CN113109838A - Coherent wind lidar capable of carrying out water vapor differential absorption measurement - Google Patents
Coherent wind lidar capable of carrying out water vapor differential absorption measurement Download PDFInfo
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- CN113109838A CN113109838A CN202110444144.6A CN202110444144A CN113109838A CN 113109838 A CN113109838 A CN 113109838A CN 202110444144 A CN202110444144 A CN 202110444144A CN 113109838 A CN113109838 A CN 113109838A
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- 238000010521 absorption reaction Methods 0.000 title claims abstract description 32
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 26
- 230000001427 coherent effect Effects 0.000 title claims abstract description 19
- 238000005259 measurement Methods 0.000 title claims abstract description 13
- 239000013307 optical fiber Substances 0.000 claims abstract description 23
- 230000003287 optical effect Effects 0.000 claims abstract description 18
- 230000007547 defect Effects 0.000 abstract description 2
- 238000001514 detection method Methods 0.000 description 7
- 230000010287 polarization Effects 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 3
- 239000000443 aerosol Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 240000007594 Oryza sativa Species 0.000 description 1
- 235000007164 Oryza sativa Nutrition 0.000 description 1
- 238000000862 absorption spectrum Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000013461 design Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 235000009566 rice Nutrition 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
- G01S17/88—Lidar systems specially adapted for specific applications
- G01S17/95—Lidar systems specially adapted for specific applications for meteorological use
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
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- Optical Radar Systems And Details Thereof (AREA)
Abstract
The coherent wind lidar capable of carrying out water vapor differential absorption measurement comprises a dual-wavelength seed laser and an acousto-optic frequency shift modulator, wherein the input end of the acousto-optic frequency shift modulator is connected with the output end of the dual-wavelength seed laser, the input end of an optical fiber amplifier is connected with the output end of the acousto-optic frequency shift modulator, the input end of an optical transceiving antenna is connected with the output end of the optical fiber amplifier, the output end of the optical transceiving antenna is connected with the input end of a 2x2 polarization-maintaining coupler, the input end of a 2x2 polarization-maintaining coupler is also connected with the output end of the dual-wavelength seed laser, the output end of the dual-wavelength seed laser is connected with the input end of a balance detector, and the input end of an acquisition controller 7 is connected with the output end of the balance detector. Therefore, the defects of complex structure, large volume and large weight of the existing water vapor differential absorption radar are overcome.
Description
Technical Field
The invention relates to the technical field of meteorological laser radars, in particular to a coherent wind lidar capable of carrying out water vapor differential absorption measurement.
Background
Differential absorption lidar is a detection device that uses the absorption lines of a gas to complete the distribution of the gas content path. The principle is that two laser beams with very close wavelengths are respectively emitted, wherein one wavelength is in an absorption spectral line and is called on-line, the other wavelength is out of the absorption spectral line and is called off-line, the emitted energy is consistent, the wavelength is almost consistent, the echo energy is also scattered from aerosol rice, and the echo ratio of the two can directly reflect the distribution condition of path absorption.
The current water vapor differential absorption laser radar has two problems: one is that the absorption line is generally not located in the wavelength range of commonly used gain materials, such as Nd: the YAG laser wavelength is at 1064nm instead of the 936nm absorption band, and requires higher laser power, resulting in the final design of necessarily using a photoparametric oscillator to complete large-energy nonlinear wavelength conversion, so that complexity and cost rise rapidly; the other is that the light splitting capacity of an optical system and the line width improving capacity of emitted laser are different by several orders of magnitude, the line width of the existing laser can easily reach 0.1pm, the FWHM of an optical filter is often 1nm, the system bandwidth and the signal bandwidth are not matched seriously, the narrow-band advantage of single-frequency laser cannot be exerted, the loss of signal-to-noise ratio is serious, the emitted energy can be improved only by relying on the pulse power of hundreds of millijoules to keep the detection distance, and therefore the economy and the volume weight of the existing water vapor differential absorption laser radar are both improved.
Disclosure of Invention
In view of the foregoing technical problems, an object of the present invention is to provide a coherent wind lidar capable of solving the disadvantages of the existing water vapor differential absorption radar, such as complex structure and large volume and weight.
The purpose of the invention is realized by the following technical scheme: a coherent wind lidar capable of carrying out water vapor differential absorption measurement comprises a dual-wavelength seed laser 1, an acousto-optic frequency shift modulator 2, an optical fiber amplifier 3, an optical transceiving antenna 4, a 2x2 polarization-maintaining coupler 5, a balance detector 6 and an acquisition controller 7, wherein the input end of the acousto-optic frequency shift modulator 2 is connected with the output end of the dual-wavelength seed laser 1, the input end of the optical fiber amplifier 3 is connected with the output end of the acousto-optic frequency shift modulator 2, the input end of the optical transceiving antenna 4 is connected with the output end of the optical fiber amplifier 3 and transmits energy pulses amplified by the optical fiber amplifier 3 to an external space, the output end of the optical transceiving antenna 4 is connected with the input end of the 2x2 polarization-maintaining coupler 5 and simultaneously transmits echo signals returned by the external space to the 2x2 polarization-maintaining coupler 5, the input end of the 2x2 polarization-maintaining coupler 5 is also connected with the output end of the dual-wavelength seed laser 1, the output end of the 2x2 polarization-maintaining coupler 5 is connected with the input end of the balance detector 6, and the input end of the acquisition controller 7 is connected with the output end of the balance detector 6 and is used for acquiring the beat signal detected by the balance detector 6 and analyzing the beat signal to obtain the information of the wind field and the water vapor.
Preferably, the optical fiber amplifier 3 is TDFA optical fiber amplifier
Preferably, the dual-wavelength seed laser 1 is provided with one or two resonators for alternately generating narrow-linewidth continuous laser light of two wavelengths.
The invention has the following advantages:
1. the invention relates to a coherent wind lidar capable of carrying out water vapor differential absorption measurement, which changes a single-frequency seed light source of an optical fiber coherent wind lidar into a double-frequency seed light source, and can enable the wind lidar to additionally obtain the capacity of measuring water vapor differential absorption without pulse energy of hundreds of millijoules. Therefore, the defects of complex structure, large volume and large weight of the existing water vapor differential absorption radar are overcome.
The foregoing is a summary of the present invention, and for the purpose of making clear the technical means of the present invention, the present invention can be implemented according to the content of the description, and for the purpose of making the above and other objects, features, and advantages of the present invention more comprehensible, the following preferred embodiments are described in detail:
attached pictureNote the book
The device comprises a 1-dual-wavelength seed laser, a 2-acousto-optic frequency shift modulator, a 3-optical fiber amplifier, a 4-optical transceiving antenna, a 5-2x2 polarization-maintaining coupler, a 6-balance detector and a 7-acquisition and control circuit.
Drawings
Fig. 1 is a schematic diagram of a coherent wind lidar capable of performing differential water vapor absorption measurement according to the embodiment.
Detailed Description
To further illustrate the technical means and effects of the present invention for achieving the intended purpose, the following description, with reference to the accompanying drawings and preferred embodiments, describes a coherent wind lidar capable of performing differential water vapor absorption measurement, and its specific implementation, structure, features and effects thereof.
Referring to fig. 1, the present invention provides a coherent wind lidar capable of performing differential water vapor absorption measurement, including a dual-wavelength seed laser 1, an acousto-optic frequency shift modulator 2, an optical fiber amplifier 3, an optical transceiver antenna 4, a 2x2 polarization maintaining coupler 5, a balance detector 6, and an acquisition controller 7, wherein an input end of the acousto-optic frequency shift modulator 2 is connected to an output end of the dual-wavelength seed laser 1, an input end of the optical fiber amplifier 3 is connected to an output end of the acousto-optic frequency shift modulator 2, an input end of the optical transceiver antenna 4 is connected to an output end of the optical fiber amplifier 3 and transmits an energy pulse amplified by the optical fiber amplifier 3 to an external space, an output end of the optical transceiver antenna 4 is connected to an input end of the 2x2 polarization maintaining coupler 5 and transmits a received echo signal returned by the external space to the 2x2 polarization maintaining coupler 5, the input end of the polarization maintaining coupler 5 is also connected with the output end of the dual-wavelength seed laser 1, the output end of the polarization maintaining coupler 5 is connected with the input end of the balance detector 6, and the input end of the acquisition controller 7 is connected with the output end of the balance detector 6 and is used for acquiring a beat signal detected by the balance detector 6 and analyzing the beat signal so as to obtain information of a wind field and water vapor.
The scheme adopted by the invention is as follows:
the dual-wavelength seed laser 1 alternately generates narrow-linewidth continuous laser with two wavelengths (on-line and off-line), then one beam of seed light is subjected to frequency shift through an acousto-optic frequency shifter 2 and forms pulse modulation, the modulated pulse passes through an optical fiber amplifier 3, the obtained energy pulse is transmitted to an external space through an optical transceiving antenna 4, the optical transceiving antenna 4 receives an echo signal returned by the external space, the echo signal and the other beam of seed light without frequency shift pass through a 2x2 polarization-preserving coupler 5 together, and then coherent heterodyne detection is carried out through a balance detector 6; the acquisition controller 7 is internally provided with an acquisition and control circuit which is mainly used for acquiring the beat signal detected by the balance detector 6 and analyzing the beat signal so as to obtain the information of the wind field and the water vapor. The invention uses the balanced detector to carry out optical coherent heterodyne detection, the system bandwidth can easily reach 1pm magnitude, and the very high detection distance can be reached with lower transmitting power.
The 2x2 polarization maintaining coupler is used in conjunction with balanced detector for coherent heterodyne detection.
In combination with the HITRAN molecular spectral line database, the water vapor has an absorption area near 2um, so in this embodiment, the TDFA optical fiber amplifier is used as the optical fiber amplifier 3, the wavelength of the seed light source is also selected near 2um, for example, the on-line is 1971.00nm, and the off-line is 1969.80nm, and the absorption coefficients of the water vapor mass of the two wavelengths are different by tens of times, so that a high-sensitivity differential absorption cross section can be obtained. Because the wavelength of the seed laser can be tuned by changing the cavity length through piezoelectricity or temperature control, in order to ensure the sensitivity consistency of different dynamic ranges such as high humidity value, low humidity value and the like, the on-line wavelength is designed to be tunable, and is adjusted to be low absorption coefficient when in high humidity, and is adjusted to be high absorption coefficient when in low humidity.
The acquisition controller 7 is further configured to control the dual-wavelength seed laser 1 such that the dual-wavelength seed laser 1 alternately generates two wavelengths (on-line and off-line) of continuous laser light with a narrow linewidth.
The dual-wavelength seed laser 1 emits the dual-wavelength seed source, can be generated by one resonant cavity arranged in the dual-wavelength seed laser 1, and also can be generated by two resonant cavities arranged in the dual-wavelength seed laser 1, and the on-line wavelength can be tuned by changing the cavity length through piezoelectricity or temperature control. When narrow linewidth continuous laser light of two wavelengths alternately generated is generated from one resonant cavity, two similar wavelengths can be obtained, respectively, by changing the cavity length of the resonant cavity using PZT installed in the dual wavelength seed laser.
When the continuous laser with narrow line width of two wavelengths is generated by two resonant cavities, the optical switch installed in the laser is used for selecting and switching the output, that is, the continuous laser with narrow line width of different wavelengths is generated in the two resonant cavities, and the optical switch is used for respectively controlling the on and off of the output of the two resonant cavities, so that the continuous laser with narrow line width of two different wavelengths alternately appears.
The invention relates to a coherent wind lidar capable of carrying out water vapor differential absorption measurement, which adopts two very close wavelengths to carry out coherent detection, has the same transmitting energy and receiving processing processes, and completely accords other transmission conditions except that the influence of a water vapor absorption spectrum line on an on-line and an off-line is different, so that the differential absorption information of the path can be obtained by comparing the energy attenuation conditions of the two wavelengths. Because of the Doppler effect, the radial velocity of the aerosol can also cause frequency shift, so that the traditional radial wind field can be obtained by analyzing and calculating Doppler frequency shift information in the echo through the acquisition controller.
The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention in any way, and any simple modification, equivalent change and modification made by those skilled in the art according to the technical spirit of the present invention are still within the technical scope of the present invention without departing from the technical scope of the present invention.
Claims (3)
1. Coherent wind lidar capable of carrying out water vapor differential absorption measurement, which is characterized in that: the dual-wavelength seed laser device comprises a dual-wavelength seed laser device (1), an acousto-optic frequency shift modulator (2), an optical fiber amplifier (3), an optical transceiving antenna (4), a 2x2 polarization-preserving coupler (5), a balance detector (6) and an acquisition controller (7), wherein the input end of the acousto-optic frequency shift modulator (2) is connected with the output end of the dual-wavelength seed laser device (1), the input end of the optical fiber amplifier (3) is connected with the output end of the acousto-optic frequency shift modulator (2), the input end of the optical transceiving antenna (4) is connected with the output end of the optical fiber amplifier (3) and transmits energy pulses amplified by the optical fiber amplifier (3) to an external space, the output end of the optical transceiving antenna (4) is connected with the input end of the 2x2 polarization-preserving coupler (5) and simultaneously transmits received echo signals returned by the external space to the 2x2 polarization-preserving coupler (5), the input end of the 2x2 polarization-maintaining coupler (5) is also connected with the output end of the dual-wavelength seed laser (1), the output end of the polarization-maintaining coupler (5) is connected with the input end of the balance detector (6), and the input end of the acquisition controller (7) is connected with the output end of the balance detector (6) and is used for acquiring a beat signal detected by the balance detector (6) and analyzing the beat signal to obtain information of a wind field and water vapor.
2. The coherent wind lidar capable of performing differential absorption measurement of water vapor according to claim 1, wherein: the optical fiber amplifier (3) is a TDFA optical fiber amplifier.
3. The coherent wind lidar capable of performing differential absorption measurement of water vapor according to claim 1, wherein: one or two resonant cavities for alternately generating narrow-linewidth continuous laser with two wavelengths are arranged in the dual-wavelength seed laser (1).
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| CN202110444144.6A CN113109838A (en) | 2021-04-23 | 2021-04-23 | Coherent wind lidar capable of carrying out water vapor differential absorption measurement |
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| CN202110444144.6A CN113109838A (en) | 2021-04-23 | 2021-04-23 | Coherent wind lidar capable of carrying out water vapor differential absorption measurement |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116609796A (en) * | 2023-07-20 | 2023-08-18 | 青岛镭测创芯科技有限公司 | Water vapor coherent differential absorption laser radar system |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103823221A (en) * | 2013-12-31 | 2014-05-28 | 西南技术物理研究所 | Pulse laser coherent wind measuring radar |
| CN110749872A (en) * | 2018-07-23 | 2020-02-04 | 中国科学技术大学 | Coherent differential absorption laser radar and method for detecting gas concentration |
| CN112505660A (en) * | 2020-11-26 | 2021-03-16 | 中国科学院合肥物质科学研究院 | Optical fiber laser device for water vapor differential absorption laser radar and use method |
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2021
- 2021-04-23 CN CN202110444144.6A patent/CN113109838A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103823221A (en) * | 2013-12-31 | 2014-05-28 | 西南技术物理研究所 | Pulse laser coherent wind measuring radar |
| CN110749872A (en) * | 2018-07-23 | 2020-02-04 | 中国科学技术大学 | Coherent differential absorption laser radar and method for detecting gas concentration |
| CN112505660A (en) * | 2020-11-26 | 2021-03-16 | 中国科学院合肥物质科学研究院 | Optical fiber laser device for water vapor differential absorption laser radar and use method |
Non-Patent Citations (6)
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116609796A (en) * | 2023-07-20 | 2023-08-18 | 青岛镭测创芯科技有限公司 | Water vapor coherent differential absorption laser radar system |
| CN116609796B (en) * | 2023-07-20 | 2023-11-10 | 青岛镭测创芯科技有限公司 | Water vapor coherent differential absorption laser radar system |
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