CN115683337A - Time-resolved micro-Raman spectrum acquisition system - Google Patents

Abstract

The present application discloses a time-resolved micro-Raman spectrum collection system. The time-resolved micro-Raman spectrum acquisition system includes a pulsed laser, an incident optical module, an exit optical module, a spectrometer, a time-resolved single-photon camera, a delay module and a data processing module. The delay module is used to control the time-resolved single-photon camera to acquire and detect the pulsed excitation spectrum in a delayed and synchronous manner according to the incident pulsed laser light emitted by the pulsed laser. The incident optical module includes a collimator, a first filter, a neutral density filter and a microscope lens arranged along the incident light path. The time-resolved single-photon camera controlled by the delay module can improve the time resolution of the Raman spectrum collection process of the spectrum acquisition system to the picosecond level. By adjusting the incident light power and spot size of the incident optical module, the spectral acquisition spatial resolution of the excitation light can be improved. At the same time, the single-photon counting function of the time-resolved single-photon camera can effectively improve the signal-to-noise ratio of the collected spectra.

Description

Time-resolved micro-Raman spectroscopy acquisition system

technical field

The present application relates to the technical field of optical systems, in particular to a time-resolved micro-Raman spectrum collection system.

Background technique

The Raman scattering effect is an inelastic scattering phenomenon caused by the interaction between light and matter discovered by Indian physicist C.V.Raman and others in the experiment of using a mercury lamp to irradiate liquid benzene. Raman spectroscopy can reflect the characteristic vibration, rotation and lattice mode of the material, and can obtain the information of the chemical bond, which is equivalent to the "fingerprint" of the material. The current mainstream Raman spectroscopy system mainly irradiates the sample with a continuous visible light laser, excites the Raman signal of the sample, and then splits the scattered Raman signal through a spectrometer, and collects the signal on a CCD camera to obtain the Raman spectrum of the sample.

Traditional continuous laser Raman systems will inevitably collect mixed interference signals such as fluorescence, ambient light, and thermal radiation while collecting Raman signals, resulting in low signal-to-noise ratio and signal-to-background ratio of Raman signals. Ambient light can generally be partially avoided by collecting signals in a dark environment, but the interference of fluorescence and high-temperature thermal radiation with a time life of microseconds or even nanoseconds is still unavoidable.

Although time-resolved pulsed laser Raman systems have been built and used in some foreign laboratories, their spot diameters are 120-150 microns, and even when remote time-resolved Raman technology is used, the spot size irradiated on the sample is mm level. In practical applications, the particle size of most synthetic and natural material samples is generally less than 50 microns, and it is impossible to use the above time-resolved Raman system for micro-domain characterization. A Finnish commercial company currently has an integrated time-gated Raman spectrometer. Due to the over-integration of its optical components, its spectral resolution is only 5cm ^-1 , and the spectral range can only be from 200-2000cm ^-1 . The spectral resolution cannot meet the measurement of effective Raman spectra of all synthetic and natural samples, and the commercial needs to be coupled into commercial microscopes through optical fibers to truly realize micro-region analysis.

Contents of the invention

Embodiments of the present application provide a time-resolved micro-Raman spectrum collection system.

The time-resolved micro-Raman spectrum acquisition system of the embodiment of the present application includes a pulse laser, an incident optical module, an exit optical module, a spectrometer, a time-resolved single-photon camera, a delay module, and a data processing module; the pulse laser is used to generate an incident pulse Laser; the incident optical module is used to transmit the incident pulsed laser light to the sample to be measured to generate excitation light; the exit optical module is used to transmit the pull excitation light to the spectrometer; the spectrometer is used to transmit the excitation light The spectrum is obtained by splitting the light; the time-resolved single-photon camera is used to collect the spectrum to obtain detection data; the delay module is used to control the delay of the time-resolved single-photon camera according to the incident pulse laser emitted by the pulse laser The detection data is collected synchronously; the data processing module is used to perform data analysis on the detection data to obtain the spectral information of the excitation light; wherein, the incident optical module includes a collimator arranged along the incident optical path, a first filter, neutral density filter and microscope lens, the collimator is used to collimate the incident pulsed laser light, the first filter is used to purify the incident pulsed laser light, the neutral density filter used to adjust the power of the incident light, and the microscope lens is used to focus the incident light onto the sample to be tested.

In some embodiments, the incident optical module further includes a second filter, the second filter is located between the neutral density filter and the microscope lens on the incident light path, and the second filter A plate is used to reflect the incident pulsed laser light to the microscope lens.

In some embodiments, the microscope lens includes a first long working distance objective lens and a second long working distance objective lens that can be selectively arranged on the incident light path.

In some embodiments, the incident pulse laser generated by the pulse laser has a wavelength of 532 nm, a repetition rate of 50 KHz, a single pulse energy of 1 μJ, a pulse width of 200 ps, and an average power of 50 mW.

In some embodiments, the first filter is a filter that transmits light with a wavelength of 532nm and blocks light with a wavelength of 532nm, and the second filter is a filter that reflects light with a wavelength of 532nm and passes through the excitation light. Filter for light with a Raman shift greater than a preset range.

In some embodiments, the exit optical module includes a third filter arranged along the exit optical path, a confocal module, a mirror, and a cylindrical mirror, and the third filter is used to filter out the excitation light in the excitation light. The Raman shift is less than the light in the preset range, the confocal module is used to filter out the stray light outside the focus point and improve the spatial resolution of the time-resolved micro-Raman spectrum acquisition system, and the reflector is used to reflect the The excitation light is sent to the cylindrical mirror, and the cylindrical mirror is used to focus the excitation light to the spectrometer.

In some embodiments, the excitation light is transmitted to the third filter after passing through the microscope lens and the second filter.

In some embodiments, the delay step of the delay module is 10 ps, and the shortest gate width of the time-resolved single photon camera is 500 ps.

In some embodiments, the time-resolved micro-Raman spectroscopy acquisition system further includes a first illumination light source, an illumination optical module, and an observation camera, and the illumination optical module is used to transmit the white light generated by the first illumination light source For the sample to be measured, the observation camera observes the sample to be measured through the illumination optical module.

In some embodiments, the illumination optical module includes a first dichroic prism, a second dichroic prism and a focusing mirror, the first dichroic prism and the second dichroic prism are arranged along the illumination optical path, and the second dichroic prism , the first dichroic prism and the focusing mirror are arranged along the observation optical path.

In the time-resolved micro-Raman spectrum acquisition system of the embodiment of the present application, a spectrometer and a time-resolved single-photon camera are used to collect the detection data of the excitation light, and the delay module controls the delay time of the data collected by the time-resolved single-photon camera, which can improve the The Mann acquisition system collects the time resolution of the Raman process, and can adjust the spectrum range by itself. The single-photon counting function of the time-resolved single-photon camera used can effectively improve the signal-to-noise ratio of the collected spectra. At the same time, through the cooperation of the collimator, the first filter, the neutral density filter and the microscope lens in the incident optical module, the power and spot size of the incident light can be effectively balanced, and the spectrum collection of the excitation light can be realized more accurately.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Description of drawings

The above and/or additional aspects and advantages of the present application will become apparent and understandable from the description of the embodiments in conjunction with the following drawings, wherein:

FIG. 1 is a schematic diagram of the time-resolved micro-Raman scattering spectrum acquisition principle in an embodiment of the present application.

FIG. 2 is a schematic structural diagram of a time-resolved micro-Raman spectrum acquisition system according to an embodiment of the present application.

FIG. 3 is a comparison chart of Raman signal spectra of apatite mineral material with fixed delay and different gate widths and conventional Raman when the time-resolved micro-Raman spectrum acquisition system according to the embodiment of the present application performs Raman testing.

Fig. 4 shows the apatite signal-to-noise ratio between Raman spectra of apatite mineral materials at different gate widths and conventional Raman Raman spectra when the time-resolved micro-Raman spectrum acquisition system according to the embodiment of the present application is used for Raman testing Comparison chart with letter-to-back ratio.

Detailed ways

Embodiments of the present application are described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the figures are exemplary, are only for explaining the present application, and should not be construed as limiting the present application.

In the description of the present application, it should be understood that the terms "first", "second", etc. are used for descriptive purposes only, and cannot be interpreted as indicating or implying relative importance or implicitly indicating the number of indicated technical features . Thus, features defined as "first" and "second" may explicitly or implicitly include one or more features.

The following disclosure provides many different implementations or examples for implementing different structures of the present application. To simplify the disclosure of the present application, components and arrangements of specific examples are described below. Of course, they are examples only and are not intended to limit the application. Furthermore, the present application may repeat reference numerals and/or reference letters in various instances, such repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and/or arrangements discussed. In addition, various specific process and material examples are provided herein, but one of ordinary skill in the art may recognize the use of other processes and/or the use of other materials.

Please refer to Figure 1. When the sample is irradiated by a beam of pulsed laser light, Rayleigh scattering and Raman scattering will first occur, and the time is generally on the order of hundreds of picoseconds. Since the sample first absorbs the energy of photons, it transitions from the ground state to the excited state, but the state at this time is not stable, and it will spontaneously radiate light to return to the ground state. This process produces fluorescence, and it is also due to the principle of Differently, the fluorescence generation time will lag behind the Raman signal generation, and will last for a long time. However, thermal radiation or light is a continuous background signal, which always exists regardless of whether the laser is irradiated to the sample. Because of the difference in the time distribution of different spectra, the time-resolved micro-Raman acquisition system of this application is based on this principle, and through the high-speed time-resolved detector, it collects most of the Raman signals and avoids the long-lived fluorescence Thermal radiation with continuous background and background light, so as to achieve the purpose of removing fluorescence and continuous background light.

Please refer to FIG. 2 , the time-resolved micro-Raman spectrum acquisition system 100 of the embodiment of the present application includes a pulse laser 101, an incident optical module 102, an exit optical module 103, a spectrometer 104, a time-resolved single-photon camera 105, a delay module 106 and a data processing module 107. The pulsed laser 101 is used to generate incident pulsed laser light. The incident optical module 102 is used to transmit the incident pulsed laser light to the sample 200 to generate excitation light. The exit optical module 103 is used to transmit the excitation light to the spectrometer 104 . The spectrometer 104 is used to split the excitation light to obtain a spectrum. The time-resolved single-photon camera 105 is used to collect the spectrum after the spectrometer 104 splits the spectrum to obtain detection data. The delay module 106 is used for controlling the time-resolved single-photon camera 105 to acquire detection data synchronously with a delay according to the incident pulsed laser light emitted by the pulsed laser 101 . The data processing module 107 is used for performing data analysis on the detection data to obtain spectral information of the excitation light. Wherein, the incident optical module 102 includes a collimator 1021 , a first filter 1022 , a neutral density filter 1023 and a microscope lens 1024 arranged along the incident light path. The collimator 1021 is used to collimate the incident pulsed laser light. The first filter 1022 is used to purify the incident pulsed laser light. The neutral density filter 1023 is used to adjust the power of the incident light. The microscope lens 1024 is used to focus the incident light onto the sample 200 to be tested.

In the time-resolved micro-Raman spectrum collection system 100 of the embodiment of the present application, the spectrometer 104 and the time-resolved single-photon camera 105 are used to cooperate to collect the detection data of the excitation light, and the delay module 106 controls the delay of data collection by the time-resolved single-photon camera 105 Time can improve the time resolution of the Raman spectrum collection system. The time resolution of the Raman spectrum collection system can be adjusted by itself, and the spectrum collection range can be adjusted by itself. The single-photon counting function of the time-resolved single-photon camera 105 used can effectively improve the signal-to-noise ratio of the collected spectrum. At the same time, through the cooperation of the collimator 1021, the first filter 1022, the neutral density filter 1023 and the microscope lens 1024 in the incident optical module 102, the power and spot size of the incident light can be effectively balanced, and the excitation light can be more accurately realized. Spectrum acquisition.

Wherein, the sample to be tested 200 can be placed on a sample displacement platform (not shown in the figure), and the sample displacement platform is driven by a three-axis motor, which can be adjusted in the front-back direction, left-right direction and height direction, so that the sample displacement platform placed on the sample displacement platform The test sample 200 can be precisely located at a predetermined position, so that the incident pulsed laser light focused by the microscope lens 1024 can be irradiated on the test sample 200 to generate excitation light. In one example, the two-axis adjustment travel of the sample stage in the front-back direction and the left-right direction can be 85 mm, and the minimum step size can be 0.2 μm, and the adjustment stroke in the height direction is deliberately 20 mm, and the minimum step size can be 0.05 μm. The load of the sample stage can be greater than 10kg.

In some embodiments, the focal length of the spectrometer 104 may be 520 mm, and the spectrometer 104 may have multiple built-in gratings (not shown in the figure).

In this way, the spectral collection range of the spectrometer 104 can be increased by setting multiple gratings, so that more comprehensive spectral information can be collected.

In one example, the spectrometer 104 can be a MS5204i spectrometer 104 . The spectrometer 104 has a focal length of 520mm and 4 built-in gratings, which are 200:500, 1200:500, 1800:500 and 2400:400. The detailed raster parameters can be shown in the following table:

Take the more commonly used 1800:500 grating after construction as an example, the grating has 1800 lines per millimeter, and its blaze wavelength is 500nm. The calibration of the spectrometer 104 uses a neon lamp standard lamp placed in the optical path to calibrate the wavelength of each grating of the spectrometer 104 . After the wavelength calibration of the spectrometer 104 is completed, and before the start of each experiment, the single crystal silicon wafer is placed at the sample, the laser is turned on, and the translation stage is adjusted so that the laser light is focused on the single crystal silicon wafer. Use the detector to collect the Raman peak of the current single crystal silicon wafer and fit the obtained Raman signal, and adjust the peak position of the obtained Raman signal to the theoretical value of the Raman peak of the single crystal silicon wafer at 520cm ^-1 to calibrate Raman Peak location. In actual use, the entrance slit of the spectrometer 104 is set to 100 μm, and the exit slit is set to 200 μm.

In some embodiments, the incident optical module 102 further includes a second filter 1025, the second filter 1025 is located between the neutral density filter 1023 and the microscope lens 1024 on the incident light path, and the second filter 1025 is used to The incident pulsed laser light is reflected to the microscope lens 1024.

In this way, reflecting the incident pulsed laser light to the microscope lens 1024 through the second filter 1025 can change the propagation path of the incident pulsed laser light, which is beneficial to the spatial arrangement of optical elements in the time-resolved micro-Raman spectroscopy acquisition system 100 . For example, the second filter 1025 can reflect the laser light ninety degrees into the sample.

In some embodiments, the incident pulse laser generated by the pulsed laser 101 has a wavelength of 532 nm, a repetition rate of 50 KHz, a single pulse energy of 1 μJ, a pulse width of 200 ps, and an average power of 50 mW.

It can be understood that in the process of using the pulsed laser 101 , when the energy of a single pulse is too large, the sample 200 to be tested may be damaged. On the premise that the sample 200 to be tested is not damaged, the upper limit of the intensity of a single pulse will be limited, but the average power of the laser can be higher by using a pulse laser 101 with a higher repetition rate, thereby obtaining Time-resolved Raman spectroscopy. However, the pulsed laser 101 with a high repetition frequency may reduce the spectral collection effect of the time-resolved Raman microspectroscopy system 100 for some excitation light under certain circumstances.

In this way, this application adopts a pulse laser 101 with a repetition rate of 50KHz, a single pulse energy of 1μJ, a pulse width of 200ps, and an average power of 50mW. Under the condition of ensuring the safety of samples, fast and accurate time-resolved Raman spectroscopy can be achieved. collection.

In some embodiments, the first filter 1022 is a filter that transmits light with a wavelength of 532nm and blocks light with a wavelength of 532nm, and the second filter 1025 reflects light with a wavelength of 532nm and the Raman shift in the transmitted excitation light is greater than a predetermined value. Set the range of filters for rays.

Specifically, the laser light emitted by the pulse laser 101 can enter the optical fiber and propagate to the collimator 1021 for calibrating the laser divergence angle and expanding the laser beam, so that the laser spot focused on the sample is smaller.

And because the laser light excited by the pulse laser 101 itself and the laser light passing through the optical fiber have a certain spectral width, for Raman scattering, the spectral width of the laser light should be as small as possible in order to obtain Raman scattered light with high spectral resolution. , the first filter 1022 of the present application transmits light with a wavelength of 532nm and blocks light with a wavelength of 532nm, that is, only allows light with a wavelength of 532nm to pass through, thereby purifying the incident pulse laser.

The neutral density filter 1023 adopts a rotatable and adjustable method, and its maximum can be adjusted to ND3.0, that is, the extinction is 1000 times, which can be used to adjust the incident pulse laser power and protect the sample 200 to be tested.

The second filter 1025 reflects light with a wavelength of 532nm and passes through the light with a Raman shift greater than a preset range in the excitation light, so that the excitation light can pass through the mirror because the wavelength of the excitation light is different from the incident pulsed laser light, and is less likely to be Reflection blocking. Wherein, the light with a Raman shift greater than the preset range may be the light with a Raman shift above 100 cm ⁻¹ , and the light beyond the Raman shift passes through the second filter 1025 .

In some embodiments, the microscope lens 1024 includes a first long working distance objective lens (not shown in the figure) and a second long working distance objective lens (not shown in the figure) which can be optionally arranged in the incident light path.

In this way, the microscope lens 1024 can adopt a rotating lens disc, which can directly switch between the first long working distance objective lens and the second long working distance objective lens. Specifically, the rotating lens disc hangs the first long working distance objective lens and the second long working distance objective lens, and the first long working distance objective lens and the second long working distance objective lens are respectively long working distance 20X Mitutoyo objective lens and long working distance 50X Mitutoyo objective lens. Further, under the long working distance 20X Mitutoyo objective lens, the cooperation of the pulse laser 101 and the various optical devices in the incident optical module 102 enables the focused spot size irradiated to the sample to be measured to be 20 μm.

In some embodiments, the exit optical module 103 includes a third filter 1031, a confocal module 1032, a mirror 1033, and a cylindrical mirror 1034 arranged along the exit optical path, and the third filter 1031 is used to filter out For the light whose Raman shift is less than the preset range, the confocal module 1032 is used to filter out the stray excitation light outside the focal point and improve the spatial resolution of the time-resolved micro-Raman spectrum acquisition system, and the mirror 1033 is used to reflect the excitation light to Cylindrical mirror 1034 , the cylindrical mirror 1034 is used to focus the excitation light to the spectrometer 104 .

It can be understood that in the case of collecting Raman spectra, since Rayleigh scattering at 532nm is many times stronger than Raman scattering, the third filter 1031 is used to filter out The light with a Raman shift smaller than the preset range is passed through, and the Raman spectrum collection is realized. Wherein, the light with a Raman shift smaller than the preset range may be light with a Raman shift below 100 cm ⁻¹ , and the light with a Raman shift exceeding the Raman shift passes through the third filter 1031 .

The confocal module 1032 may include two confocal focusing mirrors, a confocal pinhole or a confocal beam expander and the like. Specifically, the confocal module 1032 can be a double quintuple focusing objective lens, and the focusing aperture can be a pinhole with a diameter of 100 microns. The confocal module 1032 is used to filter out the stray excitation light outside the focal point and improve the spatial resolution of the time-resolved micro-Raman spectrum acquisition system. The incident light power and spot size of the incident optical module are adjusted through the incident optical module 102, combined with the aperture size of the confocal module of the exit optical module, the spatial resolution of the spectral collection of the excitation light is improved to micron level.

The mirror 1033 can be a protective silver mirror 1033 , and the mirror 1033 is used to reflect the excitation light at ninety degrees to the cylindrical mirror 1034 and enter the spectrometer 104 .

The cylindrical lens 1034 can focus the excitation light in one direction, and after focusing, the time-resolved single-photon camera 105 can have a larger area to receive light, so as to improve the signal-to-noise ratio and reduce the overexposure time. In an example, the focal length of the cylindrical lens 1034 is matched with the focal length of the spectrometer 104. Specifically, the diameter of the cylindrical lens 1034 may be 10 mm, and the focal length may be 30 mm.

In some embodiments, the excitation light is transmitted to the third filter 1031 after passing through the microscope lens 1024 and the second filter 1025 .

Specifically, both the incident light path and the outgoing light path pass through the microscope lens 1024 and the second filter 1025, and the second filter 1025 transmits and reflects light of different wavelengths to reflect the incident pulsed laser light, so that the excited The wavelength of the Raman scattered light is different from that of the incident pulsed laser light, so it passes through the second mirror 1033 and is less blocked by reflection. In this way, by rationally designing the first optical path and the second optical path, it is beneficial to optimize the spatial setting of the time-resolved Raman microspectroscopy acquisition system 100 .

In some implementations, the delay step of the delay module 106 is 10 ps, and the shortest gate width of the time-resolved single photon camera 105 is 500 ps.

The time-resolved single-photon camera 105 in the embodiment of the present application can have multiple modes: 1. Continuous mode, which is the same as a normal detector and can collect conventional Raman scattered light. 2. Internal trigger mode and external trigger mode, these two modes can be applied to time-resolved Raman spectrum acquisition, the external trigger mode is collected by the pulse laser 101 to the time-resolved single photon camera 105 trigger signal, and the internal trigger mode uses time-resolved The single photon camera 105 triggers the mode of the pulsed laser.

The time-resolved single-photon camera 105 in the embodiment of the present application uses an external trigger mode. The shortest camera gate width of the time-resolved single photon camera 105 can be set to 500 ps in the external trigger mode. In addition, the trigger delay step of the delay module 106 to trigger the time-resolved single-photon camera 105 can reach 10 ps, and the delay module 106 can be used to fine-tune the trigger delay to obtain a higher-quality time-resolved Raman signal.

The time period T shown in FIG. 1 represents the time distribution of the shutter for collecting spectra, that is, the camera gate width. In the example of FIG. 1 , the time-resolved single-photon camera 105 is controlled by a smaller delay time and a smaller gate width. Collecting excitation light can collect Raman scattered light, thereby avoiding the influence of fluorescence. Of course, in other embodiments, by controlling different delay times and gate widths to control the time-resolved single-photon camera 105 to collect excitation light, fluorescence can be collected, or Raman scattered light and fluorescence can be collected, which are not specifically limited here.

In some implementations, the time-resolved single-photon camera 105 can acquire a picture without any effective signal when the shutter of the spectrometer 104 is closed, and detect the brightness of each pixel, and shield out the pixels with a brightness exceeding 200. Pixels to remove fixed noise, these pixels are obtained by averaging the brightness of the four pixels above, below, left, and right when actually collecting signals.

In some embodiments, the time-resolved micro-Raman spectroscopy acquisition system 100 further includes a first illumination light source 108, an illumination optical module 109, and an observation camera 110, and the illumination optical module 109 is used to transmit the white light generated by the first illumination light source 108 To the sample to be tested 200 , the observation camera 110 observes the sample to be tested 200 through the illumination optical module 109 .

In this way, the time-resolved micro-Raman spectrum acquisition system 100 can observe the sample through the first illumination light source 108 , the illumination optical module 109 and the observation camera 110 .

In some embodiments, the illumination optical module 109 includes a first dichroic prism 1091, a second dichroic prism 1092 and a focusing mirror 1093, the first dichroic prism 1091 and the second dichroic prism 1092 are arranged along the illumination optical path, the second dichroic prism 1092, The first dichroic prism 1091 and the focusing mirror 1093 are arranged along the observation optical path.

In this way, the use of the dichroic prism can allow a larger area of white light illumination light to irradiate the sample 200 to be tested, while the reflected light and transmitted light of the sample 200 to be tested will not be blocked by the lens when received by the camera of the microscopic optical path. Some images are missing. Wherein, the focusing lens 1093 matches the microlens 1024, and in one example, the focal length of the focusing lens 1093 is 200mm.

In some implementations, the white light generated by the illumination source 108 passes through the second dichroic prism 1092 , and then transmits to the sample 200 to be tested through the second filter 1025 and the microscope lens 1024 .

That is to say, the illumination optical path, the incident optical path and the outgoing optical path are overlapped at the part of the second filter 1025 and the microscope lens 1024, so that the image of the sample 200 to be measured irradiated by the incident pulsed laser light is observed through the observation camera 110 .

In some implementations, the time-resolved micro-Raman spectroscopy acquisition system 100 further includes a driving module (not shown in the figure), which can be used to drive the second dichroic prism 1092 to be selectively placed on the illumination light path or moved out of the light path. outside the light path of the lighting described above.

When the second dichroic prism 1092 is set in the illumination optical path, the sample can be observed through the camera, and when the spectrum of the excitation light is collected, the second dichroic prism 1092 is driven to move out of the illumination optical path, preventing the loss of excitation light caused by the second dichroic prism 1092 .

In some implementations, the time-resolved micro-Raman spectrum acquisition system 100 further includes a second illumination light source 111, the second illumination light source 111 irradiates the sample to be tested to generate transmitted light, and the observation camera 110 receives the transmitted light through the illumination optical module 109 to obtain The sample 200 to be tested is observed.

This application uses Raman testing as an example to describe the working process of the time-resolved micro-Raman spectroscopy acquisition system 100 in the embodiment of the application, that is, during the Raman testing, the spectrometer 104 is first calibrated through a silicon wafer. A 200:500 grating is used, and the laser power detector is placed in the optical path, so that the continuous laser power at the position of the laser power detector is the same as the pulse laser power. In addition, the variables are controlled by adjusting the exposure parameters so that the total integration time of time-resolved Raman spectroscopy is the same as that of conventional Raman spectroscopy acquisition, and the sample position is not changed during acquisition. And adjust the acquisition parameters so that the intensity of the conventional continuous Raman spectrum is similar to that of the time-resolved Raman spectrum.

In Fig. 3, the two strong peaks of 2088cm ^-1 and 3300cm ^-1 and multiple peaks on the wide scan spectrum of apatite mineral material all disappear with the time-resolved mode and the gate width is reduced. According to the time-resolved According to Mann's principle, these peaks are not a Raman signal, which is beneficial to the interpretation of the spectrum of the sample. In the time-resolved single-photon camera 105 time-gated mode of the time-resolved micro-Raman spectrum acquisition system 100, and the gate width is set to 3 ns and 500 ps, the background spectrum of apatite is basically completely removed, leaving only pure Raman signal, which greatly reduces the subsequent processing pressure.

Figure 4 shows the calculated data of the apatite signal-to-noise ratio and signal-to-background ratio for Raman spectra with different gate widths and conventional Raman Raman spectra. The signal-to-background ratio is obtained by comparing the Raman signal intensity at the Raman peak position with the background signal intensity, and the signal-to-noise ratio is obtained by comparing the Raman signal intensity at the Raman peak position with the noise signal intensity. Among them, Figure 4(a) is the ratio of Raman signal to background signal intensity of apatite under different gate widths with fixed delay and conventional Raman; Figure 4(b) is the ratio of apatite under different gate widths with fixed delay and The Raman signal to noise signal intensity ratio of conventional Raman. It can be seen from the figure that the signal-to-background ratio gradually increases as the gate width keeps decreasing, and there is a sudden change between the gate width of 3ns and 500ps, which also shows that the original pull with a higher signal-to-background ratio can be obtained with a gate width of 500ps. Raman signal, thus bringing lower requirements for the interpretation and post-processing of Raman signal. According to the calculated signal-to-noise ratio, when the signal-to-background ratio of the Raman signal gradually increases, the signal-to-noise ratio also gradually increases, which means that when the time-resolved Raman is more than 3ns gate width, higher exposure time can be obtained under the same exposure time. Raman signal with signal-to-noise ratio and signal-to-background ratio. When switching to a gate width of 500 ps, the signal-to-noise ratio of the Raman signal is also reduced by about 1-3 times compared with a gate width of 3 ns due to the decrease in signal intensity under the same exposure time. However, even if the signal-to-noise ratio decreases to a certain extent, the signal-to-noise ratio of each signal is still higher than 10, the signal-to-noise ratio is high, and the signal quality can still fit the results well. In addition, for stable mineral samples, the exposure time can be appropriately increased when used at a gate width of 500ps, thereby improving the signal-to-noise ratio.

Combining the results of Fig. 3 and Fig. 4, during the Raman test, based on the time-resolved Raman principle, a 532nm picosecond-level pulsed laser 101 is used in combination with a time-resolved single-photon camera 105 to work in a time-gated mode. Combined with the high-magnification micro-optical path, avoiding the influence of the fluorescent background signal that interferes with the Raman signal, the time-resolved micro-Raman spectrum acquisition system 100 of the present application is suitable for the detection of high-fluorescence geological samples, and can obtain pure, high-signal-noise than the Raman signal.

In the description of this specification, reference to the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific examples" or "some examples" etc. The specific features, structures, materials or features described in the manner or example are included in at least one embodiment or example of the present application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the described specific features, structures, materials or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

Although the embodiments of the present application have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limitations on the present application, and those skilled in the art can make the above-mentioned The embodiments are subject to changes, modifications, substitutions and variations.

Claims (10)

1. A time-resolved microscopic Raman spectrum acquisition system, characterized in that it comprises a pulsed laser, an incident optical module, an exit optical module, a spectrometer, a time-resolved single-photon camera, a delay module and a data processing module; The pulsed laser is used to generate incident pulsed laser light; The incident optical module is used to transmit the incident pulsed laser light to the sample to be tested to generate excitation light; The exit optical module is used to transmit the excitation light to the spectrometer; The spectrometer is used to split the excitation light to obtain a spectrum; The time-resolved single-photon camera is used to collect the spectrum to obtain detection data; The delay module is used to control the time-resolved single-photon camera to acquire the detection data synchronously with delay according to the incident pulsed laser light emitted by the pulsed laser; The data processing module is used to perform data analysis on the detection data to obtain spectral information of the excitation light; Wherein, the incident optical module includes a collimator arranged along the incident optical path, a first filter, a neutral density filter and a microscope lens, the collimator is used to collimate the incident pulsed laser light, and the first A filter is used to purify the incident pulsed laser light, the neutral density filter is used to adjust the power of the incident light, and the microscope lens is used to focus the incident light to the sample to be tested. 2. The time-resolved micro-Raman spectrum acquisition system according to claim 1, wherein the incident optical module further comprises a second filter, and the second filter is located at the neutral position on the incident light path. Between the density filter and the microlens, the second filter is used to reflect the incident pulsed laser light to the microlens. 3 . The time-resolved micro-Raman spectrum acquisition system according to claim 2 , wherein the microscope lens includes a first long working distance objective lens and a second long working distance objective lens that can be selectively arranged in the incident light path. 4 . 4. The time-resolved microscopic Raman spectrum acquisition system according to claim 2, wherein the pulsed laser generates the incident pulsed laser with a wavelength of 532nm, a repetition rate of 50KHz, a single pulse energy of 1 μJ, and a pulse The width is 200ps and the average power is 50mW. 5. The time-resolved micro-Raman spectrum acquisition system according to claim 4, wherein the first filter is a filter that transmits light with a wavelength of 532nm and stops light other than the light with a wavelength of 532nm, and the first filter The second filter is a filter that reflects light with a wavelength of 532nm and transmits light with a Raman shift greater than a preset range in the excitation light. 6. The time-resolved micro-Raman spectrum acquisition system according to claim 4, wherein the exit optical module includes a third filter, a confocal module, a mirror and a cylindrical mirror arranged along the exit optical path , the third filter is used to filter out the light whose Raman shift is less than a preset range in the excitation light, and the confocal module is used to filter out the stray excitation light outside the focus point and improve the time-resolved microscopy Spatial resolution of the Raman spectroscopy acquisition system. , the mirror is used to reflect the excitation light to the cylindrical mirror, and the cylindrical mirror is used to focus the excitation light to the spectrometer. 7. The time-resolved micro-Raman spectroscopy acquisition system according to claim 6, wherein the excitation light is transmitted to the third filter after passing through the microscope lens and the second filter. 8. The time-resolved micro-Raman spectroscopy acquisition system according to claim 1, wherein the delay step of the delay module is 10 ps, and the shortest gate width of the time-resolved single photon camera is 500 ps. 9. time-resolved micro-Raman spectrum collection system according to claim 1, is characterized in that, described time-resolved micro-Raman spectrum collection system also comprises the first illumination light source, illumination optics module and observation camera, described The illumination optical module is used to transmit the white light generated by the first illumination light source to the sample to be measured, and the observation camera observes the sample to be measured through the illumination optical module. 10. The time-resolved micro-Raman spectrum acquisition system according to claim 9, wherein the illumination optical module comprises a first beamsplitter prism, a second beamsplitter prism and a focusing mirror, and the first beamsplitter prism and the second beamsplitter prism The second dichroic prism is arranged along the illumination optical path, and the second dichroic prism, the first dichroic prism and the focusing mirror are arranged along the observation optical path.

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