High-resolution Raman spectrometer

Abstract

This invention provides a high-resolution Raman spectrometer, comprising: a laser device, a dichroic mirror, a collimating lens, a Raman filter, a focusing lens, an interference assembly, a beam expander lens group, a two-dimensional dispersion assembly, and an imaging device. The laser device emits a laser beam, which is reflected by the dichroic mirror and focused by the collimating lens to irradiate the sample. A scattered beam is emitted, collimated by the collimating lens, passes through the dichroic mirror, is filtered by the Raman filter, and focused by the focusing lens before entering the interference assembly. After interference, the beam exits as a comb-shaped beam. The comb-shaped beam is transmitted through the beam expander lens group and enters the two-dimensional dispersion assembly, where longitudinal and transverse dispersion occur sequentially, forming a two-dimensional dispersed beam. This beam is then imaged in the imaging device to obtain a wavelength-intensity two-dimensional spectrum. This invention improves the resolution of the Raman spectrometer and solves the problems of traditional high-resolution dispersive spectrometers, such as large size, inability to adapt to environments with high load requirements, and non-compact structure.

Description

Technical Field

[0001] This invention relates to the field of spectroscopic analysis instrument technology, and in particular to a high-resolution Raman spectrometer. Background Technology

[0002] When light shines on an object, it is scattered. Most of the scattered light retains its frequency, only its direction of propagation changes. However, a small portion of the scattered light changes frequency; this scattering phenomenon is called Raman scattering. The magnitude of the frequency shift in Raman scattering light is related to the chemical bonds of molecules; different molecular bonds correspond to different Raman peaks. By measuring the frequency shift of the scattered light relative to the incident light, the composition of the analyte can be determined; by analyzing the intensity of the Raman peaks, the concentration of the constituent components can be determined. Furthermore, Raman scattering detection has extremely low sample requirements; no pretreatment or sampling is needed, the detection process is non-contact and does not damage the sample, and the detection speed is fast, making it convenient for on-site testing.

[0003] Dispersive Raman spectrometers use gratings to disperse Raman light, obtaining wavelength-intensity curves for compositional analysis. Generally, a single grating has limited dispersive power; to achieve high-resolution Raman spectrometers, multiple cascaded gratings are required, along with longer imaging lenses. This results in large-volume high-resolution Raman spectrometers, unsuitable for environments with demanding payload requirements. Summary of the Invention

[0004] In view of the above problems, the purpose of this invention is to propose a high-resolution Raman spectrometer. By splicing parallel plates with gratings, the resolution of the Raman spectrometer is improved, which solves the problems of traditional high-resolution dispersive spectrometers being large in size, unable to adapt to environments with high load requirements, and having a non-compact structure.

[0005] To achieve the above objectives, the present invention adopts the following specific technical solution:

[0006] This invention provides a high-resolution Raman spectrometer, comprising: a laser device, a dichroic mirror, a collimating lens, a Raman filter, a focusing lens, an interference assembly, a beam expanding lens group, a two-dimensional dispersion assembly, and an imaging device;

[0007] After the laser device emits a laser beam, it is reflected by a dichroic mirror and focused by a collimating lens to irradiate the sample.

[0008] After being irradiated by a laser beam, the sample excites a Raman scattered beam. After being collimated by a collimating lens, it becomes a parallel beam that passes through a dichroic mirror. After being filtered by a Raman filter and focused by a focusing lens, it enters the interference assembly, interferes, and exits as a comb beam.

[0009] After being expanded by the beam-expanding lens group, the comb-shaped beam enters the two-dimensional dispersion component and undergoes longitudinal and transverse dispersion in sequence to form a two-dimensional dispersed beam. The two-dimensional dispersed beam is incident on the imaging device for imaging, and a wavelength-intensity two-dimensional spectrum is obtained.

[0010] Preferably, the laser device includes: a laser and a narrowband filter;

[0011] A narrow-band pass filter is located directly in front of the laser and is used to filter stray light in the laser beam emitted by the laser.

[0012] Preferably, the dichroic mirror is placed at a 45° angle to the horizontal direction to change the propagation direction of the laser beam emitted by the laser by 90°.

[0013] Preferably, the interference component comprises: a hollow parallel plate and a piezoelectric ceramic;

[0014] The hollow parallel plate is composed of a first glass plate and a second glass plate, which together form a closed interference cavity. A through hole is provided at the center of the first glass plate, and piezoelectric ceramics are mounted on the second glass plate.

[0015] After the focused beam enters the hollow parallel plate through the through hole, a multi-beam interference effect is generated. By changing the voltage of the piezoelectric ceramic, the interference cavity length of the hollow parallel plate is controlled, and a comb-shaped beam with enhanced light intensity is obtained.

[0016] Preferably, a visible light total reflection film is coated on the inner side of the first glass plate; and a visible light high reflection film is coated on the inner side of the second glass plate.

[0017] Preferably, the interference assembly further includes: a coupling lens and an optical fiber;

[0018] The comb-shaped beam emitted from the second glass plate is coupled into the optical fiber by a coupling lens, and the beam emitted from the optical fiber is then expanded by a beam-expanding lens group before entering the two-dimensional dispersive component.

[0019] Preferably, the two-dimensional dispersive component includes: a plane mirror, a cylindrical lens, a solid parallel plate, and a grating;

[0020] After being reflected by the plane mirror, the expanded beam changes its propagation direction by 90° and enters the cylindrical lens. After being focused by the cylindrical lens, it enters the solid parallel plate and the grating in sequence to achieve longitudinal and transverse dispersion of the beam, forming a two-dimensional dispersive beam.

[0021] After exiting the grating, the two-dimensional dispersive beam changes its propagation direction by 90° again before entering the imaging device.

[0022] Preferably, the solid parallel plate is placed at an angle relative to the horizontal plane. The solid parallel plate is a rectangular glass plate. The incident area of ​​the solid parallel plate is coated with an anti-reflection film, and the non-incident area is coated with a visible light total reflection film and a visible light high reflection film, respectively.

[0023] Preferably, the incident area is located at the bottom of the first side of the solid parallel plate; the non-incident area is the first side and the second side of the solid parallel plate excluding the incident area; the non-incident area of ​​the first side is coated with a visible light total reflection film, and the second side is coated with a visible light high reflection film.

[0024] Preferably, the imaging device includes: an imaging lens group, an aspherical imaging lens, and an area array detector;

[0025] A two-dimensional dispersive beam passes sequentially through an imaging lens group and an aspherical imaging lens, forming a wavelength-intensity two-dimensional spectrum in an area array detector.

[0026] Compared with existing technologies, the present invention has the following advantages:

[0027] 1) The hollow parallel plate in this invention consists of a glass plate with a central through hole and a glass plate without a through hole. The glass plate with the through hole is coated with a total reflection film, and the glass plate without the through hole is coated with a high reflection film, thus forming a FP-like cavity structure. Due to its unique transmission characteristics, it can enhance the light intensity of the resonant wavelength, and the transmitted light intensity is tens of times that of the FP cavity.

[0028] 2) The holeless glass plate in this invention is connected to the piezoelectric ceramic, which can change the cavity length with the voltage change to achieve the effect of scanning the waveband.

[0029] 3) By combining a solid parallel plate and a grating, this invention obtains a two-dimensional spectrum of wavelength and light intensity, which further improves the resolution of the Raman spectrometer.

[0030] 4) The aspherical lens in this invention not only eliminates system aberrations and improves resolution, but also increases the system's receiving angle and light throughput.

[0031] 5) The present invention features a compact optical system structure with stable and reliable performance. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the optical path structure of a high-resolution Raman spectrometer provided according to an embodiment of the present invention.

[0033] Figure 2 This is a schematic diagram of a solid parallel plate structure in a high-resolution Raman spectrometer provided according to an embodiment of the present invention.

[0034] Figure 3This is a schematic diagram of the coating area of ​​a solid parallel plate in a high-resolution Raman spectrometer provided according to an embodiment of the present invention.

[0035] The reference numerals in the accompanying drawings include: laser 1, narrowband pass filter 2, dichroic mirror 3, collimating lens 4, Raman filter 5, focusing lens 6, interference assembly 7, hollow parallel plate 701, first glass plate 7010, second glass plate 7011, piezoelectric ceramic 702, coupling lens 703, optical fiber 704, beam expander lens group 8, two-dimensional dispersion assembly 9, plane mirror 901, cylindrical lens 902, solid parallel plate 903, grating 904, imaging lens group 10, aspherical imaging lens 11, area array detector 12, and sample 13. Detailed Implementation

[0036] In the following description, embodiments of the invention will be described with reference to the accompanying drawings. In the description below, the same modules are denoted by the same reference numerals. Where the same reference numerals are used, their names and functions are also the same. Therefore, their detailed description will not be repeated.

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0038] Figure 1 A schematic diagram of the optical path structure of a high-resolution Raman spectrometer provided according to an embodiment of the present invention is shown.

[0039] like Figure 1 The image shown is a top view of the device of the present invention. The high-resolution Raman spectrometer provided in the embodiment of the present invention includes: a laser device, a dichroic mirror 3, a collimating lens 4, a Raman filter 5, a focusing lens 6, an interference assembly 7, a beam expander lens group 8, a two-dimensional dispersion assembly 9, and an imaging device.

[0040] After the laser beam emitted by the laser device 1 is reflected by the dichroic mirror 3 and transmitted by the collimating lens 4, it irradiates the sample 13.

[0041] The laser device 1 includes a laser 1 and a narrow-bandpass filter 2. The narrow-bandpass filter 2 is located directly in front of the laser 1 and is used to filter stray light in the laser beam emitted by the laser 1. The laser 1 is a 532 Raman laser, model MSL-FN-532, manufactured by Changchun New Industries Optoelectronics Co., Ltd. The narrow-bandpass filter 2 is a product of Semrock, model number 1101-532-12.5.

[0042] The laser beam, after being filtered by the narrow-bandpass filter 2, enters the dichroic mirror 3, which is positioned at a 45° angle. The dichroic mirror 3 changes the propagation direction of the laser beam by 90° before it enters the collimating lens 4, which is an achromatic lens. The collimating lens 4 then focuses the laser beam, illuminating the sample 13. The dichroic mirror 3 is a product of Semrock, model number LPD02-532RU-25. The collimating lens 4 is a product of Edmund Optics, model number 49662.

[0043] When sample 13 is irradiated by a laser beam, it emits a Raman scattered beam. After being collimated by collimating lens 4, the Raman scattered beam becomes a parallel beam.

[0044] The parallel beam of light passes sequentially through the dichroic mirror 3, the Raman filter 5, and the focusing lens 6 before entering the interference assembly 7.

[0045] The dichroic mirror 3, collimating lens 4, Raman filter 5, and focusing lens 6 are positioned from left to right between sample 13 and interference assembly 7, with their optical axes all aligned on the same straight line. Raman filter 5, a product of Semrock, is used to filter the parallel beam; its model number is LP03-532RU-25. Focusing lens 6 is used to focus the parallel beam, ensuring that the focused beam enters interference assembly 7 precisely.

[0046] The interference component 7 includes: a hollow parallel plate 701, a piezoelectric ceramic 702, a coupling lens 703, and an optical fiber 704.

[0047] The hollow parallel plate 701 consists of a first glass plate and a second glass plate, which form a closed interference cavity. The parameters of the first and second glass plates are identical. A visible light total reflection film is coated on the inner side of the first glass plate, and a visible light high reflection film (95% reflection film) is coated on the inner side of the second glass plate. A tiny through-hole is located at the center of the circular glass plate near the focusing lens 6, i.e., the first glass plate. This through-hole is used to receive the focused beam after being focused by the focusing lens 6. The shape of the through-hole can be circular, square, rectangular, etc.

[0048] The piezoelectric ceramic 702 is mounted on the outside of the second glass plate.

[0049] After the focused beam enters the hollow parallel plate 701 through the through-hole on the first glass plate, a multi-beam interference effect is generated for the first time within the hollow parallel plate. By changing the voltage of the piezoelectric ceramic 702, the interference cavity length of the hollow parallel plate 701 is controlled, thereby changing the resonant frequency of the hollow parallel plate 701 and achieving scanning of the focused beam. Due to the special relationship between the incident light intensity and the transmitted light intensity of the hollow parallel plate 701, the light intensity of the focused beam is enhanced after passing through the hollow parallel plate 701. After scanning the incident focused beam by the hollow parallel plate 701, a comb-shaped beam with enhanced light intensity can be obtained.

[0050] After exiting the second glass plate, the comb-shaped beam enters the coupling lens 703, which couples the comb-shaped beam into the optical fiber 704.

[0051] The beam emitted from the optical fiber is expanded by the beam expanding lens group 8 and then enters the two-dimensional dispersion component 9.

[0052] The two-dimensional dispersive component 9 includes: a plane mirror 901, a cylindrical lens 902, a solid parallel plate 903, and a grating 904.

[0053] The plane mirror 901 is placed at a 45° angle. After the expanded beam is reflected by the plane mirror 901, its propagation direction changes by 90° and it enters the cylindrical lens 902. The cylindrical lens 902 is used to focus the expanded beam.

[0054] The focused beam undergoes longitudinal and transverse dispersion sequentially within the solid parallel plate 903 and grating 904, forming a two-dimensional dispersed beam that exits.

[0055] Figure 2 A schematic diagram of a solid parallel plate structure in a high-resolution Raman spectrometer provided according to an embodiment of the present invention is shown.

[0056] Figure 3 A schematic diagram of the coating region of a solid parallel plate in a high-resolution Raman spectrometer provided according to an embodiment of the present invention is shown.

[0057] like Figure 2 and Figure 3 As shown, the solid parallel plate 903 is a rectangular glass plate. The bottom of the solid parallel plate 903, i.e., the incident area, is coated with an anti-reflection film. Besides the incident area, the sides of the solid parallel plate 903, i.e., the first side, are coated with a visible light total internal reflection film; the second side is coated with a visible light high reflectance film (95% reflectance film). The solid parallel plate 903 is placed at an angle of 3 degrees to the vertical direction. After the focused beam enters the solid parallel plate 903, it is continuously reflected inside, generating a second multi-beam interference effect, thus achieving longitudinal dispersion of the focused beam.

[0058] The beam that produces longitudinal dispersion then produces transverse dispersion again in the grating.

[0059] The grating 904 has its markings parallel to the Z-axis. The XYZ coordinate system is a right-handed coordinate system, with the Z-axis perpendicular to the paper.

[0060] After exiting through grating 904, the two-dimensional dispersive beam changes its propagation direction by 90° again and enters the imaging device, resulting in a wavelength-intensity two-dimensional spectrum.

[0061] The imaging device includes: an imaging lens group 10, an aspherical imaging lens 11, and an area array detector 12.

[0062] The two-dimensional dispersive beam passes sequentially through the imaging lens group 10 and the aspherical imaging lens 11, forming a wavelength-intensity two-dimensional spectrum in the area array detector 12.

[0063] Imaging lens group 10 is used to image the two-dimensional dispersive beam; aspherical imaging lens 11 is used to eliminate aberrations; area array detector 12 is used to detect the two-dimensional dispersive beam. The area array detector is a product of Andor Corporation, model iKon-M_934BU2.

[0064] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0065] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A high-resolution Raman spectrometer, characterized in that, include: Laser devices, dichroic mirrors, collimating lenses, Raman filters, focusing lenses, interference components, beam expanding lens groups, two-dimensional dispersion components, and imaging devices; The dichroic mirror, the collimating lens, the Raman filter, and the focusing lens are located between the sample and the interference assembly, and their optical axes are all on the same straight line. After the laser device emits a laser beam, it is reflected by the dichroic mirror and focused by the collimating lens to irradiate the sample. After being irradiated by the laser beam, the sample excites a Raman scattered beam, which is collimated by the collimating lens and becomes a parallel beam that passes through the dichroic mirror. After being filtered by the Raman filter and focused by the focusing lens, it enters the interference component, interferes, and exits as a comb beam. After being expanded by the beam-expanding lens group, the comb-shaped beam enters the two-dimensional dispersion component and undergoes longitudinal and transverse dispersion in sequence to form a two-dimensional dispersion beam. The two-dimensional dispersion beam is incident on the imaging device to form an image, and a wavelength-intensity two-dimensional spectrum is obtained. The interference assembly includes a hollow parallel plate and a piezoelectric ceramic. The hollow parallel plate is composed of a first glass plate and a second glass plate. A visible light total reflection film is coated on the inner side of the first glass plate, and a visible light high reflection film with a reflectivity of 95% is coated on the inner side of the second glass plate. The first glass plate and the second glass plate form a closed interference cavity. A through hole is provided at the center of the first glass plate, and the piezoelectric ceramic is mounted on the second glass plate. After the focused beam enters the hollow parallel plate through the through hole, a multi-beam interference effect is generated. By changing the voltage of the piezoelectric ceramic, the interference cavity length of the hollow parallel plate is controlled, resulting in a comb-shaped beam with enhanced light intensity.

2. The high-resolution Raman spectrometer according to claim 1, characterized in that, The laser device includes: a laser and a narrowband filter; The narrow-band pass filter is located directly in front of the laser and is used to filter stray light in the laser beam emitted by the laser.

3. The high-resolution Raman spectrometer according to claim 2, characterized in that, The dichroic mirror is placed at a 45° angle to the horizontal direction to change the propagation direction of the laser beam emitted by the laser by 90°.

4. The high-resolution Raman spectrometer according to claim 1, characterized in that, The interference assembly further includes: a coupling lens and an optical fiber; The comb-shaped beam emitted from the second glass plate is coupled into the optical fiber by the coupling lens, and the beam emitted from the optical fiber is then expanded by the beam expanding lens group before entering the two-dimensional dispersion component.

5. The high-resolution Raman spectrometer according to claim 4, characterized in that, The two-dimensional dispersive component includes: a plane mirror, a cylindrical lens, a solid parallel plate, and a grating; The expanded beam changes its propagation direction by 90° after being reflected by the plane mirror and enters the cylindrical lens. After being focused by the cylindrical lens, it enters the solid parallel plate and the grating in sequence to achieve longitudinal and transverse dispersion of the beam, forming the two-dimensional dispersed beam. The two-dimensional dispersive beam changes its propagation direction by 90° again after exiting the grating and enters the imaging device.

6. The high-resolution Raman spectrometer according to claim 5, characterized in that, The solid parallel plate is placed at an angle relative to the horizontal plane. The solid parallel plate is a rectangular glass plate. The incident area of ​​the solid parallel plate is coated with an anti-reflection film, and the non-incident area is coated with a visible light total reflection film and a visible light high reflection film, respectively.

7. The high-resolution Raman spectrometer according to claim 6, characterized in that, The incident area is located at the bottom of the first side of the solid parallel plate; the non-incident area is the first side and the second side of the solid parallel plate excluding the incident area; the non-incident area of ​​the first side is coated with a visible light total reflection film, and the second side is coated with a visible light high reflection film.

8. The high-resolution Raman spectrometer according to claim 7, characterized in that, The imaging device includes: an imaging lens group, an aspherical imaging lens, and an area array detector; The two-dimensional dispersive beam passes sequentially through the imaging lens group and the aspherical imaging lens, forming a wavelength-intensity two-dimensional spectrum in the area array detector.

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