Imaging Method of Coherent Raman Scattering Imaging Device Based on Spectral Progressive Scanning

Abstract

An imaging method of a coherent Raman scattering imaging device based on spectral progressive scanning according to the present invention includes a synchronous two-color light source, a nonlinear amplification and spectral broadening module, a spectral progressive scanning control module, a linear amplification module, a beam combining and sample detection module, and a data processing module. The present invention does not require tuning a laser oscillator, nor does it require time scanning. By controlling the seed light and pump light of the nonlinear amplifier, adjusting parameters such as the dispersion, power, chirp of the seed light, and the pump power of the amplifier, the spectral evolution of the nonlinear amplifier is dynamically adjusted, so that it gradually transitions from a narrow spectrum to a wide spectrum, and from covering a single Raman peak to progressively covering multiple Raman peaks. This spectral progressive scanning coherent Raman light source can achieve simultaneous imaging of multiple chemical bonds, has a fast scanning speed, a flexible imaging method, and combines high spectral resolution and a wideband detection range, and also provides a new way to eliminate noise in coherent Raman scattering imaging.

Description

Technical Field

[0001] The present invention belongs to the technical field of imaging light sources, and particularly relates to an imaging method of a coherent Raman scattering imaging device based on spectral progressive scanning. Background Art

[0002] Due to the continuous development of microscopic imaging technology, people can observe the microscopic world at the sub-micron level that cannot be directly seen with the naked eye, which plays a key role in imaging various tissues or samples in the field of life sciences. Among them, coherent Raman scattering (CRS) imaging technology is widely used in the fields of biology and medicine due to its characteristics of label-free, non-invasive, and chemical specificity. To achieve CRS imaging, usually two ultrashort pulses that are synchronous in time and coincident in space (the pulse with a longer wavelength is called Stokes light, and the pulse with a shorter wavelength is called pump light) are simultaneously irradiated on the sample to be measured. When the energy corresponding to the frequency difference between these two beams of light is consistent with the vibrational-rotational energy level of the chemical bond of the sample, a beam of light with a different frequency will be generated, and the detection of molecular substances can be achieved by detecting the newly generated light.

[0003] When coherent Raman scattering imaging of multiple chemical bonds is required, it is necessary to change the frequency difference between the two excitation light beams. To achieve this goal, there are two common methods. One is to directly change the frequency of one of the excitation light beams. For example, an adjustable fiber grating or an adjustable filter is used and directly placed in the resonant cavity of one of the light sources. The output frequency of this light source is changed, and the frequency difference from the other beam of light also changes accordingly. This method is commonly used in the case where both excitation light beams are picosecond pulsed light, and the frequency tuning time can reach the millisecond level. However, since the frequency is changed in the laser resonant cavity, the tuning range is limited by the emission cross-section of the gain medium. In addition, directly changing the frequency of the oscillator is likely to cause the risk of mode-locking loss. The other method is to first broaden the femtosecond pulse with a broadband spectrum through a dispersive medium to establish a frequency-time mapping, and then adjust the delay between the broadened broadband pulse and the other pulse to make the pulses of specific frequency components coincide in the time domain. Then, by changing or scanning the delay, the coincidence of pulses with different frequency differences at different times is achieved. This method can broaden the spectrum of the pulse through a nonlinear medium, taking into account the characteristics of a wide spectral range and high spectral resolution. However, the speed of the time-domain scanning method is limited. The speed of a general displacement stage is too slow. Although a galvanometer and a grating can be used to achieve a higher-speed scan, the introduction of the spatial structure increases the system complexity while reducing the system reliability. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide an imaging method for a coherent Raman scattering imaging device based on spectral progressive scanning, aiming to solve the problems that traditional coherent Raman scattering imaging light sources and methods are difficult to achieve fast scanning speed, wide spectral range, and high spectral resolution, and to achieve fast and high-resolution imaging of multiple Raman characteristic frequencies.

[0005] A coherent Raman scattering imaging device based on spectral progressive scanning includes a synchronous two-color light source, a nonlinear amplification and spectral broadening module, a spectral progressive scanning control module, a linear amplification module, a beam combination and sample detection module, and a data processing module. Among them, the synchronous two-color light source module includes a first fiber laser and a second fiber laser that can output ultrashort pulses of two wavelengths with time-domain synchronization. The first fiber laser contains a dispersion / chirp controller. The second fiber laser realizes passive synchronization with the first fiber laser through injection or co-cavity methods. The nonlinear amplification and spectral broadening module includes a power regulator, a nonlinear amplifier, and a transmission fiber.

[0006] For the fiber lasers in the synchronous two-color light source module, the mode-locking method can be nonlinear polarization rotation, saturable absorption, or nonlinear amplifying loop mirror. The dispersion / chirp controller therein can be a device composed of a fiber grating, a spatial grating pair, or an electro-optic / acousto-optic modulator, which can actively control the intracavity dispersion or chirp. The synchronization method of the two-color laser can adopt an injection or co-cavity passive synchronization scheme.

[0007] The power regulator in the nonlinear amplification and spectral broadening module is composed of a fiber amplifier. When the pump light of this amplifier is turned on / increased, the power regulator plays a gain role. When the pump light of this amplifier is decreased / turned off, due to the absorption effect of the gain fiber, the power regulator plays a loss role. The pump power of this power regulator is actively controlled by the spectral progressive scanning control module. The nonlinear amplifier is composed of a high-power nonlinear fiber amplifier. Its function is to realize a nonlinear amplifier for spectral broadening based on the combined action of various nonlinear effects in the fiber, such as self-phase modulation, cross-phase modulation, etc. The pump power of this amplifier is actively controlled by the spectral progressive scanning control module. The transmission fiber can be an active or passive fiber. This section of fiber realizes the spectral-time mapping of ultrashort pulses with broadband spectra in the time domain by introducing large dispersion, and can further broaden the spectral width or shape the spectral shape during this process.

[0008] The beam combination and sample detection module includes a wavelength division multiplexer or dichroic mirror that realizes the spatial coincidence of two-color pulses, a spatial delay line or fiber delay line that realizes the time coincidence of two-color pulses, and also includes a focusing lens, a sample to be measured, a collimating lens, a sample console, a filtering module, a detection module, etc.

[0009] Imaging method of a coherent Raman scattering imaging device based on spectral progressive scanning: The spectral progressive scanning control module is connected to a dispersion / chirp controller, a power regulator, and a non-linear amplifier to control the non-linear spectral broadening process. In the synchronous dual-color light source, the first beam of light containing the dispersion / chirp controller sequentially passes through the non-linear amplification and spectral broadening module, and the second beam of light passing through the linear amplification module achieves temporal and spatial coincidence in the beam combining and sample detection module, and then irradiates the sample to be measured. The coherent Raman scattering signal of the sample to be measured is detected and sent to the data processing module. The data processing module simultaneously receives the signal from the spectral progressive scanning control module to achieve coherent Raman scattering imaging.

[0010] The spectral progressive scanning control module integrates the circuit part and the control program in a metal chassis. There are three control ports, one output port, one power port, and one data transmission port for an external manual controller on the outside of the chassis. Among them, the three control ports respectively control the intracavity parameters of the first fiber laser, the pump power of the power regulator and the non-linear amplifier to actively control the non-linear spectral broadening process. The output port inputs the synchronous control signal of the spectral broadening process into the data processing module. The data processing module corresponds it to different spectral components according to the synchronous control signal and combines it with the coherent Raman scattering imaging signal to achieve simultaneous imaging of multiple chemical bonds.

[0011] Compared with the prior art, the beneficial effects of the present invention are mainly reflected in:

[0012] 1. The present invention does not require time-domain scanning, but adopts spectral scanning. On the one hand, it avoids the problems of increasing the spatial optical path, unstable galvanometer scanning, and limited motor scanning speed in the existing time-domain scanning technology. On the other hand, by directly controlling the non-linear amplifier spectral broadening process such as the electro-optic modulator in the control oscillator and the pump power of the non-linear amplifier, the speed can reach the millisecond or sub-millisecond level, the scanning method is more stable, and the scanning speed is faster.

[0013] 2. In the non-linear amplification spectral broadening module of the present invention, the broadening process can be controlled by adjusting multiple parameters, such as the dispersion / chirp of the laser oscillator, the power incident on the amplifier, the pump power of the amplifier, etc. Through the regulation of multiple parameters, the spectral broadening process can be adjusted more carefully and flexibly, and the corresponding Raman wave number control is also more careful and flexible, which helps to achieve high spectral resolution and more diverse coherent Raman scattering applications in imaging forms.

[0014] 3. The imaging method proposed by the present invention can eliminate non-resonant background noise and environmental noise by subtracting the previous and subsequent spectral images. Compared with the traditional scheme of imaging only a certain Raman peak each time, the noise suppression means are more diverse.

[0015] 4. The imaging scheme proposed by the present invention to achieve spectral progressive scanning by controlling spectral broadening can quickly switch between the modes of high-resolution imaging of a single Raman peak and wide-spectrum imaging of multiple Raman peaks without changing the detection optical path, and the application method is more flexible.

[0016] 5. In the imaging device proposed by the present invention, one beam of light obtains a wide spectrum after non-linear spectral broadening, ensuring the spectral range of Raman detection. The other beam of light obtains a narrow spectrum under the action of gain narrowing after linear amplification, ensuring the spectral resolution of Raman detection. It can simultaneously achieve wide-range and high-precision spectral detection and imaging.

[0017] 6. The synchronization scheme of the dual-color synchronous light source of the present invention can adopt the master-slave injection type or the common cavity type scheme. Utilizing the cross-phase modulation effect between the dual-color pulses, compared with the active synchronization scheme, it does not require a complex circuit drive, has high synchronization accuracy and a large mismatch distance, ensuring the stability of the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is the principle structure diagram of the present invention;

[0019] Figure 2 is the mechanism diagram of the present invention;

[0020] Figure 3 is the schematic diagram of Embodiment 1 of the present invention for simultaneously imaging multiple chemical bonds by injecting a synchronous dual-color light source through a nine-word cavity;

[0021] Figure 4 is the schematic diagram of Embodiment 2 of the present invention for simultaneously imaging multiple chemical bonds by injecting a synchronous dual-color light source through a saturable absorber;

[0022] Figure 5 is the schematic diagram of Embodiment 3 of the present invention for simultaneously imaging multiple chemical bonds by a common cavity synchronous dual-color light source. DETAILED DESCRIPTION OF THE INVENTION

[0023] The imaging method of a coherent Raman scattering imaging device based on spectral progressive scanning according to the present invention will be described in more detail below with reference to the schematic diagrams, which show the preferred embodiments of the present invention. It should be understood that those skilled in the art can modify the present invention described herein while still achieving the advantageous effects of the present invention. Therefore, the following description should be understood as a broad guidance for those skilled in the art and not as a limitation to the present invention.

[0024] As Figure 1 shown, Figure 1This is the principle structure diagram of the present invention. The synchronous dual-color light source module includes an ultrashort pulse fiber laser capable of outputting two wavelengths with time-domain synchronization. One of the lasers contains a dispersion / chirp controller, and the other laser realizes passive synchronization with the first laser through injection or co-cavity methods. The nonlinear amplification and spectral broadening module includes a power regulator, a nonlinear amplifier, and a transmission fiber. The spectral progressive scanning control module is connected to the dispersion / chirp controller, the power regulator, and the nonlinear amplifier to control the nonlinear spectral broadening process. In the synchronous dual-color light source, the first beam of light containing the dispersion / chirp controller sequentially passes through the nonlinear amplification and spectral broadening module, and coincides with the second beam of light passing through the linear amplification module in time and space in the beam combining and sample detection module, and then irradiates the sample to be measured, detecting the coherent Raman scattering signal of the sample to be measured. This signal is input into the data processing module, and the data processing module simultaneously receives the synchronous control signal from the spectral progressive scanning control module to realize coherent Raman scattering imaging.

[0025] Reference Figure 2 , Figure 2This is the mechanism diagram of the present invention. The mechanism of the present invention mainly controls the seed light and pump light of the non-linear amplifier, adjusts parameters such as the dispersion, power, chirp of the seed light and the pump power of the amplifier, dynamically adjusts the spectral evolution of the non-linear amplifier, so that it gradually transitions from a narrow spectrum to a wide spectrum, from covering a single Raman peak to progressively covering multiple Raman peaks, and can achieve simultaneous imaging of multiple chemical bonds. After the two temporally synchronized excitation lights output by the synchronous two-color light source are pulse-broadened through the dispersion medium, the frequency of one excitation light is ωp, and the frequency range of the other excitation light is ωs1’-ωs1”. After beam combination, when its frequency difference 1(ωs1-ωp) matches the frequency Ωa of the sample vibration molecule (i.e., Ωa = ωs1-ωp), Raman scattering imaging can be performed on the chemical bond A within the frequency range of the sample vibration molecule Ωa. By adjusting the dispersion / chirp of one of the lasers through the spectral progression module scanning control module, a spectral-time mapping established in the time domain is made to gradually broaden from the narrow spectrum ① to the spectrum ②, and the frequency range of the output excitation light changes to ωs2’-ωs2”. After beam combination, when its frequency difference 2(ωs2-ωp) can match the frequency Ωb of the sample vibration molecule, coherent Raman scattering imaging can be simultaneously performed on the chemical bonds A and B within the frequency range of the sample vibration molecule Ωb. By dynamically adjusting the spectral evolution of the non-linear amplifier, it is further gradually broadened to the spectrum ③, and the frequency range of the output excitation light changes to ωs3’-ωs3”. After beam combination, when its frequency difference 3(ωs3-ωp) can match the frequency Ωc of the sample vibration molecule, coherent Raman scattering imaging can be simultaneously performed on the chemical bonds A, B, and C within its range. Similarly, by dynamically adjusting the spectral evolution of the non-linear amplifier, it is gradually transitioned and broadened to the spectra ④, ⑤… After beam combination, the frequency differences 4, 5… can progressively match multiple vibration molecule frequencies, cover multiple Raman characteristic peaks, and simultaneously perform coherent Raman scattering imaging. Then, through the data processing module, the synchronous control signal of the spectral broadening is combined with the coherent Raman scattering imaging signal, and it is corresponded to different spectral components to achieve simultaneous imaging of multiple chemical bonds.

[0026] Example 1

[0027] Reference Figure 3 , Figure 3 Example 1 of the imaging method of a coherent Raman scattering imaging device based on spectral progression scanning (nine-cavity injection synchronous two-color light source), and its specific implementation process is as follows:

[0028] In this embodiment, the synchronous two-color light source adopts a passive synchronization method with an injection-type master-slave structure, and both the master and slave laser resonators adopt a passive mode-locking method of a nonlinear amplifying loop mirror (NALM) with a nine-character cavity structure. The following components are included in both resonators: pump source LD (1, 12), wavelength division multiplexer WDM (2, 10, 13), gain medium Gain (3, 11), output coupler Coupler (4, 9, 15), and phase shifter PS (8, 14). Among them, the linear end of the master laser resonator is connected to the fiber collimator 5 through the output coupler 4, and after collimation, it hits the spatial grating pair 6. One of the gratings and a total reflection mirror M7 are placed on a one-dimensional translation stage, and the one-dimensional translation stage can be actively controlled by the spectral progression scanning control module to adjust the spacing of the grating pair and achieve active tunability of the intracavity dispersion. The linear end of the slave laser resonator is connected to the fiber Bragg grating 16 through the output coupler 15, and the light of a specific wavelength is reflected back into the resonator for continuous transmission. A beam of light with the same repetition frequency as the slave laser output by the master laser through the output coupler 9 is injected into the slave laser through the wavelength division multiplexer 10 to achieve the synchronization of the two fiber lasers.The first beam of light outputted from the main laser via the output coupler 4 passes through a fiber amplifier composed of a fiber isolator 17, a pump source 18, a wavelength division multiplexer 19, and a gain fiber 20 as a power regulator, wherein the fiber isolator is used to prevent the return light from damaging the device. The pump source power is actively controlled by the spectrum progressive scanning control module, so that the fiber amplifier plays a role of gain or loss. The output light passes through a high-power nonlinear fiber amplifier composed of two pump sources 22, 25, wavelength division multiplexers 23, 26, and a gain fiber 24, which are bidirectionally pumped and actively controlled by the spectrum progressive scanning control module. Based on the combined action of various nonlinear effects in the optical fiber, spectrum broadening is achieved. After passing through a section of active optical fiber 27, large dispersion is introduced to achieve spectrum-to-time mapping of ultrashort pulses of broadband spectrum in the time domain, and further broadening of the spectrum width or shaping of the spectrum shape can be achieved in this process. The second beam of light outputted from the laser passes through the fiber isolator 28 of the linear amplification module, the combiner 29, the two high-power pump sources 3 0, 31 and gain fiber 32, after amplifying the optical power and broadening the pulse, the two beams of light are overlapped in time and space through a dichroic mirror 33. The combined light passes through the first microscope objective 34 whose field of view can cover the sample to be tested, and is focused on the sample to be tested 36. The sample to be tested is placed on a displacement platform 37, which is used to move the sample to be tested to complete the line scan. When the frequency difference between the two ultrashort pulse lasers meets the Raman shift of the vibration spectrum of the chemical bond of the relevant molecules in the sample to be tested, the corresponding coherent Raman scattering nonlinear light is obtained. In order to achieve the chemical effect, the second microscope objective lens 35 is located on the side of the first microscope objective lens away from the sample to be measured, and can transmit the output light generating coherent Raman scattering to the bandpass filter 38, and then reach the photodetector 39 after filtering out the stray light, and convert the coherent Raman scattering light signal of the sample into an electrical signal. Combined with the synchronous control signal from the spectrum progressive scanning control module 41 that actively controls the nonlinear spectrum broadening process, it is sent to the computer 40 in the data processing module at the same time, and it is matched with different spectral components, thereby finally realizing the simultaneous imaging of multiple chemical bonds.

[0029] Example 2

[0030] refer to Figure 4 , Figure 4 This is a second embodiment of an imaging method of a coherent Raman scattering imaging device based on spectrum progressive scanning (saturated absorber injected with synchronous two-color light source), and its specific implementation process is as follows:

[0031] In this embodiment, the synchronous two-color light source adopts a passive synchronization method with an injection-type master-slave structure. Both the master and slave laser resonators are in the passive mode-locking method of semiconductor saturable absorber mirror (SESAM). The following components are included in both resonators: saturable absorber SESAM (1, 14), pump source LD (2, 12), wavelength division multiplexer WDM (3, 10, 13), gain medium Gain (4, 11), and output coupler Coupler (5, 15). Among them, the resonator of the master laser is connected to the fiber collimator 6 through the output coupler 5, and after collimation, it hits the spatial grating pair 7. One of the gratings and a total reflection mirror M8 are placed on a one-dimensional translation stage. The one-dimensional translation stage can be actively controlled by the spectral progressive scanning control module to adjust the spacing of the grating pair and achieve active tunability of the intracavity dispersion. The resonator of the slave laser is connected to the fiber Bragg grating 16 through the output coupler 15, and the light of a specific wavelength is reflected back into the resonator for continuous transmission. A beam of light with the same repetition frequency as the slave laser output from the master laser through the output coupler 5 is split by the output coupler 9. The light in the lower branch is injected into the slave laser through the wavelength division multiplexer 10 to achieve the synchronization of the two fiber lasers; the light in the upper branch passes through a fiber amplifier composed of a fiber isolator 17, a pump source 18, a wavelength division multiplexer 19, and a gain fiber 2 as a power regulator. Among them, the fiber isolator prevents the return light from damaging the device, and the pump source power is actively controlled by the spectral progressive scanning control module to make the fiber amplifier play a role of gain or loss. The output light passes through a high-power nonlinear fiber amplifier composed of a fiber isolator 21, a beam combiner 22, two high-power pump sources (23, 24) actively controlled by the spectral progressive scanning control module, and a gain fiber 25. Based on the combined action of the nonlinear effects in the fiber, spectral broadening is achieved. Then, through a section of active fiber 26, the spectral-time mapping of the ultrashort pulse with a broadband spectrum in the time domain is realized, and further spectral broadening or spectral shape shaping can be achieved during this process. The second beam of light output from the slave laser passes through the fiber isolator 27, the beam combiner 28, two high-power pump sources 29, 30, and a gain fiber 31 of the linear amplification module. After the optical power is amplified and the pulse is broadened, the two beams of light are made to coincide in time and space through a dichroic mirror 32. The combined light passes through a focusing lens, a sample to be measured, a collimating lens, a sample control console, a filtering module, a detection module, etc. in the sample detection module 33, and the coherent Raman scattering signal of the sample is detected. Combined with the synchronous control signal from the spectral progressive scanning control module 35 that actively controls the nonlinear spectral broadening process, it is sent into the computer 34 in the data processing module at the same time, corresponding it to different spectral components, and finally realizing the simultaneous imaging of multiple chemical bonds.

[0032] Embodiment III

[0033] Reference Figure 5 , Figure 5Example 3 (Common-cavity synchronous two-color light source) of the imaging method of a coherent Raman scattering imaging device based on spectral progressive scanning. The specific implementation process is as follows:

[0034] In this embodiment, the synchronous dual-color light source adopts a passive synchronization method with a common cavity structure. Both fiber lasers adopt a passive mode-locking method of a non-linear amplifying loop mirror (NALM) with a nine-character cavity structure and share a common resonator. The loop ends of both lasers contain the following components: pump sources LD (5, 14), wavelength division multiplexers WDM (6, 8, 9, 15), gain media Gain (7, 16), output couplers Coupler (4, 10, 12, 17), and phase shifters PS (11, 13). Among them, the wavelength division multiplexers WDM (8, 9) and a section of single-mode fiber connect the two fiber lasers to achieve common cavity synchronization. The linear end of fiber laser 1 in the upper part of the figure is connected to a fiber collimator 3 through an output coupler 4. After collimation, it hits a pair of spatial gratings 2. One of the gratings and a total reflection mirror M1 are placed on a one-dimensional translation stage. The one-dimensional translation stage can be actively controlled by a spectral progression scanning control module to adjust the spacing of the grating pair and achieve active tunability of the intracavity dispersion. The linear end of fiber laser 2 in the lower part of the figure is connected to a fiber Bragg grating 18 through an output coupler 17, and the light of a specific wavelength is reflected back into the resonator for continuous transmission. The first beam of light output from fiber laser 1 through an output coupler 10 passes through a fiber amplifier composed of a fiber isolator 19, a pump source 20 actively controlled by a spectral progression scanning control module, a wavelength division multiplexer 21, and a gain fiber 22 as a power regulator. The fiber isolator prevents the return light from damaging the device. The pump power is actively controlled by the spectral progression scanning control module to make the fiber amplifier play a role of gain or loss. The output light passes through a high-power non-linear fiber amplifier composed of a fiber isolator 23, two pump sources (24, 27) with bidirectional pumping whose pump power is actively controlled by the spectral progression scanning control module, wavelength division multiplexers (25, 28), and a gain fiber 26. Based on the combined action of various non-linear effects in the fiber, spectral broadening is achieved. Then, through a section of active fiber 29, a large amount of dispersion is introduced to achieve the spectral-time mapping of the ultrashort pulse with a broadband spectrum in the time domain, and the spectral width can be further broadened or the spectral shape can be reshaped during this process. The second beam of light output from fiber laser 2 passes through a fiber isolator 30, a beam combiner 31, two high-power pump sources (32, 33), and a gain fiber 34 in the linear amplification module. After the optical power is amplified and the pulse is broadened, the two beams of light are made to coincide in time and space through a dichroic mirror 35. The combined light then passes through a focusing lens, a sample to be measured, a collimating lens, a sample control console, a filtering module, a detection module, etc. in the sample detection module 36 to detect the coherent Raman scattering signal of the sample. Combined with the synchronous control signal from the spectral progression scanning control module 38 that actively controls the non-linear spectral broadening process, they are simultaneously sent into a computer 37 in the data processing module, which corresponds them to different spectral components, and finally realizes the simultaneous imaging of multiple chemical bonds.

[0035] The above are only the preferred embodiments of the present invention and do not impose any restrictive effect on the present invention. Any person skilled in the art, without departing from the scope of the technical solution of the present invention, makes any form of equivalent replacement or modification and other changes to the technical solution and technical content disclosed by the present invention, which are all within the content of the technical solution of the present invention and still fall within the protection scope of the present invention.

Claims

1. An imaging method for a coherent Raman scattering imaging device based on spectral progressive scanning, characterized in that Adopt a coherent Raman scattering imaging device based on spectral progressive scanning. The coherent Raman scattering imaging device includes a synchronous two-color light source, a nonlinear amplification and spectral broadening module, a spectral progressive scanning control module, a linear amplification module, a beam combining and sample detection module, and a data processing module. The synchronous two-color light source includes a first fiber laser and a second fiber laser that are synchronized in the time domain. The first fiber laser includes a dispersion controller or a chirp controller, and the first fiber laser emits a first light beam. The second fiber laser emits a second light beam, and the second light beam is sequentially connected to the linear amplification module and the beam combining and sample detection module; The nonlinear amplification and spectral broadening module includes a power regulator, a nonlinear amplifier, and a transmission fiber. The first light beam is sequentially connected to the power regulator, the nonlinear amplifier, the transmission fiber, and the beam combining and sample detection module; The beam combining and sample detection module is signal-connected to the data processing module. The spectral progressive scanning control module is respectively connected to the dispersion controller or the chirp controller, the power controller, and the nonlinear amplifier. The spectral progressive scanning control module is also signal-connected to the data processing module; The dispersion controller or the chirp controller is composed of a fiber grating, a spatial grating pair, an electro-optic modulator, or an acousto-optic modulator that actively controls the intracavity dispersion or chirp; The imaging method is as follows: The spectral progressive scanning control module controls the nonlinear spectral broadening process by being respectively connected to the dispersion controller or the chirp controller, the power regulator, and the nonlinear amplifier. In the synchronous two-color light source, the first light beam containing the dispersion controller or the chirp controller passing through the nonlinear amplification and spectral broadening module and the second light beam passing through the linear amplification module achieve temporal and spatial coincidence in the beam combining and sample detection module. The coincident light beam irradiates the sample to be measured, and the detection module detects the coherent Raman scattering signal of the sample to be measured and sends the coherent Raman scattering signal to the data processing module. The data processing module simultaneously receives the coherent Raman scattering signal and the signal from the spectral progressive scanning control module, thereby realizing coherent Raman scattering imaging.

2. The imaging method of the coherent Raman scattering imaging device based on spectral progressive scanning according to claim 1, characterized in that, The mode-locking methods of the first fiber laser and the second fiber laser are both one of nonlinear polarization rotation, saturable absorption, and nonlinear amplification environment.

3. The imaging method of the coherent Raman scattering imaging device based on spectral progressive scanning according to claim 1, characterized in that The synchronization method of the two-color light source adopts the injection type or the common cavity type.

4. The imaging method of the coherent Raman scattering imaging device based on spectral progressive scanning according to claim 1, wherein The beam combining and sample detection module includes a wavelength division multiplexer or a dichroic mirror for realizing the spatial coincidence of the two-color pulses, a spatial delay line or a fiber delay line for realizing the temporal coincidence of the two-color pulses, a focusing lens, a sample to be measured, a collimating lens, a sample console, a filtering module, and a detection module.

5. The imaging method of the coherent Raman scattering imaging device based on spectral progressive scanning according to claim 1, wherein The power regulator is composed of a fiber amplifier. When the pump light of the fiber amplifier is turned on or increased, the power regulator plays a gain role on the first light beam; when the pump light of the fiber amplifier is turned off or decreased, the power regulator plays a loss role on the first light beam. The pump power of the power regulator is actively controlled by the spectral progressive scanning control module.

6. The imaging method of the coherent Raman scattering imaging device based on spectral progressive scanning according to claim 1, characterized in that, The non-linear amplifier is composed of a non-linear fiber amplifier, and the pump power of the non-linear fiber amplifier is actively controlled by a spectral progressive scanning control module.

7. The imaging method of the coherent Raman scattering imaging device based on spectral progressive scanning according to claim 1, characterized in that, The transmission fiber is an active fiber or a passive fiber. The transmission fiber realizes the spectral-time mapping of ultrashort pulses with broadband spectra in the time domain by introducing dispersion, and further broadens the spectral width or shapes the spectral shape during the mapping process.

8. The imaging method of the coherent Raman scattering imaging device based on spectral progressive scanning according to claim 1, characterized in that, The spectral progressive scanning control module actively controls the non-linear spectral broadening process by controlling the intracavity parameters of the first fiber laser, the power regulator, and the pump power of the non-linear amplifier respectively, and inputs the synchronous control signal of the spectral broadening process to the data processing module. The data processing module corresponds it to different spectral components according to the synchronous control signal and combines it with the coherent Raman scattering imaging signal to realize the simultaneous imaging of multiple chemical bonds.

Images