A lidar wind measurement system and switching method / device

Abstract

This invention discloses a lidar wind measurement system and its switching method and apparatus. The lidar wind measurement system includes a laser, an optical amplifier, an optical switch, and multiple collimating lenses. The laser generates a seed laser, which is then incident on the optical amplifier. The optical amplifier generates a laser with the required energy based on the seed laser. The optical switch switches to any collimating lens, allowing the laser to be emitted to the outside world through that lens and received back by that lens. Before the start of the switching period of the optical switch, the pump source of the optical amplifier is turned off. Then, when the switching period begins, the optical switch is controlled to perform a switching operation. After the switching period ends, the pump source of the optical amplifier is returned to normal operation. This invention achieves the shutdown of the optical amplifier's pump source during the optical switch switching process, reducing the consumption of the optical amplifier, preventing a shortened lifespan, and reducing system power consumption.

Description

Technical Field

[0001] This invention relates to the field of optical systems, and in particular to a method and apparatus for switching a lidar wind measurement system. This invention also relates to a lidar wind measurement system. Background Technology

[0002] Current scientific research and production require wind measurement with high data update rates, and accurate remote sensing of wind is typically achieved using lidar. Coherent lidar is a mature technology that meets these practical needs.

[0003] LiDAR wind measurement systems require switching between multiple directions to obtain wind field information, achieved using optical switches in conjunction with multiple collimating lenses. Switching the optical path via the optical switch takes time. In existing LiDAR wind measurement systems, the light source continues to operate during the switching process, but the system cannot perform effective measurements. In wind measurement scenarios with high data update rates, each data update requires optical switching, and the switching time accounts for a significant proportion of the total time. For example, with a data update rate of 50%, each data set takes a total of 20ms, and the optical switch switching process takes 10ms. This means that the light source is ineffective for up to 50% of the time. This not only consumes more light source components, shortening their lifespan, but also increases system power consumption. Summary of the Invention

[0004] The purpose of this invention is to provide a switching method and apparatus for a lidar wind measurement system, which can reduce the consumption of the optical amplifier in the lidar wind measurement system, avoid shortening its service life, and reduce system power consumption. This invention also provides a lidar wind measurement system.

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

[0006] A switching method for a lidar wind measurement system is provided, which includes a laser, an optical amplifier, an optical switch, and multiple collimating lenses. The laser generates a seed laser, which is then incident on the optical amplifier. The optical amplifier generates a laser with the required energy based on the seed laser. The optical switch switches to any of the collimating lenses, allowing the laser to be emitted to the outside through the collimating lens and received by the collimating lens in return.

[0007] The method includes:

[0008] Before the start of the switching time period of the optical switch, the pump source of the optical amplifier is turned off;

[0009] When the switching time period of the optical switch is reached, the optical switch is controlled to perform a switching operation;

[0010] After the switching time period of the optical switch ends, the pump source of the optical amplifier is brought into normal operation.

[0011] Optionally, after the switching time period of the optical switch ends, bringing the pump source of the optical amplifier to normal operating status includes:

[0012] Before the end of the switching time period of the optical switch, a drive signal is input to the pump source so that the pump source is in normal working condition after the end of the switching time period of the optical switch.

[0013] Optionally, inputting a drive signal to the pump source before the end of the switching time period of the optical switch includes: inputting a drive signal to the pump source and the magnitude of the input drive signal gradually increases.

[0014] Optionally, turning off the pump source of the optical amplifier before the start of the switching time period of the optical switch includes: stopping the input of a drive signal to the pump source before the start of the switching time period of the optical switch.

[0015] Optionally, it also includes:

[0016] When the pump source of the optical amplifier is turned off, the lidar wind measurement system is controlled to stop collecting data;

[0017] Or / and, at the moment when the pump source of the optical amplifier enters normal operating state, control the lidar wind measurement system to start collecting data.

[0018] Optionally, the time interval between the moment when the pump source of the optical amplifier is turned off and the start time of the switching time period of the optical switch is matched with the duration required for the energy storage release of the pump source.

[0019] Optionally, the optical switch is controlled according to a first timing sequence, and the pump source of the optical amplifier is controlled according to a second timing sequence, both the first timing sequence and the second timing sequence being periodic.

[0020] Optionally, the lidar wind measurement system further includes a coupler, a detector, and a data acquisition board. The laser is also used to generate another seed laser, which is incident on the coupler. The coupler is used to mix the returned light and the seed laser incident on itself, and the mixed light is incident on the detector. The detector is used to convert the optical signal into an electrical signal. The data acquisition board is used to acquire signals from the detector. By controlling the data acquisition board, the lidar wind measurement system can be controlled to stop or start acquiring data.

[0021] A lidar wind measurement system switching device is applied to a lidar wind measurement system, wherein the lidar wind measurement system switching device is used to execute any of the lidar wind measurement system switching methods described above.

[0022] A lidar wind measurement system includes the lidar wind measurement system switching device described above.

[0023] As can be seen from the above technical solution, the lidar wind measurement system switching method and apparatus provided by the present invention are applied to a lidar wind measurement system. The lidar wind measurement system includes a laser, an optical amplifier, an optical switch, and multiple collimating lenses. The laser is used to generate a seed laser, which is then incident on the optical amplifier. The optical amplifier is used to generate a laser with the required energy based on the seed laser. The optical switch is used to switch to any collimating lens, so that the laser is emitted to the outside through the collimating lens and the return light is received by the collimating lens. Specifically, before the start of the switching time period of the optical switch, the pump source of the optical amplifier is turned off. Then, when the switching time period of the optical switch arrives, the optical switch is controlled to perform a switching operation. After the switching time period of the optical switch ends, the pump source of the optical amplifier is put into normal operation. The lidar wind measurement system switching method and apparatus of the present invention realizes the shutdown of the pump source of the optical amplifier during the optical switch switching process, which can reduce the consumption of the optical amplifier in the lidar wind measurement system, avoid shortening its working life, and reduce system power consumption.

[0024] The present invention provides a lidar wind measurement system that can achieve the above-mentioned beneficial effects. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A flowchart illustrating a switching method for a lidar wind measurement system according to an embodiment of the present invention;

[0027] Figure 2 This is a schematic diagram of the first timing sequence and the second timing sequence in a lidar wind measurement system switching method according to an embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of a lidar wind measurement system provided in an embodiment of the present invention.

[0029] The reference numerals in the accompanying drawings include:

[0030] 1-Laser, 2-Optical amplifier, 3-Circulator, 4-Optical switch, 5-First collimating lens, 6-Second collimating lens, 7-Third collimating lens, 8-Fourth collimating lens, 9-Coupled, 10-Detector, 11-Data acquisition board, 12-Industrial control computer. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this invention, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this invention.

[0032] This embodiment provides a switching method for a lidar wind measurement system, which is applied to a lidar wind measurement system. The lidar wind measurement system includes a laser, an optical amplifier, an optical switch, and multiple collimating lenses. The laser is used to generate a seed laser, which is then incident on the optical amplifier. The optical amplifier is used to generate a laser with the required energy based on the seed laser. The optical switch is used to switch to any of the collimating lenses, so that the laser is emitted to the outside through the collimating lens and the return light is received by the collimating lens.

[0033] For reference Figure 1 , Figure 1 A flowchart of a switching method for a lidar wind measurement system is provided as an embodiment, the method comprising the following steps:

[0034] S11: Before the start of the switching time period of the optical switch, turn off the pump source of the optical amplifier.

[0035] The switching time period of an optical switch refers to the time period during which the optical switch performs a switching operation, and the time period ends when the optical switch completes the switching.

[0036] The pump source of an optical amplifier emits pump light, which is then incident on the amplifier's working medium, causing the medium to enter a high-energy state. This allows the seed laser to generate the required energy laser light under stimulated emission when it passes through the medium. Turning off the pump source means stopping the emission of pump light.

[0037] S12: When the switching time period of the optical switch is reached, control the optical switch to perform a switching operation.

[0038] S13: After the switching time period of the optical switch ends, the pump source of the optical amplifier is brought into normal operation.

[0039] The pump source of an optical amplifier is in normal working condition, which means that the pump source normally emits pump light into the working substance of the optical amplifier, so that the optical amplifier works normally.

[0040] The lidar wind measurement system switching method in this embodiment realizes the shutdown of the pump source of the optical amplifier during the optical switch switching process, which can reduce the consumption of the optical amplifier in the lidar wind measurement system, avoid shortening its working life, and reduce system power consumption.

[0041] Considering that the energy storage and release of the optical amplifier's pump source requires a certain period of time, the pump source of the optical amplifier is turned off before the start of the switching period of the optical switch, allowing for a margin of time for the energy storage and release. Accordingly, the time interval between the moment the pump source of the optical amplifier is turned off and the start of the switching period of the optical switch matches the duration required for the energy storage and release of the pump source. In this embodiment, the specific value of the time interval between the moment the pump source of the optical amplifier is turned off and the start of the switching period of the optical switch is not limited. This time interval can be equal to or slightly greater than the duration required for the energy storage and release of the optical amplifier's pump source. If this time interval is too large, it will affect the effective working time ratio of the system. For example, this time interval can be set to 3-5ms. In practical applications, the optical switch can be controlled according to the first timing sequence, and the pump source of the optical amplifier can be controlled according to the second timing sequence, allowing for precise control through both timing sequences. For example, refer to... Figure 2 , Figure 2 The figure shows a schematic diagram of the first and second timing sequences in the switching method of a lidar wind measurement system according to an embodiment. As shown in the figure, the pump source of the optical amplifier is turned off at time t1, and the switching time period of the optical switch is t2-t4, where time t2 is the start time of the switching time period and time t4 is the end time of the switching time period.

[0042] In some implementations, the pump source is controlled to operate by inputting a drive signal to it. Optionally, turning off the pump source of the optical amplifier before the start of the switching period of the optical switch can be achieved by stopping the input of a drive signal to the pump source before the start of the switching period of the optical switch. Inputting a drive signal to the pump source can be, but is not limited to, inputting a drive current to the pump source, and stopping the input of a drive signal to the pump source can be achieved by directly reducing the drive current input to the pump source to 0.

[0043] In some embodiments, bringing the pump source of the optical amplifier to normal operation after the switching period of the optical switch ends may include: inputting a drive signal to the pump source before the end of the switching period of the optical switch, so that the pump source is in normal operation after the switching period of the optical switch ends. Due to the inherent characteristics of the optical amplifier, it takes a period of time for its pump source to transition from a closed state to a normal operation state. Only when the pump source is in a normal operation state can the optical amplifier output the required energy laser based on seed laser generation. Therefore, inputting the drive signal to the pump source before the end of the switching period of the optical switch avoids inputting the drive signal to the pump source only after the switching period of the optical switch ends. This way, the pump source is gradually powered on as the optical switch is about to complete the switching, minimizing the impact of the pump source's switching action on the data accumulation time.

[0044] Specifically, inputting a drive signal to the pump source before the end of the switching period of the optical switch may include: inputting a drive signal to the pump source before the end of the switching period of the optical switch, and the magnitude of the input drive signal gradually increases. Due to device characteristics, the magnitude of the drive signal input to the pump source when starting the pump source needs to gradually increase. For example, when inputting a drive current to the pump source to control its operation, the drive current input to the pump source when starting the pump source needs to gradually increase to a set current value. An example can be found by referring to... Figure 2 As shown, time t4 marks the end of the switching period for the optical switch. Prior to time t4, the pump source's drive current is increased starting at time t3. The pump source then enters normal operation at time t5. Thus, as the optical switch nears stable operation, the pump source current for the optical amplifier gradually increases. Once the optical switch is fully stable, the optical amplifier quickly enters normal operation as well.

[0045] Furthermore, the method in this embodiment also includes: controlling the lidar wind measurement system to stop acquiring data when the pump source of the optical amplifier is turned off. This ensures that the lidar wind measurement system operates effectively during the time the optical amplifier is in operation, making efficient use of time. Furthermore, the method in this embodiment also includes: controlling the lidar wind measurement system to start acquiring data when the pump source of the optical amplifier enters normal operating mode. This ensures that the lidar wind measurement system operates effectively during the time the optical amplifier is in operation, making efficient use of time. Additionally, considering the fluctuation of the switching time of the optical switch, the method in this embodiment interrupts data acquisition in advance during the optical switch switching action and delays the start of acquisition operation for a period of time after the switching is completed. (See reference...) Figure 2As shown, at time t1, the pump source is turned off, and the lidar wind measurement system stops collecting data. At time t5, the pump source returns to normal operation, and data acquisition and accumulation begin. From time t5 to t6, the lidar wind measurement system continues to collect data normally until the next switching operation.

[0046] Preferably, the optical switch is controlled according to the first timing sequence, and the pump source of the optical amplifier is controlled according to the second timing sequence. Both the first and second timing sequences are periodic. The optical switch, the pump source of the optical amplifier, and the data acquisition board are repeatedly and cyclically controlled according to the first and second timing sequences to realize the switching of the lidar wind measurement system to measure the wind field in multiple directions.

[0047] The seed laser generated by the laser is a continuous, narrow-bandwidth laser. After the seed laser is input into an optical amplifier, the optical amplifier converts the continuous light into pulsed light and amplifies the energy of the pulsed light to generate a high-energy laser pulse. In some embodiments, the optical amplifier includes a frequency shifter, a pump source, and an active medium. The frequency shifter is used to convert the continuous light entering the optical amplifier into pulsed light; the pump source is used to emit pump light, which is incident on the active medium of the optical amplifier, causing the active medium to enter a high-energy state. When the pulsed light passes through the active medium of the optical amplifier, laser light with the required energy is generated under stimulated emission. The frequency shifter can be, but is not limited to, an acousto-optic frequency shifter; the pump source can be a pump tube; the optical amplifier can be, but is not limited to, an optical fiber amplifier; and the active medium can be a gain fiber doped with ions. For example, after the seed laser, which is continuous light, enters the optical amplifier, it first passes through an acousto-optic frequency shifter to convert the continuous light into pulses of hundreds of nanoseconds in frequency, and then enters the subsequent gain fiber. Simultaneously, a pump tube in the gain fiber continuously emits pump light, which enters the gain fiber and excites the doped ions in the gain fiber into a high-energy state. Then, when the pulsed light also enters the gain fiber, it is excited by the seed pulse light, causing the doped ions to rapidly enter a low-gain state and simultaneously emit photons with the same wavelength as the seed pulse light. Therefore, the energy of the seed pulse light rapidly increases until it is emitted. The pump light continuously recharges the gain fiber, cyclically forming high-energy light pulses.

[0048] In some embodiments, the lidar wind measurement system further includes a coupler, a detector, and a data acquisition board. The laser is also used to generate another seed laser, which is incident on the coupler. The coupler mixes the returned light with the seed laser incident on itself, and the mixed light is incident on the detector. The detector converts the optical signal into an electrical signal. The data acquisition board acquires signals from the detector. By controlling the data acquisition board, the lidar wind measurement system can be controlled to stop or start data acquisition. The data acquisition board can be controlled according to the first timing sequence, i.e., the timing sequence of the pump source of the control optical amplifier.

[0049] The lidar wind measurement system may also include a circulator, with a first port connected to an optical amplifier, a second port connected to an optical switch, and a third port connected to a coupler. An example may be found by referring to... Figure 3 , Figure 3 The figure shows a schematic diagram of a lidar wind measurement system according to one embodiment. The laser 1 is connected to the optical amplifier 2 and the coupler 9. The first port of the circulator 3 is connected to the optical amplifier 2, and the second port is connected to the optical switch 4. The first collimating lens 5, the second collimating lens 6, the third collimating lens 7, and the fourth collimating lens 8 are all connected to the optical switch 4. The third port of the circulator 3 is connected to the coupler 9. The coupler 9, the detector 10, the data acquisition board 11, and the industrial control computer 12 are connected in sequence. All the above components can be connected via optical fibers. The optical amplifier 2 can be an optical fiber amplifier, the coupler 9 can be an optical fiber coupler, and the detector 10 can be a balanced detector.

[0050] Optical switch 4 is an optical path switching device with one input optical fiber and multiple output optical fibers. Changing the control signal changes the output optical fiber corresponding to the input optical fiber, and the optical path is reversible. The light beam enters the output optical fiber corresponding to the input optical fiber and can exit from the output optical fiber.

[0051] Circulator 3, or optical circulator, is a three-port device where light can only propagate in one direction. If a signal is input from the first port, it will output from the second port; conversely, if a signal is input from the second port, it will output from the third port, with very low output loss. However, when light is input from the second port, the loss is significant when outputting from the first port, and similarly, when light is input from the third port, the loss is significant when outputting from both the first and second ports. Optical circulators are irreversible optical devices.

[0052] Laser 1 generates a continuous, narrow-bandwidth laser beam. One beam enters optical amplifier 2, which converts the continuous beam into pulsed light and amplifies the energy of the pulsed light to generate a high-energy laser pulse. The laser pulse enters the first port of circulator 3, exits from the second port, and then enters optical switch 4. It exits from one of the output ports of the corresponding fiber input port of optical switch 4, is collimated by a collimating lens, and then enters the atmosphere. The back echo of the laser pulse in the atmosphere is received by the same collimating lens and coupled into the fiber output port of optical switch 4. Then, due to optical path reversibility, it is output from the input port of optical switch 4, enters the second port of circulator 3, and exits from the third port. Laser 1 also emits a continuous beam, which, along with the echo signal, enters coupler 9. The two beams are mixed and output to detector 10. Detector 10 converts the optical signal into an electrical signal, which is then acquired at high speed by data acquisition board 11, converted into a digital signal, and transmitted to industrial control computer 12.

[0053] This lidar wind measurement system performs data inversion and can update wind data using a moving average method. After data acquisition in one direction is completed, combined with the most recently acquired data from other directions, a wind field measurement can be achieved. Data updates at different frequencies can be achieved by controlling the switching frequency. The data acquisition board 11 performs data acquisition in different directions according to the corresponding time sequence and cyclically acquires data from multiple directions. By utilizing the projection relationship of the trigonometric functions of the actual wind field measurement results in each direction, the actual wind field information can be inverted.

[0054] Due to the structural characteristics of optical amplifiers, their lifespan is primarily limited by the pump source. During prolonged operation, the pump source's emission energy gradually decreases until the optical amplifier's pulse energy falls below the normal threshold, ending its lifespan. This method preemptively shuts down the pump source during optical switchover and re-energizes it just before the switchover is complete. In applications requiring high-frequency wind measurement data updates, the optical switchover process constitutes a significant portion of the time, during which data acquisition is impossible. Shutting down the pump source during this period effectively extends the optical amplifier's lifespan. Optimizing the pump source power supply achieves the best results in terms of lifespan savings and measurement efficiency. Furthermore, a substantial portion of the optical amplifier's overall power consumption is related to the pump source's operation. Controlling the pump source's operating state significantly reduces the optical amplifier's power consumption, which in turn contributes to overall system power consumption control, reduces system heat dissipation pressure, and increases the system's high-temperature operating limit.

[0055] The lidar wind measurement system switching method in this embodiment reduces pump source operating time, improves system lifespan, and reduces system power consumption by controlling the switching of optical switches and the shutdown and startup of pump sources without affecting data acquisition and accumulation.

[0056] This embodiment also provides a lidar wind measurement system switching device, which is applied to a lidar wind measurement system. The lidar wind measurement system switching device is used to execute the lidar wind measurement system switching method described in any of the above embodiments.

[0057] The lidar wind measurement system switching device in this embodiment realizes the shutdown of the pump source of the optical amplifier during the optical switch switching process, which can reduce the consumption of the optical amplifier in the lidar wind measurement system, avoid shortening its working life, and reduce system power consumption.

[0058] This embodiment also provides a lidar wind measurement system, including the lidar wind measurement system switching device described above.

[0059] The lidar wind measurement system in this embodiment realizes the shutdown of the pump source of the optical amplifier during the optical switch switching process, which can reduce the consumption of the optical amplifier in the lidar wind measurement system, avoid shortening its working life, and reduce system power consumption.

[0060] The present invention provides a detailed description of a lidar wind measurement system, switching method, and apparatus. Specific examples have been used to illustrate the principles and implementation methods of the invention. The descriptions of these embodiments are merely illustrative and are intended to aid in understanding the method and core concepts of the invention. It should be noted that those skilled in the art can make various improvements and modifications to the invention without departing from its principles, and these improvements and modifications also fall within the scope of protection of the claims.

Claims

1. A switching method for a lidar wind measurement system, applied to a lidar wind measurement system, characterized in that, The laser radar wind measurement system comprises a laser, an optical amplifier, an optical switch and a plurality of collimating mirrors, the laser is configured to generate a seed laser, the seed laser is incident to the optical amplifier, the optical amplifier is configured to generate a laser with required energy based on the seed laser, a pump source of the optical amplifier is configured to emit pump light, the pump light is incident to a working substance of the optical amplifier, so that the laser with required energy is generated under the action of stimulated radiation when the seed laser passes through the working substance of the optical amplifier, and the optical switch is configured to switch to any collimating mirror, so that the laser is emitted to the outside world through the collimating mirror and the return light is received through the collimating mirror. The method comprises: The pump source of the optical amplifier is turned off before the starting moment of the switching time period of the optical switch; The optical switch is controlled to perform switching operation when the switching time period of the optical switch is reached; The pump source of the optical amplifier is in a normal working state after the end of the switching time period of the optical switch.

2. The lidar wind finding system switching method of claim 1, wherein, The pump source of the optical amplifier is in a normal working state after the end of the switching time period of the optical switch, which comprises: The driving signal is input to the pump source before the ending moment of the switching time period of the optical switch, so that the pump source is in a normal working state after the end of the switching time period of the optical switch.

3. The lidar wind finding system switching method of claim 2, wherein, The driving signal is input to the pump source before the ending moment of the switching time period of the optical switch, which comprises: the driving signal is input to the pump source, and the magnitude of the input driving signal is gradually increased.

4. The lidar wind finding system switching method of claim 1, wherein, The pump source of the optical amplifier is turned off before the starting moment of the switching time period of the optical switch, which comprises: the driving signal is stopped being input to the pump source before the starting moment of the switching time period of the optical switch.

5. The lidar wind finding system switching method of claim 1, wherein, Further comprising: The laser radar wind measurement system is controlled to stop collecting data when the pump source of the optical amplifier is turned off; Or / and, the laser radar wind measurement system is controlled to start collecting data at the moment when the pump source of the optical amplifier enters a normal working state.

6. The lidar wind measurement system switching method according to any one of claims 1 to 5, characterized by, The time interval between the moment when the pump source of the optical amplifier is turned off and the starting moment of the switching time period of the optical switch matches the time length required for the energy storage of the pump source to be released.

7. The lidar wind measurement system switching method according to any one of claims 1 to 5, characterized by, The optical switch is controlled according to a first timing sequence, and the pump source of the optical amplifier is controlled according to a second timing sequence, and the first timing sequence and the second timing sequence are both periodic.

8. The lidar wind finding system switching method of claim 1, wherein, The laser radar wind measurement system further comprises a coupler, a detector and a data acquisition board, the laser is further configured to generate another seed laser, the seed laser is incident to the coupler, the coupler is configured to mix the return light and the seed laser incident to itself, the mixed light is incident to the detector, the detector is configured to convert the optical signal into an electrical signal, and the data acquisition board is configured to collect signals from the detector, and the laser radar wind measurement system is controlled to stop collecting data or start collecting data by controlling the data acquisition board.

9. A lidar wind finding system switching device, applied to a lidar wind finding system, characterized in that, The laser radar wind measurement system switching device is used to execute the laser radar wind measurement system switching method in any one of claims 1 to 8.

10. A lidar wind measurement system, characterized by, The laser radar wind measurement system switching device comprises the laser radar wind measurement system switching device in claim 9.

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