Dual comb coherent raman spectroscopy with background noise suppression by probe light delay control

Abstract

The application discloses a kind of background noise suppression systems of dual optical comb coherent raman spectrum of probe light delay control, by setting the laser that light frequency comb light source module is emitted into probe light and pump light by first beam splitter in probe light delay control module, and setting optical delay line is applied to the probe light with delay amount, utilize the characteristics that the decay time of coherent raman spectrum signal is longer than the decay time of background noise, probe using probe light with delay amount, realize the purpose of inhibiting background noise, it is beneficial to improve the signal-to-noise ratio of dual optical comb coherent raman spectrum measurement system, inhibits spectrum signal distortion.

Description

Technical Field

[0001] This invention relates to coherent Raman spectroscopy measurement technology, specifically to a background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe light delay modulation. The system involves setting a first beam splitter in the probe light delay modulation module to split the laser emitted from the optical frequency comb light source module into probe light and pump light. An optical delay line is set to apply a delay to the probe light. Utilizing the characteristic that the decay time of the coherent Raman spectral signal is longer than the decay time of background noise, the probe light with the delay is used for detection, thereby achieving the purpose of suppressing background noise. This is beneficial for improving the signal-to-noise ratio of the dual-comb coherent Raman spectroscopy measurement system and suppressing spectral signal distortion. Background Technology

[0002] Coherent Raman scattering (CRS) is a Raman scattering technique based on nonlinear effects. This method utilizes the matching of the frequency difference within the excitation pulse with the Raman energy levels of molecules to coherently excite molecules within a region, thereby generating coherent Raman signals with intensity 4-5 orders of magnitude higher than spontaneous Raman signals. Coherent Raman spectroscopy signals reflect the structural characteristics of molecules, providing rich composition-function information and possessing non-destructive, label-free detection capabilities. Therefore, it has broad application prospects in single-cell imaging and analysis, cell metabolism research, trace chemical identification, and virus detection and identification. The dual-comb coherent Raman spectroscopy method utilizes two optical comb sources as pump light (which also serves as probe light) and Stokes light, respectively. While ensuring the high peak power pulses required for coherent Raman spectroscopy, it combines a dual-comb asynchronous sampling method, overcoming the limitations of mechanical scanning methods and significantly improving measurement speed.

[0003] The inventors understand that coherent Raman excitation, as a third-order nonlinear effect, generates signals that are affected by background noise that does not carry molecular chemical information, severely impacting the signal-to-noise ratio (SNR) of the coherent Raman signal. Furthermore, the coherent superposition of background noise and resonance signal causes signal distortion, significantly affecting the accuracy of spectral data. The inventors believe that since the background noise signal mainly originates from the four-wave mixing process and occurs almost instantaneously, while the coherent Raman spectral signal has a lifetime on the order of picoseconds, if a portion of the pump light is used as an additional probe light, and the probe light delay is increased by setting an optical delay line, the coherent Raman spectral signal after the background noise has disappeared can be detected. This would suppress the background noise, improve the SNR of the coherent Raman spectroscopy measurement system, and suppress spectral signal distortion. Currently, there is no system for suppressing background noise in dual-comb coherent Raman spectroscopy using time-delayed probe light modulation. Therefore, the inventors have completed this invention. Summary of the Invention

[0004] This invention addresses the shortcomings of existing technologies by providing a background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe light delay modulation. The system utilizes a first beam splitter within the probe light delay modulation module to split the laser emitted from the optical frequency comb light source module into probe light and pump light. An optical delay line is then used to apply a delay to the probe light. By leveraging the longer decay time of the coherent Raman spectral signal compared to the background noise, the system employs probe light with a delay to suppress background noise. This improves the signal-to-noise ratio of the dual-comb coherent Raman spectroscopy measurement system and suppresses spectral signal distortion.

[0005] The technical solution of the present invention is as follows:

[0006] A background noise suppression system based on probe light delay modulation of dual-comb coherent Raman spectroscopy measurement technology is characterized by comprising, in sequence, an optical frequency comb light source module, a probe light delay modulation module, a delay compensation module, a delay monitoring module, and a spectral detection module. The optical frequency comb light source module combines two beams of light with different frequencies and perpendicular polarization directions into a first combined beam. The probe light delay modulation module splits the first combined beam into a first transmitted beam and a first reflected beam. The first transmitted beam is directly transmitted to the delay compensation module, and the first reflected beam is split into a second transmitted beam and a second reflected beam. The second reflected light is delayed and then combined with the second transmitted light to form a second combined beam. The delay compensation module causes the first transmitted light to be delayed and then combined with the second combined beam to form a third combined beam. The delay monitoring module splits the third combined beam into a third reflected light and a third transmitted light. The third reflected light is used for delay monitoring in the delay monitoring module. The spectral detection module uses the third transmitted light to detect the coherent Raman spectral signal of the sample. By using a detection light with a delay, the coherent Raman spectral signal after the background noise disappears can be detected, thereby achieving background noise suppression.

[0007] The optical frequency comb light source module includes a first dichroic mirror, the first input side of the first dichroic mirror is connected to the first optical frequency comb, the second input side of the first dichroic mirror is connected to the second optical frequency comb through a first half-wave plate, the first optical frequency comb and the second optical frequency comb are respectively connected to a reference source, and the output side of the first dichroic mirror is connected to the probe light delay control module.

[0008] The probe light delay control module includes a second dichroic mirror. The input side of the second dichroic mirror is connected to the output side of the first dichroic mirror. The transmission side of the second dichroic mirror is connected to the retroreflector in the delay compensation module. The reflection side of the second dichroic mirror is connected to a first beam splitter. The transmission side of the first beam splitter is connected to the first input side of a polarizing beam splitter through a second reflecting mirror. The reflection side of the first beam splitter is connected to the second input side of the polarizing beam splitter in sequence through a second half-wave plate, a first reflecting mirror, and an optical delay line. The output side of the polarizing beam splitter is connected to the first input side of a third dichroic mirror in the delay compensation module.

[0009] The delay compensation module includes an aspherical lens pair. The input side of the aspherical lens pair is connected to a retroreflector via a third reflecting mirror. The output side of the aspherical lens pair is connected to the second input side of a third dichroic mirror. The output side of the third dichroic mirror is connected to the delay monitoring module.

[0010] The delay monitoring module includes a second beam splitter. The input side of the second beam splitter is connected to the output side of a third dichroic mirror. The transmission side of the second beam splitter is connected to the spectral detection module. The reflection side of the second beam splitter is connected to an oscilloscope in sequence through a first focusing lens, a barium borate crystal, a second focusing lens, a first filter, and a photodetector.

[0011] The spectral detection module includes a photomultiplier tube, a third focusing lens, a second filter, a second objective lens, a sample stage, a first objective lens, and a fourth reflecting mirror connected to the transmission side of the second beam splitter.

[0012] The first optical frequency comb has a center frequency of 1030nm and a repetition frequency of 100MHz, the second optical frequency comb has a center frequency of 1550nm and a repetition frequency of 100MHz, the repetition frequency difference between the first and second optical frequency combs is adjustable, and the adjustable range of the repetition frequency difference is 0 to 100Hz; the reference signal frequency provided by the reference source is 100MHz.

[0013] The first filter is a low-pass filter with a cutoff wavelength of 700nm.

[0014] The second filter is a bandpass filter with a transmission wavelength range of 750–900 nm.

[0015] The technical effects of this invention are as follows: This invention provides a background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe light delay modulation. By setting a first beam splitter in the probe light delay modulation module to split the laser emitted from the optical frequency comb light source module into probe light and pump light, and by setting an optical delay line to apply a delay to the probe light, the system utilizes the characteristic that the decay time of the coherent Raman spectral signal is longer than that of the background noise. By using probe light with a delay, the system achieves the purpose of suppressing background noise, which is beneficial for improving the signal-to-noise ratio of the dual-comb coherent Raman spectroscopy measurement system and suppressing spectral signal distortion. This invention is an innovative application of probe light delay modulation in the field of coherent Raman spectroscopy background noise suppression.

[0016] The advantages of this invention compared with the prior art are as follows: (1) Compared with conventional coherent Raman scattering spectroscopy measurement devices, the use of probe light with delay solves the problem of background noise that is difficult to suppress due to the four-wave mixing effect, thereby improving the signal-to-noise ratio of the spectral signal and reducing distortion. (2) A delay monitoring module is set up to monitor the delay of the pump light, probe light and Stokes light respectively, providing a basis for delay control. (3) By using an optical delay line to apply the delay, the delay can be adjusted to the highest fs level, making the delay control more precise. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the dual-comb coherent Raman spectral background noise suppression system for implementing the probe delay modulation of the present invention. Figure 1 It includes an optical frequency comb light source module, a probe light delay control module, a delay compensation module, a delay monitoring module, and a spectral detection module connected in sequence.

[0018] The reference numerals in the attached figures are explained as follows: 1-First optical frequency comb; 2-Second optical frequency comb; 3-Reference source; 4-First half-wave plate; 5-First dichroic mirror (in the optical frequency comb light source module, it combines two beams into a first combined beam, which is then transmitted to the probe light delay control module); 6-Second dichroic mirror (in the probe light delay control module, it splits the first combined beam into a first transmitted beam, i.e., a Stokes beam, and a first reflected beam. The first transmitted beam is directly transmitted to the delay compensation module, and the first reflected beam, after beam splitting and delay control, forms... 7- First beam splitter (splitting the first reflected light into a second reflected light, i.e., the probe light, and a second transmitted light, i.e., the pump light); 8- Second half-wave plate; 9- First reflector; 10- Optical delay line (applying a delay to form a delayed light, i.e., a probe light with a delay); 11- Second reflector; 12- Polarizing beam splitter (combining the delayed light and the second reflected light to form a second combined beam that is transmitted to the delay compensation module); 13- Retroreflector (forming the delay compensation light). ; 14-Third reflecting mirror; 15-Aspherical lens pair; 16-Third dichroic mirror (combines the second beam combiner and the delay compensation beam into a third beam combiner for transmission to the delay monitoring module); 17-Oscilloscope; 18-Photodetector; 19-First filter; 20-Second focusing lens; 21-Barium borate crystal (generates the sum-frequency signal of the pump light and Stokes light, and the sum-frequency signal of the probe light and Stokes light); 22-First focusing lens; 23-Second beam splitter (in the delay monitoring module, combines the second beam combiner and the delay compensation beam into a third beam combiner for transmission to the delay monitoring module); The combined beam is split into a third reflected beam and a third transmitted beam. The third transmitted beam is directly transmitted to the spectral detection module, and the third reflected beam enters the photodetector through the barium borate crystal. 24-Photomultiplier tube (detects the coherent Raman spectral signal of the sample; the detector light with a delay can detect the coherent Raman spectral signal after the background noise disappears, thereby achieving background noise suppression); 25-Third focusing lens; 26-Second filter; 27-Second objective lens; 28-Sample stage; 29-First objective lens; 30-Fourth reflecting mirror. Detailed Implementation

[0019] The following is in conjunction with the attached diagram ( Figure 1 The present invention will be described in conjunction with the embodiments.

[0020] Figure 1 This is a schematic diagram of the dual-comb coherent Raman spectroscopy background noise suppression system for implementing the probe delay modulation of this invention. (Reference) Figure 1As shown, a background noise suppression system based on probe light delay modulation dual-comb coherent Raman spectroscopy measurement technology includes a frequency comb light source module, a probe light delay modulation module, a delay compensation module, a delay monitoring module, and a spectral detection module connected in sequence. The frequency comb light source module combines two beams of light with different frequencies and mutually perpendicular polarization directions into a first combined beam. The probe light delay modulation module splits the first combined beam into a first transmitted beam and a first reflected beam. The first transmitted beam is directly transmitted to the delay compensation module, and the first reflected beam is split into a second transmitted beam and a second reflected beam. The two reflected lights form a delayed beam and then combine with the second transmitted light to form a second combined beam. The delay compensation module causes the first transmitted light to form a delayed compensation beam and then combine with the second combined beam to form a third combined beam. The delay monitoring module splits the third combined beam into a third reflected light and a third transmitted light. The third reflected light is used for delay monitoring in the delay monitoring module. The spectral detection module uses the third transmitted light to detect the coherent Raman spectral signal of the sample. By using a detection light with a delay, the coherent Raman spectral signal after the background noise disappears can be detected, thereby achieving background noise suppression.

[0021] The optical frequency comb light source module includes a first dichroic mirror 5. The first input side of the first dichroic mirror 5 is connected to the first optical frequency comb 1. The second input side of the first dichroic mirror 5 is connected to the second optical frequency comb 2 through the first 1 / 2 wave plate 4. The first optical frequency comb 1 and the second optical frequency comb 2 are respectively connected to the reference source 3. The output side of the first dichroic mirror 5 is connected to the probe light delay control module. The probe light delay control module includes a second dichroic mirror 6. The input side of the second dichroic mirror 6 is connected to the output side of the first dichroic mirror 5. The transmission side of the second dichroic mirror 6 is connected to the retroreflector 13 in the delay compensation module. The reflection side of the second dichroic mirror 6 is connected to the first beam splitter 7. The transmission side of the first beam splitter 7 is connected to the first input side of the polarization beam splitter 12 through the second reflecting mirror 11. The reflection side of the first beam splitter 7 is connected to the second input side of the polarization beam splitter 12 in sequence through the second half-wave plate 8, the first reflecting mirror 9, and the optical delay line 10. The output side of the polarization beam splitter 12 is connected to the first input side of the third dichroic mirror 16 in the delay compensation module.

[0022] The delay compensation module includes an aspherical lens pair 15. The input side of the aspherical lens pair 15 is connected to the retroreflector 13 via a third reflecting mirror 14. The output side of the aspherical lens pair 15 is connected to the second input side of a third dichroic mirror 16. The output side of the third dichroic mirror 16 is connected to the delay monitoring module. The delay monitoring module includes a second beam splitter 23. The input side of the second beam splitter 23 is connected to the output side of the third dichroic mirror 16. The transmission side of the second beam splitter 23 is connected to the spectral detection module. The reflection side of the second beam splitter 23 is connected to an oscilloscope 17 via a first focusing lens 22, a barium borate crystal 21, a second focusing lens 20, a first filter 19, and a photodetector 18. The spectral detection module includes a photomultiplier tube 24. The photomultiplier tube 24 is connected to the transmission side of the second beam splitter 23 via a third focusing lens 25, a second filter 26, a second objective lens 27, a sample stage 28, a first objective lens 29, and a fourth reflecting mirror 30.

[0023] The first optical frequency comb 1 has a center frequency of 1030nm and a repetition frequency of 100MHz. The second optical frequency comb 2 has a center frequency of 1550nm and a repetition frequency of 100MHz. The repetition frequency difference between the first optical frequency comb 1 and the second optical frequency comb 2 is adjustable, with an adjustable range of 0–100Hz. The reference signal frequency provided by the reference source 3 is 100MHz. The first filter 19 is a low-pass filter with a cutoff wavelength of 700nm. The second filter 26 is a band-pass filter with a transmission wavelength range of 750–900nm.

[0024] A dual-comb coherent Raman spectroscopy background noise suppression system with probe light delay control is disclosed. This system utilizes a first beam splitter in the probe light delay control module to split the laser emitted from the optical frequency comb light source module into probe light and pump light. An optical delay line is then used to apply a delay to the probe light. Taking advantage of the longer decay time of the coherent Raman spectral signal compared to the background noise, the system uses probe light with a delay to suppress background noise. This improves the signal-to-noise ratio of the dual-comb coherent Raman spectroscopy measurement system and suppresses spectral signal distortion.

[0025] refer to Figure 1 As shown, a dual-comb coherent Raman spectral background noise suppression system with probe light delay control includes an optical frequency comb light source module, a probe light delay control module, a delay compensation module, a delay monitoring module, and a spectral detection module. The probe light delay control module includes a first beam splitter 7 that splits the laser emitted from the optical frequency comb light source module into probe light and pump light, and an optical delay line 10 that applies a delay to the probe light. The probe light with the delay and the pump light are coupled by a polarization beam splitter 12 and then act together with the Stokes light generated by the second optical frequency comb 2 on the sample, thus detecting a coherent Raman signal with suppressed background noise.

[0026] The optical frequency comb light source module includes a first optical frequency comb 1, a second optical frequency comb 2, a first half-wave plate 4, and a reference source 3. The laser emitted from the second optical frequency comb 2 is polarized by the first half-wave plate 4 and then combined with the laser emitted from the first optical frequency comb by the first dichroic mirror 5 and injected into the probe light delay control module. The reference source 3 is connected to the first optical frequency comb 1 and the second optical frequency comb 2 respectively to achieve frequency repetition lock between the first optical frequency comb 1 and the second optical frequency comb 2.

[0027] Specifically, in the optical frequency comb light source module, the center frequency of the first optical frequency comb 1 is 1030nm and the repetition frequency is 100MHz, the center frequency of the second optical frequency comb 2 is 1550nm and the repetition frequency is 100MHz, and the repetition frequency difference between the first optical frequency comb 1 and the second optical frequency comb 2 is adjustable, with an adjustable range of 0 to 100Hz.

[0028] The reference signal frequency provided by the reference source 3 is 100MHz; the laser outputs of the first optical frequency comb 1 and the second optical frequency comb 2 in the optical frequency comb light source module are both linearly polarized light, and the polarization direction of the laser output by the second optical frequency comb 2 after passing through the first 1 / 2 wave plate 4 is perpendicular to the polarization direction of the first optical frequency comb 1.

[0029] The probe light delay control module includes a second dichroic mirror 6, a first beam splitter 7, a second half-wave plate 8, an optical delay line 10, and a polarizing beam splitter 12. The second dichroic mirror 6 is connected to the transmitted beam of the first dichroic mirror 5. The transmitted beam of the second dichroic mirror 6 enters the delay compensation module. The reflected beam of the second dichroic mirror 6 is connected to the first beam splitter 7. The reflected beam of the first beam splitter 7 passes sequentially through the second half-wave plate 8, the first reflector 9, and the optical delay line 10 to form a probe light with a delay, which enters the polarizing beam splitter 12. The transmitted beam of the second dichroic mirror 6 passes through the second reflector 11 and then through the polarizing beam splitter 12 to combine with the probe light with the delay before entering the delay compensation module.

[0030] Specifically, in the probe light delay control module, the transmission and reflection ratio of the first beam splitter 7 is 70:30, and the polarization direction of the transmitted beam of the first beam splitter 7 after passing through the second half-wave plate 8, the first reflecting mirror 9 and the optical delay line 10 is perpendicular to the polarization direction of the transmitted beam of the first beam splitter 7.

[0031] The delay compensation module includes a retroreflector 13 and an aspherical lens pair 14, used to compensate for the delay of the Stokes light to match the pump light; the transmission beam of the second dichroic mirror 6 passes sequentially through the retroreflector 13, the third reflector 14, and the aspherical lens pair 15, and is coupled into the delay monitoring module through the transmission beam of the third dichroic mirror 16 and the polarization beam splitter 12.

[0032] The delay monitoring module includes a barium borate crystal 21, a first filter 19, a photodetector 18, and an oscilloscope 17. A beam transmitted through a third dichroic mirror 16 enters the second beam splitter 23. The reflected beam from the second beam splitter 23 is focused onto the barium borate crystal 21 by a first focusing lens 22, collimated by a second focusing lens 20, and then passes through the first filter 19 before entering the photodetector 18. The photodetector 18 is connected to the oscilloscope 17 to detect the delay of the laser emitted by the first and second optical frequency combs. Specifically, the first filter 19 in the delay monitoring module is a low-pass filter with a cutoff wavelength of 700 nm.

[0033] The spectral detection module includes a first objective lens 29, a second objective lens 27, a sample stage 28, a second filter 26, and a photomultiplier tube 24. The transmitted beam from the second beam splitter 23 passes sequentially through a fourth reflecting mirror 30, the first objective lens 29, the sample stage 28, the second objective lens 27, the second filter 26, and a third focusing lens 25 before entering the photomultiplier tube 24 to detect the coherent Raman spectral signal of the sample. Specifically, the second filter 26 in the spectral detection module is a bandpass filter with a transmission wavelength range of 750–900 nm.

[0034] Specifically, the laser emitted from the optical frequency comb light source module is split into two beams by the second dichroic mirror 6 in the probe light delay control module. The reflected beam from the second dichroic mirror 6 has a shorter wavelength, while the transmitted beam has a longer wavelength, serving as Stokes light. The reflected beam from the second dichroic mirror 6 is split into two parts by the first beam splitter 7. The reflected beam from the first beam splitter 7 serves as probe light and receives a certain delay after passing through the optical delay line 10. The transmitted beam from the second dichroic mirror 6 serves as pump light and is coupled with the delayed probe light through the polarization beam splitter 12 into the delay compensation module. The delay compensation module receives the Stokes light, compensates for the delay between the Stokes light and the pump light through the retroreflector 13, and then combines the pump light and the delayed probe light through the third dichroic mirror 16 into the delay monitoring module. The transmitted light from the third dichroic mirror 16 enters the second beam splitter 23 in the delay detection module. The reflected beam of the second beam splitter 23 interacts with the barium borate crystal to generate sum-frequency signals of the pump light and Stokes light, and sum-frequency signals of the probe light and Stokes light, respectively. These signals are received by the photodetector 18 and displayed on the oscilloscope 17. By adjusting the delay amount applied by the optical delay line 10, the delay of the sum-frequency signals of the pump light and Stokes light and the probe light and Stokes light is observed to several ps, achieving precise control of the probe light delay. The transmitted beam of the second beam splitter 23 enters the spectral detection module to detect the coherent Raman spectral signal of the sample. Since the lifetime of the coherent Raman spectral signal is longer than that of the background noise, the probe light with the delay amount can detect the coherent Raman spectral signal after the background noise has disappeared, thereby achieving background noise suppression.

[0035] Contents not described in detail in this specification are prior art known to those skilled in the art. It is hereby indicated that the above description is intended to help those skilled in the art understand this invention, but does not limit the scope of protection of this invention. Any equivalent substitutions, modifications, improvements, and / or simplifications of the above descriptions that do not depart from the essential content of this invention fall within the scope of protection of this invention.

Claims

1. A background noise suppression system based on dual-comb coherent Raman spectroscopy measurement technology with probe delay modulation, characterized in that, The system includes a frequency comb light source module, a probe light delay control module, a delay compensation module, a delay monitoring module, and a spectral detection module connected in sequence. The frequency comb light source module combines two beams of light with different frequencies and perpendicular polarization directions into a first combined beam. The probe light delay control module splits the first combined beam into a first transmitted beam and a first reflected beam. The first transmitted beam is directly transmitted to the delay compensation module, and the first reflected beam is split into a second transmitted beam and a second reflected beam. The second reflected beam is delayed and then combined with the second transmitted beam to form a second combined beam. The delay compensation module causes the first transmitted beam to be delayed and then combined with the second combined beam to form a third combined beam. The delay monitoring module splits the third combined beam into a third reflected beam and a third transmitted beam. The third reflected beam is used for delay monitoring in the delay monitoring module. The spectral detection module uses the third transmitted beam to detect the coherent Raman spectral signal of the sample. By using a probe light with a delay, the coherent Raman spectral signal after the background noise has disappeared can be detected, thereby achieving background noise suppression.

2. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 1, characterized in that, The optical frequency comb light source module includes a first dichroic mirror, the first input side of the first dichroic mirror is connected to the first optical frequency comb, the second input side of the first dichroic mirror is connected to the second optical frequency comb through a first half-wave plate, the first optical frequency comb and the second optical frequency comb are respectively connected to a reference source, and the output side of the first dichroic mirror is connected to the probe light delay control module.

3. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 2, characterized in that, The probe light delay control module includes a second dichroic mirror. The input side of the second dichroic mirror is connected to the output side of the first dichroic mirror. The transmission side of the second dichroic mirror is connected to the retroreflector in the delay compensation module. The reflection side of the second dichroic mirror is connected to a first beam splitter. The transmission side of the first beam splitter is connected to the first input side of a polarizing beam splitter through a second reflecting mirror. The reflection side of the first beam splitter is connected to the second input side of the polarizing beam splitter in sequence through a second half-wave plate, a first reflecting mirror, and an optical delay line. The output side of the polarizing beam splitter is connected to the first input side of a third dichroic mirror in the delay compensation module.

4. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 1, characterized in that, The delay compensation module includes an aspherical lens pair. The input side of the aspherical lens pair is connected to a retroreflector via a third reflecting mirror. The output side of the aspherical lens pair is connected to the second input side of a third dichroic mirror. The output side of the third dichroic mirror is connected to the delay monitoring module.

5. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 1, characterized in that, The delay monitoring module includes a second beam splitter. The input side of the second beam splitter is connected to the output side of a third dichroic mirror. The transmission side of the second beam splitter is connected to the spectral detection module. The reflection side of the second beam splitter is connected to an oscilloscope in sequence through a first focusing lens, a barium borate crystal, a second focusing lens, a first filter, and a photodetector.

6. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 1, characterized in that, The spectral detection module includes a photomultiplier tube, a third focusing lens, a second filter, a second objective lens, a sample stage, a first objective lens, and a fourth reflecting mirror connected to the transmission side of the second beam splitter.

7. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 2, characterized in that, The first optical frequency comb has a center frequency of 1030nm and a repetition frequency of 100MHz, the second optical frequency comb has a center frequency of 1550nm and a repetition frequency of 100MHz, the repetition frequency difference between the first and second optical frequency combs is adjustable, and the adjustable range of the repetition frequency difference is 0 to 100Hz; the reference signal frequency provided by the reference source is 100MHz.

8. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 5, characterized in that, The first filter is a low-pass filter with a cutoff wavelength of 700nm.

9. The background noise suppression system for dual-comb coherent Raman spectroscopy measurement technology based on probe delay modulation according to claim 6, characterized in that, The second filter is a bandpass filter with a transmission wavelength range of 750–900 nm.

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