A coherent pulse laser radar

Abstract

The coherent pulse laser radar involved in the present invention comprises: a seed signal generating device, a signal transmitting and receiving module, a local oscillator signal modulating device and a frequency mixing device. The seed signal generating device is used to generate a narrow linewidth seed laser signal. The signal transmitting and receiving module is used to modulate and amplify the narrow linewidth seed laser signal and transmit it, and to receive the end face return light signal reflected by the measured target. The local oscillator signal modulating device is used to pulse modulate the narrow linewidth seed laser signal to obtain a modulated signal. The frequency mixing device is used to perform beat frequency processing on the end face return light signal and the modulated signal to obtain a beat signal. The technical solution adds a local oscillator signal modulating device to the local oscillator optical path, so as to pulse modulate the narrow linewidth seed laser signal to obtain a modulated signal, and then when performing beat frequency processing with the end face return light signal, the pulse distortion and intensity distortion after the beat frequency processing are reduced, so as to finally restore the end face information as much as possible.

Description

Technical Field

[0001] The invention belongs to the technical field of radars, and in particular relates to a coherent pulse laser radar. Background Art

[0002] When coherent pulse laser radar is detecting, there will be an inherent detection blind spot. Theoretically, there is a detection blind spot of pulse width * speed of light / 2m. The inventor of this application found in the process of inventing this application that the existing coherent pulse laser radar cannot modulate the pulse width small enough due to all the rising and falling edge limitations of the modulation device itself. In view of the objectively existing pulse width limitation, when emitting coherent pulses, the return pulse and intensity distortion will occur at the position where the pulse contacts the output end face and the optical antenna. After coherent processing with the local oscillator signal, pulse broadening will occur in the time domain signal. The actual blind spot is about 1.5 times the pulse width * speed of light / 2m, and the abnormal spectrum will be analyzed at the same time. Summary of the invention

[0003] In view of this, an object of the present invention is to provide a coherent pulse laser radar to effectively improve the above-mentioned problems.

[0004] The embodiment of the present invention is achieved as follows:

[0005] An embodiment of the present invention provides a coherent pulse laser radar, comprising: a seed signal generating device, a signal transmitting and receiving module, a local oscillator signal modulating device and a frequency mixing device; the seed signal generating device is used to generate a narrow linewidth seed laser signal; the signal transmitting and receiving module is connected to the seed signal generating device, and the signal transmitting and receiving module is used to modulate and amplify the narrow linewidth seed laser signal and transmit it, and receive the end face return light signal reflected by the measured target; the local oscillator signal modulating device is connected to the seed signal generating device, and the local oscillator signal modulating device is used to pulse modulate the narrow linewidth seed laser signal to obtain a modulated signal; the frequency mixing device is respectively connected to the local oscillator signal modulating device and the signal transmitting and receiving module, and the frequency mixing device is used to perform beat frequency processing on the end face return light signal and the modulated signal to obtain a beat signal.

[0006] In an optional embodiment of the present invention, the coherent pulse laser radar also includes: a photoelectric conversion device, the mixing device is connected to the photoelectric conversion device, and the photoelectric conversion device is used to convert the beat signal into an electrical signal output.

[0007] In an optional embodiment of the present invention, the coherent pulse laser radar also includes: a signal processing device, the photoelectric conversion device is connected to the signal processing device, and the signal processing device is used to parse the required detection information from the electrical signal, wherein the detection information includes: distance information from the target to be measured and movement frequency information of the target to be measured.

[0008] In an optional embodiment of the present invention, the signal transmitting and receiving module includes: a transmitting signal modulation device, an amplifier, a signal distinguishing device and a signal transmitting and receiving device; the seed signal generating device, the transmitting signal modulation device, the amplifier, the signal distinguishing device and the signal transmitting and receiving device are connected in sequence, and the signal distinguishing device is also connected to the mixing device; the transmitting signal modulation device is used to modulate the amplitude and frequency of the narrow linewidth seed laser signal; the amplifier is used to amplify the modulated narrow linewidth seed laser signal; the signal distinguishing device is used to distinguish the amplified narrow linewidth seed laser signal and the end face return light signal received by the signal transmitting and receiving device; the signal transmitting and receiving device is used to transmit the amplified narrow linewidth seed laser signal, and receive the end face return light signal reflected by the target to be measured.

[0009] In an optional embodiment of the present invention, the local oscillation signal modulation device is an electro-optical switch, a magneto-optical switch or an acousto-optical switch.

[0010] In an optional embodiment of the present invention, the local oscillator signal modulation device is a modulator.

[0011] In an optional embodiment of the present invention, the signal distinguishing device includes an optical ring device.

[0012] In an optional embodiment of the present invention, the signal transmitting and receiving device includes a telescope device.

[0013] In an optional embodiment of the present invention, the transmission signal modulation device is an acousto-optic modulator.

[0014] The coherent pulse laser radar provided by the embodiment of the present invention includes: a seed signal generating device, a signal transmitting and receiving module, a local oscillator signal modulating device and a frequency mixing device. The seed signal generating device is connected to the signal transmitting and receiving module and the local oscillator signal modulating device respectively, and the frequency mixing device is connected to the signal transmitting and receiving module and the local oscillator signal modulating device respectively. The seed signal generating device is used to generate a narrow line width seed laser signal. The signal transmitting and receiving module is used to modulate and amplify the narrow line width seed laser signal and transmit it out, and receive the end face return light signal reflected by the measured target. The local oscillator signal modulating device is used to pulse modulate the narrow line width seed laser signal to obtain a modulated signal. The frequency mixing device is used to perform beat frequency processing on the end face return light signal and the modulated signal to obtain a beat signal. The technical solution adds a local oscillator signal modulating device to the local oscillator optical path, so as to pulse modulate the narrow line width seed laser signal to obtain a modulated signal, and then when performing beat frequency processing with the end face return light signal, the pulse distortion and intensity distortion after the beat frequency processing are reduced, so as to finally restore the end face information as much as possible, reduce the end face interference, and reduce the distortion blind area at the same time.

[0015] 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

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. As shown in the accompanying drawings, the above and other purposes, features and advantages of the present invention will be clearer. The same reference numerals in all the drawings indicate the same parts. The drawings are not deliberately scaled to the actual size, and the focus is on illustrating the main purpose of the present invention.

[0017] Figure 1 A schematic structural diagram of an existing coherent pulse laser radar is shown.

[0018] Figure 2 A schematic structural diagram of a coherent pulse laser radar provided in one embodiment of the present invention is shown.

[0019] Figure 3 The embodiment of the present invention provides Figure 2 Schematic diagram of the structure of the signal transmitting and receiving module.

[0020] Figure 4A schematic structural diagram of a coherent pulse laser radar provided in yet another embodiment of the present invention is shown.

[0021] Icons: 100 - coherent pulse laser radar; 11 - seed signal generating device; 20 - signal transmitting and receiving module; 12 - transmitting signal modulating device; 13 - amplifier; 14 - signal distinguishing device; 15 - signal transmitting and receiving device; 16 - local oscillator signal modulating device; 17 - frequency mixing device; 18 - photoelectric conversion device; 19 - signal processing device. DETAILED DESCRIPTION

[0022] 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, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments 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 scope of protection of the present invention.

[0024] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0025] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "inside", "outside", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or is the orientation or positional relationship in which the invented product is usually placed when in use. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish descriptions, and cannot be understood as indicating or implying relative importance. Furthermore, the term "and / or" in this application is merely a description of an associated relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone.

[0026] 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 mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected 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.

[0027] See also Figure 1 , Figure 1 The structure diagram of the existing coherent pulse laser radar. In the existing coherent pulse laser radar measurement technology, the laser signal generated by the coherent light source 1 is adjusted by the modulation device 2, then amplified by the amplifier 3, and then transmitted and detected by the ring device 4 and the optical antenna 5, and the returned echo signal is received by the optical antenna 5. After passing through the ring device 4, the echo signal is coherently processed with the local oscillator light signal at the device 7, and then converted into an electrical signal by the photoelectric detection device 8 and finally processed by the data processing device 9. The inventor of the present application found in the process of inventing the present application that: because of the rising and falling edge limitations of the modulation device 2 itself, the pulse width cannot be modulated small enough. In view of the objective pulse width limitation, when the coherent pulse is emitted, the pulse will be distorted in the echo pulse and intensity at the position where the output end face and the optical antenna 5 contact. After coherent processing with the local oscillator signal, pulse broadening will occur in the time domain signal. The actual blind area is about 1.5 times the pulse width * light speed / 2m, and the abnormal spectrum will be analyzed at the same time.

[0028] It should be noted that the defects existing in the above solutions are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed in the embodiments of the present invention for the above problems below should all be the contributions made by the inventor to the present invention during the process of the present invention.

[0029] In view of this, the embodiment of the present application provides a coherent pulse laser radar 100, such as Figure 2 The coherent pulse laser radar 100 comprises: a seed signal generating device 11, a signal transmitting and receiving module 20, a local oscillator signal modulating device 16 and a frequency mixing device 17. The seed signal generating device 11 is connected to the signal transmitting and receiving module 20 and the local oscillator signal modulating device 16 respectively, and the frequency mixing device 17 is connected to the signal transmitting and receiving module 20 and the local oscillator signal modulating device 16 respectively.

[0030] Among them, the seed signal generating device 11 is used to generate a narrow linewidth seed laser signal. On the one hand, the narrow linewidth seed laser signal passes through the signal transmitting and receiving module 20, so that the signal transmitting and receiving module 20 is used to modulate and amplify the narrow linewidth seed laser signal and transmit it, and receive the end face return light signal reflected by the measured target. On the other hand, the narrow linewidth seed laser signal also passes through the local oscillator signal modulating device 16, so that the local oscillator signal modulating device 16 is used to perform pulse modulation on the narrow linewidth seed laser signal to obtain a modulated signal, and then to perform pulse modulation on the narrow linewidth seed laser signal to obtain a modulated signal, and then when performing beat frequency processing with the end face return light signal, the pulse distortion and intensity distortion after the beat frequency processing are reduced, so as to finally restore the end face information as much as possible, reduce the end face interference, and reduce the distortion blind area at the same time.

[0031] Among them, the local oscillator signal modulation device 16 is used to perform pulse modulation on the narrow linewidth seed laser signal to obtain a modulated signal, and at the same time, synchronize with the transmission signal, so as to reduce the pulse distortion and intensity distortion after the beat frequency processing when performing beat frequency processing with the end face return light signal, so as to finally restore the end face information as much as possible, reduce the end face interference, and reduce the distortion blind area. Optionally, the local oscillator signal modulation device 16 is an electro-optical switch, a magneto-optical switch or an acousto-optic switch. By controlling the opening and closing time of the switch, the narrow linewidth seed laser signal can be modulated into a pulse signal. As another optional method, the local oscillator signal modulation device 16 can be a modulator, for example, an amplitude modulator.

[0032] The frequency mixer 17 is respectively connected to the local oscillator signal modulator 16 and the signal transmitting and receiving module 20. As an essential component of the coherent detection laser radar, the frequency mixer 17 is used to perform beat frequency processing on the end face return light signal (V) and the modulated signal (V0) to obtain a beat signal and reduce interference from other optical signals.

[0033] The signal transmitting and receiving module 20 is used to modulate and amplify the narrow line width seed laser signal and transmit it, and receive the end face return light signal reflected by the target to be measured. As an optional implementation, if Figure 3 As shown, the signal transmitting and receiving module 20 includes: a transmitting signal modulation device 12, an amplifier 13, a signal distinguishing device 14 and a signal transmitting and receiving device 15. The seed signal generating device 11, the transmitting signal modulation device 12, the amplifier 13, the signal distinguishing device 14 and the signal transmitting and receiving device 15 are connected in sequence, and the signal distinguishing device 14 is also connected to the mixing device 17.

[0034] The transmitting signal modulation device 12 is used to modulate the amplitude and frequency of the narrow line width seed laser signal. The amplifier 13 is used to amplify the modulated narrow line width seed laser signal. The signal distinguishing device 14 is used to distinguish the amplified narrow line width seed laser signal and the end face return light signal received by the signal transmitting and receiving device 15. The signal transmitting and receiving device 15 is used to transmit the amplified narrow line width seed laser signal and receive the end face return light signal reflected by the measured target.

[0035] For coherent laser radars of different purposes, the modulation mode of the transmission signal modulation device 12 can be scanning function modulation, pulse modulation, etc. Optionally, the transmission signal modulation device 12 is an acousto-optic modulator.

[0036] The amplifier 13 is used to amplify the narrow linewidth seed laser signal after pre-modulation so as to enable detection at a longer distance, and the amplification factor parameters are determined according to specific use requirements.

[0037] The signal distinguishing device 14 is used to distinguish the signal sent to the signal transmitting and receiving device 15 and the end-face return light signal received by the signal transmitting and receiving device 15. In the present invention, the receiving and transmitting optical paths of the signal use a structure that can minimize the size and cost of the optical path, etc. Optionally, the signal distinguishing device 14 includes an optical ring device.

[0038] The signal transmitting and receiving device 15 is used to transmit the amplified narrow line width seed laser signal sent by the signal distinguishing device 14, and receive the end face return light signal reflected by the measured target. The signal transmitting and receiving device 15 includes a telescope device. Optionally, the telescope device includes an optical antenna and a lens barrel, which ensures the transmission direction and receiving aperture of the signal in physical structure, increases the receiving efficiency, etc.

[0039] In addition, as an optional implementation, Figure 4 As shown, the coherent pulse laser radar 100 further includes: a photoelectric conversion device 18, the mixing device 17 is connected to the photoelectric conversion device 18, and the photoelectric conversion device 18 is used to convert the beat signal into an electrical signal for output. The coherent pulse laser radar 100 further includes: a signal processing device 19, the photoelectric conversion device 18 is connected to the signal processing device 19, and the signal processing device 19 is used to parse the required detection information from the electrical signal, wherein the detection information includes: distance information from the measured target and movement frequency information of the measured target.

[0040] In order to better understand the present application, in one of the specific application scenarios, taking the coherent pulse wind laser radar as an example, the detection pulse width of the traditional coherent pulse wind laser radar is 300ns, so the theoretical detection blind area is 300ns*3*10 8 m / s / 2=45m. In actual use, the pulsed laser reflected at the optical end face of the transmitting device will be broadened. After beating with the local oscillator signal, the actual measurement blind area reaches 60m, which is 50% different from the theoretical value. After the coherent pulse laser radar 100 technology in the present invention is applied to the field of wind laser radar, the local oscillator optical signal (narrow linewidth seed laser signal) is modulated and synchronized with the pulse transmission signal. After beating the signal at the end face, the signal strength and waveform are changed due to the modulation of the local oscillator signal, which will compensate for the influence caused by the distortion of the pulse signal at the end face. After actual system testing, the measurement blind area is 50m, which reduces the signal blind area in actual use and improves the use range of the coherent pulse detection wind laser radar.

[0041] In summary, the coherent pulse laser radar provided in the embodiment of the present application includes: a seed signal generating device, a signal transmitting and receiving module, a local oscillator signal modulating device, a frequency mixing device, an optoelectronic conversion device and a signal processing device. Among them, the signal transmitting and receiving module includes: a transmitting signal modulating device, an amplifier, a signal distinguishing device and a signal transmitting and receiving device. Among them, the seed signal generating device is used to generate a narrow linewidth seed laser signal; the signal transmitting and receiving module is used to modulate and amplify the narrow linewidth seed laser signal and transmit it out, and receive the end face return light signal reflected by the measured target; the local oscillator signal modulating device is used to pulse modulate the narrow linewidth seed laser signal to obtain a modulated signal; the frequency mixing device is used to beat the end face return light signal and the modulated signal to obtain a beat signal; the optoelectronic conversion device is used to convert the beat signal into an electrical signal output; the signal processing device is used to parse the required detection information from the electrical signal, wherein the detection information includes: distance information from the measured target and movement frequency information of the measured target. The technical solution adds a local oscillator signal modulation device to the local oscillator optical path to perform pulse modulation on the narrow linewidth seed laser signal to obtain a modulated signal, and then when performing beat frequency processing with the end face return light signal, the pulse distortion and intensity distortion after the beat frequency processing are reduced, so as to ultimately restore the end face information as much as possible, reduce the end face interference, and reduce the distortion blind area.

[0042] 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.

Claims

1. A coherent pulse laser radar, characterized in that: include: A seed signal generating device, used for generating a narrow line width seed laser signal; A signal transmitting and receiving module, the signal transmitting and receiving module is connected to the seed signal generating device, and is used to modulate and amplify the narrow linewidth seed laser signal and transmit it, and to receive the end face return light signal reflected by the measured target; A local oscillator signal modulation device, the local oscillator signal modulation device is connected to the seed signal generation device, and the local oscillator signal modulation device is used to pulse modulate the narrow linewidth seed laser signal to obtain a modulation signal; and a frequency mixing device, the frequency mixing device being connected to the local oscillator signal modulation device and the signal transmitting and receiving module respectively, the frequency mixing device being used for performing beat frequency processing on the end face return light signal and the modulation signal to obtain a beat signal; The signal transmitting and receiving module includes: a transmitting signal modulation device, an amplifier, a signal distinguishing device and a signal transmitting and receiving device; the signal transmitting and receiving device includes a telescope device, and the telescope device includes an optical antenna and a lens barrel; The seed signal generating device, the transmitting signal modulating device, the amplifier, the signal distinguishing device and the signal transmitting and receiving device are connected in sequence, and the signal distinguishing device is also connected to the frequency mixing device; The emission signal modulation device is used to modulate the amplitude and frequency of the narrow linewidth seed laser signal; The amplifier is used to amplify the modulated narrow linewidth seed laser signal; The signal distinguishing device is used to distinguish the amplified narrow linewidth seed laser signal and the end surface return light signal received by the signal transmitting and receiving device, and transmit the end surface return light signal to the mixing device; The signal transmitting and receiving device is used to transmit the amplified narrow line width seed laser signal and receive the end face return light signal reflected by the measured target.

2. The coherent pulse laser radar according to claim 1, characterized in that: The coherent pulse laser radar also includes: a photoelectric conversion device, the frequency mixing device is connected to the photoelectric conversion device, and the photoelectric conversion device is used to convert the beat signal into an electrical signal output.

3. The coherent pulse laser radar according to claim 2, characterized in that: The coherent pulse laser radar also includes: a signal processing device, the photoelectric conversion device is connected to the signal processing device, and the signal processing device is used to parse the required detection information from the electrical signal, wherein the detection information includes: distance information from the target to be measured and movement frequency information of the target to be measured.

4. The coherent pulse laser radar according to claim 1, characterized in that: The local oscillator signal modulation device is an electro-optical switch, a magneto-optical switch or an acousto-optical switch.

5. The coherent pulse laser radar according to claim 1, characterized in that: The local oscillator signal modulation device is a modulator.

6. The coherent pulse laser radar according to claim 1, characterized in that: The signal distinguishing device comprises an optical ring device.

7. The coherent pulse laser radar according to claim 1, characterized in that: The transmission signal modulation device is an acousto-optic modulator.

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