System and method for measuring transit time of streak camera
By using a measurement system of pulse signal source, pulse laser, stripe camera and oscilloscope in a stripe camera, the time interval between light pulse incident on the start time of the luminous signal of the fluorescent screen is accurately measured, which solves the problem that cannot be accurately measured in the prior art and achieves efficient recording efficiency.
Patent Information
- Application Number
- CN202510359186.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-25
- Publication Date
- 2025-06-20
AI Technical Summary
The prior art cannot accurately measure the time interval between the input time of the light pulse incident stripe camera and the starting time of the luminous signal of the stripe camera fluorescent screen, resulting in the exposure time of the digital camera being unable to be accurately adjusted, affecting the recording efficiency.
A measurement system for crossing time of the striped camera is adopted, including a pulse signal source, a pulse laser, a striped camera and an oscilloscope. By emitting three external triggered electrical pulses, the pulse laser, a striped camera and an oscilloscope, the arrival time of the electrical pulse and the optical signal is recorded, and the transition time is calculated as the time interval from the incident of the light pulse to the starting time of the luminous signal on the fluorescent screen.
It realizes accurate measurement of the crossing time of the striped camera, helps to adjust the time relative relationship between the arrival time of the light pulse and the exposure action of the digital camera, and ensures that the digital camera waits for the crossing time after the light pulse is incident before starting the exposure, thereby improving recording efficiency.
Smart Images
Figure CN120176996A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a streak camera, and particularly to a measurement system and method for the transit time of a streak camera. Background Art
[0002] A streak camera is an ultrafast optoelectronic recording device, usually composed of a slit, a relay lens, a streak tube, an image intensifier, and a digital camera. The slit is thin and long, and only the light within the slit area can enter the streak camera; the relay lens images the slit on the photocathode of the streak tube; when the streak camera works, the light incident on the photocathode of the streak tube through the slit is converted into photoelectrons, and the photoelectrons are distributed in a long strip shape, consistent with the shape of the slit. Under the action of the electron optical system of the streak tube, the photoelectrons accelerate and move inside the streak tube and are imaged on the fluorescent screen at the rear end of the streak tube. During the signal incident process, the photoelectrons pass through the deflection plates inside the streak tube, and a voltage varying with time is applied to the deflection plates, deflecting the photoelectrons passing at different times to different positions on the fluorescent screen, and different positions correspond to different times. The photoelectrons are converted into optical signals by the fluorescent screen, and the optical signals are amplified by the image intensifier and then recorded by the digital camera. Some streak cameras do not have an image intensifier, then the optical signal converted by the fluorescent screen of the streak camera is directly recorded by the digital camera. Due to the fast electron deflection speed, the streak camera is an instrument with high time resolution; the fastest streak camera in the world can reach a time resolution of 200 femtoseconds.
[0003] Behind the last-stage light-emitting link of the streak camera is a digital camera, which is used to record the data image formed by the light-emitting fluorescent screen. The exposure start time of the digital camera should be set slightly earlier than the light-emitting time of the fluorescent screen, and the exposure end time should be set slightly later than the light-emitting end time of the fluorescent screen, that is, the exposure period of the digital camera includes the effective light-emitting section of the fluorescent screen, so that all the light emitted by the fluorescent screen can be effectively recorded by the digital camera, achieving high-efficiency recording. However, the light-emitting time of the fluorescent screen of the streak camera and the exposure time of the digital camera have not been accurately measured and discussed. This is because the light-emitting duration of the fluorescent screen of the streak camera is several tens of milliseconds, while the exposure time of the digital camera is generally on the order of seconds or equivalent to the light-emitting time of the fluorescent screen. As long as the external trigger signals of the streak camera and the digital camera arrive simultaneously, the light-emitting image of the fluorescent screen can always be recorded with high efficiency.
[0004] However, for the sake of precise research, it is necessary to obtain the time interval between the moment when the optical pulse enters the input end of the streak camera and the starting moment when the streak camera's fluorescent screen emits light, so as to turn on the exposure of the digital camera before the fluorescent screen of the streak camera emits light. If the exposure of the digital camera is turned on after the fluorescent screen of the streak camera emits light, the light emission signal of the fluorescent screen before the exposure is turned on will not be recorded by the digital camera, resulting in a decrease in recording efficiency. Therefore, when accurately considering the light emission of the streak camera's fluorescent screen and the exposure operation of the digital camera, it is necessary to accurately measure the time interval between the moment when the optical pulse enters the input end of the streak camera and the starting moment when the streak camera's fluorescent screen emits light.
[0005] In summary, it is necessary to define and accurately measure the time interval between the moment when the optical pulse enters the input end of the streak camera and the starting moment when the streak camera's fluorescent screen emits light, and to establish the relevant measurement system and method. However, there has been no proposal of the relevant concept and establishment of the measurement system and method yet. Especially in some currently unpredictable application scenarios or system combination modes, the exposure time of the digital camera may be extremely short. At this time, this time interval should be considered. This time interval represents the most necessary time length required for the input optical signal to be converted into an image that can be recorded by the digital camera in the streak camera. The digital camera at the back end should wait at least this time length before starting to expose. Summary of the Invention
[0006] The purpose of the present invention is to solve the technical problem that the prior art cannot accurately measure the time interval between the moment when the optical pulse enters the input end of the streak camera and the starting moment when the streak camera's fluorescent screen emits a light signal, and thus provides a measurement system and method for the transit time of the streak camera.
[0007] In order to achieve the above purpose, the present invention adopts the following technical solutions:
[0008] A measurement system for the transit time of a streak camera, characterized in that it includes a pulse signal source, a pulsed laser, a streak camera, and an oscilloscope;
[0009] The pulse signal source includes signal channel A, signal channel B, and signal channel C;
[0010] The output end of signal channel A is connected to the input end of the pulsed laser;
[0011] The output end of signal channel B is connected to the trigger end of the streak camera; the input end of the streak camera is arranged on the emission optical path of the pulsed laser, and an optical detector is arranged on the optical path of the output end;
[0012] The output end of signal channel C is connected to the first input end of the oscilloscope; the second input end of the oscilloscope is connected to the output end of the optical detector;
[0013] The pulse signal source is used to emit three external trigger electrical pulses to trigger a pulsed laser, a streak camera, and an oscilloscope respectively;
[0014] The pulsed laser has an external trigger operating mode and is used to emit an optical pulse when receiving the first external trigger electrical pulse;
[0015] The streak camera has an external trigger operating mode and is used to start receiving an optical pulse and emit an optical signal using its fluorescent screen when receiving the second external trigger electrical pulse;
[0016] The photodetector is used to convert the optical signal into an electrical pulse and transmit it to the oscilloscope;
[0017] The oscilloscope is used to record the arrival times of the electrical pulse and the third external trigger electrical pulse respectively, and then calculate the transit time of the streak camera; the transit time is the time interval from the moment when the optical pulse enters the input end of the streak camera to the starting moment when the streak camera's fluorescent screen emits an optical signal.
[0018] Further, the distance between the input end of the streak camera and the output end of the pulsed laser, and the distance between the output end of the streak camera and the input end of the photodetector are both less than 10 cm.
[0019] Further, the delay jitter of the pulsed laser is less than 1 ns, the half-width of the optical pulse is less than 1 ns, and the central wavelength of the pulsed laser is within the response spectrum range of the photocathode of the streak camera.
[0020] Further, the photodetector is a photomultiplier tube or a photocell.
[0021] Meanwhile, the present invention also provides a method for measuring the transit time of a streak camera, which is characterized in that it includes the following steps:
[0022] 1) Build the above-mentioned measurement system for the transit time of the streak camera;
[0023] 2) Obtain the delay t1 of the pulsed laser;
[0024] 3) Obtain the delay t2 of the streak camera;
[0025] 4) Adjust the trigger delays of signal channel A and signal channel C of the pulse signal source according to the delay t1 of the pulsed laser and the delay t2 of the streak camera. The delay of signal channel A makes the emission moment of a single optical pulse of the pulsed laser equal to the starting moment of the streak camera's scan, and the delay of signal channel C makes the moment when the external trigger electrical pulse emitted by signal channel C arrives at the first input end of the oscilloscope equal to the emission moment of a single optical pulse of the pulsed laser;
[0026] 5) Use signal channels A, B, and C of the pulse signal source to emit three external trigger electrical pulses, which trigger a pulsed laser, a streak camera, and an oscilloscope respectively, obtain the transit time of the streak camera, and complete the measurement of the transit time of the streak camera.
[0027] Further, step 2) is specifically as follows:
[0028] 2.1 Connect the signal channel A of the pulse signal source to the input end of the pulsed laser, and connect the signal channel B to the first input end of the oscilloscope;
[0029] 2.2 Set the input end of the photodetector on the output optical path of the pulsed laser, and the distance between the input end of the photodetector and the output end of the pulsed laser is less than 10 cm; connect the output end of the photodetector to the second input end of the oscilloscope;
[0030] 2.3 Use signal channels A and B of the pulse signal source to simultaneously emit two external trigger electrical pulses and send them to the pulsed laser and the oscilloscope respectively. After receiving the external trigger electrical pulse, the pulsed laser emits an optical pulse and sends it to the photodetector. The photodetector converts the optical pulse into an electrical pulse and sends it into the oscilloscope. The oscilloscope records the arrival time of the electrical pulse as t3 and records the arrival time of the external trigger electrical pulse as t4;
[0031] 2.4 Use the arrival time of the electrical pulse t3 minus the arrival time t4 of the external trigger electrical pulse and the relaxation time of the photodetector to obtain the delay t1 of the pulsed laser.
[0032] Further, step 3) is specifically as follows:
[0033] 3.1 Connect the signal channel A of the pulse signal source to the input end of the pulsed laser, connect the signal channel B to the trigger end of the streak camera, and connect the signal channel C to the trigger end of the digital camera;
[0034] 3.2 Set the input end of the streak camera on the output optical path of the pulsed laser, and the distance between the input end of the streak camera and the output end of the pulsed laser is less than 10 cm;
[0035] 3.3 Set the input end of the digital camera on the output optical path of the streak camera, and adjust the field of view of the digital camera so that its field of view forms an inscribed rectangle within the light-emitting surface of the fluorescent screen;
[0036] 3.4. Simultaneously send three external trigger electrical pulses through signal channel A, signal channel B, and signal channel C of the pulse signal source to the pulsed laser, streak camera, and digital camera respectively; after receiving the external trigger electrical pulse, the pulsed laser emits a single optical pulse and transmits it to the input end of the streak camera, and after receiving the external trigger electrical pulse, the digital camera records the optical signal emitted from the output end of the streak camera; adjust the delay value of signal channel A of the pulse signal source until the single optical pulse completely appears at the edge of the rectangular field of view of the digital camera.
[0037] 3.5. Add the adjusted delay value of signal channel A to the delay t1 of the pulsed laser obtained in step 2.4 to obtain the delay t2 of the streak camera. After the measurement is completed, remove the digital camera.
[0038] Further, step 4) is specifically as follows:
[0039] 4.1. Set the difference between the delay t2 of the streak camera and the delay t1 of the pulsed laser as the trigger delay of signal channel A. The delay of signal channel A makes the emission time of the single optical pulse of the pulsed laser equal to the start time of the scan of the streak camera.
[0040] 4.2. Set the delay value t2 of the pulsed laser as the trigger delay of signal channel C. The delay of signal channel C makes the time when the external trigger electrical pulse emitted by signal channel C reaches the first input end of the oscilloscope equal to the emission time of the single optical pulse of the pulsed laser.
[0041] Further, in step 1), the distance between the input end of the streak camera and the output end of the pulsed laser is less than 10 cm; the distance between the input end of the photodetector and the output end of the streak camera is less than 10 cm.
[0042] Further, step 5) is specifically as follows:
[0043] 5.1. Send three external trigger electrical pulses through signal channel A, signal channel B, and signal channel C of the pulse signal source to trigger the pulsed laser, streak camera, and oscilloscope respectively. The oscilloscope records the arrival time of the external trigger electrical pulse emitted by the pulse signal source as t5 and records the arrival time of the electrical pulse emitted by the photodetector as t6.
[0044] 5.2. Subtract the arrival time t5 of the external trigger electrical pulse emitted by the pulse signal source and the relaxation time of the photodetector from the arrival time t6 of the electrical pulse emitted by the photodetector to obtain the transit time t0 of the streak camera.
[0045] Advantages of the present invention:
[0046] 1. The measurement system for the transit time of the streak camera of the present invention proposes the concept of the transit time of the streak camera, which helps to accurately adjust the relative time relationship between the arrival time of the optical pulse at the streak camera and the exposure action of the digital camera, so that the exposure action of the digital camera is accurately synchronized with the optical pulse to be measured by the streak camera.
[0047] 2. The measurement method for the transit time of the streak camera of the present invention helps to determine the shortest waiting time for the streak camera to effectively output an optical signal, that is, the transit time is the shortest limit time required for the streak camera to record an optical pulse. Even if the response speed of the digital camera or a module with a similar function reaches an ideal level, it is necessary to wait for the transit time after the optical pulse is incident to obtain the optical signal. Description of the Drawings
[0048] Figure 1 is a schematic structural diagram of an embodiment of the measurement system for the transit time of the streak camera of the present invention;
[0049] Appendix Figure 1 Marking Explanation:
[0050] 1 - Pulse signal source, 2 - Pulse laser, 3 - Streak camera, 4 - Photoelectric detector, 5 - Oscilloscope;
[0051] Figure 2 is a schematic diagram of the external trigger electrical pulse optical pulse (blue) emitted by the signal channel C of the pulse signal source and the light signal (red) emitted by the fluorescent screen of the streak camera after the trigger delay is adjusted in the embodiment of the measurement system for the transit time of the streak camera of the present invention;
[0052] Figure 3 is a schematic diagram of obtaining the transit time of the external trigger electrical pulse optical pulse (blue) emitted by the signal channel C of the pulse signal source and the light signal (red) emitted by the fluorescent screen of the streak camera after the trigger delay is adjusted in the embodiment of the measurement system for the transit time of the streak camera of the present invention. Detailed Embodiment
[0053] As Figure 1As shown in the figure, a measurement system for the transit time of a streak camera includes a pulse signal source 1, a pulsed laser 2, a streak camera 3, and an oscilloscope 5; the pulse signal source 1 includes a signal channel A, a signal channel B, and a signal channel C; the output end of the signal channel A is connected to the input end of the pulsed laser 2; the output end of the signal channel B is connected to the trigger end of the streak camera 3; the input end of the streak camera 3 is arranged on the emission optical path of the pulsed laser 2, and a photodetector 4 is arranged on the optical path of the output end; the distance between the input end of the streak camera 3 and the output end of the pulsed laser 2 is less than 10 cm, and the distance between the output end of the streak camera 3 and the input end of the photodetector 4 is less than 10 cm; the output end of the signal channel C is connected to the first input end of the oscilloscope 5; the second input end of the oscilloscope 5 is connected to the output end of the photodetector 4; the pulse signal source 1 is used to emit three-way external trigger electric pulses to trigger the pulsed laser 2, the streak camera 3, and the oscilloscope 5 respectively; the pulsed laser 2 is used to emit an optical pulse when receiving the first-way external trigger electric pulse; the streak camera 3 is used to start receiving the optical pulse and emit an optical signal when receiving the second-way external trigger electric pulse; the photodetector 4 is used to convert the optical signal emitted by the fluorescent screen of the streak camera 3 into an electric pulse and transmit it to the oscilloscope 5; the oscilloscope 5 is used to record the arrival times of the electric pulse of the photodetector 4 and the third-way external trigger electric pulse respectively, and then calculate the transit time of the streak camera 3; the transit time is the time interval from the moment when the optical pulse enters the input end of the streak camera 3 to the starting moment when the fluorescent screen of the streak camera 3 emits the optical signal.
[0054] The output of the pulse signal source 1 is an external trigger electric pulse, and the parameters of the three-way output external trigger electric pulses can be set independently. The pulse parameters are the delay, pulse width, and pulse voltage amplitude of the output electric pulse respectively; the pulse signal source 1 has a manual trigger function. After manual trigger, the three-way output of the pulse signal source 1 outputs external trigger electric pulses according to the set parameters. The pulse signal source 1 is used to synchronize the relative moments of the actions of the pulsed laser 2 and the streak camera 3 and provide a reference benchmark for the moment when the optical pulse reaches the slit.
[0055] The pulsed laser 2 has an external trigger working mode, that is, it outputs 1 optical pulse after receiving the external trigger electric pulse. The delay of the pulsed laser 2 is defined as the time interval from the moment when the external trigger electric pulse enters the pulsed laser 2 to the moment when the optical pulse exits; the delay of the pulsed laser 2 is stable, its delay jitter is less than 1 ns, the half-width of the optical pulse is less than 1 ns, and the central wavelength of the pulsed laser 2 is within the response spectrum range of the photocathode of the streak camera 3.
[0056] The streak camera 3 is used to record optical pulses. The streak camera 3 has two configurations: Configuration 1 means that the streak camera 3 is composed of a slit, a secondary lens, a streak tube, a digital camera, corresponding supporting circuit modules, and a mechanical structure; Configuration 2 means that the streak camera 3 is composed of a slit, a secondary lens, a streak tube, an image intensifier, a digital camera, corresponding supporting circuit modules, and a mechanical structure. In Configuration 1, the output end of the streak camera 3 is the fluorescent screen of the streak tube, and in Configuration 2, the output end of the streak camera 3 is the fluorescent screen of the image intensifier. The streak camera 3 has an external trigger mode, that is, the streak camera 3 can record optical pulses only after its trigger terminal receives an external trigger electrical pulse. The delay of the streak camera 3 is defined as the time interval between the moment when the external trigger electrical pulse arrives at the trigger terminal of the streak camera 3 and the moment when the streak camera 3 starts to record optical pulses. After the trigger terminal of the streak camera 3 receives an external trigger electrical pulse and at least after a time interval as long as the delay of the streak camera 3, the streak camera 3 can record the input optical pulse. Before measuring the transit time of the streak camera 3, the delay of the streak camera 3 has been measured in advance, and when measuring the transit time of the streak camera 3, the streak camera 3 operates in the external trigger mode.
[0057] The measuring system for the transit time of the streak camera of the present invention helps to accurately adjust the relative relationship between the arrival time of the optical signal of the streak camera 3 and the exposure action of the digital camera, and in some currently unpredictable application scenarios or system combination modes, helps to determine the theoretically shortest waiting time for the streak camera 3 to effectively output signals. Among them, the pulse signal source 1 simultaneously emits three-way external trigger electrical pulses. The first-way trigger pulse laser 2, the second-way triggers the streak camera 3, and the third-way is connected to the oscilloscope 5. After receiving the external trigger electrical pulse, the pulse laser 2 outputs an optical pulse, which enters the streak camera 3. The optical pulse and the external trigger electrical pulse are adjusted so that the optical pulse exactly appears at the scanning start end of the streak camera 3. The sensitive area of the photodetector 4 is aligned with the fluorescent screen of the streak camera 3 to record the process of the fluorescent screen emitting optical signals. The output optical signal is connected to the photodetector 4, and the photodetector 4 can actually select a photomultiplier tube or a phototube or other photodetectors according to the efficiency of the fluorescent screen emitting optical signals.
[0058] The transit time is used to describe the time interval between the incident of an optical pulse on the input end of the streak camera 3 and the emission of an optical signal by the fluorescent screen of the streak camera 3, and is related to links such as the travel time of the optical pulse in the relay optical system, the delay of the photocathode of the streak tube, the drift of photoelectrons, the relaxation of the emission of optical signals by the fluorescent screen of the streak tube, the transit time of the image intensifier, and the relaxation of the emission of optical signals by the fluorescent screen of the image intensifier. The transit time is usually longer than the delay. For a streak camera 3 with a sweep range of several hundred nanoseconds, the delay can be on the order of several tens of nanoseconds, while the transit time can be on the order of microseconds.
[0059] The transit time and the delay of the streak camera 3 are different concepts. The delay describes the relative time amount between the external trigger electrical pulse that triggers the scanning of the streak camera 3 and the arrival of the optical pulse at the streak camera 3. The external trigger electrical pulse arrives at the streak camera 3 earlier than the optical pulse, causing the scanning circuit to start scanning and cancel the bias voltage, so as to continue to make the electron image of the slit move from the starting end to the ending end of the scan. During the movement, the optical pulse must arrive at the streak camera 3 to be recorded. If the external trigger electrical pulse arrives too early and the streak camera 3 acts too early, then the optical pulse arrives after the scan ends, or if the external trigger electrical pulse arrives too late and the streak camera 3 acts too late, and the optical pulse has completed all the change processes before the scan starts, in both cases, no signal can be recorded. When the external trigger electrical pulse makes the optical pulse exactly appear at the starting end of the scan, the time difference between the external trigger electrical pulse and the arrival of the optical pulse at the slit of the streak camera 3 is called the delay of the streak camera 3. Different references can be taken according to actual needs, but generally the delay describes the required minimum advance amount between the external trigger electrical pulse and the optical pulse, which is related to the bias voltage and the inherent delay of the scanning circuit.
[0060] A method for measuring the transit time of a streak camera according to the present invention includes the following steps:
[0061] 1) Build the measurement system for the transit time of the above-mentioned streak camera, specifically:
[0062] 1.1. Connect the signal channel A of the pulse signal source 1 to the input end of the pulse laser 2, connect the signal channel B to the trigger end of the streak camera 3, connect the signal channel C to the first input end of the oscilloscope 5, and connect the output end of the photodetector 4 to the second input end of the oscilloscope 5;
[0063] 1.2. Set the input end of the streak camera 3 on the light path of the outgoing light of the pulse laser 2, and the distance between the input end of the streak camera 3 and the output end of the pulse laser 2 is less than 10 cm;
[0064] 1.3. Set the input end of the photodetector 4 on the light path of the outgoing light of the streak camera 3, and the distance between the input end of the photodetector 4 and the output end of the streak camera 3 is less than 10 cm, and complete the construction of the measurement system for the transit time of the above-mentioned streak camera;
[0065] 2) Obtain the delay t1 of the pulse laser 2:
[0066] 2.1. Connect the signal channel A of the pulse signal source 1 to the input end of the pulse laser 2, and connect the signal channel B to the first input end of the oscilloscope 5;
[0067] 2.2. Set the input end of the photodetector 4 on the output light path of the pulse laser 2, and the distance between the input end of the photodetector 4 and the output end of the pulse laser 2 is less than 10 cm; connect the output end of the photodetector 4 to the second input end of the oscilloscope 5;
[0068] 2.3. Simultaneously emit two external trigger electrical pulses from signal channel A and signal channel B of the pulse signal source 1 and send them to the pulsed laser 2 and the oscilloscope 5 respectively. After receiving the external trigger electrical pulse, the pulsed laser 2 emits an optical pulse and sends it to the photodetector 4. The photodetector 4 converts the optical pulse into an electrical pulse and sends it to the oscilloscope 5. The oscilloscope 5 records the arrival time of the electrical pulse as t3 and records the arrival time of the external trigger electrical pulse as t4;
[0069] 2.4. Obtain the delay t1 of the pulsed laser 2 by using the arrival time of the electrical pulse t3 minus the arrival time t4 of the external trigger electrical pulse and the relaxation time of the photodetector 4;
[0070] 3) Obtain the delay t2 of the streak camera 3, specifically as follows:
[0071] 3.1. Connect signal channel A of the pulse signal source 1 to the input end of the pulsed laser 2, connect signal channel B to the trigger end of the streak camera 3, and connect signal channel C to the trigger end of the digital camera;
[0072] 3.2. Set the input end of the streak camera 3 on the output optical path of the pulsed laser 2, and the distance between the input end of the streak camera 3 and the output end of the pulsed laser 2 is less than 10 cm;
[0073] 3.3. Set the input end of the digital camera on the output optical path of the streak camera 3, and adjust the field of view of the digital camera so that its field of view forms an inscribed rectangle within the light-emitting surface of the fluorescent screen;
[0074] Since the field of view of the fluorescent screen of the streak camera 3 is a circular field of view and the field of view of the digital camera is a rectangular field of view, adjust the rectangular field of view of the digital camera so that its field of view is exactly the inscribed rectangle of the circular field of view; The digital camera operates in the external trigger mode;
[0075] 3.4. Simultaneously emit three external trigger electrical pulses from signal channel A, signal channel B, and signal channel C of the pulse signal source 1 and send them to the pulsed laser 2, the streak camera 3, and the digital camera respectively. After receiving the external trigger electrical pulse, the pulsed laser 2 emits a single optical pulse and sends it to the input end of the streak camera 3. The digital camera records the optical signal emitted from the output end of the streak camera 3 after receiving the external trigger electrical pulse; Increase the delay value of signal channel A of the pulse signal source 1 until the single optical pulse completely appears at the edge of the rectangular field of view of the digital camera;
[0076] 3.5. Obtain the delay t2 of the streak camera 3 by adding the adjusted delay value of signal channel A to the delay t1 of the pulsed laser 2 obtained in step 2.4. After the measurement is completed, move the digital camera away from the output end of the streak camera 3;
[0077] 4) Adjust the trigger delays of signal channel A and signal channel C of the pulse signal source 1 according to the delay t1 of the pulsed laser 2 and the delay t2 of the streak camera 3. The delay of signal channel A makes the emission time of a single optical pulse of the pulsed laser 2 equal to the start time of the scan of the streak camera 3, and the delay of signal channel C makes the time when the external trigger electrical pulse emitted by signal channel C arrives at the first input terminal of the oscilloscope 5 equal to the emission time of a single optical pulse of the pulsed laser 2. Specifically:
[0078] 4.1. Set the difference between the delay t2 of the streak camera 3 and the delay t1 of the pulsed laser 2 as the trigger delay of signal channel A. The delay of signal channel A makes the emission time of a single optical pulse of the pulsed laser 2 equal to the start time of the scan of the streak camera 3;
[0079] At this time, it satisfies that the trigger pulse of signal channel A of the pulse signal source 1 triggers the pulsed laser 2 to emit a single optical pulse, so that the streak camera 3 can exactly record the entire waveform of this single optical pulse;
[0080] 4.2. Set the delay value t2 of the pulsed laser 2 as the trigger delay of signal channel C. The delay of signal channel C makes the time when the external trigger electrical pulse emitted by signal channel C arrives at the first input terminal of the oscilloscope 5 equal to the emission time of a single optical pulse of the pulsed laser 2;
[0081] 5) Use the measurement system of the transit time of the streak camera to complete the measurement of the transit time of the streak camera. Specifically:
[0082] 5.1. Use signal channel A, signal channel B, and signal channel C of the pulse signal source 1 to emit three-way external trigger electrical pulses to trigger the pulsed laser 2, the streak camera 3, and the oscilloscope 5 respectively. The oscilloscope 5 records the arrival time of the external trigger electrical pulse emitted by the pulse signal source 1 as t5 and records the arrival time of the electrical pulse emitted by the photodetector 4 as t6;
[0083] Signal channel A emits an external trigger electrical pulse according to its trigger delay to trigger the pulsed laser 2; signal channel B outputs an electrical pulse to the trigger terminal of the streak camera 3. At this time, a single optical pulse can exactly be recorded on the fluorescent screen of the streak camera 3. The photodetector 4 converts the optical signal emitted by the fluorescent screen of the streak camera 3 into an electrical pulse and transports it to the second input terminal of the oscilloscope 5. The second input terminal of the oscilloscope 5 records the time from the external trigger electrical pulse of signal channel A to the arrival time of the electrical pulse emitted by the photodetector 4 as t6, and the first input terminal of the oscilloscope 5 records the arrival time of the external trigger electrical pulse emitted by the pulse signal source 1 of signal channel C as t5;
[0084] 5.2. Subtract the arrival time t5 of the external trigger electrical pulse emitted by the pulse signal source 1 and the relaxation time of the photodetector 4 from the arrival time t6 of the electrical pulse emitted by the photodetector 4 to obtain the transit time t0 of the streak camera 3.
[0085] To describe the time interval from when an incident light pulse reaches the slit to when the fluorescence screen of the streak camera 3 starts emitting an optical signal, especially in some currently unpredictable application scenarios or system combination modes, in order to more accurately determine the relative time relationship between the exposure action of a digital camera or an image intensifier and the arrival of the incident light pulse at the slit, the method for measuring the transit time of the streak camera proposed by the present invention takes the state at the start end of the scan of the streak camera 3 where the light pulse recorded by the streak camera 3 just appears as the standard, and takes the time interval from when the light pulse enters the input end of the streak camera 3 to when the fluorescence screen of the streak camera 3 emits an optical signal as the transit time of the streak camera 3.
[0086] To further illustrate the method for measuring the transit time of the streak camera of the present invention, the following will be described in detail through specific examples.
[0087] Define the cable transit time between signal channel A of the pulse signal source 1 and the pulsed laser 2 as T1, the cable transit time between signal channel C of the pulse signal source 1 and the first input terminal of the oscilloscope 5 as T1′, and the cable transit time between the photodetector 4 and the second input terminal of the oscilloscope 5 is set to T1″, and let T1 = T1′ = T1″;
[0088] 1) The measured delay of the pulsed laser 2 is t1 = 22 ns;
[0089] The output end of the pulsed laser 2 is close to the input end of the streak camera 3, and the distance between the two is less than 10 cm. It can be considered that the light enters the input end of the streak camera 3 immediately after it exits.
[0090] 2) The measured delay of the streak camera 3 is t2 = 100 ns;
[0091] 3) Set the trigger delay of signal channel A of the pulse signal source 1 to the difference between the delay t2 of the streak camera 3 and the delay t1 of the pulsed laser 2, that is, 78 ns; set the trigger delay of signal channel C of the pulse signal source 1 to the delay value t1 of the pulsed laser 2, that is, 22 ns;
[0092] 4) Using the above measurement system for the transit time of the streak camera, it can be obtained that the external trigger electrical pulse of signal channel C is input to the first input terminal of the oscilloscope 5, and its electrical pulse width is 5 ns. Take its peak moment as the moment when a single light pulse output by the pulsed laser 2 enters the input end of the streak camera 3; the relaxation time of the photodetector 4 is Δte. In this embodiment, the photodetector 4 uses a photomultiplier tube, then its relaxation time Δte = 50 ns;
[0093] As Figure 2As shown, the blue signal is the signal on the oscilloscope 5 from the signal channel C of the pulse signal source 1. The peak moment of the blue pulse signal represents the moment when a single optical pulse emitted by the pulsed laser 2 reaches the input end of the streak camera 3; the red signal is the optical signal emitted by the phosphor screen recorded by the photomultiplier tube, and the peak amplitude is -1V.
[0094] As Figure 3 shown, it is a specific display of the method for reading the time interval. The blue signal represents the external trigger electric pulse recorded by the first input end of the oscilloscope 5. The peak moment of this pulse represents the moment when a single optical pulse of the pulsed laser 2 reaches the input end of the streak camera 3. Take the peak moment of this external trigger electric pulse as the starting point; the red signal represents the electric pulse recorded by the second input end of the oscilloscope 5, which is the electric pulse generated after the optical signal emitted by the phosphor screen of the streak camera 3 is converted by the photodetector 4. Take the moment corresponding to the point where the amplitude before the peak of this electric pulse is 10% of the peak amplitude as the end point. Here, take the moment corresponding to -0.1V as the end point. From Figure 3 it can be seen that the time interval between the read end point and the start point is 512 ns. This result represents the time interval between the incident of the optical pulse on the input end of the streak camera 3 and the output electric pulse of the photodetector 4, which is equal to the sum of the transit time of the streak camera 3 and the relaxation time Δte of the photodetector 4. Then, the time interval from the moment when a single optical pulse reaches the input end of the streak camera 3 to the starting moment of the optical signal emitted by the phosphor screen, that is, the transit time of the streak camera 3 is equal to:
[0095] 512 - Δte = 462 ns
[0096] In summary, the measured transit time of this streak camera 3 is 462 ns.
Claims
1. A streak camera transit time measurement system, characterized in that: It comprises a pulse signal source (1), a pulse laser (2), a streak camera (3) and an oscilloscope (5); The pulse signal source (1) comprises a signal channel A, a signal channel B and a signal channel C; The output end of the signal channel A is connected to the input end of the pulse laser (2); The output end of the signal channel B is connected to the trigger end of the streak camera (3); the input end of the streak camera (3) is arranged on the emission light path of the pulse laser (2), and a photodetector (4) is arranged on the light path of the output end; The output end of the signal channel C is connected to the first input end of the oscilloscope (5); the second input end of the oscilloscope (5) is connected to the output end of the photodetector (4); The pulse signal source (1) is used to emit three external triggering electrical pulses to respectively trigger the pulse laser (2), the streak camera (3) and the oscilloscope (5); The pulse laser (2) has an external triggering working mode and is used to emit a light pulse when receiving a first external triggering electrical pulse; The streak camera (3) has an external triggering working mode, and is used to start receiving light pulses and emit light signals using its fluorescent screen when receiving a second external triggering electrical pulse; The photodetector (4) is used to convert the optical signal into an electrical pulse and transmit it to the oscilloscope (5); The oscilloscope (5) is used to respectively record the arrival time of the electric pulse and the third external trigger electric pulse, and then calculate the transit time of the streak camera (3); the transit time is the time interval from the light pulse incident on the input end of the streak camera (3) to the start time of the streak camera (3) fluorescent screen emitting a light signal.
2. The streak camera transit time measurement system according to claim 1, characterized in that: The distance between the input end of the streak camera (3) and the output end of the pulse laser (2), and the distance between the output end of the streak camera (3) and the input end of the photoelectric detector (4) are both less than 10 cm.
3. The streak camera transit time measurement system according to claim 2, characterized in that: The delay jitter of the pulse laser (2) is less than 1 ns, the half width of the light pulse is less than 1 ns, and the central wavelength of the pulse laser (2) is within the response spectrum range of the photocathode of the streak camera (3).
4. The streak camera transit time measurement system according to claim 3, characterized in that: The photoelectric detector (4) is a photomultiplier tube or a photoelectric tube.
5. A method for measuring the transit time of a streak camera, characterized in that: The following steps are involved: 1) Building a streak camera transit time measurement system as described in any one of claims 1 to 4; 2) obtaining the delay t1 of the pulse laser (2); 3) Obtain the time delay t2 of the streak camera (3); 4) adjusting the trigger delays of the signal channel A and the signal channel C of the pulse signal source (1) according to the delay t1 of the pulse laser (2) and the delay t2 of the streak camera (3), the delay of the signal channel A making the time when a single light pulse of the pulse laser (2) is emitted equal to the scanning start time of the streak camera (3), and the delay of the signal channel C making the time when the external triggering electric pulse emitted by the signal channel C arrives at the first input terminal of the oscilloscope (5) equal to the time when a single light pulse of the pulse laser (2) is emitted; 5) Using the signal channel A, signal channel B and signal channel C of the pulse signal source (1) to send out three external triggering electrical pulses, respectively triggering the pulse laser (2), the streak camera (3) and the oscilloscope (5), obtaining the transit time of the streak camera (3), and completing the measurement of the streak camera transit time.
6. The method for measuring the transit time of a streak camera according to claim 5, characterized in that: Step 2) is specifically as follows: 2.
1. Connect the signal channel A of the pulse signal source (1) to the input end of the pulse laser (2), and connect the signal channel B to the first input end of the oscilloscope (5); 2.
2. The input end of the photodetector (4) is arranged on the output optical path of the pulse laser (2), and the distance between the input end of the photodetector (4) and the output end of the pulse laser (2) is less than 10 cm; the output end of the photodetector (4) is connected to the second input end of the oscilloscope (5); 2.
3. Using the signal channel A and the signal channel B of the pulse signal source (1) to simultaneously send two external triggering electric pulses to the pulse laser (2) and the oscilloscope (5) respectively. After receiving the external triggering electric pulses, the pulse laser (2) sends a light pulse to the photodetector (4). The photodetector (4) converts the light pulse into an electric pulse and sends it to the oscilloscope (5). The oscilloscope (5) records the arrival time of the electric pulse as t3 and the arrival time of the external triggering electric pulse as t4. 2.
4. The delay t1 of the pulse laser (2) is obtained by using the electric pulse arrival time t3 minus the arrival time t4 of the external trigger electric pulse and the relaxation time of the photodetector (4).
7. The method for measuring the transit time of a streak camera according to claim 6, characterized in that: Step 3) is specifically: 3.
1. Connect the signal channel A of the pulse signal source (1) to the input end of the pulse laser (2), connect the signal channel B to the trigger end of the streak camera (3), and connect the signal channel C to the trigger end of the digital camera; 3.
2. The input end of the streak camera (3) is arranged on the output optical path of the pulse laser (2), and the distance between the input end of the streak camera (3) and the output end of the pulse laser (2) is less than 10 cm; 3.
3. The input end of the digital camera is arranged on the optical path of the output end of the streak camera (3), and the field of view of the digital camera is adjusted so that the field of view forms an inscribed rectangle within the luminous surface of the fluorescent screen; 3.
4. Use the signal channel A, signal channel B and signal channel C of the pulse signal source (1) to simultaneously send out three external triggering electrical pulses, which are respectively transmitted to the pulse laser (2), the streak camera (3) and the digital camera; after receiving the external triggering electrical pulse, the pulse laser (2) sends out a single light pulse which is transmitted to the input end of the streak camera (3); after receiving the external triggering electrical pulse, the digital camera records the light signal sent out from the output end of the streak camera (3); adjust the delay value of the signal channel A of the pulse signal source (1) until all the single light pulses appear at the edge of the rectangular field of view of the digital camera; 3.
5. Add the delay value adjusted by signal channel A to the delay t1 of the pulse laser (2) obtained in step 2.4 to obtain the delay t2 of the streak camera (3). After the measurement is completed, remove the digital camera.
8. The method for measuring the transit time of a streak camera according to claim 7, characterized in that: Step 4) is specifically as follows: 4.
1. The difference between the delay t2 of the streak camera (3) and the delay t1 of the pulse laser (2) is set as the trigger delay of the signal channel A. The delay of the signal channel A makes the time when a single light pulse of the pulse laser (2) is emitted equal to the scanning start time of the streak camera (3); 4.
2. The delay value t2 of the pulse laser (2) is set as the trigger delay of the signal channel C. The delay of the signal channel C makes the time when the external triggering electrical pulse emitted by the signal channel C reaches the first input terminal of the oscilloscope (5) equal to the time when a single optical pulse of the pulse laser (2) is emitted.
9. The method for measuring the transit time of a streak camera according to claim 8, characterized in that: In step 1), the distance between the input end of the streak camera (3) and the output end of the pulse laser (2) is less than 10 cm; the distance between the input end of the photodetector (4) and the output end of the streak camera (3) is less than 10 cm.
10. The method for measuring the transit time of a streak camera according to claim 9, characterized in that: Step 5) is specifically: 5.
1. Using the signal channel A, signal channel B and signal channel C of the pulse signal source (1) to send out three external triggering electric pulses, the pulse laser (2), the streak camera (3) and the oscilloscope (5) are triggered respectively. The oscilloscope (5) records the arrival time of the external triggering electric pulse sent by the pulse signal source (1) as t5 and the arrival time of the electric pulse sent by the photodetector (4) as t6 respectively. 5.
2. The transit time t0 of the streak camera (3) is obtained by subtracting the arrival time t5 of the external triggering electric pulse emitted by the pulse signal source (1) and the relaxation time of the photodetector (4) from the arrival time t6 of the electric pulse emitted by the photodetector (4).