Synchronous clock correction device and method for time-gated spectral measurement and optical imaging system

Abstract

The invention discloses a synchronous clock correction device and method for a time-gated spectral measurement and optical imaging system, and the device comprises a pulse laser, a sample stage, a spectrometer, an image intensifier, a detector, a delayer, a gating module, a control computer, and a synchronous correction module. The pulse laser outputs sample exciting light to the sample table, the spectrograph, the image intensifier and the detector, one path of a synchronous trigger signal is output to the synchronous correction module, and the other path of the synchronous trigger signal is transmitted to the image intensifier through the delayer and the gating module; detecting a gating signal through a synchronous correction module, comparing a time difference between the gating signal and a synchronous trigger signal to obtain a delay adjustment value, and adjusting a delayer through a control computer, so that the time when the gating signal starts an image intensifier is consistent with the time when an optical signal generated after a sample is excited to reach the image intensifier; according to the invention, the influence of temperature drift in an electronic system is reduced, the stability of the system is improved, and the measurement error is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of time-gated spectral measurement and optical imaging, and in particular relates to a device and method for calibrating a synchronous clock of a time-gated spectral measurement and optical imaging system. Background Art

[0002] Spectroscopy is a method of studying the properties of matter through the interaction between matter and electromagnetic waves. It is both a general basic scientific research method and a practical application tool, widely used in many fields such as environmental testing, industrial inspection, clinical medicine, and ground detection. Optical imaging is a technology that uses optical systems to obtain target images, and is used in many fields, such as medical imaging and manufacturing. Using pulsed lasers and gated detectors, time-gated spectroscopy and imaging can be obtained. Time-gated is also called time gating, which is suitable for fluorescence spectroscopy, Raman spectroscopy, anti-Stokes spectroscopy, stimulated Raman spectroscopy, absorption spectroscopy, laser-induced breakdown spectroscopy, and other spectral measurements; it is suitable for fluorescence imaging, Raman imaging, and other optical imaging. Time-gated spectroscopy and imaging are very important in many applications, such as time-gated Raman spectroscopy, time-gated fluorescence imaging, etc.

[0003] In time-gated spectroscopy and optical imaging systems based on gated image intensifiers, the time when the image intensifier is turned on needs to be consistent with the time when the signal reaches the image intensifier, which requires the system's clock synchronization signal to be stable. However, temperature drift is common in electronic systems, which affects the stability of the synchronization clock, and thus affects the stability and accuracy of the system.

[0004] The stability of the synchronous clock is an important parameter indicator of time-gated spectroscopy and optical imaging systems. In time-gated spectroscopy and optical imaging systems based on gated image intensifiers, the delay device sets an appropriate delay value so that the time when the gated signal turns on the image intensifier is consistent with the time when the light signal reaches the image intensifier. Since the system cannot obtain and correct the synchronous clock in real time, it can only judge whether the synchronous clock drifts by the signal strength measured by the detector, and the specific delay adjustment value of the delay device cannot be determined. This method not only increases the measurement time, but also increases the measurement error. Summary of the invention

[0005] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a device and method for correcting the synchronous clock of a time-gated spectral measurement and optical imaging system, so as to correct the synchronous clock of a time-gated spectral measurement and optical imaging system based on a gated image intensifier, reduce the influence of temperature drift in the electronic system, improve the stability of the system, and reduce measurement errors.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: In one aspect of the present invention, there is provided a time-gated spectral measurement and optical imaging system synchronous clock correction device, comprising a pulse laser, a sample stage, a spectrometer, an image intensifier, a detector, a delay device, a gating module, a control computer and a synchronous correction module; The pulse laser is used to output sample excitation light and synchronous trigger signal; The sample excitation light is focused on the sample to be tested carried by the sample stage after passing through the focusing optical path, and then the scattered light is collected and the sample excitation light is filtered through the collecting optical path, and then transmitted to the spectrometer, image intensifier and detector in sequence; The synchronous trigger signal is transmitted to the synchronous correction module in one path, and is transmitted to the image intensifier through the delay device and the gate control module in the other path; The delay device is used to introduce a delay in the transmission process of the synchronous trigger signal, and the gate control module is used to convert the output signal of the delay device into a gate control signal for controlling the operation of the image intensifier, so that the time when the gate signal turns on the image intensifier is consistent with the time when the light signal generated by the sample after being excited reaches the image intensifier; The synchronization correction module detects the gate signal by voltage division or electromagnetic induction and compares the time difference with the synchronization trigger signal to obtain a delay adjustment value; The control computer is connected to the pulse laser, the time delay device, the synchronous correction module and the detector respectively, and feeds back the delay adjustment value to the time delay device for correction.

[0007] As a preferred technical solution, the laser outputs a trigger pulse or splits the output laser beam as a synchronous trigger signal.

[0008] As a preferred technical solution, the sample stage is controlled by a three-dimensional manual or stepping motor.

[0009] As a preferred technical solution, the image intensifier includes a photocathode, a microchannel plate and a fluorescent screen.

[0010] As a preferred technical solution, the gating module is connected to the photocathode of the image intensifier, and the image intensifier is turned on or off by controlling the motion state of photoelectrons generated by the photocathode of the image intensifier.

[0011] As a preferred technical solution, the detector adopts a two-dimensional pixel surface array detector, including one of an ICCD camera, an ICMOS camera and a SPAD array.

[0012] As a preferred technical solution, the synchronous correction module detects the gating signal by voltage division, specifically: A coupler is provided, the input port of the coupler is connected to the gating module, the output port of the coupler is respectively connected to the image intensifier module and the synchronous correction module, and the gating signal acquired by the synchronous correction module is measured by an oscilloscope or an acquisition card.

[0013] As a preferred technical solution, the synchronous correction module detects the gating signal by electromagnetic induction, specifically: An induction coil is wound around the connecting wire between the gating module and the image intensifier, and the obtained gating signal is measured by an oscilloscope or acquisition card.

[0014] As a preferred technical solution, the synchronization correction module detects the gate signal and compares the time difference with the synchronization trigger signal to obtain a delay adjustment value, which is specifically: In T 1 At the moment, the time difference between the gate signal and the pulse laser synchronization signal is Δt 1 , in T 2 At the moment, the time difference between the gate signal and the pulse laser synchronization signal is Δt 2 , then the delay adjustment value Δt=Δt 2 -Δt 1 .

[0015] In one aspect of the present invention, a method for calibrating a synchronous clock of a time-gated spectral measurement and an optical imaging system is provided, and the method uses the above-mentioned device for calibrating a synchronous clock of a time-gated spectral measurement and an optical imaging system, and comprises the following steps: Start the pulse laser, output the sample excitation light and focus it on the sample to be tested on the sample stage after passing through the focusing optical path, collect the scattered light and filter the sample excitation light through the collecting optical path, and transmit it to the spectrometer, image intensifier and detector in sequence; at the same time, the pulse laser outputs two synchronous trigger signals, one of which is transmitted to the synchronous correction module, and the other is transmitted to the image intensifier through the delay device and the gating module; The synchronous correction module detects the gate signal by voltage division or electromagnetic induction and compares the time difference with the synchronous trigger signal to obtain the delay adjustment value and feeds it back to the control computer; The control computer transmits the delay adjustment value to the delay device, and introduces a delay in the transmission process of the synchronous trigger signal, so that the time of turning on the image intensifier is consistent with the time when the light signal generated by the sample after being excited reaches the image intensifier.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: (1) The present invention uses a synchronous correction module to obtain a gate signal that triggers an image intensifier, uses an oscilloscope or other device or device to measure the gate signal in real time, feeds back the delay adjustment value to the delay device to adjust the delay, and completes the system synchronous clock correction. The device and method reduce the influence of temperature drift in the electronic system, improve the stability of the system, and reduce measurement errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the structure of a time-gated spectrum measurement and optical imaging system based on a gated image intensifier in the prior art; Figure 2 is a schematic structural diagram of a device for synchronizing a clock for a time-gated spectral measurement and optical imaging system according to an embodiment of the present invention; Figure 3 Schematic diagram of output signal of the synchronization correction module according to an embodiment of the present invention. DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application.

[0019] The stability of the synchronous clock is an important parameter indicator of time-gated spectroscopy and optical imaging systems. In time-gated spectroscopy and optical imaging systems based on gated image intensifiers, the delay device sets an appropriate delay value to make the time when the gated signal turns on the image intensifier consistent with the time when the light signal reaches the image intensifier, such as Figure 1 As shown in the figure. Since the system cannot obtain and correct the synchronous clock in real time, it can only judge whether the synchronous clock drifts by the signal strength measured by the detector, and it is impossible to determine the specific delay adjustment value of the delay device. This method not only increases the measurement time, but also increases the measurement error.

[0020] Therefore, the present application solves the problem of time-gated spectral measurement based on a gated image intensifier and correction of synchronous clock drift of an optical imaging system through the following embodiments.

[0021] Embodiment 1: like Figure 2 As shown, this embodiment provides a device for correcting the synchronous clock drift of a time-gated spectral measurement and optical imaging system based on a gated image intensifier, characterized in that it includes a pulse laser, a sample stage, a spectrometer, an image intensifier, a detector, a delay device, a gating module, a control computer and a synchronous correction module; The pulse laser is used to output sample excitation light and synchronous trigger signal; The sample excitation light is focused on the sample to be tested carried by the sample stage after passing through the focusing optical path, and then the scattered light is collected and the sample excitation light is filtered through the collecting optical path, and then transmitted to the spectrometer, image intensifier and detector in sequence; The synchronous trigger signal is transmitted to the synchronous correction module in one path, and is transmitted to the image intensifier through the delay device and the gate control module in the other path; The delay device is used to introduce a delay in the transmission process of the synchronous trigger signal, and the gate control module is used to convert the output signal of the delay device into a gate control signal for controlling the operation of the image intensifier, so that the time when the gate signal turns on the image intensifier is consistent with the time when the light signal generated by the sample after being excited reaches the image intensifier; The synchronization correction module detects the gate signal by voltage division or electromagnetic induction and compares the time difference with the synchronization trigger signal to obtain a delay adjustment value; The control computer is connected to the pulse laser, the time delay device, the synchronous correction module and the detector respectively, and feeds back the delay adjustment value to the time delay device for correction.

[0022] In one or more preferred embodiments, the pulse laser includes components such as a power supply, a laser driver, and a laser head, etc. These components may be distributed or integrated.

[0023] The key performance indicators of the laser output by the pulse laser are: The wavelength range is between 300-1100 nm; Line width 0.01-100 cm -1 between; Pulse width is between 10 fs-10 ns; Repetition rate is 100 Hz-80 MHz; Average power range 10 µW -1 W.

[0024] The pulse laser may or may not have an output trigger pulse function. If it has an output pulse function, the detector can be directly triggered. If it does not have an output pulse function, the laser beam is split into two beams. One laser beam is used as a trigger signal and the other is used for sample excitation.

[0025] In one or more preferred embodiments, the sample stage is used to carry the sample so that the sample can be controlled by multi-dimensional manual or stepper motor at the focal position of the excitation Raman light. The laser emitted by the pulsed laser is focused onto the sample stage through various optical devices, and then the scattered light is collected, the excitation light is filtered out, and finally sent to the spectrometer. There are various types of focusing and collecting optical paths, including but not limited to fiber Raman detectors, microscopic detectors, confocal microscopic detectors, etc.

[0026] In one or more preferred embodiments, the spectrometer mainly uses a transmission or reflection grating, or a prism or other spectroscopic optical module to spatially distinguish optical signals of different wavelengths.

[0027] In one or more preferred embodiments, the image intensifier and the gating module form a gated image intensifier, and the purpose of controlling the operation of the image intensifier is achieved by loading a gating electric pulse (gating signal) on certain electrodes of the image intensifier. The image intensifier is composed of a photocathode, a microchannel plate and a fluorescent screen. According to the different positions where the gating electric pulse is applied to the image intensifier, the gating working mode can be divided into: photocathode gating, microchannel plate gating and anode gating.

[0028] In one or more preferred embodiments, the detector is a two-dimensional pixel array detector, including an ICCD camera, an ICMOS camera, a SPAD array, etc., for acquiring spectra and imaging.

[0029] In one or more preferred embodiments, the delay device is used to introduce a delay in the transmission process of the electrical signal so that the time when the gated signal turns on the image intensifier is consistent with the time when the light signal generated by the sample after being excited reaches the image intensifier.

[0030] In one or more preferred embodiments, the gating module is used to convert the electrical signal output by the delay device into a gating electrical pulse (gating signal) for controlling the operation of the image intensifier.

[0031] In one or more preferred embodiments, the control computer controls various hardware systems and collects and analyzes data.

[0032] In one or more preferred embodiments, the synchronization correction module is used to correct the synchronization clock. The synchronization correction module has two inputs, one is a pulse laser synchronization signal, and the other is a gate signal obtained by voltage division or electromagnetic induction principle.

[0033] Specifically, the voltage division scheme can use a coupler, the input port of the coupler is connected to the gating module, and the output port of the coupler is respectively connected to the image intensifier module and the synchronous correction module. The gating signal obtained by the synchronous correction module is measured by an oscilloscope or an acquisition card.

[0034] Specifically, the electromagnetic induction solution can use a current probe or a winding coil. Figure 2 In the process, a coil winding method is adopted, that is, an induction coil is wound on the connecting wire between the gate control module and the image intensifier. The gate control signal obtained is measured by an oscilloscope or acquisition card, such as Figure 3 As shown. 1 At the moment, the time difference between the gate signal and the pulse laser synchronization signal is Δt 1 Due to system temperature drift and other factors, the synchronous clock drifts in time. 2 At the moment, the time difference between the gate signal and the pulse laser synchronization signal is Δt 2 The relative delay between the gate signal and the pulse laser synchronization signal changes by Δt=Δt 2 -Δt 1 , the synchronization correction module feeds back the delay adjustment value Δt to the delay device, and the delay device adjusts the delay value to correct the system synchronization clock.

[0035] Embodiment 2: This embodiment implements time-gated Raman spectroscopy measurement by specifically setting the components used in a device for correcting synchronous clock drift of a time-gated spectroscopy measurement based on a gated image intensifier and an optical imaging system in the above-mentioned embodiment, and includes the following 9 modules.

[0036] (1) Pulsed laser, in this embodiment, uses a wavelength of 542 nm and a line width of 0.01 cm -1 , a laser with a pulse width of 1 ps, a repetition rate of 80 MHz, and an average power of 400 mW is used as the Raman excitation light source. The laser beam is divided into two beams through a 1:9 beam splitter. The first beam of light with lower power irradiates the silicon-based detector to generate a triggering electrical signal. The other beam of stronger light is used for Raman excitation.

[0037] (2) Sample stage: In this embodiment, a common microscopic Raman detection system is used.

[0038] (3) Spectrometer: In this embodiment, a spectrometer with a standard reflective grating as its main component is used.

[0039] (4) Image intensifier: In this embodiment, a photocathode-gated image intensifier is used. The image intensifier is turned on or off by controlling the motion state of the photoelectrons generated by the photocathode.

[0040] (5) Detector: In this embodiment, an ICCD camera is used as the detector.

[0041] (6) Delay device: In this embodiment, a tunable electric delay device is used.

[0042] (7) Gating module: In this embodiment, the gating module controls the working state of the photocathode.

[0043] (8) Control computer, used to control various hardware systems, collect and analyze data. In this embodiment, a desktop computer is used.

[0044] (9) Synchronous correction module. In this embodiment, an induction coil is wound on the connecting wire between the gate control module and the image intensifier, and an oscilloscope is used to measure the relative time change between the gate control signal and the pulse laser synchronization signal, which is fed back to the delay device to correct the synchronization clock.

[0045] Embodiment 3: This embodiment adds a multi-dimensional manual or electric translation stage to the sample stage on the basis of a device for correcting the synchronous clock drift of a time-gated spectral measurement and optical imaging system based on a gated image intensifier in the above-mentioned embodiment, so as to collect fluorescence signals of various parts of the sample and realize time-gated fluorescence imaging.

[0046] It should be noted here that the device provided in the above embodiment is only illustrated by the division of the above-mentioned functional modules. In actual applications, the above-mentioned functions can be assigned to different functional modules as needed, that is, the internal structure can be divided into different functional modules to complete all or part of the functions described above.

[0047] Embodiment 4: In order to make it easier for those skilled in the art to understand the solution of the present application, in an embodiment, a method for correcting the synchronous clock drift of a time-gated spectral measurement based on a gated image intensifier and an optical imaging system is provided. A device for correcting the synchronous clock drift of a time-gated spectral measurement based on a gated image intensifier and an optical imaging system using the above embodiment includes the following steps: S1, start the pulse laser, output the sample excitation light and focus it on the sample to be tested carried by the sample stage after passing through the focusing optical path, collect the scattered light and filter the sample excitation light through the collecting optical path, and transmit it to the spectrometer, image intensifier and detector in sequence; at the same time, the pulse laser outputs two synchronous trigger signals, one of which is transmitted to the synchronous correction module, and the other is transmitted to the image intensifier through the delay device and the gating module; S2, the synchronous correction module detects the gate signal by voltage division or electromagnetic induction and compares the time difference with the synchronous trigger signal to obtain the delay adjustment value and feeds it back to the control computer; S3. The control computer transmits the delay adjustment value to the delay device, and introduces a delay in the transmission process of the synchronous trigger signal, so that the time of turning on the image intensifier is consistent with the time when the light signal generated by the sample after being excited reaches the image intensifier.

[0048] It should be understood that the various parts of the present application can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, multiple steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0049] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A time-gated spectral measurement and optical imaging system synchronous clock correction device, characterized in that: It includes pulse laser, sample stage, spectrometer, image intensifier, detector, delay device, gate control module, control computer and synchronous correction module; The pulse laser is used to output sample excitation light and synchronous trigger signal; The sample excitation light is focused on the sample to be tested carried by the sample stage after passing through the focusing optical path, and then the scattered light is collected and the sample excitation light is filtered through the collecting optical path, and then transmitted to the spectrometer, image intensifier and detector in sequence; The synchronous trigger signal is transmitted to the synchronous correction module in one path, and is transmitted to the image intensifier through the delay device and the gate control module in another path; The delay device is used to introduce a delay in the transmission process of the synchronous trigger signal, and the gate control module is used to convert the output signal of the delay device into a gate control signal for controlling the operation of the image intensifier, so that the time when the gate signal turns on the image intensifier is consistent with the time when the light signal generated by the sample after being excited reaches the image intensifier; The synchronization correction module detects the gate signal by voltage division or electromagnetic induction and compares the time difference with the synchronization trigger signal to obtain a delay adjustment value; The control computer is connected to the pulse laser, the time delay device, the synchronous correction module and the detector respectively, and feeds back the delay adjustment value to the time delay device for correction.

2. The device for synchronizing a time-gated spectral measurement and an optical imaging system according to claim 1, characterized in that: The laser outputs a trigger pulse or splits the output laser beam as a synchronous trigger signal.

3. The time-gated spectral measurement and optical imaging system synchronous clock correction device according to claim 1, characterized in that: The sample stage is controlled by a three-dimensional manual or stepper motor.

4. The time-gated spectral measurement and optical imaging system synchronous clock correction device according to claim 1, characterized in that: The image intensifier comprises a photocathode, a microchannel plate and a fluorescent screen.

5. The device for synchronizing a time-gated spectral measurement and an optical imaging system according to claim 4, characterized in that: The gate control module is connected to the photocathode of the image intensifier, and turns on or off the image intensifier by controlling the motion state of photoelectrons generated by the photocathode of the image intensifier.

6. The device for synchronizing a time-gated spectral measurement and an optical imaging system according to claim 1, characterized in that: The detector adopts a two-dimensional pixel surface array detector, including one of an ICCD camera, an ICMOS camera and a SPAD array.

7. The device for synchronizing a time-gated spectral measurement and an optical imaging system according to claim 1, characterized in that: The synchronous correction module detects the gate signal by voltage division, specifically: A coupler is provided, the input port of the coupler is connected to the gating module, the output port of the coupler is respectively connected to the image intensifier module and the synchronous correction module, and the gating signal obtained by the synchronous correction module is measured by an oscilloscope or an acquisition card.

8. The time-gated spectral measurement and optical imaging system synchronous clock correction device according to claim 1, characterized in that: The synchronous correction module detects the gate signal by electromagnetic induction, specifically: An induction coil is wound around the connecting wire between the gating module and the image intensifier, and the obtained gating signal is measured by an oscilloscope or acquisition card.

9. The device for synchronizing a time-gated spectral measurement and an optical imaging system according to claim 1, characterized in that: The synchronization correction module detects the gate signal and compares the time difference with the synchronization trigger signal to obtain the delay adjustment value, which is specifically: At time T1, the time difference between the gate signal and the pulse laser synchronization signal is Δt1, and at time T2, the time difference between the gate signal and the pulse laser synchronization signal is Δt2, so the delay adjustment value Δt=Δt2-Δt1.

10. A method for synchronizing a time-gated spectral measurement and an optical imaging system with a synchronous clock, characterized in that: The device for synchronizing a time-gated spectral measurement and an optical imaging system according to any one of claims 1 to 9 comprises the following steps: Start the pulse laser, output the sample excitation light and focus it on the sample to be tested on the sample stage after passing through the focusing optical path, collect the scattered light and filter the sample excitation light through the collecting optical path, and transmit it to the spectrometer, image intensifier and detector in sequence; at the same time, the pulse laser outputs two synchronous trigger signals, one of which is transmitted to the synchronous correction module, and the other is transmitted to the image intensifier through the delay device and the gating module; The synchronous correction module detects the gate signal by voltage division or electromagnetic induction and compares the time difference with the synchronous trigger signal to obtain the delay adjustment value and feeds it back to the control computer; The control computer transmits the delay adjustment value to the delay device, and introduces a delay in the transmission process of the synchronous trigger signal, so that the time of turning on the image intensifier is consistent with the time when the light signal generated by the sample after being excited reaches the image intensifier.

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