Transient Spectroscopy ns-level Pulse Light Delay Synchronization Control Trigger System

Abstract

The present invention discloses a transient spectroscopy ns-level pulsed light delay synchronization control trigger system, comprising: an FPGA circuit, an interface circuit, a laser driver circuit, and a detector driver circuit. The laser driver circuit is connected to a laser, and the detector driver circuit is connected to a detector. The interface circuit includes a USB adapter and an RS232 adapter, and has the function of converting RS232 to TTL level. The instructions sent by the host computer are first connected through the RS232 adapter for level conversion, and the converted TTL level is transmitted to the FPGA circuit. When measuring the light source spectrum at the ns or μs level, the FPGA circuit realizes the synchronous timing function of the FPGA circuit by adjusting the pulse delay synchronization control in the system, realizes the synchronization of the exposure time of the detector and the light emission time of the pulsed laser to be measured, and ensures that all the light energy of the light source is accurately and completely captured by the transient spectrometer. The present invention solves the problems that it is difficult to synchronously trigger light pulses and it is difficult to capture nanosecond-level pulsed laser signals in spectrometer tests.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical testing, and relates to a transient spectral pulsed light delay synchronization control trigger system, and particularly to a ns-level pulsed light delay synchronization control trigger system in a transient spectrometer. Background Art

[0002] A transient spectrometer is used to measure the wavelength and spectral curve of a light source with a flash time in the order of (ns to ms). The measured transient light sources include three types, namely pulsed lasers, flashlights, and luminescent element substances. Flashlights include pulsed xenon lamps, pulsed krypton lamps, airport obstacle lights, landing lights, special lighting fixtures, and light display devices, etc.; luminescent element substances include fields such as high-time-resolution explosion of explosives, pulsed discharge sparks, cannonball flames, missile and engine tail flames, and element plasmas. At the moment when the transient light source emits light, the light intensity changes with time, and the detector in the spectrometer cannot receive the energy synchronously, so that high-time-resolution measurement of the spectral curve cannot be achieved. In the field of explosive explosion, transient spectral parameters can provide data support for explosion processes, explosion mechanism analysis, etc.; at the moment when explosives and other substances emit light, accurate parameter testing must ensure the same standard trigger time, otherwise the data processing after the test is inaccurate.

[0003] A transient spectral pulsed light delay synchronization control trigger system can provide a trigger signal for the spectrometer. Currently, the triggering methods mainly include optical triggering method, electrical triggering method, wireless communication triggering method, acoustic triggering method, etc. The deficiencies of traditional trigger systems are mainly:

[0004] 1. Disadvantages of optical acquisition threshold triggering: Part of the optical energy is lost, and the stored data and the acquired data are inaccurate.

[0005] In the optical triggering method, the explosion light is used as the trigger signal. After the light is transmitted, it enters the spectrometer and is converted into an electrical signal. When the signal intensity threshold is greater than the noise of each pixel of the array detector in the spectrometer, the software sets the trigger to start collecting and outputting the measured spectral signal. Otherwise, the detector signal is not output. The disadvantage of this method is that the duration of the optical pulse signal is greater than the integration period of the detector, and a pulse signal is output by two frames or multiple frames of spectral curves corresponding in time sequence, which cannot ensure that the spectrometer reflects the light change in real time.

[0006] When the light reaches the rising edge of the integration period of the spectrometer, during the process of rising to the high level, the optical energy will be lost.

[0007] 2. Slow triggering speed

[0008] In the wireless communication triggering method, each node does not need to be connected by a lead wire, but the data transmission speed is slow, the synchronization time is in the millisecond level, and the synchronization performance is low.

[0009] The sound trigger method uses the sound signal generated by the explosion as the trigger signal. However, the speed of sound propagation in air is slow and it is affected by the ambient temperature. It is not convenient for on-site wiring.

[0010] 3. The optical trigger method of the photodetector has a large interference noise

[0011] The spectrometer is externally connected to an optical trigger. The optical trigger has a single-point photodetector built-in. After receiving the pulsed light emitted by the transient light source and converting it into an electrical signal, it immediately sends out a TTL level as a trigger command to the spectrometer. After receiving the command, the spectrometer immediately starts working to collect data. The first drawback of this trigger is the slow response speed. It takes time to output the acquisition command after photoelectric conversion, generally in the order of milliseconds. The second drawback is that in strong outdoor light, a large photocurrent will be generated, which is easy to mistake the ambient light for the light source signal light, and it is easy to cause false triggering. In addition, for the explosion light, its response interference is large, and the strong light instantaneously reflected by various objects in the test environment onto the optoelectronic device may also cause false triggering.

[0012] Transient spectral signal measurement device, Northwest Institute of Nuclear Technology, applied for in November 2018, patent number ZL201810718456.X; to solve the problem of high-time-resolution measurement of transient spectral signals, the device includes an optical fiber bundle, an optical fiber coupler, a monochromator, a linear array detector, and a terminal computer; the optical fiber bundle includes multiple optical fibers of different lengths. The optical fibers at the incident end of the optical fiber bundle are distributed in a plane, and the optical fibers at the output end of the optical fiber bundle are arranged linearly. The measured optical signal enters the incident end of the optical fiber bundle. The multiple optical fibers of different lengths in the optical fiber bundle transmit the incident optical signal and generate different time delays. After the optical signal passes through the monochromator spectroscopic imaging system, the optical signals corresponding to different optical fibers are imaged in different regions in the vertical direction of the linear array detector. The terminal computer obtains multiple groups of spectral signals along the vertical direction of the linear array detector. The multiple optical fibers of different lengths in the optical fiber bundle transmit the incident optical signal and generate different time delays. The optical signals corresponding to different optical fibers are imaged in different regions in the vertical direction of the linear array detector. The linear array detector has a gating function, and the opening width is less than the time delay difference t generated by adjacent optical fibers of different lengths.

[0013] Yuan Changying and Li Ping from the Institute of High Temperature and High Pressure Physics of Sichuan University published a paper titled "Trigger and Synchronization Techniques in Transient Spectral Measurement" in the 04th issue of the Journal of Atomic and Molecular Physics in 2003. It mentioned that a high-speed single-pulse trigger circuit was designed and fabricated, with the trigger threshold continuously adjustable in the range of 150 mV to 1.5 V, the output pulse width adjustable by itself, and its response time less than 50 ns. A synchronization scheme for measuring trigger delay by a short-pulse semiconductor laser was proposed. Using an ICCD detector with image intensification, a transient spectral test system was established, and the transient spectra of the deflagration-to-detonation process of 1 microsecond of propylene oxide were measured in real time. The synchronization trigger device requires fast response and single-pulse trigger, including three parts: a sensor, a trigger circuit, and a delay controller. The sensor can select a photoelectric detection and conversion device. The trigger circuit, namely the pulse formation circuit, amplifies and compares the sensor signal and gives a standard TTL pulse to trigger the delay controller.

[0014] The invention patent "Transient Temperature Measurement Device Based on Snapshot Spectral Imaging Technology (Application No. 202010467446.0)" uses a snapshot spectral imaging module and a high-speed area array image sensor to obtain a two-dimensional image of spectral information and spatial information. A band-pass filter is used to select and transmit light in a specific wavelength range. Using a microlens array and a birefringent prism group, a common-path polarized light interference is established to obtain a two-dimensional interference pattern array, and a spectral image sequence is obtained by Fourier transform. The time resolution of the high-speed area array detector is better than the microsecond level, and the area array image sensor has an internal electronic shutter to obtain the change process of the instantaneous temperature field of the object to be measured. The wavelength is 800 nm to 5000 nm; the temperature measurement range is 580 K to 1160 K;

[0015] The patents of Xi'an Institute of Applied Optics in 1981, Patent 1 Flash Spectrometer, and in 1998, Patent 2 Transient Spectroradiometer, and in 2008, Transient Spectroradiometer, use the optical trigger threshold method to disperse light by a grating and capture curves such as flashlights and explosive explosions. The National Institute of Metrology of China in 2005 used a transient spectroradiometer, a high-speed A / D conversion device, a diffuser, etc. to achieve the measurement of the spectral radiation intensity of an explosion light source within 1 second.

[0016] Nanjing Zhikongce Co., Ltd. has an explosion field wireless transient trigger control device (201720627831.0). The device includes a modulated light source device and an optoelectronic signal processing device. The first controller is connected to the modulated laser through a modulation signal line. The photosensitive device receives the square-wave light signal generated by the modulated laser, and the output end of the photosensitive device is connected to the preamplification circuit. Through this explosion field wireless transient trigger control device, a series of problems in the trigger system such as slow trigger response speed, inconvenient on-site wiring, and reduction of the influence of ambient light on the trigger system can be solved.

[0017] At present, for the measurement of transient spectral distribution characteristics, the time resolution of common spectrometers is in the order of dozens of microseconds to milliseconds. Combining a monochromator with a million-frame high-speed camera can achieve a time resolution of the microsecond order, but the system is relatively complex and expensive.

[0018] To sum up, none of the common explosion field triggering methods can meet the requirements of being wireless, having a fast response speed, and strong anti-interference ability at the same time. At present, no pulse light delay synchronization control trigger system for transient spectroscopy measurement has been seen, and there is no relevant report on a high-time-resolution time delay synchronization trigger control system for a transient spectroscopy instrument. How to achieve precise measurement of the spectral curve of transient optical pulse energy in the ns order urgently requires a new precise time delay synchronization trigger control method to achieve time series measurement and meet the high-time-resolution synchronous precise measurement of transient processes. Summary of the Invention

[0019] (1) Object of the Invention

[0020] The object of the present invention is to provide a transient spectroscopy ns-order pulse light delay synchronization control trigger system to solve the problems such as difficult synchronous triggering of optical pulses during transient spectroscopy measurement, difficult capture of nanosecond-level pulsed laser signals, precise control of the optimal delay synchronization between the pulsed light and the detector in the spectrometer, and measurement mis-triggering caused by transient ambient light.

[0021] (2) Technical Solution

[0022] To solve the above technical problems, the present invention provides a transient spectroscopy ns-order pulse light delay synchronization control trigger system, which includes: an FPGA circuit and an interface circuit, a laser driver circuit, and a detector driver circuit connected thereto. The laser driver circuit is connected to a laser, and the detector driver circuit is connected to a detector; the interface circuit includes a USB adapter and an RS232 adapter, and has the function of converting RS232 to TTL level. The instructions sent by the host computer are first connected through the RS232 adapter for level conversion and converted into TTL level and transmitted to the FPGA circuit; the laser driver circuit includes a driving level conversion circuit for controlling the laser driving level conversion and current enhancement to achieve control of the laser level command; the detector driver circuit drives the detector level conversion circuit in the spectrometer to control the detector driving level conversion and achieve control of the detector level command; during ns or μs-order light source spectrum measurement, the FPGA circuit realizes the synchronous timing function of the FPGA circuit by adjusting the pulse delay synchronization control in the system, and at the same time realizes the synchronization of the exposure time of the detector and the light output time of the pulsed laser to be measured, ensuring that all the light energy of the light source is accurately and completely captured by the transient spectrometer.

[0023] Among them, it further includes: a clock circuit, and the clock circuit provides a clock signal for the FPGA circuit.

[0024] Among them, the clock circuit includes a crystal oscillator module, a clock jitter elimination module, a phase-locked loop module, a clock buffer module, a clock frequency division module, and a clock distribution module connected in sequence; the crystal oscillator module generates a crystal oscillator clock signal, which first passes through the clock jitter elimination module to stabilize the frequency, and then the clock signal passes through the phase-locked loop module to achieve the phase synchronization of the clock on the circuit and a certain external clock. The phase-locked loop module compares the phase of the external reference signal with the phase of the clock signal, adjusts the phase of the crystal oscillator clock signal to match the phase of the reference signal, and synchronizes the phase of its on-board clock with the external reference signal; the clock buffer module copies, converts the format, and converts the level of the clock signal generated by the crystal oscillator; the function of the clock frequency division module is to adjust the frequency of the clock signal, and finally the clock distribution module distributes the adjusted high-quality clock signal to each working unit of the FPGA.

[0025] Among them, the FPGA circuit includes: a serial port protocol unit, a pulse generation unit, a delay counting unit, an energy detection unit, and a detector control signal generation unit; the pulse generation unit, the delay counting unit, the energy detection unit, and the detector control signal generation unit are all connected to the interface circuit through the serial port protocol unit. The pulse generation unit provides a laser driver circuit to connect to the laser, the delay counting unit and the energy detection unit are connected to the detector, and the detector control signal generation unit is connected to the detector through the detector driver circuit.

[0026] Among them, the pulse generation unit includes: a serial port instruction forwarding module, a pulse laser counting module, a controllable frequency pulse module, a delay counting module, a detector counting module, and a controllable frequency pulse module; the serial port instruction forwarding module is connected to the serial port protocol unit, the pulse laser counting module is connected to the serial port instruction forwarding module and the controllable frequency pulse module, the controllable frequency pulse module is connected to the laser, the delay counting module is connected to the serial port instruction forwarding module and the detector counting module, and the controllable frequency pulse module is connected to the detector counting module and the detector; the serial port protocol unit realizes the connection with the interface circuit, and then the serial port instruction forwarding module transmits the serial port input instruction to the FPGA circuit for logical processing; the pulse generation unit issues a trigger pulse signal to control the light output time of the pulse laser to be measured, and outputs a frequency pulse wave corresponding to the instruction and a frequency pulse wave with a settable delay.

[0027] Among them, the time delay counting unit includes: a sampling trigger counter module, a time counter module, and a control circuit module. The control circuit module is connected to the detector through an interface and is also connected to the sampling trigger counter module and the time counter module. The time counter module is connected to the serial port protocol unit. The time delay counting unit measures the acquisition and processing time of the detector, which is the time from the light signal output by the pulsed laser, transmitted, acquired and processed, and then delivered to the host computer software. The time delay counting unit ensures that when a frame of spectrum starts within the working time of the detector, it is synchronized to the complete capture of the light signal output by the pulsed laser by the detector, without energy loss.

[0028] Among them, the time counter module receives an instruction sent by the host computer through the interface circuit to start the sampling trigger counter module to start timing. Then it receives the optical signal data collected by the detector in real time. When the change in the optical signal data of the pulsed laser collected exceeds the threshold set by the FPGA circuit, it is determined that the detector has captured the optical signal of the pulsed laser, and the sampling is stopped. The sampling trigger counter module starts to time, and the processing time is sent to the corresponding host computer of the detector for display through the time counter module.

[0029] Among them, the energy detection unit includes: a filtering module, an energy statistics module, a maximum value detection module, a validity judgment module, and a valid value module connected in sequence. The filtering module is connected to the detector, and the valid value module is connected to the serial port protocol unit. After the optical data collected by the detector is transmitted to the energy detection unit, it first passes through the filtering module, and after filtering, specific frequency components in the signal pass through. The energy statistics module performs energy statistics on the filtered data. Then the maximum value detection module judges whether it meets the set threshold according to the statistical result. Finally, the validity judgment module performs validity judgment on the data, and the valid data is stored in the valid value module.

[0030] Among them, the detector control signal generation unit includes a protocol conversion module, a control circuit module, a counter module, and a signal generation module connected in sequence. The protocol conversion module is connected to the serial port protocol unit through an interface, and the signal generation module is connected to the detector through a detector drive circuit. After the protocol conversion module receives the level instruction sent by the host computer, the control circuit module recognizes the corresponding instruction and starts the counter module to count, and the counter continuously cycles to count, ensuring that a frequency pulse is generated to drive the detector to be in the working state all the time. The signal generation module generates a standard TTL level standard, and the pulse width is fixed, and it is output to the detector drive circuit to meet the drive requirements.

[0031] (III) Beneficial effects

[0032] The transient spectrum ns-level pulsed light delay synchronization control trigger system provided by the above technical solution has the following beneficial effects:

[0033] 1) A transient spectroscopy ns-level pulsed light delay synchronization control trigger system was designed to solve the problem of difficult capture of nanosecond-level pulsed laser signals.

[0034] 2) The transient spectroscopy pulsed light delay synchronization control trigger system realizes precise control of the optimal delay synchronization between the pulsed light to be measured and the detector in the spectrometer, adjusts to obtain the optimal synchronization delay time, ensures that all the light energy of the light source is captured in real time and in sequence by the transient spectrometer, and measures and outputs the corresponding spectral curve.

[0035] 3) The ns-level pulsed delay synchronization control trigger method is adopted to solve the problems such as difficult synchronous triggering of light pulses during transient spectroscopy measurement, measurement mis-triggering caused by transient ambient light, inaccurate acquisition data due to loss of some light energy, etc. Description of the Drawings

[0036] Figure 1 Schematic diagram of the composition of the transient spectroscopy pulsed light delay synchronization control trigger system;

[0037] Figure 2 Schematic diagram of the working process of the FPGA circuit;

[0038] Figure 3 Schematic diagram of the composition of the clock circuit;

[0039] Figure 4 Schematic diagram of the composition of the pulse generation unit;

[0040] Figure 5 Schematic diagram of the composition of the time delay counting unit;

[0041] Figure 6 Schematic diagram of the composition of the energy detection unit;

[0042] Figure 7 Schematic diagram of the composition of the detector control signal generation unit. Detailed Implementation Modes

[0043] To make the objectives, contents, and advantages of the present invention clearer, the following further describes in detail the specific implementation modes of the present invention with reference to the drawings and embodiments.

[0044] Refer to Figure 1As shown in the figure, the transient spectroscopy ns-level pulsed light delay synchronization control trigger system of this embodiment includes: an FPGA circuit and an interface circuit, a laser driver circuit, a detector driver circuit, and a clock circuit connected thereto; the interface circuit includes a USB adapter and an RS232 adapter, and has the function of converting RS232 to TTL level to ensure normal reception of instructions sent by the spectrometer software of the host computer; the instructions sent by the host computer first pass through the RS232 adapter to the TTL chip for level conversion, and are converted into standard TTL level and then transmitted to the FPGA circuit. This level is a TTL pulse level of a certain width, with characteristics such as IEC ESD protection, low power consumption, high data rate, and strong electrostatic protection. The laser driver circuit includes a drive level conversion circuit for controlling the laser drive level conversion and current enhancement to achieve the control of the laser level command. The detector driver circuit mainly drives the detector level conversion circuit in the spectrometer to control the detector drive level conversion and achieve the control of the detector level command. When measuring the light source spectrum in the ns or μs level, the FPGA circuit adjusts the pulse delay synchronization control in the system to ensure that the FPGA circuit has the synchronous timing function, realizes the synchronization of the exposure time of the detector and the light output time of the pulsed laser to be measured, and ensures that all the light energy of the light source is accurately and completely captured by the transient spectrometer. The clock circuit provides a clock signal for the FPGA circuit.

[0045] The clock circuit is as Figure 3 shown, and includes a crystal oscillator module, a clock jitter elimination module, a phase-locked loop module, a clock buffer module, a clock frequency division module, and a clock distribution module connected in sequence. The crystal oscillator module generates a crystal oscillator clock signal, which first passes through the clock jitter elimination module to stabilize the frequency. When using a logically generated clock, there are skew, jitter, and asynchronous arrival times at the target device, resulting in system instability. Using the clock jitter elimination module avoids uncontrollable situations such as clock jitter and skew arriving at the target device asynchronously. Then the clock signal passes through the phase-locked loop module to achieve the phase synchronization of the clock on the circuit and a certain external clock. The phase-locked loop (PLL) is a feedback circuit that adjusts the phase of the crystal oscillator clock signal to match the phase of the reference signal by comparing the phase of the external reference signal with the phase of the clock signal, and synchronizes the phase of its on-board clock with the external reference signal. The clock buffer module copies, formats, and converts the clock signal generated by the crystal oscillator. The function of the clock frequency division module is to adjust the frequency of the clock signal. Finally, the clock distribution module distributes the adjusted high-quality clock signal to each working unit of the FPGA.

[0046] The FPGA circuit is as Figure 2As shown in the figure, it includes: a serial port protocol unit, a pulse generation unit, a time delay counting unit, an energy detection unit, and a detector control signal generation unit; the pulse generation unit, the time delay counting unit, the energy detection unit, and the detector control signal generation unit are all connected to the interface circuit through the serial port protocol unit. The pulse generation unit provides a connection to the laser driver circuit for the laser, the time delay counting unit and the energy detection unit are connected to the detector, and the detector control signal generation unit is connected to the detector through the detector driver circuit.

[0047] The main functions of the FPGA circuit are as follows: When measuring the light source spectrum at the ns or μs level, by adjusting the pulse delay synchronization control within the system, it ensures that the FPGA circuit has a synchronous timing function, realizes the synchronization of the exposure time of the detector and the light emission time of the pulse laser to be measured, and ensures that all the light energy of the light source is accurately and completely captured by the transient spectrometer. Its design basis is: Based on the design of the clock trigger edge, timing synchronization requirements are put forward for the period, duty cycle, delay, and jitter of the clock. The global clock resource is used to drive the design of the main clock to achieve the lowest clock jitter and delay, and obtain an accurate clock signal. The power supply of the FPGA circuit is realized by an LDO chip to convert 5V to 3.3V devices; the core board uses 3 adjustable voltage modules of Huaguan Semiconductor, which are 5V to 1.1V, 5V to 1.5V, and 5V to 3.3V respectively, to ensure the normal operation and logical operation of the FPGA.

[0048] Among them, the pulse generation unit is as Figure 4 shown in the figure, which is the key part for driving the pulse laser and the detector. It controls the light emission time of the pulse laser to be measured by sending out trigger pulse signals, and outputs the frequency pulse wave corresponding to the instruction and the frequency pulse wave with a settable delay. The pulse generation unit includes: a serial port instruction forwarding module, a pulse laser counting module, a controllable frequency pulse module, a delay counting module, a detector counting module, and a controllable frequency pulse module; the serial port instruction forwarding module is connected to the serial port protocol unit, the pulse laser counting module is connected to the serial port instruction forwarding module and the controllable frequency pulse module, the controllable frequency pulse module is connected to the laser, the delay counting module is connected to the serial port instruction forwarding module and the detector counting module, and the controllable frequency pulse module is connected to the detector counting module and the detector; the serial port protocol unit realizes the connection with the interface circuit, and then the serial port input instruction is transmitted to the FPGA circuit for logical processing by the serial port instruction forwarding module.

[0049] In the pulse generation unit, the pulse laser counter module receives the pulse level command sent by the command forwarding module. There is a certain delay from when the command is sent to the laser until the laser emits light. In the counter module, a pulse train shutdown program is compiled to have the function of shutting down the pulse train. After outputting the TTL pulse, it automatically shuts down and no longer responds to subsequent inputs. Then, a reasonable control design is carried out for the command. The command control includes three parts: software switch, frequency control word, and delay control word. After the command enters the command conversion module, it starts to search for the control bytes regarding frequency and delay. After identifying the frequency and delay commands, it starts the pulse laser counter module and the delay counter module. The maximum count value will vary according to different frequencies. Finally, through the controllable frequency pulse module, a frequency pulse square wave with a specific width is output to make the laser emit light.

[0050] For the detector acquisition work, there is a software-controllable delay between the detector control level signal and the laser control level signal. After receiving the pulse level command sent by the command forwarding module, the delay counter module controls this delay to ensure that the light emitted by the laser can be completely captured by the detector during the working time. Since the FPGA is working with parallel processing logic, it does not wait until the maximum count value is reached to start generating pulses. The controllable frequency pulse module generates two frequency pulse square waves with the same quality except for the delay Δt to trigger the pulse laser and the detector respectively, realizing the control of the two pulse signals of the laser and the detector.

[0051] The time delay counting unit is composed of Figure 5 as shown in the figure, including: a sampling trigger counter module, a time counter module, and a control circuit module. The control circuit module is connected to the detector through an interface and is also connected to the sampling trigger counter module and the time counter module. The time counter module is connected to the serial port protocol unit. The time delay counting unit measures the acquisition and processing time of the detector, which is the time from the light signal of the pulse laser emitting light, transmitting, being acquired and processed, to being sent to the upper computer software. The time delay counting unit ensures that at the start of one frame of spectrum during the working time of the detector, it is synchronized to the detector completely capturing the light emitted by the pulse laser without energy loss.

[0052] The time counter module starts to be activated by receiving the command sent by the upper computer through the interface circuit

[0053] The sampling trigger counter module starts timing, and then receives the optical signal 5 data collected by the detector in real time. A fixed threshold is set inside the FPGA circuit. Once the change in the optical signal data of the pulse laser exceeds this threshold, it is determined that the detector has captured the optical signal of the pulse laser. At this time, the sampling will stop and the trigger counter will start timing. Finally, this processing time is sent to the upper computer acquisition software corresponding to the detector through the time counter module for display

[0054] Come. Since the default working state of the detector is under high-level conditions, the detector will be in a working state all the time after powering on. The time counter module first outputs a low-level signal to the detector to stop the detector from working, and then raises the output signal through an output instruction to make the detector start to prepare for work.

[0055] The energy detection unit is as shown in

[0056] and includes: a filtering module, an energy counting module, a maximum value detection module, a validity judgment module, and a valid value module connected in sequence. The filtering module 5 is connected to the detector, and the valid value module is connected to the serial port protocol unit. The optical signal data collected by the detector is transmitted to the energy detection unit for analysis and processing to judge whether the collected optical signal data meets the requirements. If the requirements are met, the delay timing unit will immediately stop timing and return the timing result of this period to the spectrometer upper computer software for display. Figure 6 as shown, including: a filtering module, an energy counting module, a maximum value detection module, a validity judgment module, and a valid value module connected in sequence. The filtering module 5 is connected to the detector, and the valid value module is connected to the serial port protocol unit. The optical signal data collected by the detector is transmitted to the energy detection unit for analysis and processing to judge whether the collected optical signal data meets the requirements. If the requirements are met, the delay timing unit will immediately stop timing and return the timing result of this period to the spectrometer upper computer software for display.

[0057] After the optical data collected by the detector is transmitted to the energy detection unit, it first passes through the filtering module. After filtering, specific frequency components in the signal pass through, while other noise frequency components are greatly attenuated. The energy counting module performs energy statistics on the filtered data under the condition of extremely low noise; then the maximum value detection module judges whether it meets the set threshold according to the statistical result, and finally the validity judgment module judges the validity of the data. If it does not meet the experimental requirements

[0058] the experimental data of this time will be discarded. The optical signal of the detector is collected again for judgment. When the spectral energy data measured is output to the software, when the energy detection value is greater than the threshold, the timing stops,

[0059] indicating that the spectral signal has been detected.

[0060] the experimental data of this time will be discarded. The optical signal of the detector is collected again for judgment. When the spectral energy data measured is output to the software, when the energy detection value is greater than the threshold, the timing stops,

[0061] indicating that the spectral signal has been detected.

[0062] indicating that the spectral signal has been detected.

[0063] The detector control signal generation unit is composed as shown in Figure 7 and includes a protocol conversion module, a control circuit module, a counter module, and a signal generation module connected in sequence; the protocol conversion module is connected to the serial port protocol unit through an interface, and the signal generation module is connected to the detector through a detector drive circuit. After the protocol conversion module receives the level instruction sent by the upper computer, the control circuit module recognizes the corresponding instruction and starts the counter module to count, and the counter will continuously cycle to count to ensure that the generated frequency pulse can drive the detector to be in a working state all the time. The signal generation module can generate a standard TTL level, and the pulse width is fixed, which is output to the detector drive circuit to meet the drive requirements.

[0064] In the spectroscopic experiment, the instantaneous luminescence of the sample is dispersed by the spectrometer and reaches the photosensitive surface of the array detector, with a certain optical signal delay. An effective spectroscopic signal can be collected only when the optical pulse to be measured and the trigger signal act on the array detector simultaneously. Usually, through estimation and debugging experiments, the setting value of the delay controller is determined. By modifying the relevant program code of the FPGA circuit, the high-level duration of the external trigger detector signal is adjusted, and finally this duration is determined. At this duration, the detector captures only one packet of data at a time. On this basis, the delay time between the trigger detector and the laser is adjusted so that the detector can first perform exposure and then capture the first light of the laser within the high-level trigger signal duration. By continuously adjusting the time delay between the detector and the laser and the high-level duration given to the detector, and through repeated verification, the external trigger process with the optimal delay is finally achieved.

[0065] Specific embodiments of the synchronous trigger control working mode for the spectral measurement of pulsed laser signals:

[0066] 1) Embodiment of the trigger control mode for a near-infrared repetitive frequency pulsed laser

[0067] For a pulsed laser, when it emits laser pulses at a repetitive frequency, the preferred embodiment is to operate in the mode of first turning on the detector and then triggering the laser after a time T1. T1 is the detector startup time, and the laser is triggered after T1 (T1 < 5 ms).

[0068] In the first step, the spectrometer software sends a start command to the transient spectroscopic pulse light delay synchronization control trigger system, and then the pulse light delay synchronization control trigger system sends a TTL pulse to the array detector in the spectrometer. The amplitude of the pulse is preferably 5V, and the duty cycle is preferably 5%. After receiving the TTL level command, the array detector establishes the detector working response time T1 according to the specific acquisition time and frame synchronization signal of the detector circuit.

[0069] In the second step, after the spectrometer detector working time T1, the pulse light delay synchronization control trigger system gives the laser an identical TTL 5V voltage pulse. After receiving this pulse, the laser emits the first light pulse after a time T2, and the time T2 is generally on the order of μs.

[0070] In the third step, when the laser emits light, the spectrometer array detector collects the signal and outputs a complete frame of spectroscopic data after a time T3. This data is the data within an integration period and contains the electrical signal after the energy superposition of several laser pulses at the repetitive frequency. The spectrometer realizes the measurement of the laser wavelength curve. The time T3 is adjustable, and the adjustable range is less than the ms order of magnitude.

[0071] 2) Embodiment of the trigger control mode for a mid-wave infrared repetitive frequency laser

[0072] For a 2040 nm mid-wave infrared pulsed laser with a repetition frequency of 10 Hz, when it emits laser pulses at a repetition frequency, the pulsed light delay synchronization control trigger system works in a way that first triggers the laser to emit light and then turns on the detector to start acquisition. After receiving the start command from the spectrometer software, the pulsed light delay synchronization control trigger system issues a TTL level pulse. The time from receiving the start command to the emission of light is the optimal synchronization delay time, generally on the order of ms, and the specific optimal delay time is adjustable and determined through experiments based on the light emission time of different lasers, the light transmission time of the spectrometer, and the integration time of the detector.

[0073] 3) Embodiment of the control method for a mid-wave infrared single-pulse laser

[0074] Preferred embodiment: First turn on the detector, and after a specific delay time, then trigger the 2040 nm laser. The optimal delay time from receiving the start command to the emission of light by this laser is on the order of ms, and the preferred time range is 30 ms to 284 ms (the specific time is adjustable and determined through experiments based on the light emission time of different lasers, the light transmission time of the spectrometer, and the integration time of the detector).

[0075] 4) Embodiment of gas plasma optical triggering

[0076] For gas plasma triggering, the pulsed light delay synchronization control trigger system issues a TTL 5V level pulse signal to start the plasma light source to emit light. The light emitted by this light source is single-pulse light, lasting for dozens of microseconds (<50 μs). And there is a certain distance between the light source and the spectrometer, and it takes less than 100 μs for the light source to be transmitted to the entrance of the spectrometer. Adjust the delay time of the pulsed light delay synchronization control trigger system, send a command to start the detector to start acquisition, so that the spectrometer collects the maximum light signal intensity. The corresponding time is the optimal synchronization delay time.

[0077] 5) Embodiment of the optical delay triggering control method for commonly used pulsed lasers

[0078] For the spectral signal test of various commonly used pulsed lasers, after the ns-level pulsed light delay synchronization control trigger system receives the acquisition command from the spectrometer software of the host computer, it sends a pulse trigger signal to the laser. Then this system changes the value of the delay taken, and judges through the signal intensity output by the array detector in the spectrometer (such as the gray value of the focal plane array image). When the signal intensity exceeds the threshold, it indicates that the pulsed light signal has been collected. When the signal intensity is the maximum, the delay value of the pulsed light delay synchronization control trigger system corresponding to it is the optimal delay time.

[0079] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the technical principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A transient spectroscopy ns-level pulsed light delay synchronization control trigger system, characterized in that, Including: An FPGA circuit, an interface circuit connected thereto, a laser driver circuit, and a detector driver circuit. The laser driver circuit is connected to a laser, and the detector driver circuit is connected to a detector. The interface circuit includes a USB adapter and an RS232 adapter, and has the function of converting RS232 to TTL level. The instructions sent by the host computer first pass through the RS232 adapter for level conversion and are converted into TTL level and transmitted to the FPGA circuit. The laser driver circuit includes a drive level conversion circuit for controlling the conversion of the laser drive level and current enhancement to achieve control of the laser level command. The detector driver circuit drives the detector level conversion circuit in the spectrometer to control the conversion of the detector drive level and achieve control of the detector level command. When measuring the light source spectrum in the ns or µs order of magnitude, the FPGA circuit realizes the synchronous timing function of the FPGA circuit by adjusting the pulse delay synchronization control in the system, and at the same time realizes the synchronous trigger of the exposure time of the detector and the light output time of the pulse laser to be measured, ensuring that all the light energy of the light source is accurately and completely captured by the transient spectrometer in time sequence. The FPGA circuit includes: a serial port protocol unit, a pulse generation unit, a time delay counting unit, an energy detection unit, and a detector control signal generation unit. The pulse generation unit, the time delay counting unit, the energy detection unit, and the detector control signal generation unit are all connected to the interface circuit through the serial port protocol unit. The pulse generation unit provides a connection to the laser for the laser driver circuit. The time delay counting unit and the energy detection unit are connected to the detector. The detector control signal generation unit is connected to the detector through the detector driver circuit. The pulse generation unit includes: a serial port instruction forwarding module, a pulse laser counting module, a controllable frequency pulse module, a delay counting module, a detector counting module, and a controllable frequency pulse module. The serial port instruction forwarding module is connected to the serial port protocol unit. The pulse laser counting module is connected to the serial port instruction forwarding module and the controllable frequency pulse module. The controllable frequency pulse module is connected to the laser. The delay counting module is connected to the serial port instruction forwarding module and the detector counting module. The controllable frequency pulse module is connected to the detector counting module and the detector. The serial port protocol unit realizes communication with the interface circuit, and then the serial port instruction forwarding module transmits the serial port input instruction to the FPGA circuit for logical processing. The pulse generation unit issues a trigger pulse signal to control the light output time of the pulse laser to be measured, and outputs a frequency pulse wave corresponding to the instruction and a frequency pulse wave with a settable delay.

2. The transient spectroscopy ns-level pulsed light delay synchronization control trigger system according to claim 1, wherein, Also including: A clock circuit and an FPGA circuit. The clock circuit provides a clock signal for the FPGA circuit.

3. The transient spectroscopy ns-level pulsed light delay synchronization control trigger system according to claim 2, characterized in that, The clock circuit includes a crystal oscillator module, a clock jitter elimination module, a phase-locked loop module, a clock buffer module, a clock frequency division module, and a clock distribution module connected in sequence. The crystal oscillator module generates a crystal oscillator clock signal, which first passes through the clock jitter elimination module to stabilize the frequency. Then, the clock signal passes through the phase-locked loop module to achieve phase synchronization between the on-chip clock and an external clock. The phase-locked loop module compares the phase of the external reference signal with the phase of the clock signal, adjusts the phase of the crystal oscillator clock signal to match the phase of the reference signal, and synchronizes the phase of its on-board clock with the external reference signal. The clock buffer module copies, converts the format, and converts the level of the clock signal generated by the crystal oscillator. The function of the clock frequency division module is to adjust the frequency of the clock signal. Finally, the clock distribution module distributes the adjusted high-quality clock signal to each working unit of the FPGA.

4. The transient spectroscopy ns-level pulsed light delay synchronization control trigger system according to claim 3, wherein The delay counting unit includes a sampling trigger counter module, a time counter module, and a control circuit module. The control circuit module is connected to the detector through an interface and is also connected to the sampling trigger counter module and the time counter module. The time counter module is connected to the serial port protocol unit. The delay counting unit measures the acquisition and processing time of the detector, which is the time from the light signal output by the pulsed laser, transmitted, acquired and processed, to being sent to the host computer software. The delay counting unit ensures that when a frame of spectrum starts during the working time of the detector, it is synchronized to the complete capture of the light signal output by the pulsed laser without energy loss.

5. The transient spectroscopy ns-level pulsed light delay synchronization control trigger system according to claim 4, characterized in that The time counter module receives an instruction sent by the host computer through the interface circuit to start the sampling trigger counter module to start timing. Then, it continuously receives the optical signal data collected by the detector. When the change in the optical signal data of the pulsed laser collected exceeds the threshold set by the FPGA circuit, it is determined that the detector has captured the optical signal of the pulsed laser, and the sampling is stopped. The sampling trigger counter module starts to time, and the processing time is sent to the corresponding host computer display of the detector through the time counter module.

6. The transient spectroscopy ns-level pulsed light delay synchronization control trigger system according to claim 5, characterized in that, The energy detection unit includes a filtering module, an energy statistics module, a maximum value detection module, a validity judgment module, and a valid value module connected in sequence. The filtering module is connected to the detector, and the valid value module is connected to the serial port protocol unit. After the optical data collected by the detector is transmitted to the energy detection unit, it first passes through the filtering module, and the set frequency components in the signal pass through after filtering. The energy statistics module performs energy statistics on the filtered data. Then, the maximum value detection module judges whether it meets the set threshold according to the statistical result. Finally, the validity judgment module judges the validity of the data, and the valid data is stored in the valid value module.

7. The transient spectroscopy ns-level pulsed light delay synchronization control triggering system according to claim 6, characterized in that, The detector control signal generation unit includes a protocol conversion module, a control circuit module, a counter module, and a signal generation module connected in sequence; the protocol conversion module is connected to the serial port protocol unit through an interface, and the signal generation module is connected to the detector through a detector drive circuit; after the protocol conversion module receives the level instruction sent by the host computer, the control circuit module recognizes the corresponding instruction and starts to activate the counter module to count, and the counter continuously cycles to time, ensuring that the generated frequency pulse drives the detector to be in the working state all the time; the signal generation module generates a standard TTL level standard, and the pulse width is fixed, and is output to the detector drive circuit to meet the drive requirements.

8. Application of the transient spectroscopy ns-level pulsed light delay synchronization control trigger system according to any one of claims 1-7 in the field of optical testing technology.

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