Dual-wavelength laser Raman spectrum experimental instrument
By designing a dual-wavelength laser Raman spectroscopy experimental instrument, with an open casing structure and multiple wavelength lasers, the problem of limited teaching content in existing technologies has been solved, and students' understanding of the internal structure of the instrument and their ability to analyze experimental results has been improved.
Patent Information
- Application Number
- CN202520134354.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-20
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2035-01-20
AI Technical Summary
The existing laser Raman spectrometers used for experimental teaching have a closed structure and use a single wavelength excitation source, which limits the teaching content and effectiveness. Students find it difficult to understand the internal structure of the instrument and the influence of different wavelengths on the experimental results.
Design a dual-wavelength laser Raman spectroscopy experimental instrument, including an external optical path system, a monochromator, and a photodetector. It is equipped with an opening in the casing and a flip cover, and has two lasers of different wavelengths, allowing students to manually switch the excitation wavelength and access the components in the external optical path system through the flip cover, thereby enhancing the interactivity of teaching.
It improves teaching effectiveness, enabling students to verify that Raman shift is independent of excitation wavelength, understand the advantages and disadvantages of different wavelengths, enhance scattered light intensity, improve signal-to-noise ratio, reduce fluorescence effects, and enhance the teaching experience.
Smart Images
Figure CN223955421U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to experimental teaching instrument technical field more specifically, relate to a kind of double-wavelength laser raman spectrum experimental instrument. BACKGROUND
[0002] Laser Raman spectrum experimental instrument can be used to analyze sample chemical composition, crystal structure, molecular orientation and intermolecular interaction information, and is widely used in petroleum, material, chemical industry, environmental protection, food, biology and geology and multiple fields.Currently, many colleges and universities have opened the teaching of "laser Raman spectrum" experiment of physics and chemistry and the like, and the experimental teaching equipment generally selects portable Raman spectrometer, such as a handheld Raman spectrum analyzer disclosed in the prior art, which is provided with a handle on the left side or right side of the box; a holding sensor is mounted on the outer side of the handle, and a trigger button is mounted at the fingertip when holding on the lower side or inner side of the handle; the handle is fixed on the same side of the box at both ends.
[0003] However, the same as the above prior art, the experimental instrument currently used for teaching basically integrates all components into a case to ensure the performance and stability of the instrument, and students can only test several samples as users of the instrument, so it is difficult for them to fully understand the structure inside the instrument and master the essentials of instrument adjustment.In addition, the Raman spectrometer currently used for experimental teaching is mostly single-wavelength, i.e., only one laser is provided as excitation light source, which causes some limitations to the design of experimental teaching content.For example, it is impossible to perform multi-wavelength comparison experiment, and students cannot study the difference in response of samples to different excitation wavelengths.In addition, some samples may show strong fluorescence background at this wavelength, which will mask the Raman signal, resulting in inaccurate experimental results. SUMMARY
[0004] In view of the problem that the laser Raman spectrum experimental instrument used for experimental teaching in the above prior art is of closed structure and adopts single-wavelength excitation light source, resulting in limited teaching content and teaching effect, the utility model provides a double-wavelength laser Raman spectrum experimental instrument, which can enable students to fully understand the internal structure of the instrument and the influence of different wavelength excitation light sources on experimental results, and improve the teaching effect.
[0005] To solve the above technical problems, the technical scheme provided by the utility model is:
[0006] The application discloses a dual-wavelength laser Raman spectrum experimental instrument, which comprises an external light path system, a monochromator and a photoelectric detector, the emitting end of the external light path system is connected with the receiving end of the monochromator, and the emitting end of the monochromator is connected with the receiving end of the photoelectric detector; the external light path system comprises a casing provided with a light path propagation cavity and a first laser, a long-pass filter, a first diaphragm, a second diaphragm, a short-focus achromatic lens, a sample stage and a long-focus achromatic lens which are all arranged in the light path propagation cavity; the instrument further comprises a second laser, a first reflector, a second reflector, a third reflector and an inclined hole reflector; the inclined hole reflector is located between the first diaphragm and the second diaphragm, the laser beam of the first laser passes through the first reflector, the long-pass filter, the first diaphragm, the inclined hole reflector, the second diaphragm, the short-focus achromatic lens, the inclined hole reflector and the sample stage in sequence, and the backscattering light beam generated by the sample on the sample stage under excitation of the laser passes through the short-focus achromatic lens, the second diaphragm, the inclined hole reflector and the long-focus achromatic lens in sequence; the wavelength of the second laser is longer than that of the first laser, and the laser beam of the second laser passes through the second reflector, the third reflector and the long-pass filter in sequence and then propagates in line with the laser beam of the first laser; the casing is provided with an opening which is in communication with the light path propagation cavity, and a flip cover is arranged on the opening.
[0007] When the above technical scheme is used, the sample is placed on the sample stage, and the student can open the first laser and / or the second laser according to needs. When the first laser is opened, the laser beam emitted by the first laser is reflected on the long-pass filter through the first reflector and then passes through the first diaphragm, the inclined hole reflector, the second diaphragm, the short-focus achromatic lens, the inclined hole reflector and the sample on the sample stage in sequence. The laser beam emitted by the second laser is reflected on the third reflector through the second reflector and then reflected on the long-pass filter through the third reflector and propagates in line with the laser beam of the first laser. The backscattering light generated by the sample under excitation of the laser beam is collimated into a parallel light beam after passing through the short-focus achromatic lens, passes through the second diaphragm which is opened, is reflected by the inclined hole reflector to change the direction (about 4% of the scattering light is lost through the small hole), is focused into the monochromator through the long-focus achromatic lens and enters the receiving end of the monochromator, that is, the entrance slit of the monochromator. The scattering light entering the monochromator is spread by the holographic grating and then focused out of the exit slit and is received by the photoelectric detector. The Raman spectrum of the sample to be measured can be scanned and recorded by rotating the grating in the monochromator under the control of a computer program.
[0008] The technical scheme has the following beneficial effects: the opening and the flip cover are arranged on the shell, so that the student can contact each element in the external light path system by opening the flip cover, and fully understand the layout of the experimental instrument and the function of each component. Moreover, the two lasers with different wavelengths are arranged, so that the student can switch the excitation wavelength of the Raman scattering spectrum through the computer program. On the one hand, the student can verify that the Raman shift is irrelevant to the excitation wavelength, and is only related to the structure of the vibration and rotation energy level of the sample to be measured. On the other hand, the student can verify that the selection of different excitation wavelengths has advantages and disadvantages. For example, some samples will generate a strong fluorescence signal background under excitation at a certain wavelength, so that the Raman peak signal is covered or the contrast is greatly reduced. Switching to another wavelength to excite the sample can weaken or eliminate the influence of fluorescence.
[0009] Preferably, the light path propagation cavity is provided with a concave mirror, and the sample stage is located between the concave mirror and the short-focus achromatic lens. If the sample to be measured is a transparent liquid, forward scattering light will also be generated when the sample is excited by the laser. The forward scattering light will pass through the liquid sample and be reflected back by the concave mirror, and then be focused on the original focus point of the sample again, and coincide with the propagation path of the backscattering light. At the same time, the remaining laser beam that passes through the transparent sample is also reflected back by the concave mirror and excites the sample again. The newly generated scattering light also coincides with the above-mentioned scattering light, and is finally focused on the entrance slit of the monochromator through the long-focus achromatic lens. Therefore, the intensity of the scattering light can be significantly increased. The remaining laser beam reflected back is also collimated by the short-focus achromatic lens, and because the beam diameter is small, the remaining laser beam will directly pass through the inclined hole mirror and the first diaphragm without being reflected to the direction of the entrance slit of the monochromator. Therefore, the concave mirror can enhance the intensity of the scattering light.
[0010] Preferably, the light path propagation cavity is provided with a first bidirectional translation stage and a unidirectional translation stage, the first bidirectional translation stage comprises a first slider and a second slider, the first slider is in sliding connection with the bottom of the light path propagation cavity, the second slider is in sliding connection with the first slider, the sliding directions of the first slider and the second slider are perpendicular to each other, and the sliding direction of one of the two is in the extension direction of the line connecting the first light barrier and the second light barrier; the sample stage is installed on the second slider; the unidirectional translation stage is in sliding connection with the bottom of the light path propagation cavity, the sliding direction of the unidirectional translation stage is in the extension direction of the line connecting the first light barrier and the second light barrier, and the concave mirror is installed on the unidirectional translation stage. Students can adjust the position of the sample on the sample stage by sliding the first slider and the second slider, so as to focus the laser beam on the sample. At the same time, the position of the concave mirror can be adjusted by sliding the unidirectional translation stage, so as to reflect the forward scattering light passing through the transparent liquid sample back to coincide with the back scattering light, and also reflect the remaining laser back to excite the sample again, thereby significantly enhancing the overall intensity of the scattered light and improving the signal-to-noise ratio of the Raman spectrum measurement.
[0011] Preferably, the light path propagation cavity is provided with a second bidirectional translation stage and a white screen plug-in board, the second bidirectional translation stage comprises a third slider and a fourth slider, the third slider is in sliding connection with the bottom of the light path propagation cavity, the fourth slider is in sliding connection with the third slider, the sliding directions of the fourth slider and the third slider are perpendicular to each other, and the sliding direction of one of the two is in the extension direction of the line connecting the inclined hole mirror and the monochromator receiving end; the long focal length achromatic lens is installed on the fourth slider; the white screen plug-in board is detachably connected with the fourth slider and is located between the trap filter and the long focal length achromatic lens, and a plurality of concentric circle structures are arranged on the side of the white screen plug-in board close to the trap filter, and the diameter of at least one of the concentric circle structures is equal to the clear aperture diameter of the short focal length achromatic lens. The second bidirectional translation stage is used to adjust the position of the long focal length achromatic lens so as to focus the scattered light into the entrance slit of the monochromator. The first bidirectional translation stage is carefully adjusted to adjust the focusing of the laser beam on the sample, until the scattered light reflected on the white screen plug-in board just fills the concentric circle structure with a diameter equal to the clear aperture diameter of the short focal length achromatic lens, at which time it can be determined that the scattered light is a collimated parallel light beam, and it also indicates that the focal point of the laser beam is just at the sample. When measuring a solid sample, the above method can be directly used to adjust the focusing of the laser beam to the surface of the sample. When measuring a liquid sample, a piece of white paper or film can be inserted into the empty cuvette, and then the cuvette is placed on the sample stage, so as to adjust the focusing of the laser beam and the collimation of the scattered light.
[0012] When the sample is solid, it is inconvenient to place and fix the sample vertically, especially for the case of powder sample. Therefore, preferably, the sample stage comprises a solid support plate and a fourth mirror, the solid support plate is detachably connected with the second slide; the fourth mirror is detachably connected with the solid support plate, the fourth mirror is provided with a sample groove, and the mirror surface of the fourth mirror is at least partially located above the sample groove and forms a 45° angle with the top surface of the solid support plate. The laser beam focused by the short focal length achromatic lens is reflected vertically downward by the fourth mirror to the solid (powder or flake) sample on the solid support plate, and careful adjustment of the first two-way translation stage can make the focal point of the laser located on the surface of the sample. The backscattered light generated thereby is collimated into parallel light after the fourth mirror and the short focal length achromatic lens, and is guided to the entrance slit of the monochromator, at this time the concave mirror is blocked by the fourth mirror and does not play a role.
[0013] Preferably, a notch filter is detachably installed in the optical path propagation cavity, and the notch filter is located between the inclined hole mirror and the long focal length achromatic lens. The notch filter can weaken the background noise formed by Rayleigh scattering light in the monochromator. The student can manually replace the notch filter matched with the wavelength of the first laser or the second laser, so as to weaken the background noise formed by Rayleigh scattering light in the monochromator.
[0014] Preferably, a polarizer and an analyzer are arranged in the optical path propagation cavity, the polarizer is located between the first diaphragm and the inclined hole mirror and is rotatably inserted into the bottom of the optical path propagation cavity, and the analyzer is located between the notch filter and the long focal length achromatic lens and is rotatably inserted into the bottom of the optical path propagation cavity. If it is necessary to measure the depolarization ratio of Raman spectrum, the polarizer and the analyzer are inserted into the optical path, and then the Raman spectrum of the sample to be measured under the conditions that the polarization directions of the polarizer and the analyzer are parallel to each other and perpendicular to each other is scanned and recorded respectively, and the symmetry of the vibration mode corresponding to each Raman peak is judged by calculating the depolarization ratio of each Raman peak of the sample to be measured.
[0015] Preferably, the sample stage comprises a liquid support plate and a cuvette holder, the liquid support plate is detachably connected with the second slide; the cuvette holder is placed on the top of the liquid support plate, the cuvette holder is provided with a containing cavity and a side window, the containing cavity is provided with a cuvette insertion slot at the bottom, and the containing cavity is communicated to the outside of the cuvette holder through the side window. When the liquid sample is to be measured during the experiment, the liquid support plate is first mounted on the second slide, then the cuvette containing the sample to be measured is inserted into the cuvette insertion slot, and then the position of the laser beam focused on the sample is adjusted by adjusting the second two-way translation stage, and the laser beam can be injected into the cuvette through the side window.
[0016] Preferably, the optical path propagation cavity is provided with an element rack.
[0017] Preferably, a push rod is arranged at the receiving end of the monochromator, the push rod is in sliding connection with the monochromator, the sliding direction of the push rod is perpendicular to the extension direction of the line connecting the long-focus achromatic lens and the receiving end of the monochromator, and a photoelectric probe is arranged on the push rod.
[0018] The utility model discloses the beneficial effect that:
[0019] 1. It is favorable to improve the teaching effect. The cover is arranged on the casing, and students can contact each element in the external optical path system through the cover, and fully understand the layout of the experimental instrument and the function of each component. Moreover, the two laser devices with different wavelengths are arranged, so that students can manually switch the excitation wavelength of the Raman scattering spectrum. On the one hand, students can verify that the Raman shift is irrelevant to the excitation wavelength, and is only related to the structure of the vibration and rotation energy level of the sample to be measured. On the other hand, students can verify that the selection of different excitation wavelengths has advantages and disadvantages. For example, some samples may generate a strong fluorescence signal background under excitation of a certain wavelength, so that the Raman peak signal is covered or the contrast is greatly reduced. By switching to another wavelength to excite the sample, the influence of fluorescence can be weakened or eliminated.
[0020] 2. A concave mirror is arranged beside the sample stage and mounted on the unidirectional translation stage. By adjusting the mirror and the unidirectional translation stage, the forward scattering light passing through the transparent liquid sample can be reflected back to coincide with the backscattering light, and the remaining laser light can also be reflected back to excite the sample again, so that the overall intensity of the scattering light can be significantly enhanced, and the signal-to-noise ratio of the Raman spectrum measurement can be improved.
[0021] 3. The white screen plugboard can assist in focusing adjustment of the sample stage. By adjusting the first bidirectional translation stage on which the sample stage is arranged, the scattering light can be determined to be collimated parallel light when the scattering light just fills the concentric circle structure of the white screen plugboard.
[0022] 4. A movable photoelectric probe is arranged behind the entrance slit of the monochromator. By arranging the photoelectric probe in the optical path, the collection of the scattering light can be optimized to improve the signal strength of the Raman spectrum as much as possible. BRIEF DESCRIPTION OF DRAWINGS
[0023] Figure 1is a structural schematic diagram of a dual-wavelength laser Raman spectrum experimental instrument, wherein the arrows represent the directions of light beam propagation or structural movement;
[0024] Figure 2 is a structural schematic diagram of a first bidirectional translation stage;
[0025] Figure 3 is a structural schematic diagram of the white screen plugboard in one of the viewing angles;
[0026] Figure 4 is a structural schematic diagram of the white screen plugboard in another viewing angle;
[0027] Figure 5 is a structural schematic diagram of the sample stage in Example 2;
[0028] Figure 6 is a structural schematic diagram of the solid support plate;
[0029] Figure 7 is a structural schematic diagram of the fourth mirror after being detached from the solid support plate;
[0030] Figure 8 is a structural schematic diagram of the fourth mirror;
[0031] Figure 9 is a structural schematic diagram of the sample stage in Example 3.
[0032] In the drawings: 1-monochromator; 2-photoelectric detector; 3-casing; 301-optical path propagation cavity; 4-first laser; 5-long-pass filter; 6-first diaphragm; 7-second diaphragm; 8-short-focus achromatic lens; 9-sample stage; 901-solid support plate; 9011-sample groove; 9012-third slot; 902-fourth mirror; 903-second pin; 904-third pin; 905-liquid support plate; 906-cuvette holder; 9061-receiving cavity; 9062-side window; 9063-cuvette slot; 907-fourth pin; 10-long-focus achromatic lens; 11-second laser; 12-first mirror; 13-second mirror; 14-third mirror; 15-beveled hole mirror; 16-concave mirror; 17-first bidirectional translation stage; 1701-first slider; 1702-second slider; 1703-second slot; 18-unidirectional translation stage; 19-second bidirectional translation stage; 20-white screen plugboard; 2001-first pin; 2002-concentric structure; 21-trap filter; 22-polarizer; 23-analyzer; 24-element holder; 25-photoelectric probe; 26-incidence slit. DETAILED DESCRIPTION
[0033] The drawings are only used for illustrative description, and cannot be understood as limitation to the patent; in order to better illustrate the embodiments, some components in the drawings can be omitted, enlarged or reduced, and do not represent the size of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings can be omitted. The positional relationship described in the drawings is only used for illustrative description, and cannot be understood as limitation to the patent.
[0034] The same or similar reference numerals in the drawings of the embodiments of the present application correspond to the same or similar components; in the description of the present application, it is understood that if the terms "upper", "lower", "left", "right", "long" and "short" indicate the orientation or positional relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, therefore the terms describing the positional relationship in the drawings are only used for illustrative description, and cannot be understood as limitation to the patent, for those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.
[0035] The technical scheme of the present application will be further described in detail below through specific embodiments, and in combination with the drawings:
[0036] Embodiment 1
[0037] This embodiment is a first embodiment of a dual-wavelength laser Raman spectrum experimental instrument, as shown in Figure 1As shown, it comprises an external optical path system, a monochromator 1 and a photodetector 2, the emission end of the external optical path system is connected with the receiving end of the monochromator 1, and the emission end of the monochromator 1 is connected with the receiving end of the photodetector 2; the external optical path system comprises a casing 3 provided with an optical path propagation cavity 301 and a first laser 4, a long-pass filter 5, a first diaphragm 6, a second diaphragm 7, a short-focus achromatic lens 8, a sample stage 9 and a long-focus achromatic lens 10 all arranged in the optical path propagation cavity 301; the instrument further comprises a second laser 11, a first mirror 12, a second mirror 13, a third mirror 14 and a slotted mirror 15; the slotted mirror 15 is located between the first diaphragm 6 and the second diaphragm 7, the laser beam of the first laser 4 passes through the first mirror 12, the long-pass filter 5, the first diaphragm 6, the slotted mirror 15, the second diaphragm 7, the short-focus achromatic lens 8 and the sample stage 9 in sequence, and the backscattered light beam generated by the sample on the sample stage 9 excited by the laser beam passes through the short-focus achromatic lens 8, the second diaphragm 7, the slotted mirror 15 and the long-focus achromatic lens 10 in sequence; the wavelength of the second laser 11 is longer than that of the first laser 4, and the laser beam of the second laser 11 passes through the second mirror 13, the third mirror 14 and the long-pass filter 5 in sequence and propagates collinearly with the laser beam of the first laser 4; the top of the casing 3 is provided with an opening communicating with the optical path propagation cavity 301, and a flip cover (not shown in the figure) is arranged on the opening.
[0038] Specifically, the first diaphragm 6 and the second diaphragm 7 are fixedly installed in the optical path propagation cavity 301 to serve as the reference for adjusting the laser beam.
[0039] Specifically, the embodiment adopts a high-sensitivity single-photon counter type photomultiplier tube as the photodetector 2 to receive the Raman spectrum signal of the sample to be measured.
[0040] Specifically, two narrow-line-width lasers with a line width ≤0.2nm are selected as the first laser 4 and the second laser 11. The wavelengths of the two lasers can be optional. It is recommended to select commonly used semiconductor lasers or solid-state lasers, such as selecting two from the following wavelengths: 405nm, 450nm, 520nm, 532nm, 650nm, 785nm and 808nm.
[0041] Further, a notch filter 21 is detachably installed in the optical path propagation cavity 301, and the notch filter 21 is located between the slotted mirror 15 and the long-focus achromatic lens 10. The notch filter 21 can weaken the background noise formed by Rayleigh scattering light in the monochromator 1. Students can manually replace the notch filter 21 matched with the wavelength of the first laser 4 or the second laser 11, so as to weaken the background noise formed by Rayleigh scattering light in the monochromator 1.
[0042] Further, the light path propagation cavity 301 is provided with a polarizer 22 and an analyzer 23, the polarizer 22 is located between the first diaphragm 6 and the inclined hole mirror 15 and rotatably inserted into the bottom of the light path propagation cavity 301, and the analyzer 23 is located between the wave filter 21 and the long-focus achromatic lens 10 and rotatably inserted into the bottom of the light path propagation cavity 301. If it is necessary to measure the depolarization ratio of the Raman spectrum, the polarizer 22 and the analyzer 23 can be inserted into the light path, and then the Raman spectrum of the sample to be measured under the condition that the polarization directions of the polarizer 22 and the analyzer 23 are parallel to each other and orthogonal to each other are scanned and recorded respectively, and the symmetry of the vibration mode corresponding to each Raman peak is judged by calculating the depolarization ratio of each Raman peak of the sample to be measured.
[0043] Further, the light path propagation cavity 301 is provided with an element rack 24. The elements switched off during the experiment can be placed on the element rack 24.
[0044] Further, the receiving end of the monochromator 1 is provided with a push rod (not shown in the figure), the push rod is in sliding connection with the monochromator 1, the sliding direction of the push rod is perpendicular to the extension direction of the line connecting the long-focus achromatic lens 10 and the receiving end of the monochromator 1; the push rod is provided with a photoelectric probe 25. By sliding the push rod to push the photoelectric probe 25 to the rear position of the incident slit 26, and then adjusting the second bidirectional translation stage 19 to focus the scattered light into the incident slit 26 of the monochromator 1, the reading of the photoelectric probe 25 is monitored to the maximum value by using the computer program, and then the photoelectric probe 25 is moved away and the scattered light passes through, which can optimize the collection of the scattered light, so as to improve the signal strength of the Raman spectrum as much as possible.
[0045] The working principle or workflow of the present embodiment: when implemented, the sample is placed on the sample stage 9, and the student can turn on the first laser 4 and / or the second laser 11 as needed. When the first laser 4 is turned on, the laser beam emitted by the first laser 4 is first reflected by the first mirror 12 on the long-pass filter 5, and then sequentially passes through the first diaphragm 6, the oblique hole mirror 15, the second diaphragm 7, the short-focus achromatic lens 8, the oblique hole mirror 15 and the sample on the sample stage 9. The laser beam emitted by the second laser 11 is first reflected by the second mirror 13 to the third mirror 14, and then reflected by the third mirror 14 to the long-pass filter 5 to propagate in the same line with the laser beam of the first laser 4. The backscattered light generated by the laser beam exciting the sample is collimated into a parallel light beam after passing through the short-focus achromatic lens 8, and then passes through the second diaphragm 7 which is turned on, and then changes direction by reflection of the oblique hole mirror 15 (about 4% of the scattered light will be lost through the small hole), and then is focused by the long-focus achromatic lens 10 into the receiving end of the monochromator 1, that is, the entrance slit 26 of the monochromator 1, after passing through the notch filter 21. The scattered light entering the monochromator 1 area is spectrally spread by the holographic grating, and then focused out of the exit slit, and then received by the photodetector 2. The grating inside the monochromator 1 is controlled by the computer program to rotate, so as to scan and record the Raman spectrum of the sample to be measured.
[0046] The present embodiment has the beneficial effect of improving the teaching effect. The opening and the flip cover are arranged on the casing, and the student can touch each element in the external optical path system by opening the flip cover, and fully understand the layout of the experimental instrument and the function of each component. Moreover, since two lasers with different wavelengths are arranged, the student can manually switch the excitation wavelength of the Raman scattering spectrum, on the one hand, the student can verify that the Raman shift is independent of the excitation wavelength, and only related to the structure of the vibration and rotation energy level of the sample to be measured; on the other hand, it can be verified that the selection of different excitation wavelengths has advantages and disadvantages, for example, some samples may produce a strong fluorescence signal background under a certain wavelength excitation, so that the Raman peak signal is covered or the contrast is greatly reduced, and switching to another wavelength to excite the sample can weaken or eliminate the influence of fluorescence.
[0047] Embodiment 2
[0048] This embodiment is a second embodiment of a dual-wavelength laser Raman spectroscopy experimental instrument. This embodiment is similar to Embodiment 1, except that a concave mirror 16 is provided inside the optical path propagation cavity 301, and the sample stage 9 is located between the concave mirror 16 and the short-focal-length achromatic lens 8. If the sample to be tested is a transparent liquid, it will generate forward-scattered light when excited by the laser. This forward-scattered light will pass through the liquid sample and be reflected back by the concave mirror 16, refocusing onto the original focal point of the sample and coinciding with the propagation path of the aforementioned backscattered light. Simultaneously, the remaining laser beam passing through the transparent sample is also reflected back by the concave mirror 16 and re-excites the sample. The newly generated scattered light will also coincide with the aforementioned scattered light, ultimately being focused by the long-focal-length achromatic lens 10 onto the entrance slit 26 of the monochromator 1, thus significantly increasing the intensity of the scattered light. The reflected remaining laser beam is also collimated by the short-focal-length achromatic lens 8. Due to its smaller beam diameter, it will directly pass through the oblique-aperture mirror 15 and the first aperture 6 without being reflected towards the entrance slit 26 of the monochromator 1. Therefore, the concave reflector 16 can enhance the intensity of scattered light.
[0049] Furthermore, the optical path propagation cavity 301 is provided with a first bidirectional translation stage 17 and a unidirectional translation stage 18, combined with Figure 1 and Figure 2 As shown, the first bidirectional translation stage 17 includes a first slider 1701 and a second slider 1702. The first slider 1701 is slidably connected to the bottom of the optical path propagation cavity 301, and the second slider 1702 is slidably connected to the first slider 1701. The sliding directions of the first slider 1701 and the second slider 1702 are perpendicular to each other, and the sliding direction of one of them is along the extension direction of the line connecting the first aperture 6 and the second aperture 7. The sample stage 9 is mounted on the second slider 1702. The unidirectional translation stage 18 is slidably connected to the bottom of the optical path propagation cavity 301. The sliding direction of the unidirectional translation stage 18 is along the extension direction of the line connecting the first aperture 6 and the second aperture 7. The concave mirror 16 is mounted on the unidirectional translation stage 18. Students can adjust the position of the sample on the sample stage 9 by sliding the first slider 1701 and the second slider 1702, thereby focusing the laser beam onto the sample. Simultaneously, the position of the concave reflector 16 can be adjusted by sliding the unidirectional translation stage 18, thereby reflecting the forward scattered light passing through the transparent liquid sample back to coincide with the backscattered light, and also reflecting the remaining laser back to excite the sample again, thus significantly enhancing the overall intensity of the scattered light and improving the signal-to-noise ratio of Raman spectroscopy measurements.
[0050] Furthermore, combined Figure 1 , Figure 3 and Figure 4 As shown, the optical path propagation cavity 301 is equipped with a second bidirectional translation stage 19 and a white screen insert plate 20. The structure of the second bidirectional translation stage 19 can be found in [reference needed]. Figure 2The structure of the first bidirectional translation stage 17 includes a third slider and a fourth slider. The third slider is in sliding connection with the bottom of the light path propagation cavity 301. The fourth slider is in sliding connection with the third slider. The sliding direction of the fourth slider is perpendicular to that of the third slider. The sliding direction of one of the two is in the extension direction of the line connecting the inclined hole mirror 15 and the receiving end of the monochromator 1. The long-focus achromatic lens 10 is installed on the fourth slider. The white screen plug-in board 20 is in detachable connection with the fourth slider and is located between the wave filter 21 and the long-focus achromatic lens 10. Three concentric circle structures 2002 are arranged on the side of the white screen plug-in board 20 close to the wave filter 21. The diameter of the concentric circle structure 2002 in the middle is equal to the light passing diameter of the short-focus achromatic lens 8. Specifically, the top of the fourth slider is provided with two first insertion slots. The bottom of the white screen plug-in board 20 is provided with two first insertion pins 2001. The first insertion pins 2001 are inserted into the first insertion slots one by one. In the implementation, the white screen plug-in board 20 can be inserted on the fourth slider of the second bidirectional translation stage 19 and located in front of the long-focus achromatic lens 10 (at this time, the wave filter 21 is removed). Then, the first bidirectional translation stage 17 is carefully adjusted until the scattered light reflected on the white screen plug-in board 20 just fills the concentric circle structure 2002. At this time, it can be determined that the scattered light is a collimated parallel light beam at this time, which also indicates that the focal point of the laser beam is just at the sample. When measuring a solid sample, the above method can be directly used to adjust the laser focusing to the sample surface. When measuring a liquid sample, a piece of white paper or film can be inserted into the empty cuvette, and then the cuvette is placed on the sample stage 9, so as to adjust the focusing of the laser beam and the collimation of the scattered light.
[0051] When the sample is a solid, it is not very convenient to vertically place and fix the sample, especially for the case of a powder sample. Therefore further, in combination with Figure 1 、 Figure 2 and Figures 5 to 8As shown, the sample stage 9 comprises a solid support plate 901 and a fourth mirror 902, the solid support plate 901 is detachably connected with the second sliding block 1702; the fourth mirror 902 is detachably connected with the solid support plate 901, the fourth mirror 902 is provided with a sample groove 9011, and a part of the mirror surface of the fourth mirror 902 is located directly above the sample groove 9011 and forms a 45° angle with the top surface of the solid support plate 901. Specifically, the second sliding block 1702 is provided with four second insertion grooves 1703, the bottom of the solid support plate 901 is provided with four second insertion pins 903, and the second insertion pins 903 are inserted into the second insertion grooves 1703 one by one; the top of the solid support plate 901 is provided with two third insertion grooves 9012, and the fourth mirror 902 is provided with two third insertion pins 904, which are inserted into the third insertion grooves 9012 one by one. The laser beam focused by the short-focus achromatic lens 8 is reflected vertically downward by the fourth mirror 902 to the solid powder or flaky sample on the solid support plate 901, and careful adjustment of the first bidirectional translation stage 17 can make the focal point of the laser located on the sample surface. The backscattered light generated thereby is collimated into parallel light after passing through the fourth mirror 902 and the short-focus achromatic lens 8, and is directed to the entrance slit 26 of the monochromator 1, at this time the concave mirror 16 will be blocked by the fourth mirror 902 and will not play a role. The sample stage 9 is inserted on the second sliding block 1702 through the third insertion pins 904, so that the sample stage 9 can be quickly replaced.
[0052] The other features, working principles and beneficial effects of this embodiment are consistent with those of embodiment 1.
[0053] Embodiment 3
[0054] This embodiment is a third embodiment of a dual-wavelength laser Raman spectrum experimental instrument, which is similar to embodiment 2, and the difference lies in that Figure 1 and Figure 9 As shown, the sample stage 9 comprises a liquid support plate 905 and a cuvette holder 906, the liquid support plate 905 is detachably connected with the second sliding block 1702; the cuvette holder 906 is placed on the top of the liquid support plate 905, the cuvette holder 906 is provided with a containing cavity 9061 and a side window 9062, the containing cavity 9061 is provided with a cuvette insertion groove 9063 at the bottom, and the containing cavity 9061 is communicated to the outside of the cuvette holder 906 through the side window 9062. Specifically, the second sliding block 1702 is provided with four fourth insertion grooves, the bottom of the liquid support plate 905 is provided with four fourth insertion pins 907, and the fourth insertion pins 907 are inserted into the fourth insertion grooves one by one. During the experiment, when a liquid sample needs to be measured, first, the liquid support plate 905 is inserted on the second sliding block 1702, then the cuvette containing the sample to be measured is inserted on the cuvette insertion groove 9063, and then the position of the laser beam focused on the sample is adjusted by adjusting the second bidirectional translation stage 19, and the laser beam can be injected into the cuvette through the side window 9062.
[0055] The other features, working principles and beneficial effects of this embodiment are consistent with those of embodiment 2.
[0056] In the specific contents of the above specific embodiments, each technical feature can be combined arbitrarily without contradiction, and in order to make the description simple, all possible combinations of the above technical features are not described, however, as long as the combination of these technical features does not exist contradiction, it should be considered as the scope of the description.
[0057] Obviously, the above embodiments of the utility model are only examples for clearly illustrating the utility model, and are not the limitation of the embodiments of the utility model. For ordinary skilled in the art, on the basis of the above description, other different forms of changes or changes can be made, here, all the embodiments need not and can not be exhausted. Any modification, equivalent replacement and improvement, etc. within the spirit and principle of the utility model, should be included in the protection scope of the claims of the utility model.
Claims
1. A dual-wavelength laser Raman spectrum experimental apparatus, comprising an external optical path system, a monochromator (1) and a photoelectric detector (2), the emission end of the external optical path system is connected with the receiving end of the monochromator (1), the emission end of the monochromator (1) is connected with the receiving end of the photoelectric detector (2); the external optical path system comprises a casing (3) provided with an optical path propagation cavity (301) and a first laser (4), a long-pass filter (5), a first diaphragm (6), a second diaphragm (7), a short-focus achromatic lens (8), a sample stage (9) and a long-focus achromatic lens (10) which are all arranged in the optical path propagation cavity (301); characterized in that, Also include second laser (11), first mirror (12), second mirror (13), third mirror (14) and oblique hole mirror (15), the oblique hole mirror (15) is located between the first diaphragm (6) and the second diaphragm (7), the laser beam of the first laser (4) passes through the first mirror (12), long pass filter (5), first diaphragm (6), oblique hole mirror (15), second diaphragm (7), short focus achromatic lens (8) and sample stage (9) in turn, the sample on the sample stage (9) is excited by the backscattering beam generated by the laser beam and passes through the short focus achromatic lens (8), second diaphragm (7), oblique hole mirror (15) and long focus achromatic lens (10) in turn, the wavelength of the second laser (11) is longer than the wavelength of the first laser (4), the laser beam of the second laser (11) passes through the second mirror (13), third mirror (14) and long pass filter (5) in turn, and is collinear with the laser beam of the first laser (4) and propagates, the opening is provided on the casing (3) and is communicated with the optical path propagation cavity (301), and the opening is provided with a flip cover.
2. The dual-wavelength laser Raman spectrometer of claim 1, wherein, The concave mirror (16) is arranged in the optical path propagation cavity (301), and the sample stage (9) is located between the concave mirror (16) and the short focus achromatic lens (8).
3. The dual-wavelength laser Raman spectrometer of claim 2, wherein, The first bidirectional translation stage (17) and the unidirectional translation stage (18) are arranged in the optical path propagation cavity (301), the first bidirectional translation stage (17) comprises a first sliding block (1701) and a second sliding block (1702), the first sliding block (1701) is slidably connected to the bottom of the optical path propagation cavity (301), the second sliding block (1702) is slidably connected to the first sliding block (1701), the sliding directions of the first sliding block (1701) and the second sliding block (1702) are perpendicular to each other, and the sliding direction of one of the first sliding block (1701) and the second sliding block (1702) is in the extension direction of the line connecting the first diaphragm (6) and the second diaphragm (7), the sample stage (9) is installed on the second sliding block (1702), the unidirectional translation stage (18) is slidably connected to the bottom of the optical path propagation cavity (301), the sliding direction of the unidirectional translation stage (18) is in the extension direction of the line connecting the first diaphragm (6) and the second diaphragm (7), and the concave mirror (16) is installed on the unidirectional translation stage (18).
4. The dual-wavelength laser Raman spectrometer of claim 3, wherein, The notch filter (21) is detachably installed in the optical path propagation cavity (301), and the notch filter (21) is located between the oblique hole mirror (15) and the long focus achromatic lens (10).
5. The dual-wavelength laser Raman spectrometer of claim 4, wherein, The light path propagation cavity (301) is provided with a second bidirectional translation table (19) and a white screen plug-in board (20). The second bidirectional translation table (19) comprises a third sliding block and a fourth sliding block. The third sliding block is in sliding connection with the bottom of the light path propagation cavity (301). The fourth sliding block is in sliding connection with the third sliding block. The sliding direction of the fourth sliding block is perpendicular to that of the third sliding block. The sliding direction of one of the two is in the extension direction of the line connecting the inclined hole mirror (15) and the receiving end of the monochromator (1). The long-focus achromatic lens (10) is installed on the fourth sliding block. The white screen plug-in board (20) is detachably connected with the fourth sliding block and is located between the trap filter (21) and the long-focus achromatic lens (10). A plurality of concentric circle structures (2002) are arranged on the side of the white screen plug-in board (20) close to the trap filter (21). The diameter of at least one of the concentric circle structures (2002) is equal to the light passing diameter of the short-focus achromatic lens (8).
6. The dual-wavelength laser Raman spectrometer of claim 3, wherein, The sample table (9) comprises a solid support plate (901) and a fourth mirror (902). The solid support plate (901) is detachably connected with the second sliding block (1702). The fourth mirror (902) is detachably connected with the solid support plate (901). The fourth mirror (902) is provided with a sample groove (9011). At least part of the mirror surface of the fourth mirror (902) is located directly above the sample groove (9011) and forms a 45° angle with the top surface of the solid support plate (901).
7. The dual-wavelength laser Raman spectrometer of claim 4, wherein, The light path propagation cavity (301) is provided with a polarizer (22) and an analyzer (23). The polarizer (22) is located between the first diaphragm (6) and the inclined hole mirror (15) and is rotatably inserted into the bottom of the light path propagation cavity (301). The analyzer (23) is located between the trap filter (21) and the long-focus achromatic lens (10) and is rotatably inserted into the bottom of the light path propagation cavity (301).
8. The dual-wavelength laser Raman spectrometer of claim 3, wherein, The sample table (9) comprises a liquid support plate (905) and a cuvette holder (906). The liquid support plate (905) is detachably connected with the second sliding block (1702). The cuvette holder (906) is placed on the top of the liquid support plate (905). The cuvette holder (906) is provided with a containing cavity (9061) and a side window (9062). The containing cavity (9061) is provided with a cuvette insertion slot (9063) at the bottom. The containing cavity (9061) is connected to the outside of the cuvette holder (906) through the side window (9062).
9. The dual-wavelength laser Raman spectrometer of claim 1, wherein, The light path propagation cavity (301) is provided with an element holder (24).
10. The dual-wavelength laser Raman spectrometer of any one of claims 1 to 9, wherein, The receiving end of the monochromator (1) is provided with a push rod. The push rod is in sliding connection with the monochromator (1). The sliding direction of the push rod is perpendicular to the extension direction of the line connecting the long-focus achromatic lens (10) and the receiving end of the monochromator (1). The push rod is provided with a photoelectric probe (25).