Multi-segment dual-scan imaging streak camera, laser processing monitoring system and method

Abstract

This invention belongs to the field of laser processing monitoring, specifically relating to a multi-segment dual-scan imaging fringe camera, a laser processing monitoring system, and a method. The camera includes a photocathode, an accelerating grid, a focusing electrode, an X-direction deflection plate, a Y-direction deflection plate, and a fluorescent screen, arranged coaxially along the photoelectron beam transmission direction. The X-direction and Y-direction deflection plates are orthogonally arranged and connected to independent scanning drive power supplies. The first and second scanning drive signals received by the plates are coordinated in timing, causing a single pulse to correspond to a photoelectron beam forming a fringe image along the X-direction, and multiple pulses to correspond to fringe images that are separated along the Y-direction. This camera requires no external illumination or ultra-high frame rate hardware; a single exposure can achieve independent segmentation imaging of several pulses of ultrafast processes. Combined with cathode gating, the signal-to-noise ratio can be improved, making it suitable for monitoring several-pulse laser processing.

Description

Technical Field

[0001] This invention belongs to the field of laser processing monitoring, specifically relating to a multi-span dual-scan imaging stripe camera, a laser processing monitoring system, and a method. Background Technology

[0002] In pulsed laser precision machining, the interaction between the laser and the material instantaneously induces the generation of a plasma plume. The spatiotemporal radiation boundary morphology of the plume directly reflects the ablation and stripping effect of the laser on the material. Simultaneously, a significant plasma shielding effect exists within the bursting plume, which not only blocks the energy of subsequent laser pulses, weakening the efficiency of subsequent material removal, but also disturbs the thermal field distribution of the processing area. This easily leads to problems such as burrs on the processing edges, surface unevenness, and accumulation of micro-defects, directly affecting the forming accuracy and surface quality of laser processing. Therefore, accurately capturing the entire process of plume bursting, expanding, and attenuating for each laser pulse in a multi-pulse processing sequence is a core prerequisite for analyzing the laser processing mechanism, revealing the plume shielding accumulation effect, optimizing process parameters, and improving processing quality.

[0003] Existing laser plume monitoring methods mostly rely on high frame rate cameras or traditional single-axis scanning fringe imaging technology, which have obvious technical limitations: High frame rate cameras are limited by hardware sampling frame rates and cannot match the ultrafast transient evolution rate of femtosecond laser plumes at the nanosecond / picosecond level. They have insufficient temporal resolution, making it difficult to capture the fine spatiotemporal radiation characteristics at the initial stage of plume outbreaks. In addition, they generally require auxiliary illumination systems to assist in imaging, resulting in poor adaptability to various operating conditions. Traditional single-axis fringe cameras only have single-dimensional temporal scanning capabilities. During the processing of several pulses, plume radiation signals from different time sequences and different evolutionary states will spatially overlap and stack, making it impossible to independently distinguish and segment the evolution process of a single-pulse plume and to reveal the cumulative interference mechanism of several pulse processing. Summary of the Invention

[0004] The purpose of this invention is to provide a multi-span dual-scan imaging stripe camera, a laser processing monitoring system and method, to solve the technical problems of insufficient temporal resolution and the inability to independently distinguish several overlapping pulse signals in existing laser plume monitoring methods.

[0005] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, this application discloses a multi-span dual-scan imaging stripe camera, comprising: a photocathode, an accelerating grid, a focusing electrode, an X-direction deflection plate, a Y-direction deflection plate, and a fluorescent screen arranged coaxially along the photoelectron beam transmission direction. An accelerating gate is positioned behind the photocathode and electrically connected to an external cathode gating module. A focusing electrode is positioned between the accelerating gate and the X-direction deflection plate. The X-direction deflection plate and the Y-direction deflection plate are arranged orthogonally along the photoelectron beam transmission direction, with the X-direction deflection plate positioned in front of the Y-direction deflection plate. The X-direction deflection plate and the Y-direction deflection plate are electrically connected to independent scanning drive power supplies. A phosphor screen is positioned behind the Y-direction deflection plate. The X-direction deflection plate is configured to receive a first scanning drive signal, and the Y-direction deflection plate is configured to receive a second scanning drive signal. The first and second scanning drive signals are coordinated in timing to form a striped image along the X-direction of the photoelectron beam corresponding to a single pulse and to separate the striped images corresponding to several pulses along the Y-direction.

[0006] Optionally, both the X-direction deflection plate and the Y-direction deflection plate are parallel plate electrostatic deflection electrode structures; along the photoelectron beam transmission direction, the X-direction deflection plate forms the pre-stage X-direction deflection electric field, and the Y-direction deflection plate forms the post-stage Y-direction deflection electric field, with the pre-stage X-direction deflection electric field and the post-stage Y-direction deflection electric field being orthogonal to each other.

[0007] Optionally, the accelerating gate is connected to the cathode gating module, which is configured to apply a timing-controllable gating voltage to the accelerating gate; the accelerating gate is located between the photocathode and the focusing electrode.

[0008] Optionally, an image intensifier and a readout camera are sequentially arranged on the rear side of the fluorescent screen; the input end of the image intensifier is optically coupled to the fluorescent screen, and the output end of the image intensifier is optically coupled to the readout camera.

[0009] Optionally, an input optical lens is provided on the front side of the photocathode; the input optical lens is optically coupled to the photocathode to image the light signal to be measured onto the surface of the photocathode.

[0010] Secondly, this application discloses a laser processing monitoring system based on a multi-span dual-scan imaging stripe camera, including the multi-span dual-scan imaging stripe camera described in any one of the above, and further including: a femtosecond laser, a synchronization signal generator, and a target platform; The output end of the femtosecond laser faces the target platform; the input end of the multi-scan imaging stripe camera faces the laser processing area on the target platform; a synchronization signal generator is electrically connected to the femtosecond laser and the multi-scan imaging stripe camera respectively; the synchronization signal generator is configured to receive the trigger signal of the femtosecond laser and output a scanning drive signal and a gating signal synchronized with the laser pulse timing to the multi-scan imaging stripe camera.

[0011] Optionally, the multi-span dual-scan imaging stripe camera includes an X-direction scanning drive power supply, a Y-direction scanning drive power supply, and a gated power supply; The X-direction scanning drive power supply is electrically connected to the X-direction deflection plate, the Y-direction scanning drive power supply is electrically connected to the Y-direction deflection plate, and the gate control power supply is electrically connected to the acceleration gate. The X-direction scanning drive power supply, Y-direction scanning drive power supply, and gate control power supply are all electrically connected to the synchronization signal generator.

[0012] Optionally, the synchronization signal generator outputs a high-speed repetitive scan drive signal to the X-direction scan drive power supply and a stepped scan drive signal to the Y-direction scan drive power supply; the scan rate of the X-direction scan drive power supply is higher than the scan rate of the Y-direction scan drive power supply, and the time resolution of the X-direction scan drive power supply is higher than the time resolution of the Y-direction scan drive power supply.

[0013] Thirdly, this application discloses a laser processing monitoring method based on a multi-segment dual-scan imaging stripe camera, implemented based on the aforementioned laser processing monitoring system based on a multi-segment dual-scan imaging stripe camera. An image intensifier and a readout camera are sequentially arranged on the rear side of the fluorescent screen; an input optical lens is arranged on the front side of the photocathode; the method includes the following steps: The femtosecond laser emits several pulses of laser light toward the target platform, and the synchronization signal generator receives the trigger signal from the femtosecond laser and outputs a synchronization timing signal. The transient light signal generated in the laser processing area is imaged onto a photocathode via an input optical lens, and the photocathode converts the transient light signal into a photoelectron beam; The photoelectron beam enters the X-direction deflection plate after passing through the accelerating gate and focusing electrode. The X-direction deflection plate performs X-direction scanning on the photoelectron beam within a single pulse cycle, so that the temporal evolution information within a single pulse is converted into a spatial fringe image in the X direction. After being deflected in the X direction, the photoelectron beam enters the Y direction deflection plate. The Y direction deflection plate performs Y direction scanning on the photoelectron beams corresponding to several pulses in a single exposure cycle, so that the stripe images corresponding to several pulses are separated from each other along the Y direction. The separated photoelectron beam is incident on the fluorescent screen, which converts it into a visible light image. The image is then captured and output as a multi-frame image by the image intensifier and readout camera.

[0014] Optionally, the accelerating gate receives a gating signal that matches the timing of the laser pulse to select the photoelectron beam within the timing interval of a single pulse; The Y-direction deflection plate receives the stepped scan drive signal, and the X-direction deflection plate receives multiple ramp scan drive signals. The gating signal, the stepped scan drive signal, and the multiple ramp scan drive signal are all synchronized with the laser pulse timing of the femtosecond laser.

[0015] Compared with the prior art, the present invention has the following beneficial effects: This application arranges a photocathode, accelerating grid, focusing electrode, X-direction deflection plate, Y-direction deflection plate, and fluorescent screen coaxially along the photoelectron beam transmission direction. The X-direction and Y-direction deflection plates are orthogonally arranged along the photoelectron beam transmission direction and connected to independent scanning drive power supplies. This allows the first and second scanning drive signals to coordinate in time. Thus, during a single exposure, the photoelectron beam corresponding to a single pulse forms a stripe image along the X-direction, while the stripe images corresponding to several pulses are separated along the Y-direction. Therefore, without relying on external illumination devices or ultra-high frame rate imaging hardware, it can obtain independent, non-spatially overlapping stripe images of several pulses within the same frame. This solves the problem of spatial overlap and stacking of several pulse signals in traditional single-axis scanning stripe imaging, making individual analysis impossible. It also avoids the systematic errors caused by repeated exposures of the same processing process, improving the temporal resolution, data comparability, and monitoring efficiency of monitoring several pulse laser processing processes.

[0016] The laser processing monitoring system disclosed in this application directs the output end of the femtosecond laser toward the target platform, directs the input end of the multi-scan imaging stripe camera toward the laser processing area on the target platform, and electrically connects a synchronization signal generator to both the femtosecond laser and the multi-scan imaging stripe camera. The synchronization signal generator receives the trigger signal from the femtosecond laser and outputs a scanning drive signal and a gating signal synchronized with the laser pulse timing to the multi-scan imaging stripe camera, thereby precisely matching the scanning process and gating process of the multi-scan imaging stripe camera with the emission timing of the femtosecond laser pulses. Therefore, when a femtosecond laser processes the target material at the target platform with several pulses, the multi-segment dual-scan imaging stripe camera can directly acquire multi-segment plume radiation images corresponding to the timing of each laser pulse in a single exposure. It does not require external illumination devices or ultra-high frame rate imaging hardware, nor does it require repeated experiments to collect processing signals of different pulses. It can achieve spatial decoupled monitoring of the entire process of plume bursting, expansion, and attenuation during several pulse laser processing, thus improving the timing accuracy, data comparability, and monitoring efficiency of several pulse laser processing monitoring.

[0017] The method disclosed in this application emits several pulsed lasers to a target platform using a femtosecond laser. A synchronization signal generator receives the trigger signal from the femtosecond laser and outputs a synchronization timing signal. This causes the transient light signal generated in the laser processing area to be imaged onto a photocathode via an input optical lens and converted into a photoelectron beam. The photoelectron beam passes through an accelerating grid and a focusing electrode and then sequentially enters an X-direction deflection plate and a Y-direction deflection plate. The X-direction deflection plate performs X-direction scanning within a single pulse cycle, and the Y-direction deflection plate performs Y-direction scanning on the photoelectron beams corresponding to several pulses within a single exposure cycle. The images are then converted into visible light images by a fluorescent screen and acquired and output by an image intensifier and a readout camera. Therefore, the ultrafast temporal evolution information within a single pulse can be unfolded into a fringe image along the X direction during a single exposure, while the fringe images corresponding to several pulses can be separated from each other along the Y direction. This enables spatial decoupling and independent amplitude segmentation monitoring of the plume radiation process of several pulse laser processing without relying on external illumination devices and ultra-high frame rate imaging hardware. This avoids systematic errors caused by repeated experiments and improves the temporal resolution, data comparability, and monitoring efficiency of monitoring several pulse laser processing processes. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a structural diagram of the laser processing monitoring system based on a multi-span dual-scan imaging stripe camera according to the present invention; Figure 2 This is a diagram of the multi-span dual-scan imaging stripe camera of the present invention; Figure 3 This is a schematic diagram showing the timing coordination of the various working circuit modules of the present invention; Figure 4 This is a schematic diagram illustrating the imaging principle of a traditional streak camera. Figure 5 This is a schematic diagram illustrating the imaging principle of the dual-scan stripe camera of the present invention.

[0020] Wherein: 1-Femtosecond laser; 2-Synchronization signal generator; 3-Multi-span dual-scan imaging stripe camera; 4-Target platform; 5-Photocathode; 6-Accelerating grid; 7-Focusing electrode; 8-X-direction deflection plate; 9-Y-direction deflection plate; 10-Fluorescent screen; 11-Image intensifier; 12-Readout camera; 13-Input optical lens. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper," "lower," "horizontal," or "inner" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of the invention is in use, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, terms such as "first" and "second" are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0025] Furthermore, the use of the term "horizontal" does not imply that the component must be absolutely horizontal, but rather that it can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0026] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention according to the specific circumstances.

[0027] The present invention will now be described in further detail with reference to the accompanying drawings: High-speed repetitive scanning: In the field of streak cameras, a scanning repetition frequency higher than 10kHz is generally defined as high-speed repetitive scanning. Currently, there are commercial streak cameras that operate stably at 100kHz, and scanning cameras in the 1MHz range are also under development. The scanning repetition frequency of this patent is determined by the scanning drive circuit of the first deflection plate. High-speed repetitive scanning above 10kHz can be achieved using a conventional high-speed pulse generator in this field, and the frequency can be adjusted according to application requirements. For typical scenarios such as laser processing, a scanning frequency within 100kHz can fully meet the requirements for processing plume observation, which matches the design positioning of this solution.

[0028] High temporal resolution: In this field, a temporal resolution better than 10 ps (10 - ¹²s) is defined as a high temporal resolution level. This patent is based on a dual-scan, multi-frame electro-optical architecture, designed to achieve a temporal resolution on the order of 1 ps, significantly better than the industry-recognized threshold, and is a typical high-temporal-resolution streak camera. This indicator is jointly determined by the cathode photoelectric response characteristics, the streak image converter tube's temporal resolution, and the deflection plate scanning speed. Those skilled in the art can calculate it using conventional electro-optical simulation tools such as CST Particle Studio and SIMION, combined with conventional streak image converter tube parameters, and there are no obstacles to its implementation.

[0029] High-precision timing synchronization: It is generally accepted in the art that a streak camera's timing jitter at its operating setting is less than 6% of the time resolution of that setting, thus qualifying as high-precision timing synchronization. For example, at the standard 500ps fastest time resolution setting, a timing jitter of less than 30ps meets the requirement. The timing synchronization in this patent is ensured by a synchronization trigger module. Using a commonly used high-precision digital signal generator (such as the DG-645), a timing accuracy within 5ps can be achieved, far exceeding industry accuracy requirements and representing a standard component selection.

[0030] See Figure 2 This application discloses a multi-span dual-scan imaging stripe camera, comprising: a photocathode 5, an accelerating grid 6, a focusing electrode 7, an X-direction deflection plate 8, a Y-direction deflection plate 9, and a fluorescent screen 10 arranged coaxially along the photoelectron beam transmission direction. An accelerating gate 6 is disposed behind the photocathode 5 and electrically connected to the cathode gating module; a focusing electrode 7 is disposed between the accelerating gate 6 and the X-direction deflection plate 8; the X-direction deflection plate 8 and the Y-direction deflection plate 9 are arranged orthogonally in the direction of photoelectron beam transmission, with the X-direction deflection plate 8 located in front of the Y-direction deflection plate 9, and the X-direction deflection plate 8 and the Y-direction deflection plate 9 being electrically connected to independent scanning drive power supplies respectively; a phosphor screen 10 is disposed behind the Y-direction deflection plate 9; the X-direction deflection plate 8 is configured to receive a first scanning drive signal, and the Y-direction deflection plate 9 is configured to receive a second scanning drive signal. The first scanning drive signal and the second scanning drive signal are coordinated in timing to form a striped image along the X-direction of the photoelectron beam corresponding to a single pulse and to separate the striped images corresponding to several pulses along the Y-direction.

[0031] By sequentially and coaxially arranging the photocathode 5, accelerating grid 6, focusing electrode 7, X-direction deflection plate 8, Y-direction deflection plate 9, and fluorescent screen 10 along the photoelectron beam transmission direction, and by orthogonally arranging the X-direction deflection plate 8 and Y-direction deflection plate 9 along the photoelectron beam transmission direction and electrically connecting them to independent scanning drive power supplies, and by having the X-direction deflection plate 8 receive the first scanning drive signal and the Y-direction deflection plate 9 receive the second scanning drive signal in a timely manner, a single pulse of photoelectron beam is formed into a stripe image along the X-direction on the same fluorescent screen 10, while stripe images corresponding to several pulses are separated along the Y-direction. Therefore, without relying on external illumination devices and ultra-high frame rate imaging hardware, several pulses of ultrafast process images can be spatially presented independently in a single exposure, avoiding the spatial overlap and stacking of several pulse signals in traditional single-axis scanning methods. This provides a structural basis for independently analyzing the plume evolution process pulse by pulse during several-pulse time-series laser processing.

[0032] In some embodiments, both the X-direction deflection plate 8 and the Y-direction deflection plate 9 are parallel-plate electrostatic deflection electrode structures. Along the photoelectron beam transmission direction, the X-direction deflection plate 8 forms a pre-stage X-direction deflection electric field, and the Y-direction deflection plate 9 forms a post-stage Y-direction deflection electric field. The pre-stage X-direction deflection electric field and the post-stage Y-direction deflection electric field are orthogonal to each other. Both the X-direction deflection plate 8 and the Y-direction deflection plate 9 adopt a parallel-plate electrostatic deflection electrode structure, forming mutually orthogonal pre-stage X-direction deflection electric fields and post-stage Y-direction deflection electric fields respectively along the photoelectron beam transmission direction. This achieves independent deflection modulation of the photoelectron beam in both the X and Y directions with a simple and stable electrode structure, ensuring the imaging effect of single-pulse stripe images unfolding along the X direction and multiple pulse stripe images separating along the Y direction.

[0033] In some embodiments, the accelerating gate 6 is connected to the cathode gating module, which is configured to apply a timing-controllable gating voltage to the accelerating gate 6. The accelerating gate 6 is located between the photocathode 5 and the focusing electrode 7. The accelerating gate 6, located between the photocathode 5 and the focusing electrode 7 and connected to the cathode gating module, allows for the application of a timing-controllable gating voltage by the cathode gating module. This enables precise gating of the photoelectron beam within any time interval of a single pulse and background noise suppression without altering the overall framing arrangement of the pulses formed by dual-axis scanning, thereby improving the clarity and signal-to-noise ratio of the framing image.

[0034] Furthermore, the cathode gating module is a functional module used in vacuum optoelectronic devices such as streak cameras and image intensifiers to control the on / off state of photocathode electron emission. Its core function is to apply a timing-controllable gating voltage to the photocathode or accelerating grid to select and extract the photoelectron beam. Its principle is similar to that of the image intensifier gating module. When a high level is applied, the cathode works normally, and photoelectrons are emitted normally and participate in imaging; when a low level is applied, photoelectron emission from the cathode is suppressed, there is no photoelectron output, and no imaging occurs. By switching the high and low levels sequentially, the on / off state of photoelectron output can be controlled, selecting only the light signal in a specific time interval to participate in imaging. In this application, this module is electrically connected to the accelerating grid and applies a timing-controllable gating voltage to the accelerating grid. Its functions are twofold: first, to close the photoelectron channel in the non-observation interval, suppressing dark current and ambient stray light, and improving the signal-to-noise ratio; second, to open the photoelectron channel in the observation interval, realizing signal clipping and extraction of any time interval within a single pulse. This gating system only optimizes the extraction of transient signals within a single pulse, without altering the overall multi-pulse framing arrangement structure formed by dual-axis scanning, and does not participate in the core scanning logic of multi-pulse framing imaging. Its specific circuit structure (such as the high-voltage pulse drive circuit and level conversion circuit) and driving method are conventional designs in the field. Those skilled in the art can implement it by combining the timing-controllable gating functional requirements with well-known cathode high-voltage gating circuit designs. The existing technical literature "Cathode-Gated Optical Stripe Camera" (Li Jin et al., Infrared and Laser Engineering, 2021, Vol. 50, No. 12, pp. 458-464) has already disclosed specific implementation methods for similar modules.

[0035] In some embodiments, an image intensifier 11 and a readout camera 12 are sequentially arranged on the rear side of the fluorescent screen 10; the input end of the image intensifier 11 is optically coupled to the fluorescent screen 10, and the output end of the image intensifier 11 is optically coupled to the readout camera 12, thereby amplifying the multi-frame optical image output by the fluorescent screen 10 and having it acquired and output by the readout camera 12 in one go, thereby improving the readout quality and acquisition efficiency of weak transient images.

[0036] In some embodiments, an input optical lens 13 is provided on the front side of the photocathode 5; the input optical lens 13 is optically coupled to the photocathode 5 and is used to image the light signal to be measured onto the surface of the photocathode 5.

[0037] This application also discloses a laser processing monitoring system based on a multi-span dual-scan imaging stripe camera, including the multi-span dual-scan imaging stripe camera 3 as described in any one of the above, and further including: a femtosecond laser 1, a synchronization signal generator 2, and a target platform 4; The output end of the femtosecond laser 1 faces the target platform 4; the input end of the multi-scan imaging stripe camera 3 faces the laser processing area on the target platform 4; the synchronization signal generator 2 is electrically connected to both the femtosecond laser 1 and the multi-scan imaging stripe camera 3; the synchronization signal generator 2 is configured to receive the trigger signal from the femtosecond laser 1 and output a scanning drive signal and a gating signal synchronized with the laser pulse timing to the multi-scan imaging stripe camera 3. Through the above connection relationship between the femtosecond laser 1, the synchronization signal generator 2, the multi-scan imaging stripe camera 3, and the target platform 4, the laser pulse, the scanning drive signal, and the gating signal are kept in high-precision timing synchronization, thereby synchronously acquiring the transient radiation signals corresponding to several pulses generated in the laser processing area of ​​the target platform 4 during a single processing cycle, realizing pulse-by-pulse independent monitoring of several pulse laser processing processes.

[0038] In some embodiments, the multi-span dual-scan imaging stripe camera 3 includes an X-direction scanning drive power supply, a Y-direction scanning drive power supply, and a gated power supply; The X-direction scanning drive power supply is electrically connected to the X-direction deflection plate 8, the Y-direction scanning drive power supply is electrically connected to the Y-direction deflection plate 9, and the gate control power supply is electrically connected to the acceleration gate 6. The X-direction scanning drive power supply, Y-direction scanning drive power supply, and gating power supply are all electrically connected to the synchronization signal generator 2. Through the above-mentioned electrical connection structure of independent driving and unified connection to the synchronization signal generator 2, the X-direction deflection plate 8, Y-direction deflection plate 9, and acceleration gate 6 obtain independently controllable scanning drive signals and gating signals, and work together under the same timing reference, ensuring the timing accuracy between dual-axis scanning and gating selection and the stability of multi-module coordination.

[0039] In some embodiments, the synchronization signal generator 2 outputs a high-speed repetitive scan drive signal to the X-direction scan drive power supply and a stepped scan drive signal to the Y-direction scan drive power supply. The scan rate of the X-direction scan drive power supply is higher than that of the Y-direction scan drive power supply, and the time resolution of the X-direction scan drive power supply is higher than that of the Y-direction scan drive power supply. Through the differentiated configuration of the X-direction and Y-direction scan drive power supplies in terms of scan speed, scan rate, and time resolution, the X-direction deflection plate 8 can capture the ultrafast transient evolution process inside a single pulse with high time resolution, while the Y-direction deflection plate 9 can cover the overall timing cycle of several pulse processing with a wide time range. Thus, without sacrificing the ultrafast time resolution of a single pulse, a wide-range timing coverage and parallel monitoring of several pulse processes can be achieved.

[0040] This application also discloses a laser processing monitoring method based on a multi-scanning dual-scanning imaging stripe camera, implemented based on the aforementioned laser processing monitoring system based on a multi-scanning dual-scanning imaging stripe camera. An image intensifier 11 and a readout camera 12 are sequentially arranged on the rear side of the fluorescent screen 10; an input optical lens 13 is arranged on the front side of the photocathode 5; the method includes the following steps: The femtosecond laser 1 emits several pulsed lasers toward the target platform 4, and the synchronization signal generator 2 receives the trigger signal of the femtosecond laser 1 and outputs the synchronization timing signal. The transient light signal generated in the laser processing area is imaged onto the photocathode 5 via the input optical lens 13, and the photocathode 5 converts the transient light signal into a photoelectron beam; The photoelectron beam enters the X-direction deflection plate 8 after passing through the accelerating gate 6 and the focusing electrode 7. The X-direction deflection plate 8 performs X-direction scanning on the photoelectron beam within a single pulse cycle, so that the temporal evolution information within a single pulse is converted into a spatial fringe image in the X direction. After being deflected in the X direction, the photoelectron beam enters the Y-direction deflection plate 9. The Y-direction deflection plate 9 performs Y-direction scanning on the photoelectron beams corresponding to several pulses in a single exposure cycle, so that the stripe images corresponding to several pulses are separated from each other along the Y direction. The separated photoelectron beam is incident on the fluorescent screen 10, where it is converted into a visible light image. This image is then acquired and output as a multi-frame image via the image intensifier 11 and readout camera 12. Through these steps, the transient radiation signals corresponding to multiple laser pulses can be converted into single-pulse fringe images unfolding along the X-direction and separated along the Y-direction within a single exposure cycle. These multi-frame images are then acquired and output simultaneously via the fluorescent screen 10, image intensifier 11, and readout camera 12. This eliminates the need for repeated experiments, allowing independent analysis of the ultrafast evolution process corresponding to each pulse during several pulse laser processing operations. This improves the comparability, accuracy, and monitoring efficiency of the monitoring data from several pulse processing operations.

[0041] In some embodiments, the accelerating gate 6 receives a gating signal that matches the timing of the laser pulse to select the photoelectron beam within the timing interval of a single pulse; The Y-direction deflection plate 9 receives the stepped scan drive signal, and the X-direction deflection plate 8 receives the multiple ramp scan drive signal. The gating signal, the stepped scan drive signal, and the multiple ramp scan drive signals are all synchronized with the laser pulse timing of the femtosecond laser 1. By receiving the timing-matched gating signal through the accelerating gate 6, the photoelectron beam within any timing interval of a single pulse can be selected without changing the overall sizing arrangement of several pulses, suppressing background noise and invalid signals. At the same time, the Y-direction deflection plate 9 receives the stepped scan drive signal to match an independent and fixed longitudinal imaging position for each pulse, and the X-direction deflection plate 8 receives the multiple ramp scan drive signals to sequentially spread the stripe images corresponding to different pulses along the horizontal direction within a single exposure cycle. All signals are synchronized with the laser pulse timing of the femtosecond laser 1, thereby ensuring that the sizing images of several pulses are spatially independent and temporally corresponding, improving the accuracy of plume boundary recognition and the signal-to-noise ratio of process monitoring.

[0042] Example 1: A simulation example using 3×3 pulses This embodiment employs a dual-time-axis electronic collaborative scanning architecture constructed using two orthogonal deflection plates. Through the cooperation of two differentiated dedicated scanning mechanisms, stable multi-fraction independent imaging monitoring of several pulsed plumes in ultrafast processes is achieved. Specifically, the Y-direction deflection plate 9 adopts a stepped scanning mode, relying on the stepped voltage deflection characteristics to match an independent and fixed longitudinal imaging position for the plume radiation signal corresponding to each laser pulse, thus regulating the imaging area of ​​the single-pulse plume and ensuring complete, non-overlapping, and non-missing spatiotemporal radiation information of the single-pulse plume. The X-direction deflection plate 8 adopts a multi-slope scanning mode, continuously completing multiple rounds of linear slope scanning within a single complete exposure cycle. It continuously adjusts the lateral displacement of several pulsed plume signals output sequentially in time, uniformly spreading the plume imaging results corresponding to different pulses along the horizontal direction and completely decoupling them in space. Finally, multiple sets of independent, time-corresponding multi-fraction plume imaging results are formed within the same frame.

[0043] This embodiment eliminates the need for external illumination and ultra-high frame rate imaging hardware. It achieves independent grouping imaging of the spatiotemporal radiation process of several pulsed laser processing streams with a single exposure, completely resolving the technical bottleneck of traditional monitoring methods where signals from several pulsed plumes overlap and cannot be individually analyzed. Furthermore, it can be combined with cathode-gated assisted timing clipping to achieve precise extraction and noise suppression of any temporal interval within a single-pulse plume without altering the overall spatial arrangement of the pulses. This effectively improves plume boundary recognition accuracy and the signal-to-noise ratio of process monitoring, accurately characterizing the coupling relationship between plume shielding effects and material stripping quality under several-pulse processing, thus meeting the high-precision, ultra-fast monitoring requirements of several-pulse time-series laser processing scenarios.

[0044] The core component of this embodiment is a multi-span dual-scan imaging stripe camera 3. (See [link]) Figure 1 The main components of the system include a femtosecond laser 1, a synchronous signal generator 2, a multi-span dual-scan imaging stripe camera 3, and a target platform 4.

[0045] See Figure 2 The multi-span dual-scan imaging stripe camera 3 is the core imaging device of the apparatus. Its tube body integrates a photocathode 5, an accelerating grid 6, a focusing electrode 7, and orthogonally arranged X-direction deflection plates 8 and Y-direction deflection plates 9. A fluorescent screen 10 is located at the end of the tube body. Simultaneously, the multi-span dual-scan imaging stripe camera 3 is externally equipped with an integrated scanning drive power supply and an image acquisition module, providing a stable high-voltage scanning drive signal to the image inverter tube and completing the acquisition and output of imaging signals. The image acquisition module includes an image intensifier 11 and a readout camera 12. The input end of the image intensifier 11 is optically coupled to the fluorescent screen 10, and the output end of the image intensifier 11 is optically coupled to the readout camera 12.

[0046] In the multi-span dual-scan imaging streak camera 3, both the X-direction deflector plate 8 and the Y-direction deflector plate 9 adopt a parallel plate electrostatic deflection electrode structure. Based on the hierarchical arrangement of the photoelectron beam transmission path, the two-stage deflection components have differentiated functions and driving modes to achieve dual-dimensional scanning imaging: along the photoelectron beam transmission direction, the front stage is the X-direction deflector plate 8, matched with a high-speed repetitive scanning driving signal, which has the technical characteristics of narrow time range and high time resolution, and can accurately capture the ultrafast transient process of laser processing; the rear stage is the Y-direction deflector plate 9, matched with a low-speed continuous scanning driving signal, which has the characteristics of wide time range and large electron beam longitudinal offset range, effectively expanding the imaging monitoring time range. Among them, the accelerating grid 6 is arranged behind the photocathode 5, which can apply a timing-controllable gating voltage to achieve precise gating and noise control of the photoelectron beam.

[0047] Inside the vacuum cavity of the multi-scanning dual-scanning imaging stripe camera 3, the functional components are arranged coaxially along the axial transmission direction of the photoelectron beam. The specific arrangement order is as follows: photocathode 5, accelerating grid 6, focusing electrode 7, X-direction deflection plate 8, Y-direction deflection plate 9, and fluorescent screen 10. The X-direction deflection plate 8 and the Y-direction deflection plate 9 form a mutually orthogonal two-dimensional deflection electric field, which can perform X and Y bidirectional deflection modulation on the photoelectron beam. After dual-axis deflection modulation, the photoelectron beam is perpendicularly incident on the fluorescent screen 10 to complete the photoelectric conversion into an image.

[0048] In the external optical system, the femtosecond transient radiation signal to be measured generated during the laser processing is focused by the input optical lens 13 and imaged onto the surface of the photocathode 5. The visualized optical image output by the fluorescent screen 10 is transmitted to the back-end image acquisition module through optical path coupling. The image acquisition module includes an image intensifier 11 and a readout camera 12. The image intensifier 11 amplifies the optical image output by the fluorescent screen 10, and the readout camera 12 acquires the amplified image signal and completes the output, thereby completing the acquisition, storage and subsequent analysis of the transient imaging signal.

[0049] Each core electrical component adopts a connection architecture with independent driving and unified timing synchronization to ensure imaging timing accuracy and multi-module collaborative stability. Specifically, the X-direction deflection plate 8 and Y-direction deflection plate 9 are independently electrically connected to their respective scanning drive power supplies, enabling independent output and control of the dual-axis scanning voltage. The cathode gating module forms an electrical connection with the accelerating grid 6, achieving precise application of the gating voltage. The X-direction scanning drive power supply, Y-direction scanning drive power supply, and gating power supply are all uniformly connected to the synchronization signal generator 2. The synchronization signal generator 2 can receive the trigger signal from the femtosecond laser 1 in real time, using this as a reference to achieve high-precision timing synchronization of the accelerating grid 6 gating signal, the two deflection scanning voltages, and the laser pulse. Simultaneously, the image acquisition module establishes an electrical connection with the synchronization signal generator 2, matching the timing signal to the single complete exposure window of the multi-frame dual-scan imaging stripe camera 3, ensuring precise synchronization between the imaging acquisition process and the laser processing and electronic scanning processes. The overall timing principle of the device is as follows: Figure 3 As shown, the laser pulse evolution timing, accelerating gate gating timing, X-axis scanning timing, and Y-axis scanning timing are synchronized and matched to obtain multiple monitoring signals with different timing sequences. The start and end times of the gating signals corresponding to each module can be arbitrarily and flexibly adjusted according to the processing conditions of several femtosecond laser pulses. At the same time, the gating signals can be configured to a constant-on working mode, which can adapt to the ultrafast imaging monitoring requirements of different pulse intervals, different pulse numbers, and different observation ranges.

[0050] During normal system operation, the transient optical signals generated during the processing of several pulses by the femtosecond laser 1 are calibrated and focused by the input optical lens 13 before being vertically incident on the surface of the photocathode 5 of the multi-frame dual-scan imaging fringe camera 3. Through the external photoelectric effect, the optical signal is converted into an electrical signal, generating a time-series photoelectron beam carrying transient laser processing information. The generated photoelectron beam first passes through the accelerating gate 6. The gating signal output by the accelerating gate 6 is precisely matched with the laser pulse timing, providing a dual control function: on the one hand, it effectively suppresses background interference such as dark current noise and ambient stray light within the exposure cycle of the multi-frame dual-scan imaging fringe camera 3, significantly improving the imaging signal-to-noise ratio; on the other hand, it enables precise clipping and extraction of signals within any time interval of a single laser pulse. It should be noted that this cathode gating control only optimizes the extraction of transient signals within a single pulse and does not change the overall framing arrangement structure of several pulses formed by dual-axis scanning. It does not participate in the core scanning logic of framing imaging of several pulses, and can precisely optimize the single-frame imaging quality while ensuring the integrity of multi-frame imaging.

[0051] After being gated and filtered, the photoelectron beam continues to propagate forward and enters the deflection region of the X-direction deflection plate 8. The high-speed time-varying deflection electric field of the X-direction deflection plate 8 can perform ultrafast scanning of the photoelectron beams corresponding to multiple femtosecond pulses in the X direction, accurately converting the ultrafast temporal evolution information inside one or more single pulses into a spatial fringe image in the X direction. It can completely distinguish the fine ultrafast physical processes at the single-pulse scale, such as plasma evolution, material ablation, and electronic relaxation, during laser processing, and achieve ultra-high temporal resolution single-pulse transient information capture.

[0052] The photoelectron beam carrying the complete temporal evolution information of a single pulse continues to propagate forward and enters the orthogonally arranged Y-direction deflection plate 9. The Y-direction deflection plate 9 outputs a low-speed deflection electric field within a single complete exposure cycle of the multi-frame dual-scan imaging fringe camera 3, continuously controlling the Y-direction offset of multiple sets of single-pulse photoelectron beams that arrive sequentially in time. The total scanning time of the Y-direction deflection plate 9 can completely cover the temporal cycle of processing several femtosecond pulses, so that the single-pulse fringe images corresponding to femtosecond pulses with different timing sequences are uniformly separated and arranged in an orderly manner from top to bottom along the Y direction on the fluorescent screen 10, ultimately forming independent, non-spatially overlapping, and temporally ordered multi-frame images, completing the spatial decoupling of several pulse superimposed signals, and realizing the core function of single-exposure multi-frame imaging.

[0053] After imaging is completed, the back-end image acquisition module acquires a full-screen multi-frame image of the fluorescent screen 10 at once. The image acquisition module includes an image intensifier 11 and a readout camera 12. The image intensifier 11 magnifies the multi-frame image output from the fluorescent screen 10, and the readout camera 12 acquires and outputs the magnified multi-frame image. Each independent frame image completely corresponds to the entire evolution information of a single femtosecond laser pulse. This allows for refined analysis of the ultrafast physical mechanisms of a single pulse, and also enables systematic study of the evolution laws, state differences, and cumulative effects of several pulses of continuous laser processing through multi-frame image comparison. This comprehensively meets the needs of dynamic monitoring and mechanism research of several pulses of ultrafast femtosecond laser processing. The dynamic imaging principle of the device is as follows: Figure 5 As shown. Traditional solutions involve only a single scanning axis in operation, see [link to documentation]. Figure 4 As the laser pulses arrive sequentially in time, the signal stripes corresponding to the laser pulses with different morphologies will overlap in spatial position, which can only achieve single exposure and repeated scanning superposition imaging. It is impossible to separate the individual pulses and make it difficult to independently study the ultrafast evolution process inside a single pulse.

[0054] Example 2 The difference between this embodiment and Embodiment 1 is that Embodiment 1 uses a 3×3 pulse simulation as an example for illustration, while this embodiment provides specific implementation methods with different numbers of pulses imaging simultaneously under different scanning levels, which can be flexibly configured according to the actual monitoring target.

[0055] In this embodiment, the total number of pulses that a multi-span dual-scan imaging stripe camera can simultaneously image in a single exposure is mainly determined by the scanning capability in the Y direction. The Y-direction deflector plate adopts a stepped scanning mode, and the number of steps of the rectangular voltage signal it can load determines the number of pulse rows that can be separated along the Y direction, i.e., the number of span rows. The X-direction deflector plate adopts a multi-slope scanning mode, and the number of slope scanning rounds it completes within a single exposure cycle determines the stripe resolution capability of the temporal information within a single pulse spread along the X direction, i.e., the temporal resolution capability within each span image. Therefore, the number of steps in the Y direction determines the number of separable pulses, and the number of slope scanning rounds in the X direction determines the temporal resolution fineness within a single pulse; both together determine the information capacity of multi-span imaging in a single exposure.

[0056] This embodiment provides several scanning gear configurations. At the low gear, the number of steps on the Y-direction deflection plate is less, and the number of ramp scanning wheels on the X-direction deflection plate is less, suitable for scenarios with fewer pulses and a larger imaging area required for a single frame image. The medium gear is the 3×3 configuration described in Embodiment 1, with 3 steps in the Y-direction and 3 ramp scanning wheels in the X-direction. At the high gear, the number of steps in the Y-direction and the number of ramp scanning wheels in the X-direction increase, allowing for the simultaneous separation of more pulses and achieving higher intra-pulse time resolution, suitable for processing scenarios with a large number of pulses. The differences between the different scanning gears are mainly reflected in three aspects. First, the ramp voltage slope of the X-direction scanning drive power supply; different gears correspond to different slopes, and the slope affects the intra-pulse time resolution in the X-direction. Second, the number of steps of the rectangular voltage signal loaded on the Y-direction deflection plate; the more steps, the more pulse rows can be separated in the Y-direction. Third, the scanning rate of the Y-direction scanning drive power supply; the Y-direction scanning rate is lower than the X-direction scanning rate to ensure that the two-dimensional scans do not interfere with each other.

[0057] In this embodiment, the number of separable pulse rows in the Y direction and the stripe resolution within each pulse in the X direction can be flexibly combined according to the actual monitoring target. Equal row-column combinations, such as 2×2, 3×3, 4×4, 5×5, and 6×6, are suitable for scenarios where the number of pulses is close to the ratio of the number of rows to columns in the CCD array. Unequal row-column combinations, such as 4×6 and 6×4, are suitable for scenarios where the number of pulses is higher in one direction and lower in another. The specific number of pulses per row and column depends on the spatial resolution of the stripe camera and the arrangement of the CCD pixel array in the readout camera. Spatial resolution determines the minimum resolvable stripe spacing in a single frame image, thus limiting the upper limit of the number of rows and columns. The row-to-column ratio of the CCD array affects the selection of the number of rows and columns. For example, for CCD arrays with a row-to-column ratio close to 1:1, it is advisable to choose combinations with similar numbers of rows and columns, such as 3×3 or 4×4; for CCD arrays with a row-to-column ratio of 4:3, combinations such as 4×3 or 3×4 are advisable; and for CCD arrays with a row-to-column ratio of 16:9, combinations such as 4×6 or 6×4 are advisable. Therefore, the specific number of rows and columns for multi-frame imaging can be flexibly adapted to the actual situation of the CCD array and the imaging surface, and is not limited to 3×3 in Example 1.

[0058] In this embodiment, both the pulse and the time interval can be adapted as needed. When the number of pulses is different, the number of steps on the Y-direction deflection plate is adjusted to accommodate different total pulse counts. When the pulse interval is different, the step hold time of the Y-direction scanning drive power supply is adjusted to accommodate different pulse intervals, ensuring that the stripe images corresponding to each pulse are still orderly separated along the Y-direction. When the observation interval is different, the pulse interval to be observed is selected by adjusting the start and end times of the gate signal of the cathode gating module.

[0059] This embodiment demonstrates, through the adaptation of different scanning levels, different combinations of swathes rows and columns, and different pulse numbers and time intervals, that the multi-swathe dual-scan imaging stripe camera is not limited to the 3×3 analog configuration of Embodiment 1, but can be flexibly configured according to the actual monitoring target and CCD array situation.

[0060] In summary, this application achieves multi-fragment independent imaging, breaking through the bottleneck of single-axis scanning technology. By adopting an orthogonal front-to-back dual-time-axis scanning architecture, it can acquire multiple sets of independent, crosstalk-free ultrafast process images, solving the technical problem of overlapping pulse signals and inability to segment and analyze them in traditional single-axis fringe cameras. It is precisely adapted to monitoring scenarios involving the processing of multiple femtosecond pulse sequences and multi-stage ultrafast evolution.

[0061] Significantly reduces experimental errors and improves monitoring accuracy and efficiency. It eliminates the need for multiple repeated experiments to collect processing signals from different pulses; a single experiment can complete the acquisition of several pulse data points. This completely avoids systematic errors caused by factors such as sample microscopic state evolution, femtosecond pulse energy drift, optical path offset, and environmental fluctuations during multiple experiments, greatly improving the comparability, accuracy, and experimental monitoring efficiency of data from several pulse processing steps.

[0062] With clear division of labor between the two axes, it balances imaging adaptability and resolution. It achieves full coverage of a wide range of temporal processes and expands the multi-process parallel monitoring capability of the streak camera without sacrificing ultra-high temporal resolution, perfectly adapting to the complex and ultrafast diagnostic needs of femtosecond laser precision micro-nano fabrication.

[0063] The auxiliary gating optimizes imaging quality, making the system more practical. The cathode gating auxiliary function is retained and used only for noise reduction and timing cropping without changing the core scanning imaging logic. While realizing the innovative multi-frame function, it effectively suppresses background noise and invalid signal interference, further improving the clarity and signal-to-noise ratio of multi-frame images, and making the overall equipment more adaptable to different operating conditions.

[0064] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-frame dual-scan imaging stripe camera, characterized in that, include: A photocathode (5), an accelerating grid (6), a focusing electrode (7), an X-direction deflection plate (8), a Y-direction deflection plate (9), and a fluorescent screen (10) are arranged coaxially along the direction of photoelectron beam transmission. An accelerating gate (6) is disposed on the rear side of the photocathode (5) and electrically connected to an external cathode gating module; a focusing electrode (7) is disposed between the accelerating gate (6) and the X-direction deflection plate (8); the X-direction deflection plate (8) and the Y-direction deflection plate (9) are arranged orthogonally in the direction of photoelectron beam transmission, with the X-direction deflection plate (8) located in front of the Y-direction deflection plate (9), and the X-direction deflection plate (8) and the Y-direction deflection plate (9) being electrically connected to independent scanning drive power supplies respectively; a fluorescent screen (10) is disposed on the rear side of the Y-direction deflection plate (9); the X-direction deflection plate (8) is configured to receive a first scanning drive signal, and the Y-direction deflection plate (9) is configured to receive a second scanning drive signal. The first scanning drive signal and the second scanning drive signal are coordinated in timing to form a striped image along the X direction of the photoelectron beam corresponding to a single pulse and to separate the striped images corresponding to several pulses along the Y direction.

2. The multi-frame dual-scan imaging stripe camera according to claim 1, characterized in that, The X-direction deflection plate (8) and the Y-direction deflection plate (9) are both parallel plate electrostatic deflection electrode structures. Along the photoelectron beam transmission direction, the X-direction deflection plate (8) forms the pre-stage X-direction deflection electric field, and the Y-direction deflection plate (9) forms the post-stage Y-direction deflection electric field. The pre-stage X-direction deflection electric field and the post-stage Y-direction deflection electric field are orthogonal to each other.

3. The multi-frame dual-scan imaging stripe camera according to claim 1, characterized in that, The accelerating gate (6) is connected to the cathode gate module, which is configured to apply a timing-controllable gating voltage to the accelerating gate (6); the accelerating gate (6) is located between the photocathode (5) and the focusing electrode (7).

4. A multi-frame dual-scan imaging stripe camera according to claim 1, characterized in that, An image intensifier (11) and a readout camera (12) are arranged sequentially on the rear side of the fluorescent screen (10); the input end of the image intensifier (11) is optically coupled to the fluorescent screen (10), and the output end of the image intensifier (11) is optically coupled to the readout camera (12).

5. A multi-frame dual-scan imaging stripe camera according to claim 1, characterized in that, An input optical lens (13) is provided on the front side of the photocathode (5); the input optical lens (13) is optically coupled to the photocathode (5) to image the light signal to be measured onto the surface of the photocathode (5).

6. A laser processing monitoring system based on a multi-frame dual-scan imaging stripe camera, characterized in that, The multi-span dual-scan imaging stripe camera (3) according to any one of claims 1 to 5 further includes: a femtosecond laser (1), a synchronization signal generator (2), and a target platform (4). The output end of the femtosecond laser (1) faces the target platform (4); the input end of the multi-scan imaging stripe camera (3) faces the laser processing area at the target platform (4); the synchronization signal generator (2) is electrically connected to the femtosecond laser (1) and the multi-scan imaging stripe camera (3) respectively; the synchronization signal generator (2) is configured to receive the trigger signal of the femtosecond laser (1) and output a scanning drive signal and a gating signal synchronized with the laser pulse timing to the multi-scan imaging stripe camera (3).

7. A laser processing monitoring system based on a multi-span dual-scan imaging stripe camera according to claim 6, characterized in that, The multi-scanning dual-scanning stripe camera (3) includes an X-direction scanning drive power supply and a Y-direction scanning drive power supply, and the laser processing monitoring system also includes a gated power supply; The X-direction scanning drive power supply is electrically connected to the X-direction deflection plate (8), the Y-direction scanning drive power supply is electrically connected to the Y-direction deflection plate (9), and the gate control power supply is electrically connected to the acceleration gate (6). The X-direction scanning drive power supply, Y-direction scanning drive power supply and gate control power supply are all electrically connected to the synchronization signal generator (2).

8. A laser processing monitoring system based on a multi-span dual-scan imaging stripe camera according to claim 7, characterized in that, The synchronization signal generator (2) outputs a high-speed repetitive scanning drive signal to the X-direction scanning drive power supply and a stepped scanning drive signal to the Y-direction scanning drive power supply; the scanning rate of the X-direction scanning drive power supply is higher than that of the Y-direction scanning drive power supply, and the time resolution of the X-direction scanning drive power supply is higher than that of the Y-direction scanning drive power supply.

9. A laser processing monitoring method based on a multi-span dual-scan imaging stripe camera, characterized in that, The laser processing monitoring system based on a multi-span dual-scan imaging stripe camera as described in claim 6 further includes a photocathode (5), a fluorescent screen (10), an image intensifier (11), a readout camera (12), and an input optical lens (13); the laser processing monitoring method includes the following steps: The femtosecond laser (1) emits several pulse lasers to the target platform (4), and the synchronization signal generator (2) receives the trigger signal of the femtosecond laser (1) and outputs the synchronization timing signal; The transient light signal generated in the laser processing area is imaged onto the photocathode (5) via the input optical lens (13), and the photocathode (5) converts the transient light signal into a photoelectron beam; The photoelectron beam enters the X-direction deflection plate (8) after passing through the accelerating gate (6) and the focusing electrode (7). The X-direction deflection plate (8) performs X-direction scanning on the photoelectron beam within a single pulse cycle, so that the temporal evolution information within a single pulse is converted into a spatial stripe image in the X direction. After being deflected in the X direction, the photoelectron beam enters the Y direction deflection plate (9). The Y direction deflection plate (9) performs Y direction scanning on the photoelectron beams corresponding to several pulses in a single exposure cycle, so that the stripe images corresponding to several pulses are separated from each other along the Y direction. The separated photoelectron beam is incident on the fluorescent screen (10), converted into a visible light image by the fluorescent screen (10), and then collected and output as a multi-frame image by the image intensifier (11) and the readout camera (12).

10. A laser processing monitoring method based on a multi-span dual-scan imaging stripe camera according to claim 9, characterized in that, The accelerating gate (6) receives a gating signal that matches the timing of the laser pulse and selects the photoelectron beam within the timing interval of the single pulse. The Y-direction deflection plate (9) receives the stepped scan drive signal, and the X-direction deflection plate (8) receives the multiple ramp scan drive signal. The gating signal, the stepped scan drive signal, and the multiple ramp scan drive signal are all synchronized with the laser pulse timing of the femtosecond laser (1).

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