system for simultaneous detection of visibility and wind field according to claim 1, characterized in that, The first wavelength laser is a 1550nm laser, and the second wavelength laser is a 1064nm laser.

5. The radar system for simultaneous detection of visibility and wind field according to claim 2, characterized in that, The optical receiving unit includes a dichroic filter, a secondary mirror, and a primary mirror arranged in sequence. The first wavelength laser echo signal passes through the primary mirror and the secondary mirror in sequence and reaches the dichroic filter. It is reflected by the dichroic filter to the first collimator and then returns to the first laser. The first wavelength laser emitted by the first laser is collimated by the first collimator and reaches the dichroic filter. It is reflected by the dichroic filter to the secondary mirror and then expanded by the secondary mirror and the primary mirror before being emitted into the atmosphere.

6. The radar system for simultaneous detection of visibility and wind field according to claim 5, characterized in that, The detector includes a photoelectric balance detector, which is connected to the data acquisition module; the first laser transmits a first wavelength laser echo signal to the photoelectric balance detector, which converts the first wavelength laser echo signal into a first electrical signal.

7. The radar system for simultaneous detection of visibility and wind field according to claim 5, characterized in that, The optical receiving unit further includes an eyepiece and a second collimator. The second collimator, eyepiece, dichroic filter, secondary mirror, and primary mirror are arranged in sequence. The second wavelength laser echo signal passes through the primary mirror and secondary mirror in sequence, then passes through the dichroic filter to reach the eyepiece. After being collimated by the eyepiece, it is received by the second collimator.

8. The radar system for simultaneous detection of visibility and wind field according to claim 7, characterized in that, The detector includes a single-photon detector, which is connected to the data acquisition module. The single-photon detector is connected to a second collimator via an optical fiber. The second collimator couples the received second-wavelength laser echo signal to the optical fiber and transmits it to the single-photon detector. The single-photon detector converts the second-wavelength laser echo signal into a second electrical signal.

9. The radar system for simultaneous detection of visibility and wind field according to claim 3, characterized in that, The primary mirror has a diameter of 110mm and a focal length of 260mm; the secondary mirror has a diameter of 12.5mm and a focal length of -10mm.

10. The radar system for simultaneous detection of visibility and wind field according to claim 3, characterized in that, The dichroic filter is used to reflect light beams in the 1180nm-1550nm band and transmit light beams in the 400nm-1180nm band.

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