Calibration system and calibration method for local exposure time and delay of image intensifier based on cathode partition

Abstract

The invention discloses a cathode partition-based image intensifier local exposure time and delay calibration system and calibration method, and solves the influence that gating pulse width and propagation time cannot be distinguished when the whole cathode surface of a gating image intensifier is subjected to shortest exposure time calibration. The exposure time cannot be accurately measured, so that a timing error is introduced; the system comprises a femtosecond pulse laser, a semi-transparent and semi-reflective mirror, a gating power supply module, a CMOS camera, a high-voltage power supply, a signal source, a high-bandwidth oscilloscope, a photoelectric detector and an upper computer. The influence of the gating electric pulse propagation time and the gating electric pulse full width at half maximum on the optical exposure time is decoupled and separated, and is respectively attributed to the sub-region relative delay and the sub-region local exposure time, so that the time resolution capability of the gating image intensifier can be improved, and for the same gating image intensifier, the time resolution capability of the gating image intensifier can be improved. And when gating electric pulse gating with the same full width at half maximum is adopted, the time measurement precision can also be improved.

Description

Technical Field

[0001] The present invention relates to an optical measurement and imaging system and method, and in particular to a cathode partition-based image intensifier local exposure time and delay calibration system and calibration method. Background Art

[0002] The gated image intensifier (GAI) is a key ultrafast optical imaging device widely used in observing a variety of high-speed transient processes. Its core operating mechanism is to respond to photons within a specific time window through fast gated cathode control, enabling the device to complete image acquisition within picoseconds to nanoseconds, followed by exposure time calibration.

[0003] Traditional exposure time calibration methods primarily perform a unified calibration across the entire cathode, known as "global exposure time" calibration. However, in practical applications, due to the limited propagation speed of the gate pulse in the cathode (a fraction of the speed of light), there is a time delay in signal propagation from the gate pulse input to the entire cathode. Especially in large-aperture cathodes, this delay can reach hundreds of picoseconds. This manifests as a mismatch between the turn-on and turn-off times at the cathode center and edges, resulting in an "iris effect." This effect can lead to significant temporal errors in currently widely used high-resolution imaging systems.

[0004] For example, in a time-resolved single-photon imaging system, single-photon events at different locations should be timestamped with their true time-of-flight. However, if a uniform global exposure time is used as a reference for all locations, the difference in turn-on time due to the iris effect will introduce systematic measurement errors. The impact of this error is non-negligible in sub-nanosecond measurement tasks.

[0005] Furthermore, when applied to multi-frame time-resolved imaging of laser-driven plasmas, optical path splitting allows mapping multiple sub-images to different cathode regions, enabling the capture of multiple dynamic frames in a single exposure. However, ignoring the temporal differences in the on / off states of each sub-image region also limits measurement accuracy. Summary of the Invention

[0006] The purpose of the present invention is to solve the problem that the shortest exposure time calibration of the entire cathode surface of a gated image intensifier cannot distinguish the influence of the gated pulse width and propagation time, resulting in an inability to accurately measure the exposure time and thus introducing timing errors. Instead, a local exposure time and delay calibration system and method for an image intensifier based on cathode partitioning are provided.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions: The local exposure time and delay calibration system for image intensifiers based on cathode partitioning is special in that it includes a femtosecond pulse laser, a semi-transparent and semi-reflective mirror, a gated power module, a CMOS camera, a high-voltage power supply, a signal source, a high-bandwidth oscilloscope, a photodetector, and a host computer. The laser pulse emitted by the femtosecond pulse laser is divided into a transmitted beam and a reflected beam through a semi-transparent and semi-reflective mirror, the photodetector is arranged on the optical path of the reflected beam, and the cathode of the gated image intensifier to be calibrated is arranged on the optical path of the transmitted beam; The photodetector is used to convert the reflected light beam into a time reference electrical signal and output it to the first input terminal of the high-bandwidth oscilloscope; The input end of the signal source is connected to the signal output end of the femtosecond pulse laser, and the output end thereof is respectively connected to the gated power supply module and the CMOS camera. The femtosecond pulse laser outputs a laser pulse and a trigger signal a at the same time. The trigger signal a triggers the signal source to generate a trigger signal b for triggering the gated power supply module and a trigger signal c for triggering the CMOS camera. The output end of the gated power supply module is connected to the cathode of the gated image intensifier. The gated power supply module generates a gated electrical pulse according to the trigger signal b, and outputs the gated electrical pulse to the cathode of the gated image intensifier to generate a cathode pulse. The lens of the CMOS camera is arranged relative to the output surface of the phosphor screen of the gated image intensifier, and the output end is connected to the host computer. The trigger signal c triggers the CMOS camera to collect an image of the output surface of the phosphor screen of the gated image intensifier and transmit it to the host computer; The high-voltage power supply is connected to the gated image intensifier and is used to supply power to the gated image intensifier; The second input end of the high-bandwidth oscilloscope is connected to the cathode output end of the gated image intensifier, and is used for receiving the cathode pulse of the gated image intensifier and calculating the time difference with the time reference electrical signal.

[0008] Furthermore, a light homogenizing mirror is provided between the semi-transparent and semi-reflective mirror and the cathode of the gated image intensifier, and the light homogenizing mirror is used to uniformly diffuse the transmitted light beam.

[0009] Furthermore, the gate-controlled electrical pulse output by the gate-controlled power module is a zero-order Gaussian negative pulse with a full width at half maximum value of less than 1 ns and a voltage greater than -200V.

[0010] Furthermore, the bandwidth of the high-bandwidth oscilloscope is ≥8 GHz, and the sampling rate is ≥100 GS / s.

[0011] The local exposure time and delay calibration method of the image intensifier based on cathode partitioning is special in that the local exposure time and delay calibration system of the image intensifier based on cathode partitioning includes the following steps: Step 1: Divide the cathode of the gated image intensifier to be calibrated into multiple sub-areas; estimate the total exposure time of the cathode of the gated image intensifier, set the exposure step length, and calculate the total number of adjustments; Step 2: Turn on the femtosecond pulse laser to emit a laser pulse and simultaneously output trigger signal a. The trigger signal source outputs trigger signal b and trigger signal c. The laser pulse is divided into a transmitted beam and a reflected beam through a semi-transparent and semi-reflective mirror. The reflected beam is incident on a photodetector and converted into a time reference electrical signal. The output delay time of trigger signal b is adjusted by the signal source so that the gated electrical pulse and the transmitted beam reach the cathode of the gated image intensifier at the same time. The gated electrical pulse triggers the cathode of the gated image intensifier to generate a cathode pulse. Step 3: Output the exposure image through the phosphor screen of the gated image intensifier, and trigger the CMOS camera to capture the exposure image through the trigger signal c; at the same time, obtain the time difference between the cathode pulse and the time reference electrical signal through a high-bandwidth oscilloscope; Step 4: Adjust the output delay time of the trigger signal b according to the exposure step length, and return to step 3 until the total number of adjustments is reached to obtain an exposure image sequence that completely covers the cathode of the gated image intensifier; Step 5: Remove the static background of each image in the exposure image sequence and calculate the sum of the pixel grayscale of each sub-region. Construct a curve of the sum of the pixel grayscale of each sub-region versus the delay time and fit it to a Gaussian function. The center time of the Gaussian function is used as the delay time of the sub-region, and the full width at half maximum of the Gaussian function is used as the local exposure time of the sub-region. Step 6: Draw a two-dimensional distribution diagram of the local exposure time and delay time of all sub-regions in each sub-region of the cathode of the gated image intensifier to obtain the time domain response parameter distribution of the cathode of the gated image intensifier, and complete the calibration of the local exposure time and delay of the gated image intensifier.

[0012] Furthermore, step 1 is specifically as follows: According to the mapping relationship between the side of the cathode of the gated image intensifier to be calibrated that receives the transmitted light beam and the equivalent pixels of the CMOS camera, the side of the cathode of the gated image intensifier that receives the transmitted light beam is divided into N rectangular sub-areas, and the sub-areas are numbered i, i=1,…,N.

[0013] Furthermore, the delay time of the trigger signal b relative to the trigger signal c is 0-100s.

[0014] Furthermore, step 5 is specifically as follows: In step 5.1, in the exposure image sequence of the gated image intensifier cathode, the sub-region i of the image captured at the time t when the gated electric pulse reaches the gated image intensifier cathode is , the corresponding background is recorded as ,in, Indicates the horizontal and vertical coordinate positions of the pixels in sub-region i; Step 5.2: Remove the static background of each image in the exposure image sequence and calculate the sum of the pixel grayscale of each sub-region i , the calculation formula is: ; Where, is the pixel set corresponding to sub-region i; Step 5.3: Construct a curve showing the variation of the sum of the pixel grayscales of each sub-region with the delay time, where the delay time is the time t when the gated electric pulse reaches the cathode of the gated image intensifier. Perform a Gaussian fit on the variation curve to obtain a Gaussian function, which is expressed as: ; in, represents the highest amplitude of the Gaussian function in sub-region i, represents the center time of the Gaussian function of sub-region i, represents the standard deviation of the Gaussian function in sub-region i; Step 5.4: The center time of the Gaussian function of sub-region i is used as the delay time of the sub-region , the expression is: ; Step 5.5: Local exposure time of sub-region i The full width at half maximum (FWHM) of the Gaussian function i Export, that is: .

[0015] Beneficial effects of the present invention: (1) The cathode partitioning-based local exposure time and delay calibration system and calibration method for image intensifiers provided by the present invention regard the photocathode of the gated image intensifier as an equivalent pixel or equivalent frame combination surface composed of multiple sub-regions, breaking the traditional understanding limitation of treating the cathode imaging area of ​​the gated image intensifier as a single frame for global calibration; through partitioning processing, shorter optical exposure time can be obtained on gated image intensifiers with larger cathode imaging sizes (such as 25mm, 40mm aperture), realizing imaging capabilities of larger areas and higher spatiotemporal resolution, and further enhancing the adaptability and scalability of large-aperture gated image intensifiers.

[0016] (2) The cathode partition-based image intensifier local exposure time and delay calibration system and calibration method provided by the present invention decouple and separate the effects of the gated electric pulse propagation time and the gated electric pulse half-height width on the optical exposure time, attribute the influence of the gated electric pulse propagation time to the relative delay of the sub-region, and attribute the influence of the gated electric pulse half-height width to the local exposure time of the sub-region, which can improve the time resolution capability of the gated image intensifier. For the same gated image intensifier, when the same half-height width of the gated electric pulse is used for gating, the global exposure time measured by the traditional calibration method is 332ps, while after adopting the present invention, the local exposure time of 195±22ps can be achieved, which can significantly improve the time measurement accuracy.

[0017] (3) The cathode partition-based image intensifier local exposure time and delay calibration system and calibration method provided by the present invention can eliminate the single-photon time error introduced by the iris effect of the gated image intensifier in different sub-regions in single-photon imaging scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic structural diagram of an embodiment of a cathode partition-based image intensifier local exposure time and delay calibration system provided by the present invention; Figure 2 The exposure image sequence obtained with different delay times in step 3 of the embodiment of the cathode partition-based image intensifier local exposure time and delay calibration method provided by the present invention; Figure 3 In an embodiment of the cathode partitioning-based image intensifier local exposure time and delay calibration method provided by the present invention, a two-dimensional distribution diagram of the local exposure time and delay time of a 64×64 pixel sub-region on the cathode imaging area; Among them, (a) is a two-dimensional distribution diagram of the local exposure time of a 64×64 pixel sub-area on the cathode imaging area, and (b) is a two-dimensional distribution diagram of the delay time of a 64×64 pixel sub-area on the cathode imaging area; Reference numerals: 1-Femtosecond pulse laser; 2-Half-transparent, half-reflective mirror; 3-Light homogenizer; 4-Gated image intensifier; 5-Gated power module; 6-CMOS camera; 7-High-voltage power supply; 8-Signal source; 9-High-bandwidth oscilloscope; 10-Photodetector; 11-Host computer. DETAILED DESCRIPTION

[0019] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some of the embodiments of the present invention, rather than 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.

[0020] This embodiment provides a local exposure time and delay calibration system for an image intensifier based on cathode partitioning, such as Figure 1 As shown, it includes a femtosecond pulse laser 1, a semi-transparent and semi-reflective mirror 2, a homogenizing mirror 3, a gated power supply module 5, a CMOS camera 6, a high-voltage power supply 7, a signal source 8, a high-bandwidth oscilloscope 9, a photodetector 10 and a host computer 11.

[0021] Among them, the femtosecond pulse laser 1 (typical parameter pulse width 220 femtoseconds) emits a laser pulse which is divided into a transmitted beam and a reflected beam through a semi-transparent and semi-reflective mirror 2. The homogenizer 3 and the cathode of the gated image intensifier 4 to be calibrated are arranged in sequence on the optical path where the transmitted beam is located. The transmitted beam passes through the homogenizer 3 and is incident on the cathode of the gated image intensifier 4. The photodetector 10 is arranged on the optical path where the reflected beam is located. The reflected beam is incident on the photodetector 10, which converts the reflected beam into a time reference electrical signal.

[0022] The input end of the signal source 8 is connected to the signal output end of the femtosecond pulse laser 1, and its output end is respectively connected to the gated power module 5 and the CMOS camera 6. The femtosecond pulse laser 1 outputs a laser pulse and simultaneously outputs a trigger signal a synchronized with the laser pulse. The trigger signal a triggers the signal source 8 to generate a trigger signal b for triggering the gated power module 5 and a trigger signal c for triggering the CMOS camera 6.

[0023] The output end of the gated power supply module 5 is connected to the cathode of the gated image intensifier 4. The trigger signal b triggers the gated power supply module 5 to generate a gated electrical pulse, which is input into the cathode of the gated image intensifier 4 to generate a cathode pulse; wherein the gated electrical pulse is a zero-order Gaussian negative pulse with a half-maximum full width value of 170ps and a voltage of -270V.

[0024] In this embodiment, by adjusting the delay time of trigger signal b output by the signal source, the time at which the gate pulse reaches the cathode of gated image intensifier 4 can be precisely adjusted, with an adjustment step accuracy of 10 ps. When the gate pulse and the laser pulse arrive at the cathode of gated image intensifier 4 simultaneously, an exposure image is obtained.

[0025] The lens of the CMOS camera 6 is arranged relative to the fluorescent screen output surface of the gated image intensifier 4, and the output end is connected to the host computer 11. The trigger signal c triggers the CMOS camera 6 to capture the image of the fluorescent screen output surface of the gated image intensifier 4 and transmit it to the host computer 11.

[0026] The high-voltage power supply 7 is connected to the gated image intensifier 4 and is used to provide a static operating voltage to the microchannel plate (MCP) and the phosphor screen of the gated image intensifier 4 .

[0027] The photodetector 10 is connected to the first input terminal of the high-bandwidth oscilloscope 9, and the second input terminal of the high-bandwidth oscilloscope 9 is connected to the cathode output terminal of the gated image intensifier 4. The high-bandwidth oscilloscope 9 is used to receive the cathode pulse of the gated image intensifier 4 and calculate the time difference between the high-bandwidth oscilloscope 9 and the time reference electrical signal, which can accurately measure the arrival time of the gated pulse. At the same time, the laser pulse passes through the reflected light beam of the semi-transparent and semi-reflective mirror 2 and is incident on the photodetector 10, obtaining a time reference electrical signal for triggering the high-bandwidth oscilloscope 9. By comparing the cathode pulse of the gated image intensifier 4 with the time reference electrical signal, the trigger jitter of the electronic system can be eliminated and the arrival time of the gated electrical pulse can be accurately measured. Among them, the bandwidth of the high-bandwidth oscilloscope 9 is ≥8GHz, and the sampling rate is ≥100GS / s.

[0028] This embodiment also provides a cathode-zoned image intensifier local exposure time and delay calibration method. This method is used to calibrate a gated image intensifier (4) with an S25 cathode. The gated image intensifier (4) has an 18 mm diameter and incorporates a microstructured metal lower electrode layer within the cathode, which improves the propagation performance of the gated pulse. Unlike traditional gated image intensifiers, this device can monitor the propagation arrival time of the gated pulse in real time.

[0029] The local exposure time and delay calibration method of an image intensifier based on cathode partitioning is based on the above-mentioned local exposure time and delay calibration system of an image intensifier based on cathode partitioning, and includes the following steps: Step 1: According to the mapping relationship between the side of the cathode of the gated image intensifier 4 to be calibrated that receives the transmitted light beam and the equivalent pixels of the CMOS camera 6, the side of the cathode of the gated image intensifier 4 that receives the transmitted light beam is divided into N rectangular sub-areas, such as 16×16, 32×32, 64×64, etc., and the sub-areas are numbered i, i=1,…,N.

[0030] The total cathode exposure time of the gated image intensifier 4 is estimated, the exposure step length is set, and the total number of adjustments is calculated.

[0031] Step 2: Turn on the femtosecond pulse laser 1 to output a laser pulse with a pulse width of 220 femtoseconds, and at the same time output a trigger signal a to trigger the signal source 8 to output trigger signals b and trigger signals c. The output delay time of the trigger signal b is adjusted by the signal source 8 to trigger the gated power supply module 5 to generate a gated electric pulse which is a zero-order Gaussian negative pulse with a half-width value of 170ps and a voltage of -270V; the laser pulse is divided into a transmitted beam and a reflected beam through the semi-transparent and semi-reflective mirror 2, and the reflected beam is incident on the photodetector 10 and converted into a time reference electrical signal. The gated electric pulse and the transmitted beam reach the cathode of the gated image intensifier 4 at the same time, and the gated electric pulse triggers the cathode of the gated image intensifier 4 to generate a cathode pulse.

[0032] Step 3: Output the exposure image through the fluorescent screen of the gated image intensifier 4, and trigger the CMOS camera 6 to collect the exposure image through the trigger signal c; at the same time, obtain the time difference between the cathode pulse and the time reference electrical signal through the high-bandwidth oscilloscope 9.

[0033] Step 4: gradually adjust the output delay time of the trigger signal b according to the exposure step length, return to step 3, until the total number of adjustments is reached, and obtain an exposure image sequence that covers the cathode of the gated image intensifier 4 as a whole, such as Figure 2 As shown in FIG, a sequence of exposure images obtained with different delay times is shown, wherein the delay moments of the multiple images are 0 ps, ​​45 ps, 86 ps, 120 ps, ​​172 ps, 200 ps, ​​235 ps, 258 ps, 298 ps, 332 ps, 395 ps, and 458 ps, respectively.

[0034] Step 5: Remove the static background of each image in the exposure image sequence and calculate the sum of the pixel grayscale of each sub-region respectively; construct a curve of the sum of the pixel grayscale of each sub-region versus the delay time and fit it to a Gaussian function, taking the center time of the Gaussian function as the delay time of the sub-region and the full width at half maximum of the Gaussian function as the local exposure time of the sub-region. Specifically: Step 5.1: In the exposure image sequence of the cathode of the gated image intensifier 4, the sub-region i of the image captured at the time t when the gated electric pulse reaches the cathode of the gated image intensifier 4 is , the corresponding background is recorded as ,in, Indicates the horizontal and vertical coordinate positions of the pixels in sub-region i.

[0035] Step 5.2: Remove the static background of each image in the exposure image sequence and calculate the sum of the pixel grayscale of each sub-region i , the calculation formula is: ; Where, is the pixel set corresponding to sub-region i; Step 5.3: Construct a curve showing the change of the sum of the pixel grayscales of each sub-region with the delay time, where the delay time is the time t when the gated electric pulse reaches the cathode of the gated image intensifier 4. Then, perform Gaussian fitting on the change curve to obtain a Gaussian function, which is expressed as: ; in, represents the highest amplitude of the Gaussian function in sub-region i, represents the center time of the Gaussian function of sub-region i, represents the standard deviation of the Gaussian function in sub-region i; Step 5.4: The N sub-regions are considered as N independent frames or independent pixels. When the sub-regions are divided into small enough parts, the effect of the gated electric pulse propagating within the sub-region on the optical exposure time of the entire sub-region will be negligible, and the local exposure time of the sub-region will be determined only by the half-maximum width of the gated electric pulse. For the entire cathode, the effect of the gated electric pulse propagation time on the cathode of the gated image intensifier 4 on the optical exposure time of the entire cathode will be converted into the exposure delay time between each sub-region. , and then the center time of the Gaussian function of sub-region i is used as the delay time of the sub-region , the expression is: ; Step 5.5: Local exposure time of sub-region i The full width at half maximum (FWHM) of the Gaussian function i Export, that is: .

[0036] Step 6: Draw a two-dimensional distribution diagram of the local exposure time and the delay time of all sub-regions on each sub-region of the cathode of the gated image intensifier 4 to obtain the time domain response parameter distribution of the cathode of the gated image intensifier 4, and complete the calibration of the local exposure time and delay of the gated image intensifier, as shown in Figure 6. Figure 3 As shown, it is a two-dimensional distribution diagram of the local exposure time and the delay time of a 64×64 pixel sub-area on the cathode imaging area, the horizontal axis represents the X-axis pixel position, and the vertical axis represents the Y-axis pixel position; among them, (a) is the two-dimensional distribution diagram of the local exposure time of the 64×64 pixel sub-area on the cathode imaging area, and (b) is the two-dimensional distribution diagram of the delay time of the 64×64 pixel sub-area on the cathode imaging area.

[0037] according to Figure 3As shown in Figures (a) and (b), the calibration method of this embodiment can be used in subsequent time-of-flight measurements. Based on the location of a single-photon event, the temporal response characteristics of the corresponding subregion can be retrieved, enabling timestamp correction at the hundred-picosecond level. In ultrafast region-based imaging, this calibration result can also be used to correct exposure and delay times for different subregions of the same cathode, significantly improving the accuracy of ultrafast imaging time measurements.

[0038] The above description is merely a specific embodiment of the present invention, and a comparison of the effects of the specific embodiment with the relevant comparative examples. However, the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention shall be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope of protection of the claims.

Claims

1. Image intensifier local exposure time and delay calibration system based on cathode partitioning, characterized by: It includes a femtosecond pulse laser (1), a semi-transparent and semi-reflective mirror (2), a gated power supply module (5), a CMOS camera (6), a high-voltage power supply (7), a signal source (8), a high-bandwidth oscilloscope (9), a photodetector (10), and a host computer (11); The femtosecond pulse laser (1) emits a laser pulse which is divided into a transmitted light beam and a reflected light beam through a semi-transparent and semi-reflective mirror (2); the photodetector (10) is arranged on the optical path where the reflected light beam is located; and the cathode of the gated image intensifier (4) to be calibrated is arranged on the optical path where the transmitted light beam is located; The photodetector (10) is used to convert the reflected light beam into a time reference electrical signal and output it to the first input end of the high-bandwidth oscilloscope (9); The input end of the signal source (8) is connected to the signal output end of the femtosecond pulse laser (1), and the output end thereof is respectively connected to the gated power supply module (5) and the CMOS camera (6). The femtosecond pulse laser (1) outputs a laser pulse and simultaneously outputs a trigger signal a. The trigger signal a triggers the signal source (8) to generate a trigger signal b for triggering the gated power supply module (5) and a trigger signal c for triggering the CMOS camera (6). The output end of the gated power supply module (5) is connected to the cathode of the gated image intensifier (4). The gated power supply module (5) generates a gated electrical pulse according to the trigger signal b, and outputs the gated electrical pulse to the cathode of the gated image intensifier (4) to generate a cathode pulse. The lens of the CMOS camera (6) is arranged relative to the output surface of the fluorescent screen of the gated image intensifier (4), and the output end is connected to the host computer (11). The trigger signal c triggers the CMOS camera (6) to collect an image of the output surface of the fluorescent screen of the gated image intensifier (4) and transmit it to the host computer (11); The high-voltage power supply (7) is connected to the gated image intensifier (4) and is used to supply power to the gated image intensifier (4); The second input end of the high-bandwidth oscilloscope (9) is connected to the cathode output end of the gated image intensifier (4) and is used to receive the cathode pulse of the gated image intensifier (4) and calculate the time difference with the time reference electrical signal.

2. The cathode partition-based image intensifier local exposure time and delay calibration system according to claim 1, characterized in that: A light homogenizing mirror (3) is provided between the semi-transparent and semi-reflective mirror (2) and the cathode of the gated image intensifier (4), and the light homogenizing mirror (3) is used for uniformly diffusing the transmitted light beam.

3. The cathode partition-based image intensifier local exposure time and delay calibration system according to claim 1, characterized in that: The gated electric pulse output by the gated power supply module (5) is a zero-order Gaussian negative pulse with a full width at half maximum value of less than 1 ns and a voltage greater than -200 V.

4. The cathode partition-based image intensifier local exposure time and delay calibration system according to claim 1, characterized in that: The high-bandwidth oscilloscope (9) has a bandwidth of ≥8 GHz and a sampling rate of ≥100 GS / s.

5. A method for calibrating local exposure time and delay of an image intensifier based on cathode partitioning, characterized in that: The cathode partition-based image intensifier local exposure time and delay calibration system according to any one of claims 1 to 4 comprises the following steps: Step 1: Divide the cathode of the gated image intensifier (4) to be calibrated into a plurality of sub-areas; estimate the total exposure time of the cathode of the gated image intensifier (4), set the exposure step length, and calculate the total number of adjustments; Step 2: Turn on the femtosecond pulse laser (1) to emit a laser pulse and simultaneously output a trigger signal a; the trigger signal source (8) outputs trigger signals b and c; the laser pulse is divided into a transmitted beam and a reflected beam through a semi-transparent and semi-reflective mirror (2); the reflected beam is incident on a photodetector (10) and converted into a time reference electrical signal; the output delay time of the trigger signal b is adjusted by the signal source (8) so that the gated electrical pulse and the transmitted beam arrive at the cathode of the gated image intensifier (4) at the same time; the gated electrical pulse triggers the cathode of the gated image intensifier (4) to generate a cathode pulse; Step 3: Output the exposure image through the fluorescent screen of the gated image intensifier (4), and trigger the CMOS camera (6) to collect the exposure image through the trigger signal c; at the same time, obtain the time difference between the cathode pulse and the time reference electrical signal through the high-bandwidth oscilloscope (9); Step 4: Adjust the output delay time of the trigger signal b according to the exposure step length, and return to step 3 until the total number of adjustments is reached, thereby obtaining an exposure image sequence that completely covers the cathode of the gated image intensifier (4); Step 5: Remove the static background of each image in the exposure image sequence and calculate the sum of the pixel grayscale of each sub-region. Construct a curve of the sum of the pixel grayscale of each sub-region versus the delay time and fit it to a Gaussian function. The center time of the Gaussian function is used as the delay time of the sub-region, and the full width at half maximum of the Gaussian function is used as the local exposure time of the sub-region. Step 6: Draw a two-dimensional distribution diagram of the local exposure time and the delay time of all sub-regions in each sub-region of the cathode of the gated image intensifier (4), obtain the time domain response parameter distribution of the cathode of the gated image intensifier (4), and complete the calibration of the local exposure time and delay of the gated image intensifier.

6. The method for calibrating local exposure time and delay of an image intensifier based on cathode partitioning according to claim 5, characterized in that: Step 1 is as follows: According to the mapping relationship between the side of the cathode of the gated image intensifier (4) to be calibrated that receives the transmitted light beam and the equivalent pixels of the CMOS camera (6), the side of the cathode of the gated image intensifier (4) that receives the transmitted light beam is divided into N rectangular sub-areas, and the sub-areas are numbered i, i=1, ..., N.

7. The method for calibrating local exposure time and delay of an image intensifier based on cathode partitioning according to claim 5, characterized in that: The delay time of the trigger signal b relative to the trigger signal c is 0-100ns.

8. The method for calibrating local exposure time and delay of an image intensifier based on cathode partitioning according to claim 6, characterized in that: Step 5 is as follows: Step 5.1: In the exposure image sequence of the cathode of the gated image intensifier (4), the sub-region i of the image captured at the time t when the gated electric pulse reaches the cathode of the gated image intensifier (4) is , the corresponding background is recorded as ,in, Indicates the horizontal and vertical coordinate positions of the pixels in sub-region i; Step 5.2: Remove the static background of each image in the exposure image sequence and calculate the sum of the pixel grayscale of each sub-region i , the calculation formula is: ； Where, is the pixel set corresponding to sub-region i; Step 5.3: Construct a curve of the sum of the pixel grayscales of each sub-region changing with the delay time, where the delay time is the time t when the gated electric pulse reaches the cathode of the gated image intensifier (4). Then, perform Gaussian fitting on the change curve to obtain a Gaussian function, which is expressed as: ； in, represents the highest amplitude of the Gaussian function in sub-region i, represents the center time of the Gaussian function of sub-region i, represents the standard deviation of the Gaussian function in sub-region i; Step 5.4: The center time of the Gaussian function of sub-region i is used as the delay time of the sub-region , the expression is: ； Step 5.5: Local exposure time of sub-region i The full width at half maximum (FWHM) of the Gaussian function i Export, that is: 。

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