A method for fast measurement of the hole barrier time of an image intensifier

Abstract

The present application relates to a kind of parameter detection methods of optical assembly, specifically to a kind of fast measurement method of image intensifier aperture barrier time, the purpose is to solve the problem of time-consuming and labor-consuming when detecting large-scale image intensifier aperture barrier time τ By existing laser pulse scanning method.The present application includes:1) obtain the aperture barrier time τ Of Y in X image intensifiers;2) obtain the S11-f relationship diagram of Y image intensifiers;3) obtain the value of the frequency domain reflection parameter S11 Corresponding when the emission frequency f In Y S11-f relationship diagram is Z;4) obtain τ-S11 relationship diagram;5) obtain the S11-f relationship diagram of remaining X-Y image intensifiers;6) obtain the value of the frequency domain reflection parameter S11 Corresponding when the emission frequency f In remaining X-Y S11-f relationship diagram is Z;7) utilize τ-S11 relationship diagram and X-Y S11 Value, obtain the aperture barrier time τ Of remaining X-Y image intensifiers.The present application has the beneficial effects of saving measurement time and high accuracy.

Description

Technical Field

[0001] This invention relates to a method for detecting parameters of an optical component, specifically a method for rapidly measuring the aperture time of an image intensifier. Background Technology

[0002] Imaging ultrafast processes such as electrical explosions and plasma reactions is of great value for studying their internal physical mechanisms. Depending on the temporal and spatial resolution of the target object, different high-speed imaging systems are used, including rotating mirror high-speed cameras, streak cameras, and image intensifier-gated framing cameras. Among these, image intensifier-gated framing cameras, with their large image size, high two-dimensional spatial resolution, wide response band, and simple structure, are widely used in imaging ultrafast physical processes. The image intensifier, as a key component, plays a crucial role in high-speed gated imaging, significantly impacting the quality of high-speed images.

[0003] Both prior art documents CN118197883A and CN118136487A disclose image intensifiers. A schematic diagram of a common image intensifier structure can be found here. Figure 1 The system includes a vacuum-sealed cavity, and a photocathode 02, a microchannel plate 03, and an output phosphor screen 04 sequentially arranged within the vacuum-sealed cavity along the optical path. The portion of the vacuum-sealed cavity near the photocathode 02 is an input window 01, allowing photoelectrons to pass through and reach the photocathode 02. The input window 01 includes an input surface and an output surface for transmitting light signals. The photocathode 02 is deposited on the output surface of the input window 01. The microchannel plate 03 has multiple through-holes (also called channels, with a diameter of up to 6 μm), and both its input and output surfaces are coated with a conductive metal thin film. The phosphor used in the output phosphor screen 04 is P20, P22, P43, P46, or P47 to meet the requirements of different output wavelengths, luminous efficiency, and afterglow times. The distance between the output phosphor screen 04 and the microchannel plate 03 is typically 0.5 mm.

[0004] Microchannel plates are devices capable of continuously multiplying the number of electrons. A microchannel plate typically consists of millions of glass capillary channels arranged at a certain angle. Each channel's inner wall has good conductivity and secondary electron emission properties, and input and output electrodes are plated on both end faces of the channel. When a voltage is applied between the two electrodes, a uniform electric field is established along the axis within the channel. Electrons entering the channel continuously collide with the inner wall of the channel under the influence of this electric field, generating secondary electrons and achieving continuous multiplication of their number. Due to their 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 an image intensifier is as follows: the photocathode converts the optical image into photoelectrons, which bombard the microchannel plate under the action of a vacuum electric field, generating electron multiplication. The multiplied electrons are then converted back into photons on the fluorescent screen. This process can achieve 10-1 times the photon count. 3 ~10 6 This process, which achieves a brightness gain of several times, is widely used in night vision visualization equipment. During the high-speed gating process, a high-voltage electric field is instantaneously gating inside the image intensifier. Within this time, photoelectrons reach the fluorescent screen to form the switching of the imaging optical path, and the switching speed can reach the nanosecond level.

[0006] The process by which the gate electric field of an image intensifier propagates from the edge of the photocathode to the center is called the "aperture barrier" effect. The duration of the "aperture barrier" effect (abbreviated as aperture barrier time, τ) is generally in the sub-nanosecond range and has a significant impact on the intensity distribution of nanosecond-level exposure images. Therefore, it is necessary to measure the aperture barrier time τ of each image intensifier.

[0007] Existing methods for measuring the aperture gate time τ of an image intensifier mainly involve laser pulse scanning. Chinese patent CN114567772B discloses a method and system for measuring the optical gate time characteristics of an image intensifier, used to obtain the optical gate time characteristic curve of the image intensifier.

[0008] See the schematic diagram of the measurement system in this patent. Figure 2The system includes a pulse generator 1, an ultrafast laser 2, a beam expander 4, a semi-reflective mirror 5, a first diffuse scattering glass plate 6, an image intensifier 7, a second diffuse scattering glass plate 8, a first photodetector 9, a second photodetector 14, a power divider 10, an oscilloscope 11, a delay pulse generator 12, and a gated shutter pulse generator 13. The pulse generator 1 is connected to the ultrafast laser 2 and is used to trigger the ultrafast laser 2 to output laser pulses. The beam expander 4 and the semi-reflective mirror 5 are sequentially arranged in the optical path of the laser pulse output from the ultrafast laser 2. After the laser pulse is expanded by the beam expander 4, it is incident on the semi-reflective mirror 5 and split into two laser pulses: one is a transmitted laser pulse, and the other is a reflected laser pulse. The first diffuse scattering glass plate 6 and the first photodetector 9 are sequentially arranged in the optical path of the transmitted laser pulse. The laser pulse in the transmitted optical path is homogenized by the first diffuse scattering glass plate 6 and then incident on the first photodetector 9. The first photodetector 9 converts the homogenized optical signal... The laser pulse is converted into an electrical signal. The input of the power divider 10 is connected to the first photodetector 9, and the output is connected to the delay pulse generator 12 and the oscilloscope 11, respectively. The power divider 10 splits the electrical signal output by the first photodetector 9 into two paths. One path is input to the oscilloscope 11 for light intensity monitoring, and the other path triggers the delay pulse generator 12. The delay pulse generator 12 is connected to the gated shutter pulse generator 13. The electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13 to provide a cathode opening pulse for the image intensifier 7. The second diffuse scattering glass plate 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 homogenized by the second diffuse scattering glass plate 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 located at the output of the image intensifier 7 and converted into an electrical signal, which is then input to the oscilloscope 11 for display.

[0009] The method steps in this patent include:

[0010] Step 1: The ultrafast laser 2 outputs two laser pulses with a fixed time interval in a single trigger. After beam expansion, the two laser pulses are divided into two paths, one is a transmitted light pulse and the other is a reflected light pulse. 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 source of the image intensifier 7.

[0011] Step 2: The transmitted light pulse of the first laser pulse is homogenized and converted into an electrical signal. This electrical signal is divided into two paths: one path is used for light intensity monitoring, and the other path triggers the delay pulse generator 12. The electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13, which provides a cathode-gated shutter pulse to the image intensifier 7, causing the cathode of the image intensifier 7 to be gated. The reflected light pulse of the second laser pulse is homogenized and incident on the photocathode of the image intensifier 7, converting it into an electronic image. When the gated shutter pulse of the gated shutter pulse generator 13 is applied to the photocathode, the electronic image is enhanced by the gated shutter pulse and then received by the second photodetector 14 located at the output of the image intensifier 7.

[0012] Step 3: By adjusting the delay step size of the delay 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 sequence is statistically analyzed to obtain the relationship curve between the signal output amplitude and the delay time, thereby obtaining the optical gating time characteristics of the image intensifier.

[0013] By making some adjustments to the system and method of this 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 added sequentially 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 removed. See [link to documentation]. Figure 3 .

[0014] At the same time, the method and steps are adjusted as follows:

[0015] Step 1': The ultrafast laser 2 outputs two laser pulses with a fixed time interval in a single trigger. After beam expansion, the two laser pulses are divided into two paths, one is a transmitted light pulse and the other is a reflected light pulse. 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 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 homogenization. The electrical signal is divided into two paths: one path is used for light intensity monitoring, and the other path triggers the delay pulse generator 12. The electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13, which provides a cathode gate shutter pulse for the image intensifier 7, so that the cathode gate of the image intensifier 7 is opened.

[0017] After the reflected light pulse of the second laser pulse is homogenized, it is incident on the photocathode of the image intensifier 7 and converted into an electronic image. When the gated shutter pulse of the gated shutter pulse generator 13 is applied to the photocathode, the electronic image is enhanced by the gated shutter pulse and then received by the camera 16 set at the output end of the image intensifier 7 through the rear lens 15.

[0018] Step 3': By adjusting the delay step size t1 of the delay pulse generator 12, the gating images of the image intensifier under different delays are obtained. The delay difference from edge gating to full gating of the output image under different delay time series is statistically analyzed, thereby obtaining the aperture time of the image intensifier.

[0019] However, the drawback of the laser pulse scanning method is that it is too time-consuming. Measuring the aperture stop time τ of a single image intensifier usually takes about 10 minutes. If there are a large number of image intensifiers to be inspected, this method is time-consuming and labor-intensive. Therefore, this method is difficult to apply to large-scale image intensifier aperture stop time τ detection scenarios. There is an urgent need to develop a fast detection method for large-scale image intensifier aperture stop time τ. Summary of the Invention

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

[0021] The design concept of this invention is as follows: First, the existing laser pulse scanning method is used to measure the aperture stop time τ and S11-f relationship diagram of Y image intensifiers out of X image intensifiers to obtain the τ-S11 relationship diagram. Then, a network analyzer and the τ-S11 relationship diagram are used to measure the aperture stop time τ of the remaining image intensifiers, thereby obtaining a rapid measurement method for the aperture stop time of image intensifiers, which greatly saves time.

[0022] To achieve the above objectives, the technical solution provided by this invention is:

[0023] A rapid measurement method for the aperture time of an enhancer, characterized by the following steps:

[0024] Step 1: Prepare X image intensifiers to be tested, select Y of them, and measure their aperture gate time τ using the laser pulse scanning method, denoted as τ1, τ2…τ Y X≥3, 2≤Y<X, where X and Y are both integers;

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

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

[0027] Step 4: In the Cartesian coordinate system, place points (S111,τ1), (S112,τ2), ..., (S11...) Y ,τ Y The τ-S11 relationship is obtained by fitting the function to a linear function.

[0028] Step 5: For the remaining XY image intensifiers, use a network analyzer to measure the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier as a function of the emission frequency f, and obtain the S11-f relationship diagrams for 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. These values ​​are as follows: S11... Y+1 S11 Y+2 …S11 X ;

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

[0031] Further, in step 1, the measurement system for measuring the aperture time τ using the laser pulse scanning method includes a pulse generator, an ultrafast laser connected to the pulse generator, a beam expander and a semi-reflective mirror sequentially arranged in the emission optical path of the ultrafast laser, a first diffuse scattering glass plate and a first photodetector sequentially arranged in the transmission optical path of the semi-reflective mirror, a second diffuse scattering glass plate and an image intensifier sequentially arranged in the reflection optical path of the semi-reflective mirror, a rear lens and a camera sequentially arranged in the output optical path of the image intensifier, a power divider electrically connected to the first photodetector, an oscilloscope and a delay pulse generator electrically connected to the two output terminals of the power divider respectively, and a gated shutter pulse generator electrically connected to the output terminal of the delay pulse generator; the output terminal of the gated shutter pulse generator is electrically connected to the gate opening control terminal of the image intensifier.

[0032] The pulse generator triggers the ultrafast laser to output laser pulses. After the laser pulses are expanded by the beam expander, they are incident on the semi-reflective mirror and divided into transmitted laser pulses and reflected laser pulses.

[0033] The transmitted laser pulse is homogenized by the first diffuse scattering glass plate and then incident on the first photodetector. The first photodetector converts the homogenized optical signal into an electrical signal. The power divider splits the electrical signal output from the first photodetector into two paths. One electrical signal is input to an oscilloscope for light intensity monitoring, and the other electrical signal triggers a delay pulse generator. The electrical pulse output from the delay pulse generator triggers a gated shutter pulse generator to provide a cathode opening pulse for the image intensifier.

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

[0035] Furthermore, in step 1, the laser pulse scanning method is used to measure the aperture time τ, specifically as follows:

[0036] Step a1: The ultrafast laser outputs two laser pulses with a fixed time interval in a single trigger. After beam expansion, the two laser pulses are divided into a transmitted light pulse and a reflected light pulse, respectively. 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 source of the image intensifier.

[0037] Step a2: The transmitted light pulse of the first laser pulse is converted into an electrical signal after homogenization. The electrical signal is divided into two paths: one path is used for light intensity monitoring, and the other path triggers a delay pulse generator. The electrical pulse output by the delay pulse generator triggers a gated shutter pulse generator, which provides a cathode gate 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 then 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 applied to the photocathode, the electronic image is enhanced by the gated shutter pulse and then received by the camera after passing through the rear lens.

[0039] Step a3: By adjusting the delay step size t1 of the delay pulse generator, the gating images of the image intensifier under different delays are obtained. The delay difference from edge gating to full gating of the output image under different delay time series is statistically analyzed, thereby obtaining the aperture time τ of the image intensifier.

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

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

[0042] Furthermore, in steps 2 and 5, the measurement of the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier using a network analyzer as a function of the emission frequency f is specifically as follows:

[0043] Step b1: Connect the photocathode lead wire of the image intensifier and the input terminal wire of the microchannel plate to the output port of the network analyzer, respectively.

[0044] Step b2: The network analyzer emits electromagnetic wave signals to the photocathode and microchannel plate of the image intensifier, wherein the emission frequency of the electromagnetic waves 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] Furthermore, in step 1, Y = 2;

[0047] Step 4 is as follows:

[0048] In a Cartesian coordinate system, connecting points (S111,τ1) and (S112,τ2) yields a linear function, i.e., the τ-S11 relationship graph.

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

[0050] In step 4, points (S111,τ1), (S112,τ2)...(S11) are... Y ,τ Y The method used to fit the function to a linear function is the least squares method.

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

[0052] Compared with the prior art, the beneficial effects of the present invention are:

[0053] 1. The rapid measurement method for aperture stop time of image intensifiers provided by the present invention first uses the existing laser pulse scanning method to measure the aperture stop time τ and S11-f relationship diagram of Y out of X image intensifiers to obtain the τ-S11 relationship diagram. Then, using a network analyzer and the τ-S11 relationship diagram, the aperture stop time τ of the remaining image intensifiers is measured, thus realizing rapid measurement of aperture stop time of image intensifiers. Compared with the method of measuring each image intensifier using the existing laser pulse scanning method, it saves a lot of time.

[0054] 2. The rapid measurement method for aperture stop time of image intensifiers provided by this invention has a high accuracy and is suitable for measuring the aperture stop time τ of a large number of image intensifiers. The error of the aperture stop time τ of each image intensifier is comparable to that of the existing laser pulse scanning method. Attached Figure Description

[0055] Figure 1 This is a schematic diagram of an existing image intensifier.

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

[0057] Figure 3 A schematic diagram of the existing image intensifier aperture time measurement system;

[0058] Figure 4 A flowchart illustrating an embodiment of the rapid measurement method for image intensifier aperture time according to the present invention;

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

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

[0061] Explanation of reference numerals in the attached figures:

[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 lens, 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 Implementation

[0064] The present invention will be further described below with reference to 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 includes a pulse generator 1, an ultrafast laser 2 connected to the pulse generator 1, a beam expander 4 and a semi-reflective mirror 5 sequentially arranged in the emission path of the ultrafast laser 2, a first diffuse scattering glass plate 6 and a first photodetector 9 sequentially arranged in the transmission path of the semi-reflective mirror 5, a second diffuse scattering glass plate 8 and an image intensifier 7 sequentially arranged in the reflection path of the semi-reflective mirror 5, a rear lens 15 and a camera 16 sequentially arranged in the output 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 the two output terminals of the power divider 10 respectively, and a gated shutter pulse generator 13 electrically connected to the output terminal of the delay pulse generator 12; the output terminal of the gated shutter pulse generator 13 is electrically connected to the gate opening control terminal of the image intensifier 7; the pulse generator 1 triggers the ultrafast laser 2. The output laser pulse is expanded by the beam expander 4 and then incident on the semi-reflective mirror 5, splitting into a transmitted laser pulse and a reflected laser pulse. The transmitted laser pulse is homogenized by the first diffuse scattering glass plate 6 and then incident on the first photodetector 9. The first photodetector 9 converts the homogenized optical signal into an electrical signal. The power divider 10 splits 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 delay pulse generator 12. The electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13 to provide the cathode opening pulse for the image intensifier 7. The reflected laser pulse is homogenized by the second diffuse scattering glass plate 8 and then incident on the photocathode of the image intensifier 7, converting it 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.

[0066] A rapid measurement method for intensifier aperture time, see flowchart. Figure 4 This includes the following steps:

[0067] Step 1: Prepare ten image intensifiers to be tested, select two of them, and measure their aperture time τ using the laser pulse scanning method, which are τ1 and τ2 respectively.

[0068] The aperture time τ was measured using the laser pulse scanning method as follows:

[0069] Step a1: The ultrafast laser 2 outputs two laser pulses with a fixed time interval in a single trigger. After beam expansion, the two laser pulses are divided into a transmitted light pulse and a reflected light pulse, respectively. 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 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 homogenization. The electrical signal is divided into two paths: one path is used for light intensity monitoring, and the other path triggers the delay pulse generator 12. The electrical pulse output by the delay pulse generator 12 triggers the gated shutter pulse generator 13, which provides a cathode gate 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 homogenized 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 applied to the photocathode, the electronic image is enhanced by the gated shutter pulse and then received by the camera 16 after passing through the rear lens 15.

[0072] Step a3: By adjusting the delay step size t1 of the delay pulse generator 12, the gated images of the image intensifier under different delays are obtained. The delay difference from edge gated to full gated in the output image under different delay time series is statistically analyzed, thereby obtaining the aperture time τ of the image intensifier.

[0073] Step 2: For the two image intensifiers from Step 1, use a network analyzer to measure the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier as a function of the emission frequency f. Obtain the S11-f relationship diagrams for the two image intensifiers. One of the S11-f relationship diagrams is shown below. Figure 5 ;

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

[0075] Step b1: Connect the photocathode lead wire of the image intensifier and the input terminal wire of the microchannel plate to the output port of the network analyzer, respectively.

[0076] Step b2: The network analyzer emits electromagnetic wave signals to the photocathode and microchannel plate of the image intensifier, wherein the emission frequency of the electromagnetic waves 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: Obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the transmission frequency f of 50MHz in the two S11-f relationship diagrams obtained in Step 2, namely S111 and S112 respectively.

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

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

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

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

[0083] It should be noted that the transmission frequency f can be between 10MHz and 100MHz. If there are more than two points in step 4, fitting is required, and the least squares 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 was compared with the actual measurement results 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 requirements. This method greatly saves the measurement time of τ for batch image intensifiers and is worth promoting and applying.

Claims

1. A rapid measurement method for the aperture time of an image intensifier, characterized in that, Includes the following steps: Step 1: Prepare X image intensifiers to be tested, select Y of them, and measure their aperture gate time τ using the laser pulse scanning method, denoted as τ1, τ2…τ Y X≥3, 2≤Y<X, where X and Y are both integers; Step 2: For the Y image intensifiers described in Step 1, use a network analyzer to measure the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier as a function of the emission frequency f, and obtain the S11-f relationship diagram of the Y image intensifiers respectively. Step 3: Obtain the values ​​of the frequency domain reflection parameter S11 corresponding to the transmission frequency f of the Y S11-f relationship diagrams obtained in Step 2 when the transmission frequency f is Z, in the following order: S111, S112…S11 Y 10MHz≤Z≤100MHz; Step 4: In the Cartesian coordinate system, place points (S111,τ1), (S112,τ2), ..., (S11...) Y ,τ Y The τ-S11 relationship is obtained by fitting the function to a linear function. Step 5: For the remaining XY image intensifiers, use a network analyzer to measure the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier as a function of the emission frequency f, and obtain the S11-f relationship diagrams for the XY image intensifiers respectively. 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. These values ​​are as follows: S11... Y+1 S11 Y+2 …S11 X ; Step 7: Find the value of S11 obtained in step 6 on the τ-S11 relationship diagram obtained in step 4. Y+1 S11 Y+2 …S11 X The corresponding τ value at time is used to obtain the aperture time τ of the remaining XY image intensifiers. Y+1 τ Y+2 …τ X The measurement is now complete.

2. The rapid measurement method for image intensifier aperture time according to claim 1, characterized in that: In step 1, the measurement system for measuring the aperture time τ using the laser pulse scanning method includes a pulse generator (1), an ultrafast laser (2) connected to the pulse generator (1), a beam expander (4) and a semi-reflective mirror (5) sequentially arranged in the emission optical path of the ultrafast laser (2), a first diffuse scattering glass plate (6) and a first photodetector (9) sequentially arranged in the transmission optical path of the semi-reflective mirror (5), and a second diffuse scattering glass plate (8) and an image intensifier sequentially arranged in the reflection optical path of the semi-reflective mirror (5). The image intensifier (7) consists of a rear lens (15) and a camera (16) arranged sequentially on the output optical 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 the two output terminals of the power divider (10) respectively, and a gated shutter pulse generator (13) electrically connected to the output terminal of the delay pulse generator (12); the output terminal of the gated shutter pulse generator (13) is electrically connected to the opening control terminal of the image intensifier (7); The pulse generator (1) triggers the ultrafast laser (2) to output laser pulses. The laser pulses are expanded by the beam expander (4) and then incident on the semi-reflective 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 plate (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 to the oscilloscope (11) 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) to provide the cathode opening pulse for the image intensifier (7); The reflected laser pulse is homogenized by the second diffuse scattering glass plate (8) and then incident on the photocathode of the image intensifier (7) to be converted into an electronic image. The electronic image is enhanced by the selected shutter pulse and then received by the camera (16) after passing through the rear lens (15).

3. The rapid measurement method for image intensifier aperture time according to claim 2, characterized in that: In step 1, the laser pulse scanning method is used to measure the aperture time τ, specifically as follows: Step a1: The ultrafast laser (2) outputs two laser pulses with a fixed time interval in a single trigger. After beam expansion, the two laser pulses are divided into a transmitted light pulse and a reflected light pulse, respectively. 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 source of the image intensifier (7). Step a2: The transmitted light pulse of the first laser pulse is converted into an electrical signal after homogenization. The electrical signal is divided into two paths: one path is used for light intensity monitoring, and the other path 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 the cathode gate shutter pulse for the image intensifier (7), so that the cathode gate of the image intensifier (7) is opened. After the reflected light pulse of the second laser pulse is homogenized, it is incident on the photocathode of the image intensifier (7) and converted into an electronic image. When the gated shutter pulse of the gated shutter pulse generator (13) is applied to 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). Step a3: By adjusting the delay step size t1 of the delay pulse generator (12), the gating images of the image intensifier under different delays are obtained. The delay difference from edge gating to full gating of the output image under different delay time sequences is statistically analyzed, thereby obtaining the aperture time τ of the image intensifier.

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

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

6. The rapid measurement method for image intensifier aperture time according to claim 5, characterized in that: In steps 2 and 5, the measurement of the frequency domain reflection parameter S11 between the photocathode and the input surface of the microchannel plate in the image intensifier using a network analyzer as a function of the emission frequency f is specifically as follows: Step b1: Connect the photocathode lead wire of the image intensifier and the input terminal wire of the microchannel plate to the output port of the network analyzer, respectively. Step b2: The network analyzer emits electromagnetic wave signals to the photocathode and microchannel plate of the image intensifier, wherein the emission frequency of the electromagnetic waves 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 rapid measurement method for image intensifier aperture time according to claim 6, characterized in that: In step 1, Y = 2; Step 4 is as follows: In a Cartesian coordinate system, connecting points (S111,τ1) and (S112,τ2) yields a linear function, i.e., the τ-S11 relationship graph.

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

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

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