Synchronous Clock Correction Device and Method for Time-Gated Spectral Measurement and Optical Imaging System

Abstract

The present invention discloses a synchronous clock correction device and method for a time-gated spectroscopy measurement and optical imaging system. The device includes a pulsed laser, a sample stage, a spectrometer, an image intensifier, a detector, a delay line, a gating module, a control computer, and a synchronous correction module. The pulsed laser outputs sample excitation light to the sample stage, the spectrometer, the image intensifier, and the detector, and outputs a synchronous trigger signal. One path of the synchronous trigger signal is output to the synchronous correction module, and the other path is transmitted to the image intensifier through the delay line and the gating module. The synchronous correction module detects the gating signal and compares the time difference with the synchronous trigger signal to obtain a delay adjustment value, and the control computer adjusts the delay line so that the time when the gating signal turns on the image intensifier is consistent with the time when the optical signal generated after the sample is excited reaches the image intensifier. The present invention reduces the influence of temperature drift in the electronic system, improves the stability of the system, and reduces the measurement error.

Description

Technical Field

[0001] The present invention belongs to the technical field of time-gated spectroscopic measurement and optical imaging, and particularly relates to a synchronous clock correction device and method for a time-gated spectroscopic measurement and optical imaging system. Background Art

[0002] Spectroscopy is a method for studying the properties of substances through the interaction between substances and electromagnetic waves. It is both a general basic scientific research method and a practical application tool, and is widely used in many fields such as environmental detection, industrial inspection, clinical medicine, and earth exploration. Optical imaging is a technology that uses an optical system to obtain a target image and has applications in many fields such as medical imaging and manufacturing. By using a pulsed laser and a gated detector, time-gated spectroscopy and imaging can be obtained. Time-gated is also known as time selection and is applicable to fluorescence spectroscopy, Raman spectroscopy, anti-Stokes spectroscopy, stimulated Raman spectroscopy, absorption spectroscopy, laser-induced breakdown spectroscopy, and other spectroscopic measurements; it is applicable to fluorescence imaging, Raman imaging, and other optical imaging. Time-gated spectroscopy and imaging are very important in many applications. For example, time-gated Raman spectroscopy, time-gated fluorescence imaging, etc.

[0003] In a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier, the time when the image intensifier is turned on needs to be consistent with the time when the signal arrives at the image intensifier, which requires the clock synchronization signal of the system to be stable. However, due to the widespread temperature drift in electronic systems, the stability of the synchronous clock is affected, which in turn affects the stability and accuracy of the system.

[0004] The stability of the synchronous clock is an important parameter index for a time-gated spectroscopic measurement and optical imaging system. In a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier, the delay unit 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 optical signal arrives at the image intensifier. Since the system cannot obtain and correct the synchronous clock in real time, currently, only the strength of the signal measured by the detector can be used to determine whether the synchronous clock drifts, and the specific delay adjustment value of the delay unit cannot be determined. This method not only increases the measurement time but also increases the measurement error. Summary of the Invention

[0005] The main object of the present invention is to overcome the disadvantages and deficiencies of the prior art, and provide a synchronous clock correction device and method for a time-gated spectroscopic measurement and optical imaging system, to correct the synchronous clock of a time-gated spectroscopic 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 the measurement error.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In one aspect of the present invention, a synchronous clock correction device for time-gated spectroscopy measurement and optical imaging system is provided, including a pulsed laser, a sample stage, a spectrometer, an image intensifier, a detector, a delay line, a gating module, a control computer, and a synchronous correction module;

[0008] The pulsed laser is used to output sample excitation light and a synchronous trigger signal;

[0009] The sample excitation light is focused on the sample to be measured carried by the sample stage through a focusing optical path, and then the scattered light is collected through a collection optical path and the sample excitation light is filtered, and then transmitted to the spectrometer, the image intensifier, and the detector in sequence;

[0010] One path of the synchronous trigger signal is transmitted to the synchronous correction module, and the other path is transmitted to the image intensifier through the delay line and the gating module;

[0011] The delay line is used to introduce a delay during the transmission of the synchronous trigger signal, and the gating module is used to convert the output signal of the delay line into a gating signal for controlling the operation of the image intensifier, so that the time when the gating signal turns on the image intensifier is consistent with the time when the optical signal generated after the sample is excited reaches the image intensifier;

[0012] The synchronous correction module detects the gating signal by means of voltage division or electromagnetic induction and compares the time difference with the synchronous trigger signal to obtain a delay adjustment value;

[0013] The control computer is respectively connected to the pulsed laser, the delay line, the synchronous correction module, and the detector, and feeds back the delay adjustment value to the delay line for correction.

[0014] As a preferred technical solution, the laser outputs a trigger pulse or splits the output laser beam as the synchronous trigger signal.

[0015] As a preferred technical solution, the sample stage is controlled by a three-dimensional manual or stepper motor.

[0016] As a preferred technical solution, the image intensifier includes a photocathode, a microchannel plate, and a phosphor screen.

[0017] 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 the photoelectrons generated by the photocathode of the image intensifier.

[0018] As a preferred technical solution, the detector adopts a two-dimensional pixel area array detector, including one of an ICCD camera, an ICMOS camera, and an SPAD array.

[0019] As a preferred technical solution, the synchronization correction module detects the gating signal by voltage division, specifically as follows:

[0020] A coupler is provided. 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 synchronization correction module. The gating signal obtained by the synchronization correction module is measured by an oscilloscope or a data acquisition card.

[0021] As a preferred technical solution, the synchronization correction module detects the gating signal by electromagnetic induction, specifically as follows:

[0022] An induction coil is wound around the connection wire between the gating module and the image intensifier, and the obtained gating signal is measured by an oscilloscope or a data acquisition card.

[0023] As a preferred technical solution, the synchronization correction module detects the gating signal and compares the time difference with the synchronization trigger signal to obtain a delay adjustment value, specifically as follows:

[0024] At time T1, the time difference between the gating signal and the pulse laser synchronization signal is Δt1. At time T2, the time difference between the gating signal and the pulse laser synchronization signal is Δt2. Then the delay adjustment value Δt = Δt2 - Δt1.

[0025] In one aspect of the present invention, a method for synchronizing the clock of a time-gated spectroscopy measurement and optical imaging system is provided. By applying the above-mentioned device for synchronizing the clock of a time-gated spectroscopy measurement and optical imaging system, the method includes the following steps:

[0026] Start the pulse laser, output the sample excitation light, and after passing through the focusing optical path, focus it on the sample to be measured carried on the sample stage. Collect the scattered light through the collection optical path and filter the sample excitation light, and then transmit it to the spectrometer, the image intensifier, and the detector in sequence; at the same time, the pulse laser outputs two synchronization trigger signals, one of which is transmitted to the synchronization correction module, and the other is transmitted to the image intensifier through the delay unit and the gating module;

[0027] The synchronization correction module detects the gating signal by voltage division or electromagnetic induction and compares the time difference with the synchronization trigger signal to obtain a delay adjustment value, and feeds it back to the control computer;

[0028] The control computer transmits the delay adjustment value to the delay unit, introduces a delay during the transmission of the synchronization trigger signal, so that the time to turn on the image intensifier is consistent with the time when the optical signal generated after the sample is excited reaches the image intensifier.

[0029] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0030] (1) The present invention uses a synchronization correction module to obtain the gating signal for triggering the image intensifier, and uses devices or components such as an oscilloscope to measure the gating signal in real time, and feeds back the delay adjustment value to the delay device to adjust the delay, thereby completing the synchronization clock correction of the system. This device and method reduce the influence of temperature drift in the electronic system, improve the stability of the system, and reduce the measurement error. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic structural diagram of a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier in the prior art;

[0032] Figure 2 is a schematic structural diagram of a synchronization clock correction device for a time-gated spectroscopic measurement and optical imaging system according to an embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of the output signal of the synchronization correction module according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0034] In order to enable those skilled in the art to better understand the solution of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the scope of protection of the present application.

[0035] The stability of the synchronization clock is an important parameter index for a time-gated spectroscopic measurement and optical imaging system. In a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier, the delay device sets an appropriate delay value so that the time when the gating signal turns on the image intensifier is consistent with the time when the optical signal reaches the image intensifier, as Figure 1 shown. Since the system cannot obtain and correct the synchronization clock in real time, currently, it can only judge whether the synchronization clock drifts by the strength of the signal 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.

[0036] Therefore, the present application solves the problem of correcting the synchronization clock drift of a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier through the following embodiments.

[0037] Embodiment 1:

[0038] As Figure 2As shown, this embodiment provides a correction device for synchronous clock drift of a time-gated spectral measurement and optical imaging system based on a gated image intensifier, which is characterized by including a pulsed laser, a sample stage, a spectrometer, an image intensifier, a detector, a delay unit, a gating module, a control computer, and a synchronization correction module;

[0039] The pulsed laser is used to output sample excitation light and a synchronous trigger signal;

[0040] The sample excitation light is focused on the sample to be measured carried by the sample stage through a focusing optical path, and then the scattered light is collected through a collection optical path and the sample excitation light is filtered, and is sequentially transmitted to the spectrometer, the image intensifier, and the detector;

[0041] One path of the synchronous trigger signal is transmitted to the synchronization correction module, and the other path is transmitted to the image intensifier through the delay unit and the gating module;

[0042] The delay unit is used to introduce a delay during the transmission of the synchronous trigger signal, and the gating module is used to convert the output signal of the delay unit into a gating signal for controlling the operation of the image intensifier, so that the time when the gating signal turns on the image intensifier is consistent with the time when the optical signal generated after the sample is excited reaches the image intensifier;

[0043] The synchronization correction module detects the gating signal by means of voltage division or electromagnetic induction and compares the time difference with the synchronous trigger signal to obtain a delay adjustment value;

[0044] The control computer is respectively connected to the pulsed laser, the delay unit, the synchronization correction module, and the detector, and feeds back the delay adjustment value to the delay unit for correction.

[0045] In one or more preferred embodiments, the pulsed laser includes components such as a power supply, a laser driver, and a laser head. These components can be distributed or integrated into one body.

[0046] The key performance indicators of the laser output by the pulsed laser are:

[0047] The wavelength range is between 300 - 1100 nm;

[0048] The line width is between 0.01 - 100 cm -1 ;

[0049] The pulse width is between 10 fs - 10 ns;

[0050] The repetition rate is between 100 Hz - 80 MHz;

[0051] The average power range is 10 µW -1 W.

[0052] The pulsed laser may or may not have an output trigger pulse function. If it has an output pulse function, it can directly trigger the detector. If it does not have an output pulse function, the laser beam is split into two beams. One beam of laser is used as a trigger signal, and the other is used for sample excitation.

[0053] In one or more preferred embodiments, the sample stage is used to hold the sample so that the sample can be controlled manually or by a stepping motor in multiple dimensions at the focusing position for exciting 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 collection optical paths, including but not limited to fiber Raman detectors, microscopic detectors, confocal microscopic detectors, etc.

[0054] In one or more preferred embodiments, the spectrometer mainly uses transmissive or reflective gratings, or prism and other spectroscopic optical modules to spatially distinguish optical signals of different wavelengths.

[0055] In one or more preferred embodiments, the image intensifier and the gating module form a gated image intensifier. By applying a selected electric pulse (gating signal) to certain electrodes of the image intensifier, the purpose of controlling the operation of the image intensifier is achieved. The image intensifier consists of a photocathode, a microchannel plate, and a phosphor screen. According to the different positions where the selected electric pulse is applied to the image intensifier, the gating operation modes can be divided into: photocathode gating, microchannel plate gating, and anode gating.

[0056] In one or more preferred embodiments, the detector uses a two-dimensional pixel area array detector, including ICCD cameras, ICMOS cameras, SPAD arrays, etc., for acquiring spectra and imaging.

[0057] In one or more preferred embodiments, the delay unit is used to introduce a delay in the transmission process of the electrical signal so that the time when the gating signal turns on the image intensifier is consistent with the time when the optical signal generated after the sample is excited reaches the image intensifier.

[0058] In one or more preferred embodiments, the gating module is used to convert the electrical signal output by the delay unit into a selected electric pulse (gating signal) for controlling the operation of the image intensifier.

[0059] In one or more preferred embodiments, the control computer controls each hardware system, collects and analyzes data.

[0060] In one or more preferred embodiments, the synchronization correction module is used to correct the synchronization clock. The synchronization correction module has two inputs. Input one is the synchronization signal of the pulsed laser, and input two is the gating signal obtained by using the voltage division or electromagnetic induction principle.

[0061] Specifically, a voltage division scheme can employ a coupler. The input port of the coupler is connected to the gating module, and the output ports of the coupler are respectively connected to the image intensifier module and the synchronization correction module. The gating signal obtained by the synchronization correction module is measured by an oscilloscope or a data acquisition card.

[0062] Specifically, an electromagnetic induction scheme can utilize a current probe or a way of winding coils. In Figure 2 it, a way of winding coils is adopted, that is, an induction coil is wound around the connecting wire between the gating module and the image intensifier. The obtained gating signal is measured by an oscilloscope or a data acquisition card, as Figure 3 shown. At time T1, the time difference between the gating signal and the synchronization signal of the pulsed laser is Δt1. Due to factors such as system temperature drift, the synchronization clock drifts in time. At time T2, the time difference between the gating signal and the synchronization signal of the pulsed laser is Δt2. The relative delay change between the gating signal and the synchronization signal of the pulsed laser is Δt = Δt2 - Δt1. The synchronization correction module feeds the delay adjustment value Δt back to the delay unit, and the delay unit adjusts the delay value to correct the system synchronization clock.

[0063] Embodiment 2:

[0064] In this embodiment, specific settings are made for the components used in the correction device for the synchronization clock drift of a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier in the above embodiment to achieve time-gated Raman spectroscopic measurement, including the following nine modules.

[0065] (1) Pulsed laser. In this embodiment, a laser with a wavelength of 542 nm, a line width of 0.01 cm -1 , a pulse width of 1 ps, a repetition frequency of 80 MHz, and an average power of 400 mW is used as the Raman excitation light source. The laser beam passes through a 1:9 beam splitter and is divided into two beams of light. The first beam of light with lower power irradiates a silicon-based detector to generate a trigger electrical signal. The other beam of stronger light is used for Raman excitation.

[0066] (2) Sample stage. In this embodiment, an ordinary microscopic Raman detection system is adopted.

[0067] (3) Spectrometer. In this embodiment, a spectrometer with a standard reflective grating as the main component is used.

[0068] (4) Image intensifier. In this embodiment, a photocathode-gated image intensifier is used, and the image intensifier is turned on or off by controlling the motion state of the photoelectrons generated by the photocathode.

[0069] (5) Detector. In this embodiment, an ICCD camera is used as the detector.

[0070] (6) A time delay unit, which is a tunable electrical delay unit in this embodiment.

[0071] (7) A gating module, which controls the working state of the photocathode in this embodiment.

[0072] (8) A control computer, which is used to control each hardware system, collect and analyze data. A desktop computer is adopted in this embodiment.

[0073] (9) A synchronization correction module. In this embodiment, an induction coil is wound around the connection wire between the gating module and the image intensifier, and an oscilloscope is used to measure the relative time change between the gating signal and the synchronization signal of the pulsed laser, and feedback it to the time delay unit to correct the synchronization clock.

[0074] Embodiment 3:

[0075] Based on the device for correcting the synchronization clock drift of a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier in the above embodiment, in this embodiment, a multi-dimensional manual or electric translation stage is added to the sample stage to collect the fluorescence signals of each part of the sample, so as to achieve time-gated fluorescence imaging.

[0076] It should be noted here that the device provided in the above embodiment is only illustrated by dividing into the above function modules. In practical applications, the above functions can be allocated to different function modules according to needs, that is, the internal structure is divided into different function modules to complete all or part of the functions described above.

[0077] Embodiment 4:

[0078] To make it easier for those skilled in the art to understand the solution of this application, in the embodiment, a method for correcting the synchronization clock drift of a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier is provided. Applying the device for correcting the synchronization clock drift of a time-gated spectroscopic measurement and optical imaging system based on a gated image intensifier in the above embodiment, the method includes the following steps:

[0079] S1. Start the pulsed laser, output the sample excitation light and focus it on the sample to be measured carried on the sample stage through the focusing optical path. Collect the scattered light through the collection optical path and filter the sample excitation light, and then transmit them to the spectrometer, the image intensifier and the detector in sequence; at the same time, the pulsed laser outputs two synchronization trigger signals, one of which is transmitted to the synchronization correction module, and the other is transmitted to the image intensifier through the time delay unit and the gating module;

[0080] S2. The synchronization correction module detects the gating signal by means of voltage division or electromagnetic induction, compares the time difference with the synchronization trigger signal, obtains the delay adjustment value, and feeds it back to the control computer;

[0081] S3. The control computer transmits the delay adjustment value to the delay unit, introducing a delay during the transmission of the synchronous trigger signal, so that the time to turn on the image intensifier is consistent with the time when the optical signal generated after the sample is excited reaches the image intensifier.

[0082] It should be understood that each part of the present application can be implemented by hardware, software, firmware, or a combination thereof. In the above 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, any one or a combination of the following techniques well known in the art can be used: discrete logic circuits having logic gate circuits for implementing logical functions on data signals, application specific integrated circuits having appropriate combinational logic gate circuits, programmable gate arrays (PGAs), field programmable gate arrays (FPGAs), etc.

[0083] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all 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 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 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 connected to the image intensifier module and the synchronous correction module respectively, and the gating signal obtained by the synchronous correction module is measured by an oscilloscope or an acquisition card; The synchronous correction module detects the gate signal by electromagnetic induction, specifically: Wrap the induction coil around the connecting wires between the gating module and the image intensifier, and measure the acquired gating signal through an oscilloscope or acquisition card; 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, then the delay adjustment value Δt=Δt2-Δt1; 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 clock of time-gated spectral measurement and 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. 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 6 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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