Synchronous timing control system for high repetition rate pulsed laser illumination measurement

Abstract

The present invention discloses a synchronous timing control system for high-repetition-rate burst pulse laser illumination measurement, which relates to the field of laser illumination measurement technology. The system includes a first signal generator, a second signal generator, a third signal generator, a laser seed source, a laser amplifier, and a camera system. The first signal generator is configured to output a first control signal to the laser seed source and a second control signal to the second signal generator. The third signal generator is configured to output a third control signal to the laser amplifier and a fourth control signal to the second signal generator. The second signal generator generates a camera trigger signal based on the second control signal and only outputs the camera trigger signal to the camera system within the high-level range of the fourth control signal. The present invention ensures that camera exposure is strictly synchronized with the laser pulse, allowing the camera system to capture the laser illumination effect throughout the entire duration of the macropulse.

Description

Technical Field

[0001] The present invention relates to the technical field of laser illumination measurement, and in particular to a synchronous timing control system for high repetition rate burst pulse laser illumination measurement. Background Art

[0002] Laser lighting measurement systems are mainly divided into conventional low-repetition-rate dual-channel systems (single-channel pulse frequency 1Hz-1KHz) and high-repetition-rate train pulse systems (pulse frequency above 10KHz).

[0003] In a low repetition rate dual-channel system, the two lasers are output independently and the delay is relatively adjustable. The timing control system gives the 2 or 4 trigger signals required by the laser and the 1 trigger signal required by the camera at the same time. The delay of the three signals is as follows: Figure 1 This type of system places the laser pulse within the camera exposure time, ensuring that the camera captures the measurement field after laser illumination in every frame.

[0004] Due to the inherent characteristics of the laser, high-repetition-rate burst pulse systems cannot output a single laser pulse per trigger signal, as low-repetition-rate systems do. Their sub-pulse timing is determined internally by the laser, while the macro-pulse start time and width can be controlled externally. However, existing high-repetition-rate burst pulse lighting systems have two major drawbacks.

[0005] The first technical defect is that the camera exposure clock and the laser output laser pulse clock are non-isochronous clocks and cannot be accurately synchronized. Non-isochronous clocks have different periods due to inconsistent clock sources. After working for a certain period of time, the pulse delay will change, such as Figure 2 This resulted in the front delay being adjusted during debugging so that the laser pulse could be captured in each exposure. However, as the macro pulse width increased, the laser pulse at the tail of the macro pulse could not be synchronized with the camera exposure moment, making it impossible to capture the complete illumination field.

[0006] The second technical drawback is that conventional systems are limited by camera storage speed and exposure time, making high-repetition-rate photography impossible. For example, with a 1MHz laser output, the laser cycle is only 1μs, while the shortest exposure time of current cameras is approximately 500ns. Storing high-quality, large-format photos requires a long time, making it impossible to complete storage and start the next image acquisition within such a short period. Summary of the Invention

[0007] The present invention discloses a synchronous timing control system for high repetition rate pulsed laser illumination measurement, aiming to solve the technical problems existing in the prior art. The present invention adopts the following technical solutions:

[0008] An embodiment of the present invention provides a synchronous timing control system for high repetition rate burst pulse laser illumination measurement, comprising a first signal generator, a second signal generator, a third signal generator, a laser seed source, a laser amplifier, and a camera system;

[0009] The first signal generator is used to output a first control signal to the laser seed source, and simultaneously output a second control signal as a clock source signal to the second signal generator; the first control signal and the second control signal are both sub-pulse frequency signals;

[0010] The third signal generator is used to output a third control signal to the laser amplifier and simultaneously output a fourth control signal to the second signal generator; the third control signal and the fourth control signal are both low repetition rate macro pulse trigger signals;

[0011] The second signal generator generates a camera trigger signal according to the second control signal, and outputs the camera trigger signal to the camera system only within a high level range of the fourth control signal.

[0012] As a preferred technical solution, the first control signal output by the first signal generator has the same frequency as the second control signal.

[0013] As a preferred technical solution, the frequency of the sub-pulse frequency signal is higher than the maximum shooting frequency that can be achieved when a single camera in the camera system is working.

[0014] As a preferred technical solution, the third control signal and the fourth control signal output by the third signal generator have the same frequency, the same pulse width, and an adjustable relative delay.

[0015] As a preferred technical solution, the third signal generator is configured to operate by internal triggering, or to operate by receiving an external trigger signal, so that the third signal generator can be synchronized with an external device.

[0016] As a preferred technical solution, the frequency of the low repetition rate macro pulse trigger signal is lower than the frequency of the sub-pulse frequency signal.

[0017] As a preferred technical solution, the laser amplifier only amplifies the laser sub-pulses within the high level range according to the high level range of the third control signal.

[0018] As a preferred technical solution, the second signal generator can perform frequency division processing on the second control signal to generate a camera trigger signal.

[0019] As a preferred technical solution, the second signal generator is configured to operate in a gated mode and output a camera trigger signal only when a high level fourth control signal is received, so that the exposure time of the camera system is synchronized with the laser pulse amplified by the laser amplifier.

[0020] As a preferred technical solution, the camera system includes a single camera or multiple cameras;

[0021] When the camera system includes multiple cameras, the second signal generator is provided with multiple output ports, and the delay and pulse width between the camera trigger signals output by each output port can be adjusted individually to adapt to the synchronous shooting of multiple cameras in the camera system.

[0022] One embodiment of the above invention has the following advantages or beneficial effects:

[0023] The present invention primarily provides a synchronous timing control system for high-repetition-rate burst-pulse laser illumination measurement. The system comprises three coordinated signal generators, including a first signal generator, a second signal generator, and a third signal generator. The first signal generator simultaneously provides a cognate clock signal to both the laser seed source and the second signal generator, ensuring strict synchronization between the laser pulse output and the camera exposure trigger signal. This resolves the synchronization issues associated with non-cognate clocks in conventional systems, enabling the camera to accurately capture the laser illumination effect during each exposure. Even in the case of long macropulse durations, the laser pulse at the end of the macropulse is accurately recorded by the camera.

[0024] In addition, the present invention uses a second signal generator to perform frequency division processing on the clock signal, allowing the system to support the synchronous operation of multiple cameras. This effectively overcomes the technical obstacle of a single camera being unable to perform high-repetition-rate photography due to storage speed and exposure time limitations. This allows operators to use multiple ordinary cameras instead of expensive high-speed cameras, or to achieve more refined photography effects through the collaborative work of multiple high-speed cameras, thereby significantly reducing the cost of using the measurement system and improving experimental efficiency.

[0025] Furthermore, the timing control system provided by the present invention has strong adaptability and flexibility. By adjusting the parameter settings of different signal generators, it can adapt to laser illumination scenarios with sub-pulse frequencies ranging from 10KHz to 1MHz or even higher frequencies. At the same time, the system supports single-camera and multi-camera system configurations and can be flexibly adjusted according to actual measurement needs to meet the precise measurement requirements under different experimental conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments, which constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the drawings:

[0027] Figure 1 A schematic diagram of the timing relationship of a low-repetition-rate dual-path lighting system in the prior art;

[0028] Figure 2Schematic diagram of the relationship between exposure and laser signal timing of a high repetition rate burst pulse camera in the prior art;

[0029] Figure 3 This is a structural diagram of a synchronous timing control system for high-repetition-rate burst pulse laser illumination measurement disclosed in Example 1 of the present invention;

[0030] Figure 4 This is a structural diagram of a synchronous timing control system for high-repetition-rate burst pulse laser illumination measurement disclosed in Example 2 of the present invention;

[0031] Figure 5 This is a structural diagram of a synchronous timing control system for high repetition rate pulsed laser illumination measurement disclosed in Example 3 of the present invention.

[0032] Description of reference numerals:

[0033] A first signal generator 11 , a second signal generator 12 , a third signal generator 13 , a laser seed source 14 , a laser amplifier 15 , and a camera system 16 . DETAILED DESCRIPTION

[0034] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention will be clearly and completely described below in conjunction with specific embodiments of the present invention and corresponding drawings. In the description of the present invention, it should be noted that the term "or" is generally used in the sense of including "and / or" unless the content clearly indicates otherwise.

[0035] In the description of the present invention, the terms "first", "second", etc. are only used to distinguish the descriptions and should not be understood as indicating or implying relative importance.

[0036] Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0037] In the existing technology, since the camera exposure clock and the laser output laser pulse clock are non-homologous clocks, precise synchronization cannot be achieved. In particular, when the macro pulse width increases, the laser pulse at the tail of the macro pulse cannot be synchronized with the camera exposure moment, making it difficult to capture the complete illumination field in the experiment. Example 1

[0038] refer to Figure 3In order to solve the problems existing in the prior art, an embodiment of the present invention provides a synchronous timing control system for high repetition rate pulsed laser illumination measurement. Preferably, the system includes a first signal generator 11, a second signal generator 12, a third signal generator 13, a laser seed source 14, a laser amplifier 15 and a camera system 16.

[0039] Preferably, the first signal generator 11 can simultaneously output a first control signal and a second control signal, both of which are sub-pulse frequency signals, wherein the first control signal is sent to the laser seed source 14, and the second control signal is sent to the second signal generator 12 as a clock source signal.

[0040] In a preferred embodiment, the first signal generator 11 is configured as a precision timing control device capable of generating a stable high-frequency signal as a reference clock source for the entire system. Preferably, the output frequency of the first signal generator 11 is adjustable within a range of 1 Hz to 1 MHz to accommodate the needs of different experimental scenarios.

[0041] Specifically, the sub-pulse frequency signal refers to an electrical signal with high frequency and short pulse width. The purpose of setting the sub-pulse frequency signal is to provide a stable trigger reference for the laser seed source 14, and at the same time provide the signal of the same frequency as the clock source to the second signal generator 12, thereby ensuring that the laser pulse output and the exposure time of the camera system 16 are based on the same clock source, solving the synchronization drift problem caused by non-homologous clocks.

[0042] Preferably, the third signal generator 13 can simultaneously output a third control signal and a fourth control signal, both of which are low repetition rate macro pulse trigger signals, wherein the third control signal is sent to the laser amplifier 15 and the fourth control signal is sent to the second signal generator 12 .

[0043] In a preferred embodiment, the low-repetition-rate macropulse trigger signal has a low frequency of 0.1 Hz to 1 Hz, but its pulse width is adjustable from milliseconds to seconds. This low-repetition-rate macropulse trigger signal controls the operating time window of the laser amplifier 15 and enables the output of the second signal generator 12. By setting the low-repetition-rate macropulse trigger signal, the measurement cycle of the entire system can be controlled, avoiding thermal effects caused by prolonged laser operation. Furthermore, by controlling the gate input of the second signal generator 12, precise synchronization between the exposure of the camera system 16 and the output of the laser amplifier is achieved.

[0044] Preferably, after receiving the second control signal and the fourth control signal, the second signal generator 12 generates a camera trigger signal according to the second control signal, and outputs the camera trigger signal to the camera system 16 only within the high level range of the fourth control signal.

[0045] In a preferred embodiment, the second signal generator 12 is a device responsible for generating a camera trigger signal, and its operating mode is set to a gated mode. Specifically, the gated mode is the GATE mode. In the gated mode, the second signal generator 12 will output a trigger signal only when it receives a high level of the fourth control signal to ensure that the camera system 16 is exposed only during the time period of laser illumination; preferably, the second signal generator 12 has a frequency division function, which can divide the input high-frequency clock signal according to actual needs to adapt to the maximum operating frequency limit of a single camera.

[0046] In a preferred embodiment, the first control signal output by the first signal generator 11 has the same frequency as the second control signal. Specifically, when the first signal generator 11 provides the first control signal to the laser seed source 14 and simultaneously provides the second control signal of the same frequency to the second signal generator 12 as a clock source, the camera trigger signal generated by the second signal generator 12 establishes a strict homologous relationship with the laser output signal of the laser seed source 14, enabling the system to perform precise synchronous delay adjustment and eliminating the inevitable time drift problem in traditional non-homologous clock systems. For example, even during long experiments or at the end of a laser macro pulse, the phase relationship between the camera trigger signal and the laser pulse can remain strictly stable, ensuring that each camera exposure accurately captures the scene at the moment of laser illumination.

[0047] In a preferred embodiment, the second signal generator 12 is capable of frequency-dividing the second control signal to generate a camera trigger signal. Specifically, because the sub-pulse frequency of a high-repetition-rate laser system (e.g., 1 MHz) is much higher than the maximum continuous capture rate of a conventional camera, even a high-speed camera, the camera would be unable to store and transmit image data without frequency division. By appropriately frequency-dividing the second control signal, the trigger frequency can be reduced to a range that the camera can handle while maintaining a precise phase relationship between the trigger signal and the laser pulse, thereby resolving the technical conflict between high-frequency laser illumination and the camera's operating speed.

[0048] In a preferred embodiment, the third and fourth control signals output by the third signal generator 13 have the same frequency and pulse width, and an adjustable relative delay. Specifically, the consistent frequency and pulse width ensure that the laser amplifier 15 and camera system 16 operate within the same time window, while the adjustable relative delay provides flexibility for fine-tuning system timing, allowing the operator to precisely control the time offset between the start of camera exposure and the start of laser amplification based on the characteristics of the specific measurement object, thereby optimizing capture quality.

[0049] In a preferred embodiment, the third signal generator 13 is configured to operate with either an internal trigger or an external trigger signal, enabling synchronization with external devices. Preferably, in standalone experiments, the third signal generator 13 can operate autonomously at a preset frequency using an internal trigger mode. In complex integrated test environments, such as when working with fluid control systems, mechanical motion control systems, or other measuring instruments, the third signal generator 13 can receive trigger signals from external devices, ensuring that the entire measurement system remains precisely synchronized with external events.

[0050] In a preferred embodiment, the frequency of the sub-pulse frequency signal is higher than the maximum shooting frequency that can be achieved when a single camera in the camera system 16 is working. Through the frequency division processing of the second signal generator 12, the hardware limitations of the single camera can be overcome; further, the frequency of the low repetition rate macro pulse trigger signal is lower than the frequency of the sub-pulse frequency signal, so that the system can achieve short-time high-frequency sampling at a lower repetition rate.

[0051] Preferably, the laser seed source 14 is configured as a high-repetition-rate fiber seed source; preferably, the laser amplifier 15 only amplifies the laser sub-pulses within the high-level range according to the high-level range of the third control signal. This gated amplification mode ensures that only the sub-pulses falling within the macro-pulse time window are amplified and output, forming a typical burst pulse laser output characteristic.

[0052] In a preferred embodiment, the camera system 16 is configured with only one camera. In this case, the system can still ensure synchronization of camera exposure and laser pulses through frequency division processing.

[0053] In another preferred embodiment, the camera system 16 is configured with multiple cameras to break through the bottleneck of the hardware limitations of a single camera; in this case, the second signal generator 12 is provided with multiple output ports, and the delay and pulse width between the camera trigger signals output by each output port can be adjusted individually to adapt to the synchronous shooting of multiple cameras in the camera system 16.

[0054] In this embodiment, through the coordinated cooperation of the first signal generator 11, the second signal generator 12, and the third signal generator 13, the laser output clock and the camera shooting exposure clock are output from the same source and synchronously, thereby ensuring that in the high-repetition-rate string pulse laser illumination scenario, the camera can accurately capture the laser pulse each time it exposes; secondly, the embodiment of the present invention also reduces the demand for high-speed cameras in high-repetition-rate illumination fields. Through the coordination of sub-pulse frequency signals and low-repetition-rate macro-pulse trigger signals, as well as the frequency division function of the second signal generator 12, a camera with a lower configuration can still complete the shooting task of high-repetition-rate and high-speed illumination fields. Example 2

[0055] refer to Figure 4An embodiment of the present invention provides a synchronous timing control system for high repetition rate pulsed laser illumination measurement. Preferably, the system includes a first signal generator 11, a second signal generator 12, a third signal generator 13, a laser seed source 14, a laser amplifier 15 and a camera system 16. Preferably, the sub-pulse frequency signal in this embodiment is 1 MHz, the low repetition rate macro pulse trigger signal is 0.1 Hz, and the camera system 16 is provided with 5 cameras.

[0056] In a preferred embodiment, the first signal generator 11 serves as the reference clock source for the entire system, simultaneously providing a first control signal to the laser seed source 14 and a second control signal to the second signal generator 12. Both the first and second control signals have a frequency of 1 MHz. The first control signal serves as the timing signal for the laser pulses output by the laser seed source 14, while the second control signal serves as the clock source signal for the second signal generator 12. In this case, the laser pulses and the camera trigger signal are based on the exact same clock source, fundamentally resolving the synchronization drift problem caused by non-cognate clocks.

[0057] In a preferred embodiment, the second signal generator 12 receives the second control signal, performs frequency division processing, and outputs a trigger signal to the camera system 16 through its multiple output ports. In this embodiment, since the camera system 16 is equipped with five cameras, the second signal generator 12 divides the 1 MHz input signal so that the frequency of each output is 20 kHz. The delay and pulse width of each output can be adjusted independently to ensure that the trigger signal output to each camera is strictly synchronized with the laser pulse timing. This frequency division design effectively overcomes the hardware limitation of a single camera that cannot achieve 1 MHz high-speed acquisition.

[0058] During actual photography, the first signal generator 11 begins operating in advance to ensure the normal output of the laser seed source 14. However, the laser has not yet been amplified, and the system awaits the output of a control signal from the third signal generator 13. The third signal generator 13 is configured to output a third control signal to the laser amplifier 15, causing the laser amplifier 15 to begin operating and outputting amplified bursts of laser light. In this embodiment, the third control signal has a frequency of 0.1 Hz and a pulse width of 1 ms. Simultaneously, the third signal generator 13 also outputs a fourth control signal to the gate input of the second signal generator 12. This fourth control signal also has a frequency of 0.1 Hz and a pulse width of 1 ms, but with an adjustable delay. The second signal generator 12 is configured to operate in gated mode, i.e., active-high mode. In this mode, only upon receiving a high level from the fourth control signal will the second signal generator 12 begin outputting a camera trigger signal at a preset delay and frequency. While simultaneously outputting the third control signal to the laser amplifier 15, the system also outputs a burst signal with a duration of 1-2 ms to the camera system 16 at a preset frequency and delay, serving as the camera trigger signal.

[0059] Since the second signal generator 12 operates in a gated mode and outputs a signal only when it receives a high level fourth control signal, by adjusting the delay of the third control signal output to the laser amplifier 15, it can be ensured that each camera in the camera system 16 can capture the laser pulse, so that the system can accurately control the time relationship between camera exposure and laser output, ensuring high-quality synchronous measurement under the conditions of high-repetition-rate pulsed laser illumination.

[0060] In this embodiment, the 1MHz sub-pulse frequency signal output by the first signal generator 11 is much higher than the speed that a single camera can process, and through the multi-channel frequency division output of the second signal generator 12, the system successfully achieves complete capture of the 1MHz high-frequency laser pulse; at the same time, the 0.1Hz low-repetition-rate macro-pulse trigger signal generated by the third signal generator 13 ensures that the system achieves short-term high-frequency sampling at a lower repetition rate, avoiding equipment overheating and data redundancy problems that may be caused by long-term high-frequency operation.

[0061] Through the configuration of this embodiment, the system can use five ordinary cameras instead of expensive ultra-high-speed cameras under 1MHz high-repetition-rate laser illumination conditions to accurately capture and measure high-speed transient phenomena, significantly reducing experimental costs and improving measurement efficiency. Example 3

[0062] refer to Figure 5An embodiment of the present invention provides a synchronous timing control system for high repetition rate pulsed laser illumination measurement. Preferably, the system includes a first signal generator 11, a second signal generator 12, a third signal generator 13, a laser seed source 14, a laser amplifier 15 and a camera system 16. Preferably, the sub-pulse frequency signal in this embodiment is 10KHz, the low repetition rate macro-pulse trigger signal is 0.1Hz, and the camera system 16 is provided with only one camera.

[0063] In a preferred embodiment, the first signal generator 11 serves as the reference clock source of the entire system, and simultaneously provides a first control signal to the laser seed source 14 and a second control signal to the second signal generator 12. The frequencies of the first control signal and the second control signal are both 10KHz. The first control signal serves as a timing signal for the laser seed source 14 to output laser pulses, and the second control signal serves as a clock source signal for the second signal generator 12.

[0064] During actual photography, the first signal generator 11 begins operating in advance to ensure the normal output of the laser seed source 14, but the laser has not yet been amplified. The third signal generator 13 outputs a third control signal with a frequency of 0.1 Hz and a pulse width of 10 ms to the laser amplifier 15, causing the laser amplifier 15 to start operating and output an amplified burst of laser pulses. Simultaneously, the third signal generator 13 outputs a fourth control signal with an adjustable delay of 0.1 Hz and a pulse width of 10 ms to the gate input of the second signal generator 12. The second signal generator 12 is configured to operate in gated mode. In this mode, a trigger signal is output only when the input signal is high. Upon receiving the high-level signal, the second signal generator 12 begins outputting camera trigger signals at a preset delay and frequency. Each time a trigger signal is output to the laser amplifier 15, a burst signal with a duration of 10 ms is also provided to the camera system 16 at the preset frequency and delay, serving as the camera trigger signal.

[0065] Since the second signal generator 12 operates in the gated mode and only outputs a signal when it receives the fourth control signal, the delay of the third control signal given to the laser amplifier 15 is adjusted to ensure that the camera can capture the laser pulse in every frame.

[0066] Those skilled in the art will understand that, except where mutually exclusive, all features disclosed in this specification (including the accompanying claims, abstract, and drawings), as well as all processes or units of any method or apparatus disclosed herein, may be combined in any combination. Unless expressly stated otherwise, each feature disclosed in this specification (including the accompanying claims, abstract, and drawings) may be replaced by an alternative feature that provides the same, equivalent, or similar purpose.

Claims

1. A synchronous timing control system for high repetition rate pulsed laser illumination measurement, characterized in that: It includes a first signal generator, a second signal generator, a third signal generator, a laser seed source, a laser amplifier and a camera system; The first signal generator is used to output a first control signal to the laser seed source, and simultaneously output a second control signal as a clock source signal to the second signal generator; the first control signal and the second control signal are both sub-pulse frequency signals, and the frequencies of the two signals are the same; The third signal generator is used to output a third control signal to the laser amplifier and simultaneously output a fourth control signal to the second signal generator; the third control signal and the fourth control signal are both low-repetition-rate macro-pulse trigger signals, and both have the same frequency and pulse width, and the relative delay is adjustable; The laser amplifier amplifies only the laser sub-pulses within the high level range of the third control signal according to the high level range of the third control signal; The second signal generator generates a camera trigger signal according to the second control signal, and outputs the camera trigger signal to the camera system only within a high level range of the fourth control signal.

2. The synchronous timing control system for high repetition rate burst pulse laser illumination measurement according to claim 1, characterized in that: The frequency of the sub-pulse frequency signal is higher than the maximum shooting frequency that can be achieved when a single camera in the camera system is working.

3. The synchronous timing control system for high repetition rate pulsed laser illumination measurement according to claim 1, characterized in that: The third signal generator is configured to operate by internal triggering, or to operate by receiving an external trigger signal, so that the third signal generator can be synchronized with an external device.

4. The synchronous timing control system for high repetition rate burst pulse laser illumination measurement according to claim 1, characterized in that: The frequency of the low repetition rate macro pulse trigger signal is lower than the frequency of the sub pulse frequency signal.

5. The synchronous timing control system for high repetition rate burst pulse laser illumination measurement according to claim 1, characterized in that: The second signal generator can perform frequency division processing on the second control signal to generate the camera trigger signal.

6. The synchronous timing control system for high repetition rate burst pulse laser illumination measurement according to claim 5, characterized in that: The second signal generator is configured to operate in a gated mode and output the camera trigger signal only when receiving a high level of the fourth control signal, so that the exposure time of the camera system is synchronized with the laser pulse amplified by the laser amplifier.

7. The synchronous timing control system for high repetition rate burst pulse laser illumination measurement according to claim 1, characterized in that: The camera system includes a single camera or multiple cameras; When the camera system includes multiple cameras, the second signal generator is provided with multiple output ports, and the delay and pulse width between the camera trigger signals output by each output port can be adjusted individually to adapt to the synchronous shooting of multiple cameras in the camera system.

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