Rapid measurement method for hole column time of image intensifier

Abstract

The invention relates to a parameter detection method of an optical assembly, in particular to a method for rapidly measuring aperture bar time of an image intensifier, and aims to solve the problem that time and labor are consumed when the aperture bar time tau of the large-scale image intensifier is detected by an existing laser pulse scanning method. The method comprises the following steps of: 1) obtaining hole column time tau of Y image intensifiers in X image intensifiers; 2) obtaining an S11-f relation graph of the Y image intensifiers; 3) obtaining the value of a corresponding frequency domain reflection parameter S11 when the transmitting frequency f in the Y S11-f relation graphs is Z; 4) obtaining a tau-S11 relation graph; 5) obtaining an S11-f relation graph of the rest X-Y image intensifiers; 6) obtaining the value of a corresponding frequency domain reflection parameter S11 when the transmitting frequency f in the rest X-Y S11-f relation graphs is Z; and 7) utilizing the tau-S11 relation graph and the X-Y S11 values to obtain the hole column time tau of the rest X-Y image intensifiers. The method has the beneficial effects that the measurement time is saved, and the accuracy is high.

Description

Technical Field

[0001] The invention relates to a parameter detection method of an optical component, in particular to a fast measurement method of aperture time of an image intensifier. Background Art

[0002] The imaging of ultrafast processes such as electric explosions and plasma reactions is of great value for studying their internal physical mechanisms. Generally, different high-speed imaging systems such as rotating mirror high-speed cameras, streak cameras, and image intensifier-gated framing cameras are used according to the different time and space resolutions of the research targets. Among them, the image intensifier-gated framing camera has large imaging size, high two-dimensional spatial resolution, large response band range, and simple structure, and is widely used in the imaging of ultrafast physical processes. As a key component, the image intensifier's performance in high-speed gated imaging is a key link affecting the quality of high-speed imaging.

[0003] Reference documents CN118197883A and CN118136487A both disclose image intensifiers. For a schematic diagram of a common image intensifier structure, see Figure 1 , including a vacuum sealed cavity, and a photocathode 02, a microchannel plate 03 and an output fluorescent screen 04 arranged in sequence in the vacuum sealed cavity along the propagation direction of the light path; the part of the vacuum sealed cavity close to the photocathode 02 is an input window 01, which is used for photoelectrons to pass through and reach the photocathode 02; the input window 01 includes an input surface and an output surface, which are used to transmit light signals; the photocathode 02 is plated on the output surface of the input window 01; the microchannel plate 03 is provided with a plurality of through holes (also called channels, the diameter of the through holes can be 6μm), and its input surface and output surface are plated with a conductive metal film. The phosphor of the output fluorescent screen 04 is P20, P22, P43, P46 or P47 to meet the requirements of different output wavelengths, luminous efficiency and afterglow time. The distance between the output fluorescent screen 04 and the microchannel plate 03 is generally 0.5mm.

[0004] Among them, the microchannel plate is a device that can continuously multiply the number of electrons. A microchannel plate is usually composed of millions of glass capillary channels arranged at a certain angle. The inner wall of each channel has good conductivity and secondary electron emission performance, and the two end faces of the channel are plated with input and output electrodes. When a voltage is applied between the two electrodes, a uniform electric field is established along the axial direction in the channel. The electrons entering the channel continuously hit the inner wall of the channel under the action of the electric field, generating secondary electrons and achieving continuous multiplication of the number. Due to its high gain, fast response, and excellent magnetic field resistance, microchannel plates are widely used in weak photoelectric detection and imaging devices such as photomultiplier tubes and image intensifiers.

[0005] The working principle of the image intensifier is: the photocathode converts the optical image into photoelectrons, which bombard the microchannel plate under the action of the vacuum electric field to produce electron multiplication. The multiplied electrons are converted into photons again on the fluorescent screen. The process can achieve 10 3 ~10 6 The brightness gain is times, and this process is widely used in visual night equipment. During the high-speed gating process, the image intensifier realizes an instantaneous gating high-voltage electric field. During this time, the photoelectrons reach the fluorescent screen to form a switch of the imaging light path. The switching speed can reach the order of ns.

[0006] The process of the image intensifier's gating electric field propagating from the edge of the photocathode to the center is called the "aperture bar" effect. The duration of the "aperture bar" effect (abbreviated as aperture bar time, τ) is generally in the sub-nanosecond time range, which has a great influence on the intensity distribution of the nanosecond exposure image. Therefore, it is necessary to measure the aperture bar time τ of each image intensifier.

[0007] The existing method for measuring the aperture time τ of an image intensifier is mainly a laser pulse scanning method. Chinese patent CN114567772B discloses a method and a system for measuring the optical gating time characteristic of an image intensifier, which is used to obtain the optical gating time characteristic curve of the image intensifier.

[0008] The schematic diagram of the measurement system principle of this patent is shown in Figure 2, comprising a pulse generator 1, an ultrafast laser 2, a beam expander 4, a semi-reflective and semi-mirror 5, a first diffuse scattering glass sheet 6, an image intensifier 7, a second diffuse scattering glass sheet 8, a first photodetector 9, a second photodetector 14, a power divider 10, an oscilloscope 11, a delayed pulse generator 12, and a gated shutter pulse generator 13; the pulse generator 1 is connected to the ultrafast laser 2 to trigger the ultrafast laser 2 to output a laser pulse; the beam expander 4 and the semi-reflective and semi-mirror 5 are sequentially arranged on the optical path of the laser pulse output by the ultrafast laser 2, and the laser pulse is incident on the semi-reflective and semi-mirror 5 after being expanded by the beam expander 4 and divided into two laser pulses, one for the transmitted laser pulse and the other for the reflected laser pulse; the first diffuse scattering glass sheet 6 and the first photodetector 9 are sequentially arranged on the optical path of the transmitted laser pulse, and the laser pulse on the transmitted optical path is homogenized by the first diffuse scattering glass sheet 6 and then incident on the first photodetector 9; the first photodetector 9 converts the homogenized optical signal The power divider 10 is converted into an electrical signal. The input end of the power divider 10 is connected to the first photodetector 9, and the output end is respectively connected to the delayed pulse generator 12 and the oscilloscope 11. The power divider 10 divides the electrical signal output by the first photodetector 9 into two paths. One electrical signal is input to the oscilloscope 11 for light intensity monitoring, and the other electrical signal triggers the delayed pulse generator 12. The delayed pulse generator 12 is connected to the gated shutter pulse generator 13. The electrical pulse output by the delayed pulse generator 12 triggers the gated shutter pulse generator 13 to provide a cathode gate-opening pulse for the image intensifier 7. The second diffuse scattering glass sheet 8 and the image intensifier 7 are sequentially arranged in the optical path of the reflected laser pulse. The laser pulse on the reflected optical path is averaged by the second diffuse scattering glass sheet 8 and then incident on the photocathode of the image intensifier 7 to be converted into an electronic image. The electronic image is received by the second photodetector 14 arranged at the output end of the image intensifier 7 and converted into an electrical signal, which is input to the oscilloscope 11 for display.

[0009] The method steps of the patent include:

[0010] Step 1, the ultrafast laser 2 is triggered once to output two laser pulses with a fixed time interval, and the two laser pulses are respectively divided into two paths after beam expansion, one is a transmitted light pulse, and the other is a reflected light pulse, wherein the transmitted light pulse of the first laser pulse is the trigger source, and the reflected light pulse of the second laser pulse is used as the exposure light source of the image intensifier 7;

[0011] Step 2, the transmitted light pulse of the first laser pulse is converted into an electrical signal after being averaged; the electrical signal is divided into two paths, one electrical signal is used for light intensity monitoring, and the other electrical signal triggers the delay pulse generator 12; the electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13, which is used to provide a cathode gated shutter pulse for the image intensifier 7, so that the cathode of the image intensifier 7 is gated and opened; the reflected light pulse of the second laser pulse is averaged and incident on the photocathode of the image intensifier 7 to be converted into an electronic image; when the gated shutter pulse of the gated shutter pulse generator 13 is loaded on the photocathode, the electronic image is enhanced by the gated shutter pulse, and then received by the second photodetector 14 arranged at the output end of the image intensifier 7;

[0012] Step 3: By adjusting the delay step of the delayed pulse generator 12, the output waveform of the second photodetector 14 under different delays is obtained, the amplitude of the output waveform under the delay time series is counted, and the relationship curve between the signal output amplitude and the delay time is obtained, thereby obtaining the optical gating time characteristics of the image intensifier.

[0013] By making some adjustments to the system and method of the patent, the existing laser pulse scanning method can be obtained for measuring the aperture time τ of the image intensifier. Specifically, a rear lens 15 and a camera 16 are sequentially added to the output end of the image intensifier 7, the rear lens 15 is used for imaging by the camera 16, and the second photodetector 14 is deleted. Figure 3 .

[0014] At the same time, adjust the method steps to:

[0015] Step 1', the ultrafast laser 2 is triggered once to output two laser pulses with a fixed time interval, and the two laser pulses are respectively divided into two paths after beam expansion, one is a transmitted light pulse, and the other is a reflected light pulse, wherein the transmitted light pulse of the first laser pulse is the trigger source, and the reflected light pulse of the second laser pulse is used as the exposure light source of the image intensifier 7;

[0016] Step 2', the transmitted light pulse of the first laser pulse is converted into an electrical signal after being averaged; the electrical signal is divided into two paths, one electrical signal is used for light intensity monitoring, and the other electrical signal triggers the delay pulse generator 12; the electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13, which is used to provide a cathode gated shutter pulse for the image intensifier 7, so that the cathode gate of the image intensifier 7 is opened;

[0017] The reflected light pulse of the second laser pulse is homogenized and incident on the photocathode of the image intensifier 7 to be converted into an electronic image; when the gated shutter pulse of the gated shutter pulse generator 13 is loaded on the photocathode, the electronic image is enhanced by the gated shutter pulse and then received by the camera 16 arranged at the output end of the image intensifier 7 through the rear lens 15;

[0018] Step 3', by adjusting the delay step t1 of the delay pulse generator 12, the gating images of the image intensifier under different delays are obtained, and the delay difference from edge gating to full gating of the output image under different delay time sequences is counted to obtain the aperture time of the image intensifier.

[0019] However, the disadvantage of the laser pulse scanning method is that it is too time-consuming. It usually takes about 10 minutes to measure the aperture time τ of a single image intensifier. If there are a large number of image intensifiers to be detected, this method is time-consuming and labor-intensive. Therefore, this method is difficult to apply to large-scale image intensifier aperture time τ detection scenarios. It is urgent to develop a large-scale intensifier aperture time τ rapid detection method. Summary of the invention

[0020] The purpose of the present invention is to solve the problem that the existing laser pulse scanning method is time-consuming and labor-intensive when detecting the aperture time τ of a large-scale image intensifier, and to provide a fast measurement method for the aperture time of an image intensifier.

[0021] The design idea of ​​the present invention is: firstly, the aperture fence time τ and the S11-f relationship diagram of Y image intensifiers among X image intensifiers are measured by using the existing laser pulse scanning method to obtain the τ-S11 relationship diagram, and then the network analyzer and the τ-S11 relationship diagram are used to measure the aperture fence time τ of the remaining image intensifiers, thereby obtaining a fast measurement method for the aperture fence time of the image intensifier, which greatly saves time.

[0022] To achieve the above purpose, the technical solution provided by the present invention is:

[0023] A method for quickly measuring the aperture time of an image intensifier is characterized in that it comprises the following steps:

[0024] Step 1: Prepare X image intensifiers to be tested, select Y of them, and use laser pulse scanning method to measure their aperture time τ, which are τ1, τ2, ... τ Y , X ≥ 3, 2 ≤ Y < X, X and Y are both integers;

[0025] Step 2: for the Y image intensifiers described in step 1, respectively use a network analyzer to measure the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f, and obtain the S11-f relationship diagrams of the Y image intensifiers;

[0026] Step 3: Obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the Y S11-f relationship diagrams obtained in step 2 when the transmission frequency f is all Z, which are S111, S112…S11 in sequence. Y , 10MHz≤Z≤100MHz;

[0027] Step 4: In the plane rectangular coordinate system, place the points (S111, τ1), (S112, τ2)…(S11 Y ,τ Y ) is fitted into a linear function to obtain the τ-S11 relationship diagram;

[0028] Step 5: for the remaining XY image intensifiers, respectively use a network analyzer to measure the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f, and obtain the S11-f relationship diagrams of the XY image intensifiers respectively;

[0029] Step 6: Obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the transmission frequency f of the XY S11-f relationship diagrams obtained in step 5 when the transmission frequency f is Z, which are S11 Y+1 、S11 Y+2 …S11 X ;

[0030] Step 7: Find the value of S11 on the τ-S11 relationship diagram obtained in step 4, which is the S11 obtained in step 6. Y+1 、S11 Y+2 …S11 X The τ value corresponding to the time is obtained to obtain the aperture time τ of the remaining XY image intensifiers Y+1 , τ Y+2 …τ X , the measurement is completed.

[0031] Further, in step 1, the measurement system for measuring the aperture fence time τ by the laser pulse scanning method includes a pulse generator, an ultrafast laser connected to the pulse generator, a beam expander and a half-reflecting half-mirror arranged in sequence on the emission light path of the ultrafast laser, a first diffuse scattering glass sheet and a first photodetector arranged in sequence on the transmission light path of the half-reflecting half-mirror, a second diffuse scattering glass sheet and an image intensifier arranged in sequence on the reflection light path of the half-reflecting half-mirror, a rear lens and a camera arranged in sequence on the output light path of the image intensifier, a power divider electrically connected to the first photodetector, an oscilloscope and a delay pulse generator electrically connected to two output ends of the power divider respectively, and a gated shutter pulse generator electrically connected to the output end of the delay pulse generator; the output end of the gated shutter pulse generator is electrically connected to the door opening control end of the image intensifier;

[0032] The pulse generator triggers the ultrafast laser to output laser pulses, and the laser pulses are expanded by a beam expander and incident on a half-reflecting half-mirror to be divided into transmitted laser pulses and reflected laser pulses.

[0033] The transmitted laser pulse is homogenized by the first diffuse scattering glass sheet and then incident on the first photodetector; the first photodetector converts the homogenized optical signal into an electrical signal, and the power divider divides the electrical signal output by the first photodetector into two paths, one of which is input into an oscilloscope for light intensity monitoring, and the other is used to trigger a delayed pulse generator; the electrical pulse output by the delayed pulse generator triggers a gated shutter pulse generator for providing a cathode gate opening pulse for the image intensifier;

[0034] The reflected laser pulse is homogenized by the second diffuse scattering glass sheet and then incident on the photocathode of the image intensifier to be converted into an electronic image. The electronic image is enhanced by the gated shutter pulse and then received by the camera after passing through the rear lens.

[0035] Furthermore, in step 1, the hole fence time τ is measured by using a laser pulse scanning method:

[0036] Step a1, the ultrafast laser is triggered once to output two laser pulses with a fixed time interval, and the two laser pulses are respectively divided into a transmitted light pulse and a reflected light pulse after beam expansion, wherein the transmitted light pulse of the first laser pulse is used as a trigger source, and the reflected light pulse of the second laser pulse is used as an exposure light source of the image intensifier;

[0037] Step a2, the transmitted light pulse of the first laser pulse is converted into an electrical signal after being averaged; the electrical signal is divided into two paths, one electrical signal is used for light intensity monitoring, and the other electrical signal triggers a delayed pulse generator; the electrical pulse output by the delayed pulse generator triggers a gated shutter pulse generator, which is used to provide a cathode gated shutter pulse for the image intensifier, so that the cathode gate of the image intensifier is opened;

[0038] The reflected light pulse of the second laser pulse is homogenized and incident on the photocathode of the image intensifier to be converted into an electronic image. When the gated shutter pulse of the gated shutter pulse generator is loaded on the photocathode, the electronic image is enhanced by the gated shutter pulse and received by the camera after passing through the rear lens.

[0039] Step a3, by adjusting the delay step t1 of the delay pulse generator, the gating image of the image intensifier under different delays is obtained, and the delay difference from edge gating to full gating of the output image under different delay time sequences is counted to obtain the aperture time τ of the image intensifier.

[0040] Furthermore, in step a3, the delay step length t1 adjusted by the delay pulse generator each time is 0.05 ns.

[0041] Furthermore, in step 1, a BBO frequency doubling crystal is arranged between the ultrafast laser and the beam expander to change the wavelength of the laser pulse.

[0042] Furthermore, in step 2 and step 5, the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f measured by the network analyzer is specifically:

[0043] Step b1, connecting the photocathode lead wire of the image intensifier and the input end wire of the microchannel plate to the output port of the network analyzer respectively;

[0044] Step b2, the network analyzer sends an electromagnetic wave signal to the photocathode and the microchannel plate of the image intensifier, wherein the emission frequency of the electromagnetic wave is f;

[0045] Step b3: The network analyzer obtains the relationship between the frequency domain reflection parameter S11 of the image intensifier and the transmission frequency f.

[0046] Further, in step 1, Y=2;

[0047] Step 4 is as follows:

[0048] In the rectangular coordinate system, connect the points (S111, τ1) and (S112, τ2) to obtain a linear function, that is, the τ-S11 relationship diagram.

[0049] Further, in step 1, Y>2;

[0050] In step 4, the points (S111, τ1), (S112, τ2)…(S11 Y ,τ Y ) is fitted into a linear function using the least squares method.

[0051] Furthermore, in step 3 and step 6, Z=50 MHz.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] 1. The method for quickly measuring the aperture time of an image intensifier provided by the present invention first uses the existing laser pulse scanning method to measure the aperture time τ and the S11-f relationship diagram of Y of the X image intensifiers to obtain the τ-S11 relationship diagram, and then uses a network analyzer and the τ-S11 relationship diagram to measure the aperture time τ of the remaining image intensifiers, thereby realizing the rapid measurement of the aperture time of the image intensifier. Compared with the method of measuring each image intensifier using the existing laser pulse scanning method, this method greatly saves time.

[0054] 2. The rapid measurement method of the aperture time of the image intensifier provided by the present invention measures the error of the aperture time τ of each image intensifier, which is equivalent to the error of the aperture time τ measured by the existing laser pulse scanning method, has high accuracy and is suitable for the measurement of the aperture time τ of a large number of image intensifiers. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a structural schematic diagram of an existing image intensifier;

[0056] Figure 2 The schematic diagram is a principle diagram of a measurement system for the optical gating time characteristics of an existing image intensifier;

[0057] Figure 3 It is a schematic diagram of the principle of the existing image intensifier aperture time measurement system;

[0058] Figure 4 It is a flow chart of an embodiment of a method for quickly measuring aperture time of an image intensifier according to the present invention;

[0059] Figure 5 It is one of the S11-f relationship diagrams obtained in step 2 of the embodiment of the method for rapid measurement of aperture time of an image intensifier of the present invention;

[0060] Figure 6 It is an error analysis diagram of the τ-S11 relationship diagram obtained in step 4 of the embodiment of the method for rapid measurement of aperture time of an image intensifier of the present invention;

[0061] Description of reference numerals:

[0062] 01-input window, 02-photocathode, 03-microchannel plate, 04-output phosphor screen;

[0063] 1-pulse generator, 2-ultrafast laser, 3-BBO frequency doubling crystal, 4-beam expander, 5-semi-reflective and semi-transparent, 6-first diffuse scattering glass plate, 7-image intensifier, 8-second diffuse scattering glass plate, 9-first photodetector, 10-power divider, 11-oscilloscope, 12-delay pulse generator, 13-gated shutter pulse generator, 14-second photodetector, 15-rear lens, 16-camera. DETAILED DESCRIPTION

[0064] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0065] The system used in step 1 to measure the aperture time τ using the laser pulse scanning method can be as follows: Figure 3The device shown comprises a pulse generator 1, an ultrafast laser 2 connected to the pulse generator 1, a beam expander 4 and a half-reflecting half-mirror 5 sequentially arranged on the emission light path of the ultrafast laser 2, a first diffuse scattering glass sheet 6 and a first photodetector 9 sequentially arranged on the transmission light path of the half-reflecting half-mirror 5, a second diffuse scattering glass sheet 8 and an image intensifier 7 sequentially arranged on the reflection light path of the half-reflecting half-mirror 5, a rear lens 15 and a camera 16 sequentially arranged on the output light path of the image intensifier 7, a power divider 10 electrically connected to the first photodetector 9, an oscilloscope 11 and a delayed pulse generator 12 electrically connected to two output ends of the power divider 10 respectively, and a gated shutter pulse generator 13 electrically connected to the output end of the delayed pulse generator 12; the output end of the gated shutter pulse generator 13 is electrically connected to the gate opening control end of the image intensifier 7; the pulse generator 1 triggers the ultrafast laser 2 Output laser pulses, which are expanded by a beam expander 4 and incident on a semi-reflective mirror 5 to be divided into transmitted laser pulses and reflected laser pulses; the transmitted laser pulses are homogenized by a first diffuse scattering glass sheet 6 and incident on a first photodetector 9; the first photodetector 9 converts the homogenized optical signal into an electrical signal, and a power divider 10 divides the electrical signal output by the first photodetector 9 into two paths, one electrical signal is input into an oscilloscope 11 for light intensity monitoring, and the other electrical signal triggers a delay pulse generator 12; the electrical pulse output by the delay pulse generator 12 triggers a gated shutter pulse generator 13 to provide a cathode gate-opening pulse for the image intensifier 7; the reflected laser pulses are homogenized by a second diffuse scattering glass sheet 8 and incident on the photocathode of the image intensifier 7 to be converted into an electronic image, which is enhanced by a gated shutter pulse and then received by a camera 16 after passing through a rear lens 15.

[0066] A fast measurement method for the aperture time of an image intensifier. The flowchart is shown in Figure 4 , including the following steps:

[0067] Step 1, prepare ten image intensifiers to be tested, select two of them, and use laser pulse scanning method to measure their aperture fence time τ, which are τ1 and τ2 respectively;

[0068] The hole fence time τ is measured by laser pulse scanning method:

[0069] Step a1, the ultrafast laser 2 is triggered once to output two laser pulses with a fixed time interval, and the two laser pulses are respectively divided into a transmitted light pulse and a reflected light pulse after beam expansion, wherein the transmitted light pulse of the first laser pulse is the trigger source, and the reflected light pulse of the second laser pulse is the exposure light source of the image intensifier 7;

[0070] Step a2, the transmitted light pulse of the first laser pulse is converted into an electrical signal after being averaged; the electrical signal is divided into two paths, one electrical signal is used for light intensity monitoring, and the other electrical signal triggers the delay pulse generator 12; the electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13, which is used to provide a cathode gated shutter pulse for the image intensifier 7, so that the cathode gate of the image intensifier 7 is opened;

[0071] The reflected light pulse of the second laser pulse is processed by averaging and then incident on the photocathode of the image intensifier 7 to be converted into an electronic image. When the gated shutter pulse of the gated shutter pulse generator 13 is loaded on the photocathode, the electronic image is enhanced by the gated shutter pulse and is received by the camera 16 after passing through the rear lens 15.

[0072] Step a3, by adjusting the delay step t1 of the delay pulse generator 12, the gating image of the image intensifier under different delays is obtained, and the delay difference from edge gating to full gating of the output image under different delay time sequences is counted, so as to obtain the aperture time τ of the image intensifier;

[0073] Step 2: For the two image intensifiers in step 1, use a network analyzer to measure the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f, and obtain the S11-f relationship diagrams of the two image intensifiers, one of which is shown in FIG. Figure 5 ;

[0074] The frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier is measured by a network analyzer:

[0075] Step b1, connecting the photocathode lead wire of the image intensifier and the input end wire of the microchannel plate to the output port of the network analyzer respectively;

[0076] Step b2, the network analyzer sends an electromagnetic wave signal to the photocathode and the microchannel plate of the image intensifier, wherein the emission frequency of the electromagnetic wave is f;

[0077] Step b3, the network analyzer obtains the relationship between the frequency domain reflection parameter S11 of the image intensifier and the transmission frequency f;

[0078] Step 3, respectively obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the two S11-f relationship diagrams obtained in step 2 when the transmission frequency f is 50 MHz, which are S111 and S112 respectively;

[0079] Step 4: In a plane rectangular coordinate system, connect the points (S111, τ1) and (S112, τ2) into a linear function to obtain a τ-S11 relationship diagram;

[0080] Step 5: For the remaining eight image intensifiers, use a network analyzer to measure the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f, and obtain the S11-f relationship diagrams of the eight image intensifiers respectively;

[0081] Step 6: Obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the eight S11-f relationship diagrams obtained in step 5 when the transmission frequency f is 50 MHz, which are S113, S114, ... S11 respectively. 10 ;

[0082] Step 7: Find the value of S11 on the τ-S11 relationship diagram obtained in step 4, which is the S11 obtained in step 6. Y+1 、S11 Y+2 …S11 X The τ value corresponding to the time is obtained to obtain the aperture time τ of the remaining XY image intensifiers Y+1 , τ Y+2 …τ X , the measurement is completed.

[0083] It should be noted that the transmission frequency f can be 10 MHz to 100 MHz. If there are more than two points in step 4, fitting is required, and the least square method can be used to obtain the linear regression equation. Figure 6 The τ-S11 relationship diagram obtained in the embodiment of the present invention is compared with the results of actual measurement of the remaining eight image intensifiers. "Calibration sample" is the linear function of the τ-S11 relationship obtained in the embodiment of the present invention, and "Sample" is the τ result of the actual measurement of the remaining eight image intensifiers. It can be seen that the error is less than 0.03ns, which meets the actual needs. This method greatly saves the measurement time of τ of batch image intensifiers and is worthy of popularization and application.

Claims

1. A method for quickly measuring the aperture time of an image intensifier, characterized in that: The following steps are involved: Step 1: Prepare X image intensifiers to be tested, select Y of them, and use laser pulse scanning method to measure their aperture time τ, which are τ1, τ2, ... τ Y , X ≥ 3, 2 ≤ Y < X, X and Y are both integers; Step 2: for the Y image intensifiers described in step 1, respectively use a network analyzer to measure the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f, and obtain the S11-f relationship diagrams of the Y image intensifiers; Step 3: Obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the Y S11-f relationship diagrams obtained in step 2 when the transmission frequency f is Z, which are S111, S112, ... S11 in sequence. Y , 10MHz≤Z≤100MHz; Step 4: In the plane rectangular coordinate system, place the points (S111, τ1), (S112, τ2)…(S11 Y ,τ Y ) is fitted into a linear function to obtain the τ-S11 relationship diagram; Step 5: for the remaining XY image intensifiers, respectively use a network analyzer to measure the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f, and obtain the S11-f relationship diagrams of the XY image intensifiers; Step 6: Obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the transmission frequency f of the XY S11-f relationship diagrams obtained in step 5 when the transmission frequency f is Z, which are S11 Y+1 、S11 Y+2 …S11 X ; Step 7: Find the value of S11 on the τ-S11 relationship diagram obtained in step 4, which is the S11 obtained in step 6. Y+1 、S11 Y+2 …S11 X The τ value corresponding to the time is obtained to obtain the aperture time τ of the remaining XY image intensifiers Y+1 , τ Y+2 …τ X , the measurement is completed.

2. The method for rapid measurement of aperture time of an image intensifier according to claim 1, characterized in that: In step 1, the measuring system for measuring the aperture time τ by the laser pulse scanning method comprises a pulse generator (1), an ultrafast laser (2) connected to the pulse generator (1), a beam expander (4) and a half-reflecting half-mirror (5) arranged in sequence on the emission light path of the ultrafast laser (2), a first diffuse scattering glass sheet (6) and a first photodetector (9) arranged in sequence on the transmission light path of the half-reflecting half-mirror (5), a second diffuse scattering glass sheet (8) and an image intensifier (9) arranged in sequence on the reflection light path of the half-reflecting half-mirror (5) An image intensifier (7), a rear lens (15) and a camera (16) sequentially arranged on the output light path of the image intensifier (7), a power divider (10) electrically connected to the first photodetector (9), an oscilloscope (11) and a delay pulse generator (12) electrically connected to two output ends of the power divider (10), and a gated shutter pulse generator (13) electrically connected to the output end of the delay pulse generator (12); the output end of the gated shutter pulse generator (13) is electrically connected to the gate opening control end of the image intensifier (7); The pulse generator (1) triggers the ultrafast laser (2) to output laser pulses, and the laser pulses are expanded by a beam expander (4) and then incident on a half-reflecting half-mirror (5) to be divided into transmitted laser pulses and reflected laser pulses; The transmitted laser pulse is homogenized by the first diffuse scattering glass sheet (6) and then incident on the first photodetector (9); the first photodetector (9) converts the homogenized optical signal into an electrical signal, and the power divider (10) divides the electrical signal output by the first photodetector (9) into two paths, one electrical signal is input into an oscilloscope (11) for light intensity monitoring, and the other electrical signal triggers a delayed pulse generator (12); the electrical pulse output by the delayed pulse generator (12) triggers a gated shutter pulse generator (13) for providing a cathode gate opening pulse for the image intensifier (7); The reflected laser pulse is homogenized by the second diffuse scattering glass sheet (8) and incident on the photocathode of the image intensifier (7) to be converted into an electronic image. The electronic image is enhanced by the gated shutter pulse and then received by the camera (16) after passing through the rear lens (15).

3. The method for rapid measurement of aperture time of an image intensifier according to claim 2, characterized in that: In step 1, the hole fence time τ is measured by laser pulse scanning method as follows: Step a1, the ultrafast laser (2) is triggered once to output two laser pulses with a fixed time interval, and the two laser pulses are respectively divided into a transmitted light pulse and a reflected light pulse after beam expansion, wherein the transmitted light pulse of the first laser pulse is used as a trigger source, and the reflected light pulse of the second laser pulse is used as an exposure light source of the image intensifier (7); Step a2, the transmitted light pulse of the first laser pulse is converted into an electrical signal after being averaged; the electrical signal is divided into two paths, one electrical signal is used for light intensity monitoring, and the other electrical signal triggers a delayed pulse generator (12); the electrical pulse output by the delayed pulse generator (12) triggers a gated shutter pulse generator (13) for providing a cathode gated shutter pulse for the image intensifier (7), so that the cathode gate of the image intensifier (7) is opened; The reflected light pulse of the second laser pulse is homogenized and incident on the photocathode of the image intensifier (7) to be converted into an electronic image; when the gated shutter pulse of the gated shutter pulse generator (13) is loaded on the photocathode, the electronic image is enhanced by the gated shutter pulse and received by the camera (16) after passing through the rear lens (15); Step a3, by adjusting the delay step t1 of the delay pulse generator (12), the gating image of the image intensifier under different delays is obtained, and the delay difference from edge gating to full gating of the output image under different delay time sequences is counted, so as to obtain the aperture time τ of the image intensifier.

4. The method for rapid measurement of aperture time of an image intensifier according to claim 3, characterized in that: In step a3, the delay step length t1 of each adjustment of the delay pulse generator (12) is 0.05ns.

5. The method for rapid measurement of aperture time of an image intensifier according to claim 4, characterized in that: In step 1, a BBO frequency doubling crystal (3) is arranged between the ultrafast laser (2) and the beam expander (4) to change the wavelength of the laser pulse.

6. A method for rapid measurement of aperture time of an image intensifier according to claim 5, characterized in that: In step 2 and step 5, the relationship between the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier and the emission frequency f measured by the network analyzer is specifically: Step b1, connecting the photocathode lead wire of the image intensifier and the input end wire of the microchannel plate to the output port of the network analyzer respectively; Step b2, the network analyzer sends an electromagnetic wave signal to the photocathode and the microchannel plate of the image intensifier, wherein the emission frequency of the electromagnetic wave is f; Step b3: The network analyzer obtains the relationship between the frequency domain reflection parameter S11 of the image intensifier and the transmission frequency f.

7. A method for rapid measurement of aperture time of an image intensifier according to claim 6, characterized in that: In step 1, Y=2; Step 4 is as follows: In the rectangular coordinate system, connect the points (S111, τ1) and (S112, τ2) to obtain a linear function, that is, the τ-S11 relationship diagram.

8. The method for rapid measurement of aperture time of an image intensifier according to claim 6, characterized in that: In step 1, Y>2; In step 4, the points (S111, τ1), (S112, τ2)…(S11 Y ,τ Y ) is fitted into a linear function using the least squares method.

9. The method for rapid measurement of aperture time of an image intensifier according to claim 1, characterized in that: In step 3 and step 6, Z=50 MHz.

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