Detailed Description
In the following description, for purposes of explanation and not limitation, specific details are set forth, such as particular system structures, techniques, etc. in order to provide a thorough understanding of the embodiments of the present application. It will be apparent, however, to one skilled in the art that the present application may be practiced in other embodiments that depart from these specific details. In other instances, detailed descriptions of well-known systems, devices, circuits, and spectral detection methods are omitted so as not to obscure the description of the present application with unnecessary detail.
Terahertz waves (THz) refer to electromagnetic radiation with a frequency of 0.1-10THz, and the wavelength band (0.03-3mm) is between microwave and infrared. Terahertz waves have many excellent characteristics compared to other wavelength bands, such as: the micro-structure difference detection and component analysis method has the advantages of ultrahigh sensitivity to water molecules, low photon energy, no harmful biological radiation, strong radiation coherence and the like, can realize micro-structure difference detection and component analysis on a sample to be detected, and has very wide application prospect. The terahertz time-domain spectroscopy and the imaging technology belong to synchronous coherent detection, are insensitive to thermal background noise, have high signal-to-noise ratio and sensitivity, and can analyze and identify the subtle changes of the material composition and the structure of a sample to be detected. According to the image obtained by the technology, each pixel point not only has the geometric information of the sample to be detected, but also contains complete information such as the intensity, phase and time of response of the sample to be detected to the terahertz pulse, and the necessary information such as the physical and chemical structure and components of the sample to be detected can be analyzed.
Raman spectroscopy is a light scattering technique. When high-intensity incident light of the laser light source is scattered by molecules, a part of scattered light with a very small wavelength is different from the incident light, and the change of the wavelength of the scattered light is determined by the chemical structure of a sample to be detected. A raman spectrum is typically composed of a certain number of raman peaks. Each peak corresponds to a specific molecular bond vibration, which includes both a single chemical bond, such as C-C, C ═ C, N-O, C-H, etc., and vibrations of groups composed of several chemical bonds, such as respiratory vibrations of benzene rings, vibrations of polymer long chains, and lattice vibrations, etc., and thus, the raman spectrum is also referred to as a molecular fingerprint. As a spectrum analysis technology, the Raman spectrum detection technology has the advantages of short test time, high sensitivity, quick operation, simple sample pretreatment and the like, and is widely applied to material component analysis and structure detection.
The terahertz spectrum is mainly used for detecting the absorption characteristic of target molecule vibration, while the Raman spectrum is used for detecting the scattering characteristic of the molecular vibration, and although the selection modes and the instruments and equipment of the target molecule test are obviously different, the terahertz spectrum and the Raman spectrum can be used for representing molecular chemical bonds. Therefore, the terahertz spectrum and the low-frequency Raman spectrum have strong complementarity.
At present, a terahertz spectrometer and a low-frequency Raman spectrometer in the market are independent detection systems, a sample to be detected needs to be placed in different systems for detection operation during detection, operation steps and processes are added, the sample is easy to damage, and due to switching of the sample in a test process, acquisition of a terahertz spectrum and a Raman spectrum at the same position of the same sample cannot be achieved, and practical application and popularization of the spectrum detection system are limited to a certain extent.
Based on this, the embodiment of the application provides a spectrum detection device and a spectrum detection method, which can realize the acquisition of a terahertz spectrum and a low-frequency Raman spectrum of the same sample at the same position.
In order to explain the technical means of the present application, the following description will be given by way of specific examples.
As shown in fig. 1, a schematic diagram of a spectrum detection apparatus provided in an embodiment of the present application, the spectrum detection apparatus may include: the device comprises a laser light source 10, a beam splitter module 20, a terahertz module 30, a Raman module 40, a sample bin 50 and an industrial personal computer 60.
Specifically, the laser emitted from the laser light source 10 is split into pump light, probe light and raman laser pulses by the beam splitter module 20; the terahertz module 30 is used for receiving the pump light and the probe light and generating a terahertz light beam; the terahertz light beam irradiates a sample to be detected in the sample bin 50 to obtain a sample terahertz signal of the sample to be detected; the raman module 40 is configured to receive the raman laser pulse, and focus the raman laser pulse to a sample to be detected in the sample bin 50 to obtain a sample raman signal of the sample to be detected; the industrial personal computer 60 is connected with the terahertz module 30 and the raman module 40, and is configured to receive the sample terahertz signal and the sample raman signal, and process the sample terahertz signal and the sample raman signal to obtain multimode information of the sample to be detected.
The laser light source 10 may include a femtosecond pulse laser for emitting laser pulses; in practical applications, parameters or types of the laser light source 10 may be adjusted or replaced according to the requirements for the detection accuracy and the imaging resolution.
In some embodiments of the present application, the beam splitter module may specifically include a first beam splitter and a second beam splitter, where the first beam splitter and the second beam splitter may split laser into pump light, probe light, and raman laser pulse according to a certain ratio, and a power ratio of the pump light, the probe light, and the raman laser pulse light may be 1:1:1, or may be other ratios set according to an actual application scenario.
Specifically, the splitting the laser emitted from the laser light source into the pump light, the probe light, and the raman laser pulse by the first beam splitter and the second beam splitter may include: after the first beam splitter divides laser emitted by the laser light source into terahertz laser pulses and Raman laser pulses, the second beam splitter divides the terahertz laser pulses into pump light and probe light; or after the first beam splitter splits laser emitted by the laser light source into probe light and laser to be split, the second beam splitter splits the laser to be split into pump light and raman laser pulses; or after the first beam splitter splits the laser light emitted by the laser light source into the pump light and the laser light to be split, the second beam splitter splits the laser light to be split into the probe light and the raman laser pulse.
After the beam splitter module splits the laser emitted by the laser light source 10 into the pump light, the probe light, and the raman laser pulse, the terahertz module 30 may receive the pump light and the probe light and generate a sample terahertz signal of the sample to be detected. As shown in fig. 2, in some embodiments of the present application, the terahertz module 30 may include: a terahertz radiation antenna 301 and a terahertz detection antenna 302.
Specifically, after the terahertz module 30 receives the pump light and the probe light, the probe light can be emitted into the terahertz detection antenna 302; the pump light can be emitted into the terahertz radiation antenna 301 and generate a terahertz light beam; after the terahertz light beam is emitted into the sample bin 50 and irradiates a sample to be detected in the sample bin 50 to obtain sample light, the sample light is emitted into the terahertz detection antenna 302, and the terahertz detection antenna 302 receives the detection light and the sample light and generates a sample terahertz signal of the sample to be detected.
The sample light can be reflected sample light obtained by reflecting the terahertz light beam by the sample to be detected, or transmitted sample light obtained by transmitting the sample to be detected by the terahertz light beam.
Generally, when the thickness of a sample to be detected is greater than or equal to a thickness threshold value, or when transmission detection cannot be realized due to the form of the sample to be detected (such as detecting the back skin of a living mouse), reflected sample light obtained by reflecting a terahertz light beam by the sample to be detected can be used, and a terahertz detection antenna receives the detection light and the reflected sample light to generate a sample terahertz reflection signal of the sample to be detected; for example, when a sample terahertz signal of an animal in-vivo sample is acquired, reflected sample light obtained by reflecting an animal by using a terahertz light beam can be used, and the terahertz detection antenna receives the detection light and the reflected sample light to generate a sample terahertz reflected signal of the animal in-vivo sample.
Specifically, fig. 3 shows a schematic structural diagram of the terahertz module 30 for acquiring a terahertz reflection signal of a sample.
As shown in fig. 3, the detection light enters the terahertz detection antenna 302 via the first optical mirror group 303; the pumping light is incident into the terahertz radiation antenna 301 through the first optical reflector group 303 and generates a terahertz light beam; the terahertz light beam is emitted into the sample bin 50 through the optical parabolic mirror 304, and irradiates a sample to be detected in the sample bin 50 to obtain reflected sample light; the reflected sample light is emitted into the terahertz detection antenna 302 through an optical parabolic mirror 304; the terahertz detection antenna 302 receives the detection light and the reflected sample light and generates a sample terahertz reflection signal of the sample to be detected.
In practical application, under the condition that the sample form allows, and when the thickness of a sample to be detected is smaller than a thickness threshold, a terahertz light beam can be used for transmitting the sample to be detected to obtain transmission sample light, and a terahertz detection antenna receives the detection light and the transmission sample light to generate a sample terahertz transmission signal of the sample to be detected; for example, when components of a sample to be detected with a small thickness need to be accurately detected, terahertz light beams can be used for transmitting the sample to be detected to obtain transmitted sample light, and the terahertz detection antenna receives the detection light and the transmitted sample light to generate a sample terahertz transmission signal of the sample to be detected.
Specifically, fig. 4 shows a schematic structural diagram of the terahertz module 30 for acquiring a terahertz transmission signal of a sample.
As shown in fig. 4, the detection light enters the terahertz detection antenna 302 through the first optical transflective set 303; the pumping light is incident into the terahertz radiation antenna 301 through the first optical reflector group 303 and generates a terahertz light beam; the terahertz light beam is emitted into the sample bin 50 through the optical parabolic mirror 304, and irradiates a sample to be detected in the sample bin 50 to obtain transmission sample light; the transmission sample light is emitted into the terahertz detection antenna 302 through an optical parabolic mirror 304; the terahertz detection antenna 302 receives the detection light and the transmission sample light and generates a sample terahertz transmission signal of the sample to be detected.
In some embodiments of the present application, as shown in fig. 3 and 4, the first transflective set 303 may form an optical delay line 3031 for adjusting a relative delay time between the pump light and the probe light, so that the probe light and the sample light reach the terahertz detection antenna at the same time.
In some embodiments of the present application, the terahertz module may further include: the phase-locked amplifier is respectively connected with the bias voltage module, the terahertz detection antenna and the industrial personal computer; such as the bias voltage module 305 of fig. 3 and 4, and the lock-in amplifier 306 of fig. 3 and 4.
The phase-locked amplifier can also generate a specific modulation frequency for driving the bias voltage module to be in a rated working state and improving the control response speed of the bias voltage module; the bias voltage module is connected with the terahertz radiation antenna and can provide electric field drive for the terahertz radiation antenna according to the modulation frequency output by the phase-locked amplifier.
In addition, the phase-locked amplifier can also be used for collecting and amplifying a sample terahertz signal and sending the amplified sample terahertz signal to the industrial personal computer.
In some embodiments of the present application, the connections between the above components (e.g., the connections between the bias voltage module, the terahertz detection antenna, the industrial personal computer, and the lock-in amplifier) may be made through cables; the components are connected through the cable, so that the transmission cost of the terahertz information is reduced, the terahertz information is convenient to transmit and compatible, the industrial personal computer can obtain the form detail information of the sample to be detected according to the sample terahertz signal output by the cable, and the situation that the obtained form detail information of the sample to be detected has large detection errors is avoided.
In some embodiments of the present application, the terahertz module may further include: a first optical attenuator; for example, the first optical attenuator 307 in fig. 3 and 4.
The first optical attenuator is connected with the industrial personal computer and used for adjusting the power of the pumping light and the power of the detecting light, and the damage of optical components caused by overhigh power of the pumping light and the power of the detecting light is avoided.
Accordingly, after the beam splitter module splits the laser emitted from the laser source 10 into the pump light, the probe light, and the raman laser pulse, the raman module 40 may receive the raman laser pulse and generate a sample raman signal of the sample to be measured. As shown in fig. 5, in some embodiments of the present application, the raman module 40 may include: a filter module 401, an optical microscope objective 402, a grating 403 and a detector 404.
Specifically, after the raman module 40 receives the raman laser pulse, the raman laser pulse is subjected to line width cleaning by the filter module 401, focused to the sample bin 50 by the optical microscope objective 402, and irradiates a sample to be detected in the sample bin 50 to obtain sample raman light; the optical microscope objective 402 collects the sample raman light, and the sample raman light is emitted into the grating 403 after being filtered by the filter module 401 to obtain the spectroscopic sample raman light; the detector 404 collects the raman light of the sample after the light splitting to obtain the raman signal of the sample.
In some embodiments of the present application, the raman laser pulse may be a low frequency raman laser pulse; compared with a sample Raman signal obtained by common Raman laser pulse, the sample Raman signal obtained by low-frequency Raman laser pulse has higher signal intensity, richer fingerprint characteristics and structural characteristics of a reactive crystal, and higher feasibility in molecular crystal form research, drug characteristics and toxicity detection research.
In the embodiment of the present application, the raman module 40 may be precisely coupled to the terahertz module 30.
Fig. 6 shows a schematic structural diagram of a raman module 40 closely coupled to the terahertz module 30 shown in fig. 3.
As shown in fig. 6, after the raman module 40 receives the raman laser pulse, the raman laser pulse is subjected to line width cleaning by the filtering module 401 and reflected by the second optical mirror group 405, and then is focused to the sample bin 50 by the optical microscope objective 402, and irradiates the sample to be measured in the sample bin 50, so as to obtain sample raman light; the optical microscope objective 402 collects the sample raman light, and makes the sample raman light enter the grating 403 after being filtered by the second optical reflector group 405 and the filter module 401, so as to obtain the spectroscopic sample raman light; the detector 404 collects the raman light of the sample after the light splitting to obtain the raman signal of the sample.
In practical applications, the intensity of the raman signal of the sample is often smaller than the intensity of the raman laser pulse, and if the bandwidth range of the raman laser pulse is large, the raman signal may be covered, and the detector may not detect the raman signal of the sample, so in some embodiments of the present application, the filtering module 401 may perform line width cleaning on the raman laser pulse, remove spectral noise of the raman laser pulse, and ensure that a good laser beam can be obtained; moreover, the filtering module 401 can filter out the raman laser pulse included in the raman signal of the sample, so as to measure the stokes and anti-stokes raman spectrum.
Specifically, as shown in fig. 6, the filtering module 401 may specifically include: a first filter 4011, a second filter 4012, and a third filter 4013.
The first optical filter 4011 is configured to perform line width cleaning on the raman laser pulse, and vertically inject the raman laser pulse after the line width cleaning into the optical microscope objective; the first optical Filter can be a volume Bragg Bandpass Filter (BPF), the reflectivity of the optical Filter to laser pulse with the central wavelength is very high and can reach over 90 percent, the bandwidth can be as low as 5cm < -1 >, laser noise can be well removed to 5cm < -1 >, and the suppression ratio can reach-70 dB.
The third optical filter 4013 is configured to filter, for the second time, the raman laser pulse included in the raman light of the sample, and inject the raman light of the sample after the raman laser pulse is filtered for the second time into the grating. The third optical Filter can be a volume Bragg Notch Filter (BNF), which is a reflector Bragg grating engraved in a photosensitive silicate glass body, and can reflect light with the bandwidth as narrow as 5cm < -1 >, while other wavelengths are not affected when passing through, and the total transmittance is almost 95%; in addition, the optical filter can bear higher power, can bear the temperature of 400 ℃, and has high environmental stability. In addition, due to the particularity of BNF, it is required to be within a certain angle range with the optical axis in practical application, and this can be set according to practical application.
The second optical filter 4012 is configured to filter a raman laser pulse included in the raman light of the sample acquired by the optical microscope objective, and inject the raman light of the sample after the raman laser pulse is filtered into the third optical filter; the second filter can be a filter formed by combining BPF and BNF.
In some embodiments of the present application, the raman module 40 may further include: a second optical attenuator 406. The second optical attenuator is connected with an industrial personal computer and used for adjusting the power of the Raman laser pulse, so that the laser pulse with proper power is obtained, and the damage of optical components caused by overhigh laser pulse power is avoided.
Fig. 7 is a schematic structural diagram of the spectrum detection apparatus after the terahertz module 30 shown in fig. 3 is tightly coupled with the raman module 40 shown in fig. 6.
As shown in fig. 7, in the embodiment of the present application, laser light emitted from a laser light source is divided into pump light, probe light, and raman laser pulses; the method comprises the steps that when a Raman module is used for focusing Raman laser pulses to a sample to be detected in a sample bin to obtain a sample Raman signal of the sample to be detected, a terahertz module is used for receiving pumping light and detecting light to generate terahertz light beams, and the sample to be detected in the sample bin is irradiated by the terahertz light beams to obtain a sample terahertz reflection signal of the sample to be detected; and then simultaneously acquiring a terahertz reflection signal and a Raman signal of the same sample to be detected in the sample bin, and then processing the terahertz reflection signal and the Raman signal of the sample to be detected to obtain multimode information of the sample to be detected, thereby solving the problem that the acquisition of the terahertz spectrum and the Raman spectrum of the same sample at the same position cannot be realized.
Correspondingly, fig. 8 shows a schematic structural diagram of the raman module 40 precisely coupled to the terahertz module 30 shown in fig. 4, wherein the specific working process of the raman module can refer to the description of fig. 7, which is not repeated herein.
As shown in fig. 8, in some embodiments of the present application, the filtering module may include: a first filter 4011 and a third filter 4013; the first optical filter is used for cleaning the line width of the Raman laser pulse and obliquely emitting the Raman laser pulse subjected to line width cleaning into the optical microscope objective; the third optical filter is used for filtering Raman laser pulses mixed in the Raman light of the sample acquired by the optical microscope objective and sending the Raman laser pulses filtered out of the Raman laser pulses into the grating.
Fig. 9 is a schematic structural diagram of the spectrum detection apparatus after the terahertz module 30 shown in fig. 4 is tightly coupled with the raman module 40 shown in fig. 8.
As shown in fig. 9, in the embodiment of the present application, laser light emitted from a laser light source is divided into pump light, probe light, and raman laser pulses; the method comprises the steps that when a Raman module is used for focusing Raman laser pulses to a sample to be detected in a sample bin to obtain a sample Raman signal of the sample to be detected, a terahertz module is used for receiving pumping light and detecting light to generate terahertz light beams, and the sample to be detected in the sample bin is irradiated by the terahertz light beams to obtain a sample terahertz transmission signal of the sample to be detected; and then simultaneously acquiring a terahertz transmission signal and a Raman signal of the same sample to be detected in the sample bin, and then processing the terahertz transmission signal and the Raman signal of the sample to be detected to obtain multimode information of the sample to be detected, thereby solving the problem that the acquisition of the terahertz spectrum and the Raman spectrum of the same sample at the same position cannot be realized.
Those skilled in the art will understand that the terahertz module shown in fig. 3 can also be coupled with the raman module shown in fig. 8, and the terahertz module shown in fig. 4 can also be coupled with the raman module shown in fig. 6, which is not described herein again.
In some embodiments of the present application, the sample chamber may have a three-dimensional movement function, the spectrum detection apparatus may control the sample chamber to perform three-dimensional movement, may select a most suitable test region, and may acquire a terahertz signal and a raman signal of the sample from different positions of the same sample.
Fig. 10 is a schematic diagram illustrating an implementation flow of a spectrum detection method provided in an embodiment of the present application, where the spectrum detection method can be applied to the spectrum detection apparatuses of the above-mentioned embodiments, step 1001 to step 1004.
Step 1001, laser emitted by a laser light source is divided into pump light, probe light and raman laser pulses.
Step 1002, receiving application pumping light and detection light by using a terahertz module, and generating a terahertz light beam; and irradiating the sample to be detected in the sample bin by applying the terahertz light beam to obtain a sample terahertz signal of the sample to be detected.
And 1003, receiving the application Raman laser pulse by using a Raman module, and focusing the application Raman laser pulse to the sample to be detected in the sample bin to obtain a sample Raman signal of the application sample to be detected.
And 1004, receiving the terahertz signal of the application sample and the Raman signal of the application sample, and processing the terahertz signal of the application sample and the Raman signal of the application sample to obtain multimode information of the application to-be-detected sample.
Optionally, the spectrum detection apparatus may include a memory, a processor, and a computer program stored in the memory and executable on the processor, the processor implementing when executing the computer program: and receiving the sample terahertz signal and the sample Raman signal, and processing the sample terahertz signal and the sample Raman signal to obtain the multimode information of the sample to be detected.
The processor may be a central processing unit CPU, but may also be other general purpose processors, digital signal processors DSP, application specific integrated circuits ASIC, field programmable gate arrays FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc.
The memory may include both read-only memory and random access memory, and provides instructions and data to the processor.
In the embodiment of the application, laser emitted by a laser light source is divided into pump light, probe light and Raman laser pulses; the method comprises the steps that when a Raman module is used for focusing Raman laser pulses to a sample to be detected in a sample bin to obtain a sample Raman signal of the sample to be detected, a terahertz module is used for receiving pumping light and detecting light to generate terahertz light beams, and the sample to be detected in the sample bin is irradiated by the terahertz light beams to obtain the sample terahertz signal of the sample to be detected; and then simultaneously acquiring a terahertz signal and a Raman signal of the same sample to be detected in the sample bin, and then processing the terahertz signal and the Raman signal of the sample to be detected to obtain multimode information of the sample to be detected, thereby solving the problem that the acquisition of the terahertz spectrum and the Raman spectrum of the same sample at the same position cannot be realized.
It should be noted that, for convenience and brevity of description, reference may be made to each embodiment of the foregoing apparatus for a specific process of the spectrum detection method in the embodiment of the present application, and details are not described here again.
In the embodiments provided in the present application, it should be understood that the disclosed devices may also be implemented in other manners. For example, the terahertz spectrometers described above are merely illustrative; for another example, the division of each component is only one functional division, and there may be other division ways in actual implementation, for example, a plurality of components may be combined or may be integrated into another system, or some features may be omitted.
The above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.