Blind-zone-free wind lidar system based on polarization extinction

Abstract

Disclosed in the present invention is a blind-zone-free wind lidar system based on polarization extinction, comprising a light emitting module. A first collimating lens, a polarization module, a rotator, a lens assembly, a second collimating lens and an echo signal receiving port are arranged at the rear side of the light emitting module. The light emitting module emits linearly-polarized pulsed light; the linearly-polarized pulsed light is emitted into the air through the first collimating lens, the polarization module, the rotator and the lens assembly in sequence; and the linearly-polarized pulsed light is reflected by an aerosol in the air, and returns through the lens assembly, the rotator, the polarization module and the second collimating lens in sequence and enters the echo signal receiving port. Compared with the prior art, by making the polarization states of light transmitted and reflected by the polarization module orthogonal, the present invention eliminates the reflection caused by a laser exit port, the first collimating lens and the polarization module.

Description

Wind measurement lidar system based on polarization extinction and no blind zone Technical Field

[0001] The present invention relates to the field of wind measurement, and in particular to a wind measurement laser radar system based on polarization extinction and without blind zones. Background Art

[0002] The primary cause of blind spots in fully coherent fiber-optic pulsed lidar is excessive light return from fiber components and reflected light from fiber end faces and telescopes, which overwhelms the low-altitude return signal. Therefore, eliminating these light return signals can fundamentally resolve the blind spot issue.

[0003] Due to bottlenecks in device and material development, it's difficult to completely eliminate backlight and reflected light. In this case, narrowing the pulse width can be used as a primary auxiliary measure to reduce the blind spot. This solution can reduce the blind spot, but it can't completely eliminate it. Furthermore, the high peak power of short pulses complicates fiber laser design. Summary of the Invention

[0004] The purpose of the present invention is to address the problems in existing wind measurement radars, such as good blind spot elimination effect but high device cost, or low device cost but poor blind spot elimination effect. To address these shortcomings, a wind measurement lidar system based on polarization extinction and without blind spots is proposed.

[0005] In order to achieve the above objectives, the present invention adopts the following technical solutions:

[0006] The wind measurement lidar system based on polarization extinction and no blind zone includes an optical transmission module, the rear side of which is provided with a first collimator, a polarization module, an optical rotator, a lens assembly, a second collimator and an echo signal receiving port;

[0007] The optical transmission module emits linearly polarized pulsed light, which is sequentially transmitted through the first collimator, polarization module, optical rotator and lens assembly into the air. The linearly polarized pulsed light is reflected by the aerosol in the air and returns sequentially through the lens assembly, optical rotator, polarization module and second collimator to enter the echo signal receiving port.

[0008] As a further preferred embodiment of the present invention, the polarization module includes a circulator and a polarizer. After being reflected in the air, the linearly polarized pulse light sequentially passes through the optical rotator, the lens assembly, the circulator, and enters the polarizer.

[0009] As a further preferred embodiment of the present invention, the polarization module is configured as a polarization beam splitter;

[0010] The linearly polarized pulse light passes through the first collimator, polarization beam splitter, optical rotator and lens assembly, is emitted into the air, reflects off the aerosol in the air, and returns through the lens assembly and optical rotator in sequence to enter the polarization beam splitter.

[0011] As a further preferred embodiment of the present invention, the optical rotator is arranged on the front side or the rear side of the lens assembly, and the optical rotator is set as a 1 / 2 glass plate or fiber-type 45° polarization rotator.

[0012] As a further preferred embodiment of the present invention, the 1 / 2 glass slide is tilted and forms an angle of 6°-10° with the horizontal plane.

[0013] As a further preferred embodiment of the present invention, the polarization direction of the linearly polarized pulse light emitted by the optical emission module forms an angle of 45° with the polarization direction of the linearly polarized pulse light after passing through the optical rotator.

[0014] As a further preferred embodiment of the present invention, after being reflected in the air, the polarization direction of the linearly polarized pulse light passing through the optical rotator forms an angle of 90° with the polarization direction of the linearly polarized pulse light emitted by the optical transmission module.

[0015] The wind measurement lidar system based on polarization extinction and no blind zone proposed in the present invention has the following beneficial effects compared with the prior art:

[0016] 1. By setting up a polarization module, when receiving the reflected linearly polarized pulse light, only the linearly polarized pulse light that is 90° to the linearly polarized pulse light emitted by the optical transmitter module is allowed to enter, so that the light reflected from the optical fiber end face and the mirror reflection of the lens component cannot be received, thus eliminating the blind spot;

[0017] 2. The lens assembly can be placed in front of or behind the optical rotator, and the position is flexible and can be adjusted according to specific needs;

[0018] 3. By tilting 1 / 2 of the glass slide at 6°-10°, the interference of reflected light caused by the glass slide and lens assembly is reduced;

[0019] 4. The present invention has a simple structure and uses mature commercial products. It does not require a complex spatial optical path and does not require two sets of optoelectronic processing systems required by the separate transmitter and receiver method.

[0020] 5. The polarization states of the light transmitted and reflected by the polarization module are orthogonal, eliminating the reflection caused by the laser output port, the first collimator and the polarization module. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG1 is a schematic diagram showing the connection relationship when the polarization module is a circulator and a polarizer;

[0022] FIG2 is a schematic diagram showing the connection relationship when the polarization module is a polarization beam splitter.

[0023] The meanings of the reference numerals in the figure are: 1. optical transmission module, 2. first collimator, 3. polarization module, 31. circulator, 32. polarizer, 33. polarization beam splitter, 4. optical rotator, 5. lens assembly, 6. second collimator, 7. echo signal receiving port. DETAILED DESCRIPTION

[0024] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0025] The present invention is suitable for eliminating blind areas of coherent wind measurement laser radar.

[0026] Embodiment 1: A wind measurement lidar system based on polarization extinction and no blind zone includes an optical transmitting module 1, and a first collimator 2, a polarization module 3, a rotator 4, a lens assembly 5, a second collimator 6 and an echo signal receiving port 7 are provided on the rear side of the optical transmitting module 1.

[0027] The optical transmitter module 1 emits linearly polarized pulsed light, which is sequentially transmitted through the first collimator 2, the polarization module 3, the optical rotator 4, and the lens assembly 5 into the air. The polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1 forms a 45° angle with the polarization direction of the linearly polarized pulsed light after passing through the optical rotator 4. The linearly polarized pulsed light is reflected by aerosols in the air and returns sequentially through the lens assembly 5, the optical rotator 4, the polarization module 3, and the second collimator 6 to enter the echo signal receiving port 7. After being reflected in the air, the polarization direction of the linearly polarized pulsed light after passing through the optical rotator 4 forms a 90° angle with the polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1.

[0028] Example 2: In conjunction with Figure 1, a wind measurement lidar system based on polarization extinction and no blind spot includes an optical transmitting module 1, and a first collimator 2, a polarization module 3, a rotator 4, a lens assembly 5, a second collimator 6 and an echo signal receiving port 7 are provided on the rear side of the optical transmitting module 1; the polarization module 3 includes a circulator 31 and a polarizer 32, and the rotator 4 is provided on the rear side of the lens assembly 5.

[0029] The optical transmitter module 1 emits linearly polarized pulsed light, which sequentially passes through the first collimator 2, the circulator 31, the lens assembly 5, and the optical rotator 4 and is emitted into the air. The polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1 forms a 45° angle with the polarization direction of the linearly polarized pulsed light after passing through the optical rotator 4. The linearly polarized pulsed light is reflected by aerosols in the air and returns to pass through the optical rotator 4, the lens assembly 5, the circulator 31, the polarizer 32, and the second collimator 6 in sequence, and enters the echo signal receiving port 7. After being reflected in the air, the polarization direction of the linearly polarized pulsed light after passing through the optical rotator 4 forms a 90° angle with the polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1.

[0030] Example 3: In conjunction with Figure 2, a wind measurement lidar system based on polarization extinction and no blind spot includes an optical transmitting module 1, and a first collimator 2, a polarization module 3, an optical rotator 4, a lens assembly 5, a second collimator 6 and an echo signal receiving port 7 are provided on the rear side of the optical transmitting module 1; the polarization module 3 is configured as a polarization beam splitter 33, and the optical rotator 4 is provided on the front side of the lens assembly 5.

[0031] The optical transmitter module 1 emits linearly polarized pulsed light, which sequentially passes through the first collimator 2, the polarization beam splitter 33, the optical rotator 4, and the lens assembly 5 and is emitted into the air. The polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1 is at a 45° angle to the polarization direction of the linearly polarized pulsed light after passing through the optical rotator 4. The linearly polarized pulsed light is reflected by aerosols in the air and returns to pass through the lens assembly 5, the optical rotator 4, the polarization beam splitter 33, and the second collimator 6 in sequence, and enters the echo signal receiving port 7. After being reflected in the air, the polarization direction of the linearly polarized pulsed light after passing through the optical rotator 4 is at a 90° angle to the polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1.

[0032] Example 4: In conjunction with Figure 2, a wind measurement lidar system based on polarization extinction and no blind spot includes an optical transmitting module 1, and a first collimator 2, a polarization module 3, an optical rotator 4, a lens assembly 5, a second collimator 6 and an echo signal receiving port 7 are provided on the rear side of the optical transmitting module 1. The optical rotator 4 is configured as a 1 / 2 glass slide, and the 1 / 2 glass slide is configured at an angle and forms an angle of 6°-10° with the horizontal plane.

[0033] In which, the optical transmitter module 1 emits linearly polarized pulsed light, which is sequentially transmitted through the first collimator 2, the polarization beam splitter 33, the 1 / 2 glass slide and the lens assembly 5 into the air. The polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1 is 45° to the polarization direction of the linearly polarized pulsed light after passing through the 1 / 2 glass slide; the linearly polarized pulsed light is reflected by the aerosol in the air, and returns sequentially through the lens assembly 5, the 1 / 2 glass slide, the polarization beam splitter 33, and the second collimator 6, and enters the echo signal receiving port 7. After being reflected in the air, the polarization direction of the linearly polarized pulsed light after passing through the 1 / 2 glass slide is 90° to the polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1.

[0034] Example 5: In conjunction with Figure 1, a wind measurement lidar system based on polarization extinction and no blind zone includes an optical transmitting module 1, and a first collimator 2, a polarization module 3, a rotator 4, a lens assembly 5, a second collimator 6 and an echo signal receiving port 7 are provided on the rear side of the optical transmitting module 1. The rotator 4 is configured as a fiber-type ° polarization rotator.

[0035] In which, the optical transmitter module 1 emits linearly polarized pulsed light, which is sequentially transmitted through the first collimator 2, the circulator 31, the lens assembly 5 and the optical fiber polarization rotator into the air. The polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1 is 45° to the polarization direction of the linearly polarized pulsed light after passing through the optical fiber polarization rotator. The linearly polarized pulsed light is reflected by the aerosol in the air and returns to pass through the optical fiber polarization rotator, the lens assembly 5, the circulator 31, the polarizer 32 and the second collimator 6 in sequence, and enters the echo signal receiving port 7. After being reflected in the air, the polarization direction of the linearly polarized pulsed light after passing through the optical fiber polarization rotator is 90° to the polarization direction of the linearly polarized pulsed light emitted by the optical transmitter module 1.

[0036] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of the present invention.

Claims

1. A wind measurement laser radar system based on polarization extinction and without blind spots, comprising a light transmitting module (1), characterized in that: The rear side of the optical transmission module (1) is provided with a first collimator (2), a polarization module (3), an optical rotator (4), a lens assembly (5), a second collimator (6) and an echo signal receiving port (7); The optical transmission module (1) emits linearly polarized pulsed light, which is sequentially transmitted through a first collimator (2), a polarization module (3), an optical rotator (4), and a lens assembly (5) and emitted into the air. The linearly polarized pulsed light is reflected by aerosols in the air and returns sequentially through the lens assembly (5), the optical rotator (4), the polarization module (3), and the second collimator (6) to enter an echo signal receiving port (7).

2. The wind laser radar system based on polarization extinction and no blind zone according to claim 1 is characterized in that: The polarization module (3) comprises a circulator (31) and a polarizer (32); the linearly polarized pulse light is reflected in the air and then sequentially passes through the optical rotator (4), the lens assembly (5), and the circulator (31) to enter the polarizer (32).

3. The wind measurement laser radar system based on polarization extinction and without blind zone according to claim 1 is characterized in that: The polarization module (3) is configured as a polarization beam splitter (33); The linearly polarized pulse light passes through the first collimator (2), the polarization beam splitter (33), the optical rotator (4) and the lens assembly (5), is emitted into the air, reflects off the aerosol in the air, and returns to pass through the lens assembly (5) and the optical rotator (4) in sequence, and enters the polarization beam splitter (33).

4. The wind measurement laser radar system based on polarization extinction and without blind zone according to claim 1 is characterized in that: The optical rotator (4) is arranged on the front side of the lens assembly (5) or on the rear side of the lens assembly (5), and the optical rotator (4) is arranged as a 1 / 2 glass plate or optical fiber type 45° polarization rotator.

5. The wind measurement laser radar system based on polarization extinction and without blind zone according to claim 4 is characterized in that: The 1 / 2 glass slide is tilted and forms an angle of 6°-10° with the horizontal plane.

6. The wind measurement laser radar system based on polarization extinction and without blind zone according to any one of claims 1 to 5, characterized in that: The polarization direction of the linearly polarized pulse light emitted by the optical transmission module (1) forms an angle of 45° with the polarization direction of the linearly polarized pulse light after passing through the optical rotator (4).

7. The wind measurement laser radar system based on polarization extinction and without blind zone according to any one of claims 1 to 5, characterized in that: After being reflected in the air, the polarization direction of the linearly polarized pulse light after passing through the optical rotator (4) forms an angle of 90° with the polarization direction of the linearly polarized pulse light emitted by the optical emission module (1).

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