Portable gated Raman probe and Raman spectrum acquisition device

Abstract

The present invention provides a portable gated Raman probe and a Raman spectrum acquisition device. The portable gated Raman probe includes: a laser for emitting a laser beam; an active amplifying photodetector for acquiring the laser beam emitted by the laser and synchronously outputting an electrical signal; an emitting optical path component for performing optical path adjustment, optical signal beam expansion and optical signal attenuation processing on the laser beam emitted by the laser and then transmitting it to a converging lens, which at least includes an optical path reflection adjustment unit, a shaping beam expansion unit and an attenuation unit; a converging lens for converging the laser beam processed by the emitting optical path component to a sample to be tested, and converging the optical signal scattered and returned by the sample to be tested to a collecting optical path component; a collecting optical path component for filtering and then outputting the optical signal converged by the converging lens, and the collecting optical path component and the converging lens form a confocal optical path. The present invention can overcome optical signal interference, realize contactless and rapid acquisition of Raman spectra, and has a compact overall structure and is easy to carry.

Description

Technical Field

[0001] The invention relates to the technical field of spectrum measurement, and in particular to a portable gated Raman probe and a Raman spectrum acquisition device. Background Art

[0002] With the advancement of detection technology, gated spectroscopy technology is widely used in spectral measurement of ultrafast evolution processes, especially gated Raman technology, which shields fluorescence interference by gating and is widely used in biomedical imaging, material science, material analysis and other fields; the laser pulse and detector gate width have entered the picosecond level or even femtosecond level, making the role of gated Raman technology increasingly prominent.

[0003] At present, conventional Raman probes commercially available on the market are still used for close-range sampling and detection in laboratories, and cannot overcome interference from harsh environments such as strong ambient light, high temperature radiation, and fluorescence interference from sample impurities. On the other hand, the design of separating the Raman probe from the laser loses the flexibility and portability of the Raman probe. Therefore, how to solve the application difficulties of harsh environments such as strong ambient light, high temperature radiation, and remote contactless detection, and how to make the Raman probe flexible to assemble and easy to carry, is the key to the large-scale expansion of commercial Raman probes in multiple industries. Summary of the invention

[0004] The embodiment of the present invention provides a portable gated Raman probe and a Raman spectrum acquisition device. The gated Raman probe cooperates with the gated spectrum acquisition device to overcome optical signal interference and realize contactless and rapid acquisition of Raman spectra. The overall structure is compact and easy to carry.

[0005] An embodiment of the present invention provides a portable gated Raman probe, comprising:

[0006] A laser for emitting a laser beam;

[0007] An active amplified photodetector, used to acquire the laser beam emitted by the laser and synchronously output an electrical signal;

[0008] An emission optical path component is used to adjust the optical path of the laser beam emitted by the laser, expand the optical signal and attenuate the optical signal, and then transmit it to the converging lens, and at least includes an optical path reflection adjustment unit, a shaping and expanding unit and an attenuation unit;

[0009] A converging lens is used to converge the laser beam processed by the emission optical path component to the sample to be tested, and to converge the light signal scattered and returned by the sample to be tested to the collection optical path component;

[0010] A collecting optical path component is used to filter and process the optical signal collected by the converging lens and then output it, wherein the collecting optical path component and the converging lens form a confocal optical path;

[0011] Among them, the optical path reflection adjustment unit includes a plurality of reflectors, and the plurality of reflectors are used to adjust the propagation direction of the laser light beam so that the laser light beam is spatially folded to form a folded optical path to compress the optical path space. The shaping and expanding unit and the attenuation unit are both arranged on the folded optical path. The shaping and expanding unit includes at least two lenses for outputting a light beam with a set magnification; the attenuation unit includes a half-wave plate and a polarization beam splitter prism for outputting a light beam with a set attenuation ratio.

[0012] Preferably, a first reflector is provided at the front end of the laser, and part of the laser beam emitted by the laser is incident on the active amplifying photodetector through the first reflector, and the active amplifying photodetector synchronously outputs an electrical signal after acquiring the laser beam; another part of the laser beam emitted by the laser is reflected by the first reflector to the optical path reflection adjustment unit of the emitting optical path component.

[0013] Preferably, the optical path reflection adjustment unit includes a second reflector, a third reflector, a fourth reflector and a fifth reflector which are arranged in sequence along the folded optical path, the second reflector and the third reflector as well as the fourth reflector and the fifth reflector are arranged in parallel respectively; the third reflector and the fourth reflector are arranged symmetrically.

[0014] Preferably, the shaping and expanding unit includes at least a first lens and a second lens, the first lens is a short focal length lens, the first lens is a concave lens or a convex lens, and is used to diverge a nearly parallel laser light beam; the second lens is a long focal length convex lens, and is used to converge the divergent light beam into parallel light; the shaping and expanding unit obtains a light beam with a set magnification by matching the focal lengths of the first lens and the second lens, while improving the parallelism of the light beam.

[0015] Preferably, the attenuation unit is arranged behind the shaping and expanding unit on the folded optical path; the half-wave plate is a polarizer, which is used to adjust the polarization direction of the laser light beam, and the polarization direction of the laser light input to the polarization beam splitter prism is changed by rotating the half-wave plate, thereby changing the proportion of the laser polarization component input to the polarization beam splitter prism; the polarization beam splitter prism is an analyzer, which is used to decompose the laser light beam into two components of horizontal polarized light and vertical polarized light; the laser light beam outputs two beams of horizontal polarized light and vertical polarized light with adjustable light intensity through the half-wave plate and the polarization beam splitter prism, and one of the horizontal polarized light and the vertical polarized light is selected as the output light beam.

[0016] Preferably, the emission optical path component also includes a spatial filtering unit, which is arranged behind the attenuation unit on the optical path, and includes a third lens, a pinhole and a fourth lens arranged in sequence, and the third lens and the fourth lens are convex lenses with the same parameters; the pinhole is a pinhole aperture or an optical pinhole; the laser beam is spatially Fourier transformed through the third lens, and the wave vector distribution of the laser is obtained in the focal plane of the third lens; a specific wave vector is screened in the focal plane through the pinhole; and the light beam is restored through the fourth lens.

[0017] Preferably, the emission optical path component also includes a first filter, which is arranged behind the attenuation unit on the optical path. The first filter is a narrow bandpass filter. The first filter performs bidirectional filtering to filter stray light in the laser beam to obtain a laser beam with high wavelength consistency, while preventing the scattered light signals converged by the converging lens from returning to the emission optical path component unit again through the collecting optical path unit.

[0018] Preferably, the converging lens comprises at least a fifth lens, and the fifth lens is used to converge the parallel laser to a focal point, and at the same time converge the light signal scattered and returned by the sample to be tested at the focal position into parallel light through the fifth lens and enter the collecting light path component.

[0019] Preferably, the collecting optical path component includes a dichroic mirror, a second filter and a sixth lens. The laser beam output by the emitting optical path component is reflected by the dichroic mirror and then output through the converging lens. The light signal scattered and returned by the sample to be tested is collected by the converging lens. The dichroic mirror filters the scattered light signal collected by the converging lens, and after secondary filtering through the second filter, it is converged to a focus through the sixth lens and coupled into the optical fiber output through the optical fiber signal port.

[0020] Based on the same concept, the present invention also provides a Raman spectrum acquisition device, including a Raman probe, a gated spectrum acquisition device and a control and data processing device. The Raman probe adopts the above-mentioned portable gated Raman probe, the Raman probe is connected to the gated spectrum acquisition device, and the gated spectrum acquisition device is connected to the control and data processing device.

[0021] Compared with the prior art, the technical solution of the embodiment of the present invention has beneficial effects.

[0022] For example, the portable gated Raman probe and Raman spectrum acquisition device provided by the present invention integrate a laser in the probe, and transmit the laser beam emitted by the laser to a converging lens after performing optical path adjustment, optical signal expansion and optical signal attenuation through an emitting optical path component, thereby optimizing the performance of the laser beam; the optical path reflection adjustment unit uses multiple mirrors to adjust the propagation direction of the laser beam, so that the laser beam is folded in space to form a folded optical path to compress the optical path space, thereby reducing the volume of the probe for easy carrying.

[0023] For another example, the position of the fifth lens of the converging lens can be adjusted in a small range through the focus ring to adjust the focus of the laser emitted by the probe.

[0024] For example, the laser beam can be synchronously output with an active amplified photodetector to eliminate the reliance on external triggering of a specific laser.

[0025] For another example, the Raman probe only needs to connect the delayed optical fiber and the photodetector to output the electrical signal to the gated spectrum acquisition device. The installation and configuration are simple. The Raman probe is synchronized with the gated spectrum acquisition device with high precision, and the shutter can be opened only when the pulse of the laser scattering signal arrives. Within the gate width of the nanosecond order, the intensity of the laser scattering signal is much higher than the indoor ambient light, thereby achieving effective suppression of the background and obtaining a high signal-to-noise ratio Raman spectrum with a near-zero background. Continuous backgrounds such as ambient light can be suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the portable gated Raman probe of the present invention;

[0027] Figure 2 It is a schematic diagram of the structure of the Raman spectrum acquisition device of the present invention;

[0028] Figure 3 This is a Raman spectrum of a gypsum crystal sample collected by the Raman spectrum collection device of the present invention.

[0029] Description of reference numerals:

[0030] 100-Raman probe; 200-gated spectrum acquisition device; 300-control and data processing device; 400-gypsum crystal sample;

[0031] 110 - laser; 111 - first reflector; 112 - active amplified photodetector; 113 - cable;

[0032] 120 - optical path reflection adjustment unit; 121 - second reflector; 122 - third reflector; 123 - fourth reflector; 124 - fifth reflector;

[0033] 130- beam shaping and expansion unit; 131- first lens; 132- second lens;

[0034] 140- attenuation unit; 141- half-wave plate; 142- polarization beam splitter prism;

[0035] 150-spatial filter unit; 151-third lens; 152-pinhole; 153-fourth lens;

[0036] 160-first filter;

[0037] 170-converging lens; 171-fifth lens; 172-variable aperture;

[0038] 180 - collecting optical path component; 181 - dichroic mirror; 182 - second filter; 183 - sixth lens; 184 - optical fiber coupling port; 185 - optical fiber. DETAILED DESCRIPTION

[0039] In order to make the purpose, features and beneficial effects of the present invention more obvious and understandable, the specific embodiments of the present invention are described in detail below in conjunction with the accompanying drawings. It is understood that the specific embodiments described below are only used to explain the present invention, rather than to limit the present invention. In addition, the same or similar reference numerals may be used in the figures to refer to the same or similar elements in different embodiments, and the description of the same or similar elements in different embodiments and the description of the prior art elements, features, effects, etc. may be omitted.

[0040] Reference Figures 1 to 3 , an embodiment of the present invention provides a portable gated Raman probe and a Raman spectrum acquisition device.

[0041] Specifically, the portable gated Raman probe 100 provided in the embodiment of the present invention includes:

[0042] A laser 110 for emitting a laser beam;

[0043] An active amplified photodetector 112 is used to obtain the laser beam emitted by the laser 110 and synchronously output an electrical signal;

[0044] The transmitting optical path component performs optical path adjustment, optical signal expansion and optical signal attenuation processing on the laser beam emitted by the laser 110 and transmits it to the converging lens 170, and at least includes an optical path reflection adjustment unit 120, a shaping and expanding unit 130 and an attenuation unit 140;

[0045] The focusing lens 170 focuses the laser beam processed by the emission optical path component to the sample to be tested, and focuses the light signal scattered and returned by the sample to be tested to the collection optical path component 180;

[0046] The collecting optical path component 180 filters and processes the optical signal collected by the converging lens 170 and then outputs the optical signal. The collecting optical path component 180 and the converging lens 170 form a confocal optical path.

[0047] Among them, the optical path reflection adjustment unit 120 includes multiple reflectors, which are used to adjust the propagation direction of the laser light beam so that the laser light beam is spatially folded to form a folded optical path to compress the optical path space. The shaping and expansion unit 130 and the attenuation unit 140 are both arranged on the folded optical path. The shaping and expansion unit 130 includes at least two lenses for outputting a light beam with a set magnification; the attenuation unit 140 includes a half-wave plate 141 and a polarization beam splitter prism 142 for outputting a light beam with a set attenuation ratio.

[0048] In some embodiments, a first reflector 111 is provided at the front end of the laser 110. A small portion of the laser beam emitted by the laser 110 passes through the first reflector 111 and is incident on the active amplifying photodetector 112. After the active amplifying photodetector 112 acquires the laser beam, it synchronously outputs an electrical signal through a cable 113. Most of the laser beam emitted by the laser 110 is reflected by the first reflector 111 to the optical path reflection adjustment unit 120 of the transmitting optical path assembly.

[0049] In some embodiments, the optical path reflection adjustment unit 120 includes a second reflector 121, a third reflector 122, a fourth reflector 123 and a fifth reflector 124 which are sequentially arranged along the folded optical path, and the second reflector 121 and the third reflector 122 as well as the fourth reflector 123 and the fifth reflector 124 are respectively arranged in parallel; the third reflector 122 and the fourth reflector 123 are symmetrically arranged so that the laser beam is folded in space, reducing the space occupied by the optical path and thus reducing the volume of the Raman probe 100.

[0050] In some embodiments, the beam shaping and expansion unit 130 includes at least a first lens 131 and a second lens 132. The first lens 131 is a short focal length lens. The first lens 131 is a concave lens or a convex lens, which is used to diverge a nearly parallel laser light beam; the second lens 132 is a long focal length convex lens, which is used to converge the divergent light beam into parallel light; the beam shaping and expansion unit 130 obtains a light beam with a set magnification by matching the focal lengths of the first lens 131 and the second lens 132, while improving the parallelism of the light beam.

[0051] In some embodiments, the attenuation unit 140 is arranged behind the shaping and expanding unit 130 on the folded optical path; the half-wave plate 141 is a polarizer, which is used to adjust the polarization direction of the laser beam, and the polarization direction of the laser input to the polarization beam splitter prism 142 is changed by rotating the half-wave plate 141, thereby changing the proportion of the laser polarization component input to the polarization beam splitter prism 142; the polarization beam splitter prism 142 is a polarizer, which is used to decompose the laser beam into two components of horizontal polarized light and vertical polarized light; the laser beam outputs two beams of horizontal polarized light and vertical polarized light with adjustable light intensity through the half-wave plate 141 and the polarization beam splitter prism 142, and one of the horizontal polarized light and the vertical polarized light is selected as the output beam, which is the attenuated laser beam.

[0052] In some embodiments, the emission optical path component also includes a spatial filtering unit 150, which is arranged behind the attenuation unit 140 on the optical path. The spatial filtering unit 150 includes a third lens 151, a pinhole 152 and a fourth lens 153 arranged in sequence, and the third lens 151 and the fourth lens 153 are convex lenses with the same parameters; the pinhole 152 is a pinhole aperture or an optical pinhole; the laser beam is subjected to spatial Fourier transform through the third lens 151, and the wave vector distribution of the laser is obtained in the focal plane of the third lens 151; the pinhole 152 is used to screen specific wave vectors in the focal plane (for example, at the focal position, only the wave vector with the same propagation direction is allowed to pass); and then the light beam is restored through the fourth lens 153; at this time, the light beam obtained is filtered out of other modes of light by the pinhole 152, and the coherence, polarization characteristics, stability and spot quality of the output light beam are optimized, which has a good effect on applications such as in-situ Raman and confocal Raman.

[0053] In some embodiments, the emission optical path component also includes a first filter 160, which is arranged on the optical path behind the attenuation unit 140. The first filter 160 is a narrow bandpass filter. The first filter 160 performs bidirectional filtering to filter out stray light in the laser beam to obtain a laser beam with high wavelength consistency, while preventing the scattered light signals converged by the converging lens 170 from returning to the emission optical path component unit again through the collecting optical path unit 180.

[0054] In some embodiments, the converging lens 170 includes at least a fifth lens 171 , which is used to converge the parallel laser to a focal point, and at the same time converge the light signal scattered and returned by the sample to be tested at the focal position into parallel light through the fifth lens 171 and enter the collecting light path component 180 .

[0055] In some embodiments, a variable aperture 172 is built into the converging lens 170 , which can be used to filter some excessively strong laser signals and block some stray light in the converged parallel light.

[0056] In some embodiments, the collecting light path component 180 includes a dichroic mirror 181, a second filter 182 and a sixth lens 183. The laser beam output by the transmitting light path component is reflected by the dichroic mirror 181 and then output through the converging lens 170. The light signal scattered back by the sample to be tested is collected by the converging lens 170. The dichroic mirror 181 filters the scattered light signal collected by the converging lens 170, and then after secondary filtering through the second filter 182, it is converged to a focus through the sixth lens 183 and coupled into the optical fiber 185 through the optical fiber coupling port 184 for output.

[0057] In some embodiments, the second filter 182 may be a notch filter or a long-wave pass filter, etc., which is mainly used to filter the scattered light of the laser wavelength that is still strong after passing through the dichroic mirror 181; the notch filter only filters an extremely narrow band near the laser wavelength and can be used for most Raman applications; the long-wave pass filter will filter Raman scattering signals with wavelengths lower than the laser wavelength while filtering wavelengths near the laser, and can only be used for conventional Raman spectroscopy.

[0058] See also Figure 2 The present invention provides a Raman spectrum acquisition device, including a Raman probe, a gated spectrum acquisition device 200 and a control and data processing device 300. The Raman probe adopts the above-mentioned portable gated Raman probe 100. The cable 113 and the optical fiber 185 of the portable gated Raman probe 100 are respectively connected to the gated spectrum acquisition device 200, and the gated spectrum acquisition device 200 is connected to the control and data processing device 300.

[0059] In a specific implementation, the laser 110 uses a pulsed laser with a pulse duration of ≤100ns, an average power of ≥30mW, a typical wavelength of 532nm, and a variety of wavelengths from ultraviolet to near-infrared. The active amplified photodetector 112 has a response band covering ultraviolet to near-infrared wavelengths and is suitable for pulsed lasers in most commonly used bands.

[0060] Please continue to see Figure 2 A Raman spectrum acquisition device is used to collect the Raman spectrum of the gypsum crystal sample 400. The gypsum crystal sample 400 is set at the convergence point of the laser emitted by the portable gated Raman probe 100 in space; the cable 113 of the active amplified photodetector 112 outputting the synchronous electrical signal is connected to the external trigger input of the gated camera of the gated spectrum acquisition device 200, which is used for the gating of the gated camera and the laser pulse synchronization; the optical fiber 185 is a multimode optical fiber with a single fiber core diameter of 100μm and a length of 20m. One end of the optical fiber 185 is connected to the optical fiber coupling port 184 of the portable gated Raman probe 100, and the other end is coupled to the entrance slit of the spectrometer of the gated spectrum acquisition device 200; the gated camera is installed at the exit of the spectrometer.

[0061] The Raman probe 100 has a built-in laser 110 with a wavelength of 532nm, a pulse energy of 15μJ@FWHM1.5ns, and a pulse repetition frequency of 20kHz. The spectrometer of the gated spectrum acquisition device 200 adopts a CT structure mechanical rotating grating spectrometer with an equivalent focal length of 350mm; the slit opening is 200um, the grating configuration is 1800l / mm@Blaze270nm, and the wavelength is set to 550nm. The gated camera is an image-intensified CMOS gated camera with single-photon recognition and counting function, the MCP gain is set to 3300, set to external trigger mode, the trigger frequency is 20kHz, and the trigger level threshold is set to 0.5V; the gate delay is set to 46ns, and the optical gate width is set to 3ns; the camera shooting frame rate is 98 frames per second, the single exposure time is 10ms, and at the current trigger frequency, the camera on-chip integration times are set to the maximum value of 160.

[0062] The gypsum crystal sample 400 was 10 cm away from the focusing lens; the indoor ambient light was not shielded during the acquisition process; the results of the shooting showed a significant calcium sulfate Raman characteristic peak, such as Figure 3 As shown, the horizontal axis in the figure is the Raman shift, the unit is cm^-1 (per centimeter), and the vertical axis is the Raman signal intensity, which is the relative intensity; Figure 3 The characteristic peaks shown in the figure are the Raman characteristic peaks of calcium sulfate. When conventional Raman probes collect signals under ambient light, the calcium sulfate Raman characteristic peaks are often submerged by ambient noise, and the main characteristic peaks displayed are the main characteristic peaks of gypsum. When the gated Raman technology is used, the relative positions and relative intensities of these relatively weak characteristic peaks (calcium sulfate Raman characteristic peaks) are basically correct, highlighting the adaptability of the gated Raman probe to environments with background radiation such as daytime indoor environments.

[0063] In summary, the portable gated Raman probe and Raman spectrum acquisition device provided by the present invention integrate the laser 110 in the probe, and transmit the laser beam emitted by the laser 110 to the converging lens 170 after performing optical path adjustment, optical signal expansion and optical signal attenuation through the transmitting optical path component, so as to optimize the performance of the laser beam; the optical path reflection adjustment unit 120 uses multiple mirrors to adjust the propagation direction of the laser beam, so that the laser beam is folded in space to form a folded optical path to compress the optical path space, thereby reducing the volume of the probe for easy carrying.

[0064] Furthermore, the position of the fifth lens 171 of the converging lens 170 of the present invention can be adjusted in a small range by a focus ring to achieve the adjustment of the focus of the laser emitted by the probe.

[0065] Furthermore, the present invention obtains the laser beam and synchronously outputs an electrical signal through the active amplified photodetector 112, thereby getting rid of the dependence on external triggering of a specific laser.

[0066] Furthermore, the Raman probe of the present invention only needs to connect the optical fiber 185 and the cable 113 for transmitting the output electrical signal of the photodetector to the gated spectrum acquisition device 200. The installation and configuration are simple. The Raman probe 100 cooperates with the gated spectrum acquisition device 200 for high-precision synchronization, and the shutter can be opened only at the moment when the pulse of the laser scattering signal arrives. Within the gate width of the nanosecond order, the intensity of the laser scattering signal is much higher than the indoor ambient light, thereby achieving effective suppression of the background and obtaining a high signal-to-noise ratio Raman spectrum with a near-zero background. Continuous backgrounds such as ambient light can be suppressed.

[0067] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the present disclosure, even when only a single embodiment is described with respect to specific features. The feature examples provided in the present disclosure are intended to be illustrative rather than limiting, unless otherwise stated. In specific implementations, the technical features of one or more dependent claims may be combined with the technical features of the independent claim, based on actual needs and where technically feasible, and may be derived from the technical features of the corresponding independent claim in any appropriate manner rather than simply through the specific combination listed in the claims.

[0068] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A portable gated Raman probe, characterized in that: include: A laser for emitting a laser beam; An active amplified photodetector, used to acquire the laser beam emitted by the laser and synchronously output an electrical signal; An emission optical path component is used to adjust the optical path of the laser beam emitted by the laser, expand the optical signal and attenuate the optical signal, and then transmit it to the converging lens, and at least includes an optical path reflection adjustment unit, a shaping and expanding unit and an attenuation unit; A converging lens is used to converge the laser beam processed by the emission optical path component to the sample to be tested, and to converge the light signal scattered and returned by the sample to be tested to the collection optical path component; A collecting optical path component is used to filter and process the optical signal collected by the converging lens and then output it, wherein the collecting optical path component and the converging lens form a confocal optical path; Among them, the optical path reflection adjustment unit includes a plurality of reflectors, and the plurality of reflectors are used to adjust the propagation direction of the laser light beam so that the laser light beam is spatially folded to form a folded optical path to compress the optical path space. The shaping and expanding unit and the attenuation unit are both arranged on the folded optical path. The shaping and expanding unit includes at least two lenses for outputting a light beam with a set magnification; the attenuation unit includes a half-wave plate and a polarization beam splitter prism for outputting a light beam with a set attenuation ratio.

2. The portable gated Raman probe according to claim 1, characterized in that: A first reflector is provided at the front end of the laser, and part of the laser beam emitted by the laser is incident on the active amplifying photodetector through the first reflector. The active amplifying photodetector synchronously outputs an electrical signal after acquiring the laser beam; another part of the laser beam emitted by the laser is reflected by the first reflector to the optical path reflection adjustment unit of the emitting optical path component.

3. The portable gated Raman probe according to claim 1, characterized in that: The optical path reflection adjustment unit includes a second reflector, a third reflector, a fourth reflector and a fifth reflector arranged in sequence along the folded optical path, the second reflector and the third reflector as well as the fourth reflector and the fifth reflector are arranged in parallel respectively; the third reflector and the fourth reflector are arranged symmetrically.

4. The portable gated Raman probe according to claim 1, characterized in that: The shaping and expanding unit includes at least a first lens and a second lens, wherein the first lens is a short focal length lens, which is a concave lens or a convex lens, and is used to diverge a nearly parallel laser light beam; the second lens is a long focal length convex lens, and is used to converge the divergent light beam into parallel light; the shaping and expanding unit obtains a light beam with a set magnification by matching the focal lengths of the first lens and the second lens, and improves the parallelism of the light beam.

5. The portable gated Raman probe according to claim 1, characterized in that: The attenuation unit is arranged behind the shaping and expanding unit on the folded optical path; the half-wave plate is a polarizer, which is used to adjust the polarization direction of the laser light beam, and the polarization direction of the laser light input to the polarization beam splitter prism is changed by rotating the half-wave plate, thereby changing the proportion of the polarization component of the laser light input to the polarization beam splitter prism; the polarization beam splitter prism is an analyzer, which is used to decompose the laser light beam into two components of horizontal polarized light and vertical polarized light; the laser light beam outputs two beams of horizontal polarized light and vertical polarized light with adjustable light intensity through the half-wave plate and the polarization beam splitter prism, and one of the horizontal polarized light and the vertical polarized light is selected as the output light beam.

6. The portable gated Raman probe according to claim 1, characterized in that: The emission optical path component also includes a spatial filtering unit, which is arranged behind the attenuation unit on the optical path. The spatial filtering unit includes a third lens, a pinhole and a fourth lens arranged in sequence, and the third lens and the fourth lens are convex lenses with the same parameters; the pinhole is a pinhole aperture or an optical pinhole; the laser beam is spatially Fourier transformed through the third lens, and the wave vector distribution of the laser is obtained in the focal plane of the third lens; a specific wave vector is screened in the focal plane through the pinhole; and the beam is restored through the fourth lens.

7. The portable gated Raman probe according to claim 1, characterized in that: The emission optical path component also includes a first filter, which is arranged behind the attenuation unit on the optical path. The first filter is a narrow bandpass filter. The first filter performs bidirectional filtering to filter stray light in the laser beam to obtain a laser beam with high wavelength consistency, while preventing the scattered light signals converged by the converging lens from returning to the emission optical path component again through the collecting optical path component.

8. The portable gated Raman probe according to claim 1, characterized in that: The converging lens includes at least a fifth lens, which is used to converge the parallel laser to a focal point, and at the same time, converge the light signal scattered and returned by the sample to be tested at the focal position into parallel light through the fifth lens and enter the collecting light path component; the converging lens is provided with a focusing ring, and the focusing ring is used to adjust the position of the fifth lens.

9. The portable gated Raman probe according to claim 1, characterized in that: The collecting optical path component includes a dichroic mirror, a second filter and a sixth lens. The laser beam output by the emitting optical path component is reflected by the dichroic mirror and then output through the converging lens. The light signal scattered and returned by the sample to be tested is collected by the converging lens. The dichroic mirror filters the scattered light signal collected by the converging lens, and after secondary filtering through the second filter, it is converged to a focus through the sixth lens and coupled into the optical fiber output through the optical fiber signal port.

10. A Raman spectrum acquisition device, characterized in that: It comprises a Raman probe, a gated spectrum acquisition device and a control and data processing device, wherein the Raman probe adopts the portable gated Raman probe as described in any one of claims 1 to 9, the Raman probe is connected to the gated spectrum acquisition device, and the gated spectrum acquisition device is connected to the control and data processing device.

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