Two-dimensional infrared spectrum device with high signal-to-noise ratio based on single-point detector

Abstract

The invention relates to the technical field of laser spectrum, and particularly discloses a two-dimensional infrared spectrum device with a high signal-to-noise ratio based on a single-point detector, and the device comprises a laser light source which generates a required femtosecond laser pulse based on a laser, generates an intermediate infrared laser through the femtosecond laser pulse, and is used for exciting and detecting a sample signal; the test light path is used for guiding and shaping laser pulses of the mid-infrared laser to enable the laser pulses to act on a sample, and then a high-sensitivity single-point detector is used for capturing generated spectral signal changes; the signal amplification and acquisition circuit is used for detecting the spectral signal passing through the sample, converting the spectral signal into an electric signal, and amplifying and processing the electric signal; the instrument data control module is used for controlling the operation of the spectrum device, adjusting a delay line, a monochromator and a pulse shaping instrument in a light path, and carrying out two-dimensional Fourier transform on acquired data so as to obtain a two-dimensional infrared spectrogram and extract the molecular structure and dynamic information of the sample.

Description

Technical Field

[0001] The invention relates to the technical field of laser spectroscopy, and more particularly to a two-dimensional infrared spectroscopy device with a high signal-to-noise ratio based on a single-point detector. Background Art

[0002] Two-dimensional infrared spectroscopy is a technology that uses ultrafast lasers to detect the vibration characteristics of molecules. Unlike infrared absorption spectroscopy, which can only detect vibration frequency and intensity, two-dimensional infrared spectroscopy can measure the anharmonicity and excited state lifetime of vibration modes, as well as the degree of coupling, relative orientation, and energy transfer between different vibration modes, and can also provide ultrafast dynamic information of molecules.

[0003] With the development of ultrafast spectroscopy technology, two-dimensional infrared spectroscopy has gradually been applied to many fields. For example, in physical and chemical research and biomedicine, two-dimensional infrared spectroscopy can detect the microenvironment of enzyme active sites, protein-protein binding or protein-small molecule binding sites, characterize the specific state of various biological molecules when they function, and can also be used to detect the microscopic properties of various materials. Two-dimensional infrared technology can be divided into two technical routes: time domain and frequency domain. Among them, time domain two-dimensional infrared has become the current mainstream route because of its higher time and frequency resolution. There are two main ways to implement time domain two-dimensional infrared:

[0004] One is to use three beams of phase-matched infrared light to generate photon echo signals on the sample, and then perform heterodyne detection. This method has very high requirements on beam quality and optical path stability. Otherwise, the signal-to-noise ratio will be seriously affected due to poor phase matching and phase drift.

[0005] The second method is to use an interferometer or pulse shaper to generate double-pulse infrared light and use a pump-probe configuration for measurement. The signal intensity generated by this method is weaker than the first method, and both the interferometer and pulse shaper will cause the infrared light to lose more than half of its energy, requiring a high light source energy, otherwise it is difficult to obtain a high signal-to-noise ratio. However, this method has excellent phase stability, so it has become the mainstream method.

[0006] Since the sample signal is usually weak and two-dimensional data need to be scanned, the acquisition of high-quality data in two-dimensional infrared spectroscopy usually relies on highly sensitive mid-infrared array detectors. However, highly sensitive mid-infrared array detectors are very expensive, so we need to develop alternative methods.

[0007] In view of this, the present invention provides a two-dimensional infrared spectroscopy device with a high signal-to-noise ratio based on a single-point detector to solve the above problems. Summary of the invention

[0008] In order to overcome the problems in the prior art, the present invention proposes a two-dimensional infrared spectroscopy device with a high signal-to-noise ratio based on a single-point detector. By optimizing the optical path design and combining an efficient data acquisition and analysis system, a two-dimensional mid-infrared spectroscopy device with a high signal-to-noise ratio based on a single-point detector is constructed.

[0009] The present invention provides a two-dimensional infrared spectroscopy device with a high signal-to-noise ratio based on a single-point detector, including a laser light source, a test optical path, a signal amplification and acquisition circuit, and an instrument data control module:

[0010] Laser light source, based on femtosecond laser to generate femtosecond laser pulses, which are converted into mid-infrared lasers through optical parametric amplifier system and non-collinear difference frequency module;

[0011] Test the optical path, guide and shape the mid-infrared laser, make the infrared laser act on the sample, and perform pump detection or two-dimensional infrared detection;

[0012] The signal amplification and acquisition circuit converts the pulse laser signal into a digital signal, and performs amplification and analog-to-digital conversion to obtain a spectral digital signal;

[0013] The instrument data control module controls the operation of the spectral device, adjusts the delay line, monochromator and pulse shaper in the optical path, uses a single-point detector to capture spectral signals in the pump-probe operation mode or the two-dimensional infrared detection operation mode, and performs a two-dimensional Fourier transform on the collected spectral digital signal to obtain a two-dimensional infrared spectrum.

[0014] As a preferred technical solution of the present invention, the test optical path includes a front-end collimating optical path, a pulse shaper, a pump optical path, a detection optical path, a reference light / pump calibration optical path, a tracer optical path, a sample displacement stage and an optical path housing;

[0015] The front end collimates the optical path, uses a reflector and an aperture to adjust the mid-infrared laser, and collimates the pump light and detection light generated by the laser;

[0016] A pulse shaper processes the pump light and the detection light through a pulse signal generator and an amplifier, and a computer controls and adjusts the pulse laser signals corresponding to the pump light and the detection light;

[0017] The pump light path guides the shaped pump light to the parabolic mirror through the reflector, aperture, half-wave plate and polarizer, and focuses it on the sample;

[0018] The detection light path passes through a reflector, a delay line, and a beam splitter, controls the optical path difference with the pump light, and is focused onto the sample. The reflected or transmitted spectral signal is collected based on a single-point detector.

[0019] A reference light / pump calibration optical path, which introduces pump light and / or reference light into the monochromator through a foldable reflector, for calibration and synchronization of the detection light;

[0020] Tracer optical path, using visible light generated by semiconductor lasers to simulate the path of infrared light, used to adjust and align the optical path;

[0021] The sample translation stage precisely moves the sample in three dimensions so that the beam and the sample interact according to preset rules and the sample is positioned at the focus of the laser beam;

[0022] The optical path housing is purged with nitrogen to reduce the absorption and disturbance of mid-infrared laser by water vapor and protect the optical path system.

[0023] As a preferred technical solution of the present invention, the tracer optical path is used to simulate the path of infrared light, and the following steps are performed to assist in adjusting the optical path:

[0024] Semiconductor laser, a semiconductor laser emitting visible light is used as a tracer light source. The laser is mounted on an adjustable mirror frame to position the beam in space;

[0025] Reflectors M24, M25, and M26 guide the tracer light onto the same path as the infrared light based on a foldable reflector, thereby adjusting the path of the tracer light;

[0026] Apertures I2, I3, I4, and I5 can be adjusted to collimate the tracer light so that it can accurately simulate the propagation path of infrared light, and are used to limit and adjust the diameter of the light beam to ensure that the tracer light and the infrared light path overlap accurately;

[0027] The optical path overlaps by adjusting the reflector M24 and the apertures I2 and I3 so that the tracer light overlaps with the detection light and the pump light path before the pulse shaping crystal. Similarly, by adjusting the reflector M26 and the apertures I4 and I5, the tracer light overlaps with the pump light path after pulse shaping, thereby assisting in the precise adjustment of the optical path.

[0028] As a preferred technical solution of the first aspect of the present invention, the sample displacement stage includes a manual displacement stage and two electric displacement stages; the sample is moved in three spatial dimensions based on the sample displacement stage so that the sample is positioned at the focus of the laser beam to obtain the best spectral signal;

[0029] The sample pool is fixed based on the sample displacement stage so that the direction of the sample pool is consistent with the moving direction of the sample stage. At the same time, the sample displacement stage is designed to be compatible with the sample flow pool, so that fresh samples can be continuously added to the sample pool during the experiment.

[0030] As a preferred technical solution of the present invention, the optical path housing is composed of an aluminum profile frame and an acrylic plate. A vent is provided on the acrylic plate to connect the nitrogen purge optical path system, and the light shaped by the pulse shaper is wrapped through a pipe.

[0031] As a preferred technical solution of the present invention, the instrument data control module includes a pump-probe operation mode and a fast two-dimensional infrared mode;

[0032] Pump-probe operation mode, by moving the delay line and monochromator, scanning different time delays and wavelengths in sequence, collecting transient absorption signals, setting the number of repetitions and order of scanning as needed, and obtaining spectral signals of different samples;

[0033] Fast 2D IR mode replaces the delay line adjustment with the double pulse interval generated by the pulse shaper to quickly acquire 2D IR spectra and eliminates scattered signals and pump-probe signals using different phase masks.

[0034] As a preferred technical solution of the present invention, in the pump-probe mode, the transient absorption signal is corrected using the linear fitting result of the intensity of the probe light and the reference light, and the transient absorption intensity of the pump on-off pulse pair is calculated based on the formula:

[0035]

[0036] Wherein: k and b are the slope and intercept obtained by linearly fitting the intensities of the detection light and the reference light in advance, and the slope and intercept are the average values ​​of the slope and intercept corresponding to the absorption wavelength signals of all pulse pairs.

[0037] As a preferred technical solution of the present invention, in the fast two-dimensional infrared mode, by uploading all masks to the AWG pulse generator at one time and executing them cyclically, a complete two-dimensional infrared spectrum can be obtained with fewer scanning repetitions.

[0038] As a preferred technical solution of the present invention, the AWG pulse generator calculates the mask according to the double pulse interval, and generates four phase masks of (0,0), (0,π), (π,0), and (π,π) for each pulse interval. Through multiple masks, scattered signals and pump-detection signals can be eliminated, and the intensity of two-dimensional infrared signals can be doubled.

[0039] The specific advantages of the present invention are as follows:

[0040] The present invention focuses on the geometric structure of the optical path, the signal calculation method and the optimization of the control software for a single-point detector. In the optical path design, a short and compact layout is adopted to reduce laser divergence, the aperture is reasonably arranged to improve the system stability, and a tracer optical path is introduced to simplify the adjustment process. At the same time, the reference optical path and the pump calibration optical path are integrated to simplify the structure. In terms of signal processing, the signal-to-noise ratio is effectively improved and the influence of light source jitter is reduced by deducting bad points three times and performing high-pass filtering and linear fitting on the signal light and the reference light. In addition, the optimization of the control software provides a flexible scanning mode to adapt to different experimental requirements, and realizes the parallel operation of time-consuming operations, thereby significantly improving the efficiency of data acquisition. These innovations jointly improve the performance and user experience of two-dimensional infrared spectroscopy devices using single-point detectors. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] Figure 1 This is a light path diagram of the two-dimensional infrared spectroscopic device with high signal-to-noise ratio of the present invention.

[0042] Figure 2 The present invention is a flow chart of the method for sequentially controlling the pump-probe mode of the instrument.

[0043] Figure 3 A flow chart of a method for timing control of a fast two-dimensional infrared mode of an instrument of the present invention;

[0044] In the figure: M1-M24, reflectors; I1-I7, apertures; BS1-BS2, beam splitters; P1-P2, parabolic mirrors; L1, convex lens. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] Embodiment 1: The present invention provides a technical solution: a two-dimensional infrared spectroscopy device with a high signal-to-noise ratio based on a single-point detector, comprising a laser light source, a test optical path, a signal amplification and acquisition circuit, and an instrument data control module;

[0047] Laser light source, based on femtosecond laser to generate femtosecond laser pulses, which are converted into mid-infrared lasers through optical parametric amplifier system and non-collinear difference frequency module;

[0048] Specifically, the laser light source consists of a titanium:sapphire femtosecond laser, an optical parametric amplifier system and a non-collinear difference frequency module. The femtosecond pulse laser generated by the laser is sent to the optical parametric amplifier system to generate signal light and idler light of specific frequencies, and then the signal light and idler light are sent to the non-collinear difference frequency module to generate mid-infrared laser of the required wavelength.

[0049] More specifically, the mid-infrared laser has a pulse energy of more than 10μJ and a pulse width of about hundreds of femtoseconds, a divergence angle of no more than 1mrad, and the wavelength, energy and time characteristics of the output light pulse are precisely controlled through an optical parametric amplification system and a non-collinear difference frequency module.

[0050] Test the optical path, guide and shape the mid-infrared laser, so that the infrared laser interacts with the sample to generate a pulsed laser signal corresponding to the adjusted pump light and probe light;

[0051] Specifically, if Figure 1 As shown, the test optical path includes a front-end collimating optical path, a pulse shaper, a pump optical path, a detection optical path, a reference light / pump calibration optical path, a tracer optical path, a sample displacement stage and an optical path housing.

[0052] The front-end collimating optical path includes a reflector M1, a reflector M2, an aperture I1, a reflector M3, a beam splitter BS1, two reflectors M4 and M5 in the transmission direction of the beam splitter, and two apertures I2 and I3 in the reflection direction (aperture function) which are placed in sequence.

[0053] More specifically, the mid-infrared laser is guided to the position of the preset optical path through three mirrors M1, M2, and M3.

[0054] The propagation directions of the residual signal light and idler light of the mid-infrared laser and the difference frequency module will differ by a small angle. After passing through this optical path of about 1.5m, the two will be separated by a sufficient distance to avoid the interference of the signal light and idler light on the optical path adjustment. At the same time, M1 can be adjusted to make this section of the optical path have a small inclination angle upward or downward to change the height of the laser to match the subsequent components.

[0055] At the end of the collimated optical path, a beam splitter BS1 is used to split the transmitted stronger pump light and the reflected weaker detection light. The three apertures I1, I2, and I3 are used for the collimated optical path to ensure that no matter how the light source changes, it will not affect the use of the subsequent optical path. When in use, adjust M1 to align the laser with aperture I1, and then adjust M3 and M4 to make the laser accurately pass through apertures I2 and I3. At this time, the laser propagation direction is completely determined by the aperture position and has nothing to do with the light source.

[0056] The pump light is then introduced into the pulse shaper through the two reflectors M4 and M5. These two reflectors provide freedom in adjusting the direction of the beam. By adjusting these two mirrors, the pump light can accurately match the incident position and direction of the pulse shaper.

[0057] The pulse shaper includes an AWG pulse signal generator, an ARF pulse amplifier, a pulse shaping optical path, a water cooler and a computer. The pulse peak shape of the pulse laser is manipulated by the pulse signal generated by computer control. In order to generate the dual-pulse pump light required for two-dimensional infrared scanning, the computer calculates the peak shape of the acoustic wave signal required for modulation, and then the AWG pulse signal generator generates an electrical signal with the same peak shape. The electrical signal is amplified by the AFR pulse amplifier, and the amplified signal is converted into an acoustic wave in the pulse shaping optical path and propagated to the acousto-optic modulation crystal. At this time, the pump light will become a dual-pulse laser after passing through the pulse shaping optical path, and the interval and phase of the pulses are determined by the parameters set by the computer.

[0058] The pump light path includes four reflectors M6, M7, M8, and M9, among which two apertures I4 and I5, as well as a half-wave plate and a polarizer are placed between the reflectors M7 and M8. The shaped pump light is propagated to the parabolic mirror P1 with the shortest optical path. The two apertures ensure that the pump light path will not deviate, and the reflector M9 can control the subsequent propagation direction of the light. The half-wave plate and the polarizer can control the polarization direction of the pump light.

[0059] The detection optical path includes six-sided reflectors M10-M15, a delay line with a hollow reflector, a reflector M16, a beam splitter BS2, an aperture I6, a half-wave plate, a polarizer, a reflector M17, a parabolic mirror P1, a parabolic mirror P2, a reflector M18, a reflector M19 and a convex lens L1. The six-sided reflectors M10-M15 are designed to guide the detection optical path, while ensuring that the optical path of the detection light is almost the same as that of the pump light. Multiple reflections are to avoid taking up too much space when supplementing the optical path. Then, the optical path difference between the pump light and the detection light is accurately controlled by the delay line, and a beam of light is separated as a reference light through the beam splitter BS2. The remaining detection light is sent to the parabolic mirror P1 by the reflector M17. The aperture, half-wave plate and polarizer on the way are used to adjust the spot size, intensity and polarization direction of the detection light. The parabolic mirror P1 focuses the parallel pump and probe light to the same point, after which the probe light diverges and is readjusted to parallel light by the second parabolic mirror P2. The two subsequent mirrors M18 and M19 are used to adjust the direction of the probe light so that it is aligned with the monochromator, and then the convex lens L1 focuses it to the entrance of the monochromator.

[0060] The reference light / pump calibration optical path includes two foldable mirrors M20 and M21, and two mirrors M22 and M23 placed in the transmission direction of the beam splitter BS2, and two apertures I7 and I8 are placed between the two mirrors. The design of the two folding mirrors can choose whether to lead the pump light to the reference light path, and this pump light or the reference light transmitted by the beam splitter BS2 will pass through the two mirrors M22 and M23 and enter the monochromator from below the detection light.

[0061] The tracer optical path includes a semiconductor laser, a foldable reflector M24, a reflector M25, and a foldable reflector M26. The semiconductor laser is also mounted on an adjustable mirror frame. This part of the optical path is used to solve the problem that infrared light is invisible and the optical path is difficult to adjust. The visible tracer light generated by the semiconductor laser can show the optical path of the infrared light. By turning up the reflector M24 and using the apertures I2 and I3 to collimate the tracer light, it can overlap with the optical path of the detection light and the pump light before the pulse shaping crystal. By turning up the reflector M26 and using the apertures I4 and I5 to collimate the tracer light, it can overlap with the pump optical path after pulse shaping. This design can greatly simplify the process of adjusting the optical path while improving the quality of the optical path.

[0062] The sample stage consists of a manual stage and two motorized stages that can move the sample in three dimensions and can automatically translate the sample in two dimensions during the experiment. The sample stage can hold the sample cell and is adjustable to ensure that its direction is consistent with the direction of the sample stage movement to avoid the sample from deviating from the position where the pump and probe light coincide during translation. The sample stage is compatible with the sample flow cell to ensure the freshness of the sample.

[0063] The optical path housing is a box made of aluminum profile frame and acrylic plate, which wraps the main part of the optical path and leaves holes near the pulse shaper and where the light passes. The front section of the optical path that is not in the box is wrapped by paper or aluminum pipes, and vents are left to ensure that nitrogen can pass through. This shell is mainly used for nitrogen purging to remove water vapor in the air to reduce the absorption and disturbance of water vapor to the mid-infrared laser. The overall optical path is designed to be relatively compact, making the shell volume as small as possible to improve the effect of nitrogen purging. At the same time, it can also reduce the interference of various other factors in the laboratory on the experiment during the experiment, and it can also act as a dust cover when the system is not in use.

[0064] The signal amplification and acquisition circuit converts the pulse laser signal into a digital signal, and performs amplification and analog-to-digital conversion to obtain a spectral digital signal;

[0065] Specifically, the signal amplification and acquisition circuit includes a monochromator, a binary HgCdTe detector, a preamplifier, a boxcar integrator, an oscilloscope, a high-speed data acquisition card, and a computer. After the detection light and the reference light enter the monochromator for spectroscopy, the light of a specific wavelength is detected by the binary HgCdTe detector and output as an electrical signal. The preamplifier pre-amplifies it and then sends it to the boxcar integrator to calculate the average voltage and convert it into a long straight voltage. The integrator is triggered by the synchronization signal output by the laser, and the start signal of the mask cycle given by the pulse shaper is also sent to the integrator and converted into a long straight voltage. These three signals are converted into digital signals by the high-speed data acquisition card and submitted to the computer.

[0066] The instrument data control module controls the operation of the spectral device, adjusts the delay line, monochromator and pulse shaper in the optical path, uses a single-point detector to capture spectral signals in the pump-probe operation mode or the two-dimensional infrared detection operation mode, and performs a two-dimensional Fourier transform on the collected spectral digital signal to obtain a two-dimensional infrared spectrum.

[0067] Specifically, the instrument data control module controls the delay line, monochromator and pulse shaper in the optical path, collects data from the high-speed data acquisition card, calculates and saves the two-dimensional infrared spectrum. The software includes two operating modes: pump-probe and fast two-dimensional infrared.

[0068] like Figure 2 As shown in the figure, in the pump-probe mode, the delay line and the monochromator can be moved in sequence to scan the transient absorption signals of different delays and wavelengths. Usually, the delay and wavelength are kept for 1 second for data acquisition (1000 pulses). If the signal-to-noise ratio is not enough, repeated scanning can be set. The number of repetitions and the scanning order of wavelength, delay, and repetition can be set according to the needs. The specific control logic is as follows: Figure 2 As shown, this degree of freedom allows the experimenter to independently choose a better scanning order according to the purpose of the experiment when detecting easily damaged or volatile samples. By replacing the delay with the double pulse interval generated by the pulse shaper, a two-dimensional infrared spectrum can be obtained. When collecting data, the shaping settings of the pulse shaper are four cycles of basic mask (or specific mask required to generate double pulses), no mask, inverted basic mask (or specific mask), and no mask to produce pulses alternating with pumping and no pumping. The inverted mask will eventually produce scattering signals with opposite signs. After averaging with the signal of the normal mask, the scattering signal can be eliminated. After collecting the data, the program will first detect whether the total light intensity jitter is qualified, deduct the points with excessive jitter, and automatically repeat the scan of the wavelength and delay if the overall jitter is too large. Then calculate the transient absorption intensity of each pump on-off pulse pair, and use the corrected reference light in the calculation to correct the transient signal;

[0069]

[0070] Among them: k and b are the slope and intercept obtained by linear fitting the intensity of the detection light and the reference light in advance. It is necessary to fit each wavelength once to obtain the corresponding slope and intercept. Finally, the absorption signal of all pulse pairs is averaged, and the points with excessive jitter will be deducted again according to the threshold in the process.

[0071] like Figure 3 As shown, in the fast two-dimensional infrared mode, the mask is calculated according to each required double pulse interval, and four phase masks of (0,0), (0,π), (π,0), and (π,π) are generated for each pulse interval. Through multiple masks, the scattered signal and pump-detection signal can be eliminated and the two-dimensional infrared signal intensity can be doubled.

[0072] All masks are uploaded to the AWG pulse generator together and executed in a loop. When collecting data, the number of data collected for each detection wavelength is an integer multiple of the number of masks. Then, the corresponding relationship between the mask and the pulse interval is determined based on the collected mask cycle start signal, and the absorption signal is calculated in the same way as the pump-probe mode. After completing the data collection of all wavelengths, the data will be saved, and the pulse interval will be Fourier transformed to give a two-dimensional infrared spectrum. Compared with scanning two-dimensional infrared in pump-probe mode, this mode avoids the process of repeatedly starting and stopping the pulse generator and uploading the mask, saving experimental time. At the same time, it will use fewer scanning repetitions to give a complete two-dimensional infrared spectrum, which makes it easier for us to judge the required number of repetitions more quickly, and can give results with higher signal-to-noise ratio for non-uniform or easily damaged samples.

[0073] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

[0074] Finally: The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A two-dimensional infrared spectroscopy device with high signal-to-noise ratio based on a single-point detector, characterized in that: include: Laser light source, test optical path, signal amplification and acquisition circuit, instrument data control module; Laser light source, based on femtosecond laser to generate femtosecond laser pulses, which are converted into mid-infrared lasers through optical parametric amplifier system and non-collinear difference frequency module; Test the optical path, guide and shape the mid-infrared laser, make the infrared laser act on the sample, and perform pump detection or two-dimensional infrared detection; The signal amplification and acquisition circuit converts the pulse laser signal into a digital signal, and performs amplification and analog-to-digital conversion to obtain a spectral digital signal; The instrument data control module controls the operation of the spectral device, adjusts the delay line, monochromator and pulse shaper in the optical path, uses a single-point detector to capture spectral signals in the pump-probe operation mode or the two-dimensional infrared detection operation mode, and performs a two-dimensional Fourier transform on the collected spectral digital signal to obtain a two-dimensional infrared spectrum.

2. A two-dimensional infrared spectrometer with a high signal-to-noise ratio based on a single-point detector according to claim 1, characterized in that: The test optical path includes a front-end collimating optical path, a pulse shaper, a pump optical path, a detection optical path, a reference light / pump calibration optical path, a tracer optical path, a sample displacement stage and an optical path housing; The front end collimates the optical path, uses a reflector and an aperture to adjust the mid-infrared laser, and collimates the pump light and detection light generated by the laser; A pulse shaper processes the pump light and the detection light through a pulse signal generator and an amplifier, and a computer controls and adjusts the pulse laser signals corresponding to the pump light and the detection light; The pump light path guides the shaped pump light to the parabolic mirror through the reflector, aperture, half-wave plate and polarizer, and focuses it on the sample; The detection light path passes through a reflector, a delay line, and a beam splitter, controls the optical path difference with the pump light, and is focused onto the sample. The reflected or transmitted spectral signal is collected based on a single-point detector. A reference light / pump calibration optical path, which introduces pump light and / or reference light into the monochromator through a foldable reflector, for calibration and synchronization of the detection light; Tracer optical path, using visible light generated by semiconductor lasers to simulate the path of infrared light, used to adjust and align the optical path; The sample translation stage precisely moves the sample in three dimensions so that the beam and the sample interact according to preset rules and the sample is positioned at the focus of the laser beam; The optical path housing is purged with nitrogen to reduce the absorption and disturbance of mid-infrared laser by water vapor and protect the optical path system.

3. A two-dimensional infrared spectrometer with a high signal-to-noise ratio based on a single-point detector according to claim 2, characterized in that: The tracer light path is used to simulate the path of infrared light, and the following steps are used to assist in adjusting the light path: Semiconductor laser, a semiconductor laser emitting visible light is used as a tracer light source. The laser is mounted on an adjustable mirror frame to position the beam in space; Reflectors M24, M25, and M26 guide the tracer light onto the same path as the infrared light based on a foldable reflector, thereby adjusting the path of the tracer light; Apertures I2, I3, I4, and I5 can be adjusted to collimate the tracer light so that it can accurately simulate the propagation path of infrared light, and are used to limit and adjust the diameter of the light beam to ensure that the tracer light and the infrared light path overlap accurately; The optical path overlaps by adjusting the reflector M24 and the apertures I2 and I3 so that the tracer light overlaps with the detection light and the pump light path before the pulse shaping crystal. Similarly, by adjusting the reflector M26 and the apertures I4 and I5, the tracer light overlaps with the pump light path after pulse shaping, thereby assisting in the precise adjustment of the optical path.

4. A two-dimensional infrared spectrometer with a high signal-to-noise ratio based on a single-point detector according to claim 3, characterized in that: The sample displacement stage includes a manual displacement stage and two electric displacement stages; the sample is moved in three spatial dimensions based on the sample displacement stage so that the sample is positioned at the focus of the laser beam to obtain the best spectral signal; The sample pool is fixed based on the sample displacement stage so that the direction of the sample pool is consistent with the moving direction of the sample stage. At the same time, the sample displacement stage is designed to be compatible with the sample flow pool, so that fresh samples can be continuously added to the sample pool during the experiment.

5. A two-dimensional infrared spectroscopic device with a high signal-to-noise ratio based on a single-point detector according to claim 4, characterized in that: The optical path housing is composed of an aluminum profile frame and an acrylic plate. A vent is arranged on the acrylic plate, which is connected to the nitrogen purge optical path system and wraps the light shaped by the pulse shaper through a pipeline.

6. A two-dimensional infrared spectroscopic device with a high signal-to-noise ratio based on a single-point detector according to claim 5, characterized in that: The instrument data control module includes pump-probe operation mode and fast 2D infrared mode; Pump-probe operation mode, by moving the delay line and monochromator, scanning different time delays and wavelengths in sequence, collecting transient absorption signals, setting the number of repetitions and order of scanning as needed, and obtaining spectral signals of different samples; Fast 2D IR mode replaces the delay line adjustment with the double pulse interval generated by the pulse shaper to quickly acquire 2D IR spectra and eliminates scattered signals and pump-probe signals using different phase masks.

7. A two-dimensional infrared spectrometer with a high signal-to-noise ratio based on a single-point detector according to claim 6, characterized in that: In the pump-probe mode, the transient absorption signal is corrected using the linear fitting results of the probe light and reference light intensities, and the transient absorption intensity of the pump on-off pulse pair is calculated based on the formula: Wherein: k and b are the slope and intercept obtained by linearly fitting the intensities of the detection light and the reference light in advance, and the slope and intercept are the average values ​​of the slope and intercept corresponding to the absorption wavelength signals of all pulse pairs.

8. A two-dimensional infrared spectroscopic device with a high signal-to-noise ratio based on a single-point detector according to claim 7, characterized in that: In the fast 2D IR mode, by uploading all masks to the AWG pulse generator at one time and executing it in a loop, a complete 2D IR spectrum can be obtained with fewer scanning repetitions.

9. A two-dimensional infrared spectroscopic device with a high signal-to-noise ratio based on a single-point detector according to claim 8, characterized in that: The AWG pulse generator calculates the mask according to the double pulse interval, and generates masks with four phases of (0,0), (0,π), (π,0), and (π,π) for each pulse interval. The scattered signal and the pump-detection signal can be eliminated through multiple masks, and the two-dimensional infrared signal intensity can be doubled.

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