A high-flux miniature Raman spectrometer

Abstract

A high-throughput miniature Raman spectrometer, belonging to the field of spectroscopic analysis instruments, includes a laser module, an external optical path system, and a beam splitting system. The laser module comprises a narrowband laser module and a collimating mirror; the external optical path system includes a dichroic mirror, an aspherical lens, a stage, a long-pass filter, a cemented doublet lens, and a slit; the beam splitting system includes a collimating mirror, a blazed grating, a focusing mirror, and a linear charge-coupled device (CCD). By integrating the laser module and external optical path system with the beam splitting system, signal attenuation during fiber optic transmission is avoided; a large numerical aperture aspherical lens is used to achieve efficient sample excitation and signal collection; the cemented doublet lens converges the beam to the slit, reducing the optical path size and eliminating axial chromatic aberration; and the cascaded filtering structure of the dichroic mirror and long-pass filter effectively suppresses Rayleigh scattering interference. While maintaining resolution, the luminous throughput is significantly improved, offering low cost, high precision, and portability, making it suitable for fields such as food safety testing.

Description

Technical Field

[0001] This invention relates to the field of spectroscopic analysis instrument technology, specifically to a high-throughput miniature Raman spectrometer. Background Technology

[0002] Raman spectroscopy, as an advanced spectroscopic analysis technique, provides an important means for non-destructive analysis of molecular structure and chemical composition by detecting changes in photon frequency caused by molecular vibration, rotation, and stretching. Researchers have long been continuously improving and innovating Raman spectrometers, with a growing trend towards miniaturization, portability, and intelligence to meet the needs of diverse applications. As scientific research and industrial applications deepen, the performance requirements for Raman spectrometers are also increasing. Portable Raman spectrometers, characterized by high sensitivity, small size, and light weight, show broad application prospects in fields such as food safety, chemistry, biomedicine, environmental protection, and national defense and customs. Due to their compact optical structure, small size, and portability, portable spectrometers are more suitable for use as a basis for the development of miniature Raman spectrometers, thus facilitating their widespread application. Miniature spectrometers used for Raman spectroscopy detection, in addition to their small size, must also consider key indicators such as sensitivity, spectral detection range, and resolution. Therefore, the design of a Raman spectrometer requires a comprehensive consideration of multiple factors to effectively improve the overall performance of the instrument.

[0003] Currently, most spectrometers use traditional discrete spectrometers. Due to the low probability of Raman scattering and the generally weak Raman light emitted by substances, spectrometers with low light transmission efficiency will have low sensitivity, which will ultimately affect the detected Raman spectrum. Therefore, improving light transmission is one of the performance aspects that needs to be improved in the design of Raman spectrometers. Summary of the Invention

[0004] To address the problems of low light flux, easy signal attenuation, and difficulty in balancing system size and performance in existing Raman spectrometers, the purpose of this invention is to provide a high-light-flux miniature Raman spectrometer. This spectrometer can maintain a 7cm diameter while maintaining high light flux. -1 ~10 cm -1 This invention significantly improves luminous flux while maintaining high resolution, achieving low cost, high precision, and portability. It designs an optical system integrating an excitation module, an external optical path system, and a beam splitting system. The external optical path system employs a large numerical aperture aspherical lens to achieve effective sample excitation and efficient signal collection. Finally, a cemented doublet lens reduces the size of the converging optical path and eliminates axial chromatic aberration, followed by the beam splitting system to achieve the separation and focused detection of Raman light of different wavelengths.

[0005] To achieve the above objectives, the technical solution of the present invention is as follows: The present invention provides a high-flux micro Raman spectrometer, comprising an excitation module, an external optical path system, and a spectroscopic system; The excitation module includes a narrowband laser module and a collimating lens. The axes of the narrowband laser module and the collimating lens are coincident, and the laser emitted from the narrowband laser module passes through the collimating lens. The external optical path system includes a stage, an aspherical lens, a dichroic mirror, a long-pass filter, a cemented doublet lens, and a slit. A dichroic mirror is positioned in the direction of the laser emission from the collimating mirror. An aspherical lens is positioned in the direction of the laser emission from the dichroic mirror, and a stage for placing the sample to be tested is positioned at the focal plane of the aspherical lens. A long-pass filter is positioned in the direction of the light emission from the dichroic mirror, and a cemented doublet lens is positioned in the direction of the light emission from the long-pass filter. A slit is positioned at the focal plane of the cemented doublet lens. The beam splitting system includes a collimating mirror, a collimating mirror positioned in the direction of the outgoing light from the slit, a blazed grating positioned in the direction of the outgoing light from the collimating mirror, a focusing mirror positioned in the direction of the outgoing light from the blazed grating, and a linear CCD positioned in the direction of the outgoing light from the focusing mirror.

[0006] The optical path structure of the high-throughput miniature Raman spectrometer is as follows: A laser beam emitted from a narrowband laser module passes through a collimating lens and is incident on a dichroic mirror. Due to the high reflectivity (>95%) of the dichroic mirror to the emitted laser beam, most of the laser energy is guided to an aspherical lens. After passing through the aspherical lens, the beam is focused into the stage containing the sample to be tested, exciting the sample to generate Raman and Rayleigh scattered light. A portion of these scattered lights are collimated by the aspherical lens and then pass through the dichroic mirror and a long-pass filter in sequence. At this point, most of the Rayleigh scattered light is filtered out, while the Raman scattered light passes normally and is then focused into a slit by a cemented doublet lens before entering the beam splitting system.

[0007] Spectroscopic system: The Raman scattered light collected by the external optical path system is collimated by the collimating mirror and continues to propagate. When it passes through the blazed grating, it is dispersed. These beams are finally converged by the focusing mirror onto the linear charge-coupled device (linear CCD).

[0008] The narrowband laser module outputs a narrow-linewidth laser with a half-width of 0.6nm, which effectively suppresses the spontaneous emission noise and mode jump of the laser, ensuring a highly stable center wavelength of the output laser.

[0009] The collimating lens is used to collimate the laser emitted from the narrowband laser module to obtain a parallel beam.

[0010] The dichroic mirror is used to reflect the narrow-linewidth laser generated by the narrow-band laser module, transmit Raman scattered light, and filter out most of the Rayleigh scattered light. The dichroic mirror has a narrow-linewidth laser reflectivity of ≥95% and a Raman scattered light transmittance of ≥90%.

[0011] The aspherical lens is used to converge the narrow-linewidth laser light reflected by the dichroic mirror, while simultaneously collecting the Raman scattered light and Rayleigh scattered light to be measured. Its numerical aperture is 0.79.

[0012] The long-pass filter is used to further filter out Rayleigh scattered light, with an optical density OD≥6.

[0013] The cemented doublet lens is used to converge the light beam to the slit, thereby reducing the size of the converged light path and eliminating axial chromatic aberration. Preferably, the focal length of the cemented doublet lens is designed to be 15mm to 28mm.

[0014] The slit allows Raman scattered light of a specific wavelength to pass through smoothly, and the width of the slit is preferably set to 25μm~50μm.

[0015] The collimating mirror is used to incident the light passing through the slit parallel to the blazed grating; preferably, the focal length of the collimating mirror is designed to be 50mm~100mm.

[0016] The blazed grating is used to direct light of different wavelengths to the focusing mirror at different diffraction angles.

[0017] The focusing mirror is used to converge light rays with different diffraction angles to different positions on the linear CCD; its focal length is designed to match the focal length of the collimating mirror.

[0018] The linear CCD is used to convert converged optical signals of different wavelengths into electrical signals, and to achieve rapid readout and high-sensitivity detection of spectral signals through multi-pixel synchronous acquisition; preferably, the spectral response range of the linear CCD covers 540nm~650nm.

[0019] Furthermore, the components of the high-flux micro Raman spectrometer are assembled and mounted on the housing; wherein the narrowband laser module is fixed inside the heat sink, and the heat sink is fixed on the housing.

[0020] Furthermore, the aspherical lens is fixed inside the first lens sleeve, and the inner wall of the first lens sleeve is provided with an annular mounting groove for installing the aspherical lens retainer; the first lens retainer is connected to the inner wall of the first lens sleeve by threaded or interference fit, and abuts against the edge of the incident or exit surface of the aspherical lens, so as to realize the axial limiting and fixing of the aspherical lens in the optical axis direction, forming an aspherical lens mounting assembly.

[0021] Furthermore, the dichroic mirror and long-pass filter are fixed within the filter holder, forming a filter and dichroic mirror mounting assembly, and are connected to the aspherical lens mounting assembly. Specifically, the two ends of the dichroic mirror are located diagonally opposite each other on the filter holder, the long-pass filter and dichroic mirror are set at a 45° angle, parallel to the laser emission direction, and located on the side of the dichroic mirror that transmits Raman scattered light.

[0022] Furthermore, the cemented doublet lens is fixed inside the second lens sleeve, and the inner wall of the second lens sleeve is provided with an annular mounting groove for installing the cemented doublet lens retaining ring; the second lens retaining ring is connected to the inner wall of the second lens sleeve by threaded or interference fit, and abuts against the edge of the incident or exit surface of the cemented doublet lens, so as to realize the axial limiting and fixing of the cemented doublet lens in the optical axis direction, forming a cemented doublet lens mounting assembly, and is connected to the filter and dichroic mirror mounting assembly and the housing.

[0023] Furthermore, the collimating mirror, blazed grating, and focusing mirror are respectively fixed on the mounting bracket, and the mounting bracket is fixed on the housing.

[0024] Furthermore, the linear CCD array is fixed to the housing.

[0025] The high-throughput miniature Raman spectrometer of this invention achieves a light throughput of 15% to 30%, which is more than 3 times higher than that of conventional discrete CT Raman spectrometers, with a resolution of 7 cm⁻¹. -1 ~10cm -1 .

[0026] The high-flux micro Raman spectrometer of the present invention has the following advantages compared with existing spectrometers: 1. Traditional discrete structures use fiber-coupled structures at the slit, resulting in high transmission loss and low luminous flux. This invention integrates the excitation module, external optical path system, and beam splitting system into one unit. The Raman signal collected by the external optical path system is directly focused at the slit, resulting in low transmission loss and high luminous flux, which is three times that of the traditional fiber-coupled structure. This avoids the attenuation problem caused by using discrete commercial probes to transmit signals through optical fibers.

[0027] 2. In the excitation optical path and the collection optical path of the external optical path system of the excitation module, an aspherical lens structure with a large numerical aperture (NA) of 0.79 is adopted. Compared with the front lens NA of 0.22–0.5 in general portable or miniature Raman spectrometers, this achieves efficient excitation of the sample Raman signal and signal collection with a large numerical aperture. While ensuring good matching between the external optical path system and the dispersive system, the system size is effectively shortened by designing a double cemented lens, and the axial chromatic aberration generated when the Raman signal passes through the slit is eliminated. Attached Figure Description

[0028] Figure 1 A schematic diagram of the optical path structure of the high-throughput micro Raman spectrometer provided in an embodiment of the present invention is shown.

[0029] Figure 2 A schematic diagram of the structure of the high-throughput micro Raman spectrometer provided in an embodiment of the present invention is shown.

[0030] Figure 3 A schematic diagram of the aspherical lens mounting assembly provided in an embodiment of the present invention is shown.

[0031] Figure 4 A schematic diagram of the structure of the double-bonded lens mounting assembly provided in an embodiment of the present invention is shown.

[0032] Figure 5 A schematic diagram of the structure of the filter and dichroic mirror mounting assembly provided in an embodiment of the present invention is shown.

[0033] In the above diagram, 1 is a narrowband laser module, 2 is a collimating lens, 3 is a dichroic mirror, 4 is an aspherical lens, 5 is a stage, 6 is a long-pass filter, 7 is a cemented doublet lens, 8 is a slit, 9 is a collimating mirror, 10 is a blazed grating, 11 is a focusing mirror, 12 is a linear CCD array, 13 is a heat sink, 14 is an aspherical lens mounting assembly, 15 is a filter and dichroic mirror mounting assembly, 16 is a cemented doublet lens mounting assembly, 17 is a first mounting bracket, 18 is a second mounting bracket, 19 is a third mounting bracket, 20 is a housing, 21 is a light path schematic slot, 22 is a first lens sleeve, 23 is a first lens retainer, 24 is a second lens retainer, 25 is a second lens sleeve, and 26 is a filter holder. Detailed Implementation

[0034] 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 for illustrative purposes only and do not constitute a limitation thereof. In different embodiments, similar elements are referred to by associated element numbers. The following embodiments contain numerous detailed descriptions to aid in a better understanding of this invention. However, those skilled in the art will understand that some features may be omitted or replaced by other elements, materials, or methods in different situations. In some cases, some operations related to this invention are not shown or described in the specification to avoid obscuring the core content with excessive detail. For those skilled in the art, the specific details of these operations are not necessary and can be fully understood based on the description in the specification and general technical knowledge in the art.

[0035] It should be noted that, without conflict, the embodiments and features of this invention can be combined to form various implementation methods. Furthermore, the order of the steps or actions described in the method description can be adjusted in a manner readily apparent to those skilled in the art. Therefore, the order in the specification and drawings is only for clearly illustrating a particular embodiment and does not constitute a limitation on the order of execution, unless otherwise stated that the order must be followed.

[0036] In one embodiment, the present invention discloses a high-flux micro Raman spectrometer, see [link to relevant documentation]. Figure 1 and Figure 2 As shown, this high-throughput miniature spectrometer includes an excitation module, an external optical path system, and a beam splitting system. The excitation module includes a narrowband laser module 1 and a collimating lens 2; the external optical path system includes an aspherical lens 2, a dichroic mirror 3, an aspherical lens 4, a stage 5, a long-pass filter 6, a cemented doublet lens 7, and a slit 8; the beam splitting system includes a collimating mirror 9, a blazed grating 10, a focusing mirror 11, and a linear CCD array 12. The narrowband laser module 1 is fixed inside the heat sink 13, and the heat sink 13 is fixed on the housing 20; the aspherical lens 4 forms an aspherical lens mounting assembly 14 through the first lens sleeve 22 and the first lens retainer 23; the dichroic mirror 3 and the long-pass filter 6 are fixed inside the filter holder 30 to form a filter and dichroic mirror mounting assembly 15; the cemented doublet lens 7 forms a cemented doublet lens mounting assembly 16 through the second lens sleeve 25 and the second lens retainer 24, one end of the filter and dichroic mirror mounting assembly 15 is connected to one end of the cemented doublet lens mounting assembly 16, the other end of the filter and dichroic mirror mounting assembly 15 is connected to the aspherical lens mounting assembly 14, and the other end of the cemented doublet lens mounting assembly 16 is mounted on the housing 20; The collimating mirror 9, blazed grating 10, and focusing mirror 11 are respectively fixed on the mounting bracket and fixed on the housing 20 according to their setting positions; the linear CCD 12 is fixed on the housing 20.

[0037] In operation, the narrow-band laser module 1 outputs a narrow-linewidth laser beam, which is collimated by the collimating lens 2 and then incident on the dichroic mirror 3. After reflection by the dichroic mirror 3, the beam is converged by the aspherical lens 4 onto the stage 5 containing the sample to be tested, exciting the sample to generate Raman and Rayleigh scattered light. A portion of the Raman and Rayleigh scattered light is collimated by the aspherical lens 4 and then passes sequentially through the dichroic mirror 3 and the long-pass filter 6. At this point, most of the Rayleigh scattered light is filtered out, while the Raman scattered light passes through normally. Subsequently, the Raman scattered light is converged at the slit 8 by the cemented doublet lens 7 and enters the beam splitting system.

[0038] The Raman scattered light entering the spectral system is collimated into a parallel beam by the collimating mirror 9 and continues to propagate to the blazed grating 10 where it is dispersed. Light of different wavelengths is emitted at different diffraction angles and finally converges at different positions on the linear CCD 12 by the focusing mirror 11, thus completing the acquisition of the spectral signal.

[0039] The narrow-linewidth laser module 1 of this invention employs a narrow-linewidth design, effectively suppressing spontaneous emission noise and mode jumps in the laser, ensuring a highly stable center wavelength of the output laser. In Raman spectroscopy detection, the narrow-linewidth laser, as the excitation source, significantly reduces background broadening of the excitation light, preventing the masking of adjacent weak Raman signals due to excessively wide laser linewidth, thereby effectively improving spectral resolution and signal-to-noise ratio, providing a high-quality excitation source foundation for subsequent high-precision analysis. Preferably, the narrow-linewidth laser module 1 uses a 532nm wavelength laser, which has a high Raman scattering cross-section and is suitable for various target substances in food safety detection.

[0040] The aspherical lens 4 described in this invention employs a large numerical aperture (NA) design, reaching 0.79. In the excitation optical path, it enables high-density laser focusing, improving excitation efficiency per unit area. In the collection optical path, it achieves signal collection with a large numerical aperture in the object side, effectively increasing the solid angle of Raman signal acquisition. Through the rational arrangement of the same set of aspherical lenses, the excitation and collection efficiency of Raman signals are significantly improved while ensuring good matching between the excitation and collection optical paths. The surface of the aspherical lens adopts an aspherical shape design, which effectively corrects spherical aberration, improves the quality of the focused spot, and ensures good matching between the excitation spot size and the sample detection area. In practical applications, for the detection of trace samples or substances with weak Raman signals, this structure can effectively increase the signal acquisition amount, providing a sufficient optical signal basis for subsequent analysis.

[0041] The dichroic mirror 3 of this invention possesses optical characteristics of high reflectivity and high transmittance. It can efficiently reflect the narrow-linewidth laser generated by the narrowband laser module 1 with a reflectivity ≥95%, while transmitting Raman scattered light with a transmittance ≥90%, and filtering out most of the Rayleigh scattered light. Through the wavelength selectivity of the dichroic mirror 3, effective separation of the excitation and collection optical paths is achieved, avoiding interference from strong excitation light on weak Raman signals and ensuring the purity of the signal entering the subsequent optical system. The cutoff wavelength of the dichroic mirror 3 is designed to be 535nm, matching the 532nm excitation wavelength of the narrowband laser module 1 and the cutoff wavelength of the long-pass filter 6, forming a cascaded filtering structure that effectively improves the suppression ratio of Rayleigh scattered light.

[0042] The long-pass filter 6 of this invention employs a 535nm long-pass design with an optical density OD≥6, used to further filter out residual Rayleigh scattering light. After preliminary filtering by the dichroic mirror 3, some Rayleigh scattering light may still remain in the beam. The long-pass filter 6, through its deep cutoff characteristics, suppresses the Rayleigh scattering light to a level acceptable to the detector, ensuring that only Raman scattering light with wavelengths greater than 535nm can pass smoothly and enter the beam splitting system, thereby effectively improving the system's signal-to-noise ratio and detection sensitivity. The long-pass filter 6 uses a multilayer dielectric film deposition process, possessing a steep cutoff transition band and high-pass band transmittance, ensuring sufficient suppression of Rayleigh scattering light while maximizing the retention of Raman scattering signals.

[0043] The cemented doublet lens 7 of this invention is made of two pieces of optical glass with different dispersion characteristics cemented together. It is used to focus the converging beam onto the slit 8, while also reducing the size of the converging optical path and eliminating axial chromatic aberration. Through the chromatic aberration correction of the cemented doublet lens, Raman signals of different wavelengths can be accurately focused at the same focal position, ensuring that the subsequent spectroscopic system can accurately distinguish light signals of different wavelengths, meeting the stringent requirements for wide spectral range and high-resolution detection. The focal length of the cemented doublet lens 7 is designed to be 15mm~28mm, which can efficiently focus the collected Raman scattered light onto the slit 8, while effectively compressing the optical path size, which is beneficial for the miniaturization of the spectrometer.

[0044] The slit 8 described in this invention plays a crucial role in limiting the width of the incident light in the entire external optical path system. The slit width directly affects the resolution of the spectrometer; a suitable slit width setting can effectively improve the system resolution. In this embodiment, the width of the slit 8 is set to 25μm~50μm. The Raman scattered light, converged by the doublet lens 7, is adapted to the slit 8, making the light entering the subsequent beam splitting system more regular and orderly. This ensures that while maintaining a certain light transmission efficiency, the spectrometer can achieve a high resolution and accurately distinguish light signals of different wavelengths. The slit 8 is manufactured using precision machining or laser cutting technology, with an edge flatness better than 0.5μm to ensure its optical performance.

[0045] The collimating mirror 9 of this invention employs an off-axis parabolic or spherical mirror structure to reflect the diverging beam exiting the slit 8 into a collimated parallel beam, which is then incident on the blazed grating 10 at a specific angle. This reflective collimation structure avoids chromatic aberration introduced by transmissive optical elements and also possesses high reflection efficiency (≥95%), which is beneficial for improving the system's light transmission efficiency. The collimating mirror 9 has a focal length of 50mm~100mm, effectively collimating the diverging beam from the slit 8 and ensuring good parallelism of the beam incident on the blazed grating 10.

[0046] The blazed grating 10 of this invention employs a scribe line density of 1200 lp / mm, and maximizes diffraction efficiency for a specific wavelength band through blaze angle design. The blazed grating 10 is used to direct light of different wavelengths to the focusing mirror 11 at different diffraction angles, achieving spectral dispersion separation. This ensures that within 7cm... -1 ~10cm -1 While maintaining the required resolution, the use of a 1200 lp / mm blazed grating effectively reduces the cost of the optical system, while still meeting the stringent requirements for spectral resolution. The blazed grating 10 is designed with a blaze wavelength of 550 nm, exhibiting a high diffraction efficiency of ≥70% within the commonly used Raman spectroscopy detection band of 540 nm to 650 nm.

[0047] The focusing mirror 11 of this invention is used to receive light beams of different wavelengths dispersed by the blazed grating 10 and converge them onto different positions of the linear CCD 12. The focusing mirror 11 employs an off-axis spherical or parabolic surface design, enabling it to accurately image light rays with different diffraction angles onto different pixels of the detector, ensuring accurate acquisition of spectral information. The focal length of the focusing mirror 11 is designed to be 50mm~100mm, matching the focal length of the collimating mirror 9, forming a symmetrical optical structure and effectively reducing optical aberrations.

[0048] The linear CCD12 described in this invention is used to convert converged light signals of different wavelengths into electrical signals, and achieves rapid readout and high-sensitivity detection of spectral signals through multi-pixel synchronous acquisition. Each pixel position of the linear CCD12 corresponds one-to-one with the wavelength of the dispersed spectrum. By converting the light intensity distribution into a digital signal output, real-time acquisition and transmission of spectral data are achieved. Its linear array structure ensures high quantum efficiency (QE) ≥ 60% and low readout noise ≤ 10e while maintaining spectral resolution. - This technology is suitable for detecting weak Raman scattering signals, thereby enabling rapid acquisition of spectra with a wide spectral range and high signal-to-noise ratio. In this embodiment, the linear CCD12 uses a 2048-pixel specification, and its spectral response range covers 540nm~650nm, which can meet the Raman spectral detection requirements of common target substances in food safety testing.

[0049] As a preferred embodiment of the present invention, see Figure 2 As shown, the narrowband laser module 1 is fixed inside the heat sink 13, which is fixed to the housing 20. The heat sink 13 is made of aluminum alloy or copper alloy with good thermal conductivity and has a heat dissipation fin structure on its surface, which can effectively conduct the heat generated by the narrowband laser module 1 during operation, avoiding laser wavelength drift or output power reduction due to temperature rise, and ensuring long-term stable operation of the laser module. Thermal grease or thermal pads can be placed between the heat sink 13 and the housing 20 to reduce contact thermal resistance and improve heat dissipation efficiency.

[0050] As a preferred embodiment of the present invention, see Figure 2 and Figure 3 As shown, the aspherical lens 4 is fixed inside the first lens sleeve 22, and the inner wall of the first lens sleeve 22 is provided with an annular mounting groove for installing the first lens retainer 23. The first lens retainer 23 is connected to the inner wall of the first lens sleeve 22 by threaded or interference fit, and abuts against the edge of the incident or exit surface of the aspherical lens 4 to achieve axial positioning and fixation of the aspherical lens 4 in the optical axis direction. The first lens sleeve 22 is connected to the filter and dichroic mirror mounting assembly 15. Through the fastening structure of the first lens retainer 23, the aspherical lens 4 is firmly positioned inside the first lens sleeve 22, which not only ensures its coaxiality with the optical axis of the system, but also facilitates assembly, adjustment and maintenance, and helps to improve the assembly consistency and long-term stability of the optical system. Preferably, an elastic gasket such as a polytetrafluoroethylene gasket or a rubber gasket can be provided between the first lens retainer 23 and the aspherical lens 4 to buffer assembly stress and avoid lens damage. Furthermore, the outer wall of the first lens sleeve 22 may be provided with a positioning step or positioning groove for precise docking with the filter and dichroic mirror mounting assembly 15 to ensure optical axis consistency.

[0051] As a preferred embodiment of the present invention, see Figure 2 and Figure 5 As shown, the dichroic mirror 3 and the long-pass filter 6 are fixed within the filter holder 30, and the filter holder 30 is connected to the aspherical lens mounting assembly 14 and the cemented doublet lens mounting assembly 16. The filter holder 30 adopts a precision-machined structure, with mounting grooves inside that are adapted to the thickness of the dichroic mirror 3 and the long-pass filter 6, ensuring that the mounting angles of the dichroic mirror 3 and the long-pass filter 6 are accurate, typically at a 45° angle of incidence, to ensure the consistency of the optical axes of the excitation and collection light paths. The filter holder 30 can be made of aluminum alloy material and CNC machined, with a blackened surface treatment to reduce stray light. The integrated design of the filter holder 30 simplifies the assembly process and improves the positioning accuracy of the optical components. Furthermore, the filter holder 30 can be equipped with adjusting screws or fine-tuning mechanisms for fine-tuning the angles of the dichroic mirror 3 and the long-pass filter 6 to optimize the optical path alignment.

[0052] As a preferred embodiment of the present invention, see Figure 2 and Figure 4As shown, the cemented doublet lens 7 is fixed inside the second lens sleeve 25, and the inner wall of the second lens sleeve 25 is provided with an annular mounting groove for installing the second lens retainer 24. The second lens retainer 24 is connected to the inner wall of the second lens sleeve 25 by threaded or interference fit, and abuts against the edge of the incident or exit surface of the cemented doublet lens 7 to achieve axial positioning and fixation of the cemented doublet lens 7 in the optical axis direction. The second lens sleeve 25 is connected to the filter and dichroic mirror mounting assembly 15 and the housing 20. Through the fastening structure of the second lens retainer 24, the cemented doublet lens 7 is precisely fixed in the optical path, ensuring its beam convergence and chromatic aberration correction effects. For ease of assembly, the outer wall of the second lens sleeve 25 can be provided with a threaded or flanged structure for connection with the corresponding interface on the housing 20.

[0053] As a preferred embodiment of the present invention, see Figure 2 As shown, the collimating mirror 9, blazed grating 10, and focusing mirror 11 are respectively fixed on the first mounting bracket 17, the second mounting bracket 18, and the third mounting bracket 19, while the first mounting bracket 17, the second mounting bracket 18, and the third mounting bracket 19 are all fixed on the housing 20. The mounting bracket configuration greatly facilitates installation and adjustment. In the actual assembly process, technicians can individually install and finely adjust the collimating mirror 9, blazed grating 10, and focusing mirror 11 without being restricted by the fixed positions of other components. For example, when installing the collimating mirror 9, its angle and position can be precisely adjusted according to the actual optical path requirements to ensure optimal collimation. After adjusting the collimating mirror 9, the blazed grating 10 and focusing mirror 11 are then operated sequentially. This method of adjusting each component individually effectively improves assembly accuracy and efficiency; among them, Figure 2 The optical path schematic slot 21 shows the schematic structure of the optical path.

[0054] Furthermore, the first mounting bracket 17, the second mounting bracket 18, and the third mounting bracket 19 can be fixed to the housing 20 in a detachable manner, for example, by screws. Each mounting bracket can be provided with mounting holes, positioning slots, or adjustment mechanisms to facilitate the positioning and angle adjustment of optical elements. For example, the first mounting bracket 17 and the third mounting bracket 19 can be provided with a two-dimensional tilt adjustment mechanism for adjusting the reflection angles of the collimating mirror 9 and the focusing mirror 11; the second mounting bracket 18 can be provided with a rotation adjustment mechanism for adjusting the incident angle of the blazed grating 10 to optimize spectral resolution and diffraction efficiency.

[0055] The collimating mirror 9, blazed grating 10, and focusing mirror 11 are each fixed to an independent mounting bracket and then to the housing 20, forming a stable integrated structure. This integrated fixing method effectively reduces the impact of external vibrations and impacts on the optical system. In practical applications, such as home or community testing environments, the equipment may be subject to varying degrees of vibration interference. In this case, the components fixed to the housing 20 maintain a relatively stable positional relationship, ensuring the stability of the optical path and thus ensuring the spectrometer can operate continuously and accurately, improving the system's reliability.

[0056] When an optical component malfunctions or needs replacement, because it is fixed on an independent mounting bracket and the connection methods between each component and the housing 20 are clearly defined, maintenance personnel can easily locate and disassemble the corresponding mounting bracket to replace or repair the faulty component. This avoids maintenance difficulties caused by the complex overall structure, greatly shortens maintenance time, and reduces maintenance costs. If the blazed grating 10 is damaged, maintenance personnel only need to remove the second mounting bracket 18 that fixes the blazed grating 10 to replace it, without having to perform a large-scale disassembly and reassembly of the entire optical system.

[0057] In a preferred embodiment of the present invention, the linear CCD 12 is fixed to the housing 20, with its photosensitive surface located at the focal plane of the focusing mirror 11 to ensure that light signals of different wavelengths can be accurately focused onto the corresponding pixels. The linear CCD 12 and the housing 20 can be connected by a detachable method such as screws or snap-fit ​​connections, facilitating subsequent maintenance and upgrades. Furthermore, a fine-tuning mechanism can be provided at the mounting position of the linear CCD 12 to precisely adjust the spatial position of the detector, ensuring that the spectral signal is accurately focused onto the pixel array and improving the accuracy of spectral acquisition.

[0058] This invention integrates the probe optical path and the spectrometer system of a portable Raman spectrometer into a single unit. The Raman signal collected by the probe is directly focused onto the slit of the spectrometer system, avoiding the attenuation problem caused by signal transmission via fiber optics in discrete commercial probes. A large numerical aperture aspherical lens structure is used in both the excitation and collection optical paths of the probe, achieving efficient excitation of the sample Raman signal and large numerical aperture signal collection. While ensuring good matching between the probe optical path and the spectrometer system, the system size is effectively shortened by designing a cemented lens group, and axial chromatic aberration generated when the Raman signal passes through the slit is eliminated.

[0059] This invention, through integrated design, ensures a 7cm diameter. -1 ~10cm -1While significantly reducing manufacturing costs, this high-throughput miniature Raman spectrometer achieves a balance between low cost, high precision, portability, and intelligence. Suitable for home and community food safety testing scenarios, it enables rapid detection of methanol, pesticide residues, food additives, and illegal additives in food, demonstrating broad application prospects. The system is compact, easy to operate, and fast, meeting the daily food safety testing needs of non-professionals and playing a vital role in ensuring public food safety.

Claims

1. A high-flux micro Raman spectrometer, characterized in that, This high-flux micro Raman spectrometer includes: a laser module, an external optical path system, and a spectroscopic system; The excitation module includes a narrowband laser module (1) and a collimating lens (2). The axes of the narrowband laser module (1) and the collimating lens (2) are coincident, and the laser emitted from the narrowband laser module (1) passes through the collimating lens (2). The external optical path system includes a stage (5), an aspherical lens (4), a dichroic mirror (3), a long-pass filter (6), a cemented doublet (7), and a slit (8); a dichroic mirror (3) is provided in the direction of laser emission from the collimating lens (2), an aspherical lens (4) is provided in the direction of laser emission from the dichroic mirror (3), and a stage (5) for placing the sample to be tested is provided at the focal plane of the aspherical lens (4); a long-pass filter (6) is provided in the direction of light emission from the dichroic mirror (3), a cemented doublet (7) is provided in the direction of light emission from the long-pass filter (6), and a slit (8) is provided at the focal plane of the cemented doublet (7); The beam splitting system includes a collimating mirror (9), a collimating mirror (9) is provided in the direction of the outgoing light of the slit (8), a blazed grating (10) is provided in the direction of the outgoing light of the collimating mirror (9), a focusing mirror (11) is provided in the direction of the outgoing light of the blazed grating (10), and a linear CCD (12) is provided in the direction of the outgoing light of the focusing mirror (11).

2. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The laser beam emitted from the narrowband laser module (1) is incident on the dichroic mirror (3) through the collimating lens (2). After being reflected by the dichroic mirror (3), the laser beam is focused by the aspherical lens (4) onto the sample to be tested in the stage (5) to excite Raman scattered light and Rayleigh scattered light. After being collimated by the aspherical lens (4), the Raman scattered light and Rayleigh scattered light pass through the dichroic mirror (3) and the long-pass filter (6) in sequence to filter out the Rayleigh scattered light. Then, they are focused by the doublet lens (7) onto the slit (8). The Raman scattered light emitted from the slit (8) is collimated by the collimating mirror (9) and dispersed by the blazed grating (10) in sequence. Finally, it is focused by the focusing mirror (11) onto the linear CCD (12).

3. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The narrowband laser module (1) is fixed inside the heat sink (13), and the heat sink (13) is fixed on the housing (20).

4. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The aspherical lens (4) is fixed inside the first lens sleeve (22). The inner wall of the first lens sleeve (22) is provided with an annular mounting groove. The first lens retainer (23) cooperates with the annular mounting groove and abuts against the edge of the aspherical lens (4) to achieve axial fixation of the aspherical lens (4) and form an aspherical lens mounting assembly (14).

5. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The dichroic mirror (3) and the long-pass filter (6) are fixed inside the filter holder (26) to form a filter and dichroic mirror mounting assembly (15), and are connected to the aspherical lens mounting assembly (14); wherein, the two ends of the dichroic mirror (3) are located at opposite corners of the filter holder (26), the long-pass filter (6) and the dichroic mirror (3) are set at a 45° angle, and are parallel to the laser emission direction, and are located on the side of the dichroic mirror (3) that transmits Raman scattered light.

6. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The cemented doublet lens (7) is fixed inside the second lens sleeve (25), and the inner wall of the second lens sleeve (25) is provided with an annular mounting groove for mounting the retaining ring of the cemented doublet lens (7); the second lens retaining ring (24) is connected to the inner wall of the second lens sleeve (25) by threaded fit or interference fit, and abuts against the edge of the incident surface or exit surface of the cemented doublet lens (7) to realize the axial limiting and fixing of the cemented doublet lens (7) in the optical axis direction, forming a cemented doublet lens mounting assembly (16), and connected to the filter and dichroic mirror mounting assembly (15) and the housing (20).

7. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The collimating mirror (9), the blazed grating (10) and the focusing mirror (11) are respectively fixed on the first mounting bracket (17), the second mounting bracket (18) and the third mounting bracket (19), and the first mounting bracket (17), the second mounting bracket (18) and the third mounting bracket (19) are all detachably connected to the housing (20); the linear CCD (12) is fixed on the housing (20).

8. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The numerical aperture of the aspherical lens (4) is 0.79; and / or the width of the slit (8) is 25 μm to 50 μm.

9. The high-flux micro Raman spectrometer according to claim 1, characterized in that, The dichroic mirror (3) has a narrow linewidth laser reflectivity ≥95% and a Raman scattering transmittance ≥90%; and / or, the long-pass filter (6) has an optical density OD ≥6; and / or, the cemented doublet lens (7) has a focal length of 15mm~28mm; and / or, the collimating mirror (9) has a focal length of 50mm~100mm; and / or, the linear CCD (12) has a spectral response range covering 540nm~650nm.

10. The high-flux micro Raman spectrometer according to any one of claims 1-9, characterized in that, The high-flux miniature Raman spectrometer achieves a light flux of 15% to 30%, more than three times higher than that of conventional discrete CT Raman spectrometers, with a resolution of 7 cm⁻¹. -1 ~10cm -1 .

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