Large-view-field snapshot type Raman imaging system

Abstract

The invention relates to the technical field of spectral analysis, in particular to a large-view-field snapshot type Raman imaging system, in a microscopic imaging light path, a first light source irradiates a to-be-detected sample, and a microscopic imaging assembly receives a light beam generated by the to-be-detected sample and performs microscopic imaging on the to-be-detected sample; a first micro-lens array in the Raman excitation light path corrects a light beam emitted by a second light source into a surface-excited point light source array, and the point light source array irradiates a to-be-detected sample, so that the to-be-detected sample is excited by the point light source array to form Raman scattering light; raman scattering light in the imaging spectrum light path enters the spectrograph through the second micro-lens array, the second micro-lens array cuts the image surface of the microscopic imaging light path and divides the image surface into a plurality of units, and the units are rearranged in the two-dimensional space dimension. By adopting the microlens array, Raman spectrum imaging is realized while high-resolution microscopic imaging is performed, and the problems of small imaging area and low analysis speed of Raman spectrum imaging detection are solved.

Description

Technical Field

[0001] This invention belongs to the field of spectral analysis technology, and in particular relates to a large field-of-view snapshot Raman imaging system. Background Technology

[0002] Raman spectroscopy imaging systems are analytical devices that deeply integrate Raman spectroscopy and imaging technologies, enabling simultaneous characterization of the chemical composition and molecular structure of materials. This system expands the initial detection field of view into a planar field of view through different scanning modes such as point scanning, line scanning, and wide field of view, thereby acquiring and generating a Raman imaging spectral data cube. This data cube possesses a three-dimensional information structure with dual spatial dimensions and a single spectral dimension. Based on this data cube, both single-wavelength images at specific wavelengths can be extracted to observe the spatial distribution of the target, and the spectral information of the target can also be obtained. By extracting the column vector data corresponding to a certain spatial location in the data cube, it can be converted into the Raman spectral curve of the target at that location. This characteristic embodies the core advantage of the spectral imaging system's data cube—"image and spectrum integration"—allowing the Raman spectroscopy imaging system to conveniently perform simultaneous imaging and spectral analysis of samples.

[0003] To address the challenges of stimulated Raman spectroscopy in large-field imaging applications, current research has proposed corresponding scanning schemes: one involves using a sinusoidal galvanometer scanning method combined with motorized sample stage movement, controlling the galvanometer via a servo drive board, and precisely adjusting the galvanometer deflection angle by regulating the input voltage amplitude; the other utilizes a multi-faceted scanning mirror paired with a high-speed rotating polygonal prism to cause rapid periodic changes in the incident laser angle, allowing reflected laser light at different angles to be focused onto different spatial positions on the sample surface. While these scanning methods can achieve high scanning frequencies, they suffer from significant shortcomings in stability and accuracy, making it difficult to meet the requirements for high-resolution image acquisition in microscopic imaging scenarios. Summary of the Invention

[0004] In view of this, the present invention aims to provide a large field-of-view snapshot Raman imaging system, which uses a microlens array to generate a high-resolution single-source array, thereby achieving uniform beam intensity distribution and surface excitation of sample Raman scattering. At the same time, the microlens array is used at the spectrometer to improve the field of view, thus solving the problems of small imaging area and slow analysis speed in Raman spectroscopy imaging.

[0005] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A large field-of-view snapshot Raman imaging system includes: The microscopic imaging optical path includes a first light source and a microscopic imaging component. The first light source illuminates the sample to be tested, and the microscopic imaging component receives the light beam generated from the sample to be tested and performs microscopic imaging on the sample to be tested. The Raman excitation optical path includes a second light source and a first microlens array. The first microlens array corrects the beam emitted by the second light source into a point light source array that is excited by the surface. The point light source array illuminates the sample to be tested, so that the sample to be tested is excited by the point light source array to form Raman scattered light. The imaging spectral optical path includes a second microlens array and a spectrometer. Raman scattered light enters the spectrometer through the second microlens array. The second microlens array cuts and divides the image plane of the microscopic imaging optical path into several units, and rearranges these units in a two-dimensional space dimension.

[0006] Furthermore, the microscopic imaging component includes a telescope, a first lens, and a detector, wherein: the telescope receives a light beam generated from the sample under test and converts the light beam into parallel light, while simultaneously focusing the point light source array from the first microlens array onto the sample under test; the first lens focuses the parallel light from the telescope into the detector and the second microlens array; the detector receives the light beam from the first lens, so that the sample under test is imaged in the detector.

[0007] Furthermore, it also includes a beam-shaping optical path, which includes a second lens, a bandpass filter, and a notch filter. The second lens is placed between the first microlens array and the tube mirror to convert the point source array into parallel light. The bandpass filter is placed between the second lens and the tube mirror to filter out the light of the detector response wavelength from the parallel light from the second lens and transmits the filtered beam to the tube mirror for focusing, so that the sample under test is excited by the focused light to form Raman scattered light. The tube mirror then converts the Raman scattered light into parallel Raman scattered light. The notch filter is placed between the first lens and the second microlens array to filter and reduce noise from the Raman scattered light from the first lens.

[0008] Furthermore, the second microlens array is located at the back focal plane of the tube lens.

[0009] Furthermore, a first dichroic mirror is provided between the bandpass filter and the tube lens. The first dichroic mirror reflects the parallel light from the bandpass filter onto the tube lens, and the light from the tube lens passes through the first dichroic mirror into the second lens.

[0010] Furthermore, a second dichroic mirror is provided between the first lens and the detector. The second dichroic mirror transmits the Raman scattered light from the first lens to the notch filter and reflects the light from the first light source into the detector.

[0011] Compared with the prior art, the present invention can achieve the following beneficial effects: This invention creates a large field-of-view snapshot Raman imaging system that utilizes a microlens array to divide the parallel laser wavefront emitted by the light source into multiple sub-wavefronts. Each sub-beam is independently phase- and wavefront-modulated using designed micrometer-level units, allowing a single laser beam to acquire multiple laser points on the object surface. This broadens the point light source to a millimeter-scale spot size, achieving uniform beam intensity distribution and surface excitation of Raman scattering from the sample. This provides a larger sampling area, improving detection efficiency and spectral throughput. Simultaneously, the back-end utilizes the microlens array to achieve Raman spectral imaging simultaneously with high-resolution microscopic imaging, acquiring sample surface-excited Raman scattering information in an extremely short time, significantly improving imaging speed. Finally, the absence of moving parts reduces system complexity, improves detection speed and measurement repeatability, and makes it more suitable for in-situ real-time monitoring. Attached Figure Description

[0012] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the structure of the large field-of-view snapshot Raman imaging system described in the embodiment of the present invention; Figure 2 The optical path diagram of the microlens array described in the embodiments of the present invention; Figure 3 A dot diagram of the microlens array described in the embodiments of the present invention.

[0013] Explanation of reference numerals in the attached figures: 1. Sample to be tested; 2. First light source; 3. Second light source; 4. First microlens array; 5. Second microlens array; 6. Spectrometer; 7. Tube lens; 8. First lens; 9. Detector; 10. Beam expander; 11. Second lens; 12. Bandpass filter; 13. Notch filter; 14. First dichroic mirror; 15. Second dichroic mirror. Detailed Implementation

[0014] 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.

[0015] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0016] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0017] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0018] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] like Figure 1As shown in the embodiment of the present invention, the large field-of-view snapshot Raman imaging system includes a microscopic imaging optical path, a Raman excitation optical path, and an imaging spectral optical path. The microscopic imaging optical path performs microscopic imaging on the sample 1 under test. The Raman excitation optical path generates a laser that excites the sample 1 under test to form Raman scattered light. The imaging spectral optical path receives the Raman scattered light generated by the sample 1 under test and performs large field-of-view imaging. The microscopic imaging optical path includes a first light source 2 and a microscopic imaging component. The first light source 2 illuminates the sample 1 under test, and the microscopic imaging component receives the light beam generated from the sample 1 under test and performs microscopic imaging on the sample 1 under test. The Raman excitation optical path includes a second light source 3 and a first microlens array 4. The first microlens array 4 corrects the light beam emitted by the second light source 3 into a point light source array that is excited by a surface. The point light source array illuminates the sample 1 under test, causing the sample 1 under test to be excited by the point light source array to form Raman scattered light. The imaging spectral optical path includes a second microlens array 5 and a spectrometer 6. Raman scattered light enters the spectrometer 6 through the second microlens array 5. The second microlens array 5 cuts and divides the image plane of the microscopic imaging optical path into several units, and rearranges these units in two-dimensional space. At this time, the second microlens array 5 acts as the entrance pinhole of the spectrometer 6, replacing the entrance slit of a traditional hyperspectral imager. In addition, the first microlens array 4 and the second microlens array 5 modulate the numerical aperture of both the microscopic imaging optical path and the imaging spectral optical path.

[0020] In this embodiment of the invention, the first light source 2 is a halogen lamp, meaning the light emitted by the halogen lamp is transmitted through the back of the sample 1 under test before entering the microscopic imaging assembly. Furthermore, a beam expander 10 is provided between the second light source 3 and the first microlens array 4. The beam expander 10 expands the light from the first light source 2 to form parallel light and transmits the parallel light to the first microlens array 4. The first microlens array 4 homogenizes the parallel light, correcting a beam of parallel light into a point light source array excited by a surface. Raman spectroscopy imaging typically uses visible or near-infrared light for excitation. For biological samples, this embodiment of the invention preferably uses the second light source 3, which has a smaller thermal effect; that is, the laser wavelength emitted by the second light source 3 is 785 nm. The power of the second light source 3 should be sufficiently high. To adapt to the testing of different types of samples, adjustable excitation power can improve the signal-to-noise ratio and significance.

[0021] The first microlens array 4 and the second microlens array 5 are as follows Figure 2 and Figure 3As shown, an array of lenses with apertures and relief depths in the micrometer range is used. It possesses the basic functions of traditional lenses, such as focusing and imaging, with small unit size and high integration. The smaller the center distance between the first microlens array 4 and the second microlens array 5, the higher the spatial resolution; the larger the center distance, the wider the spectral range of dispersion of a single microlens unit on the detector. In this embodiment, the dimensions of the first microlens array 4 and the second microlens array 5 are 10mm × 10mm, their center distance is 250μm, and the radius of curvature of a single microlens unit is 297μm.

[0022] In some embodiments, the microscopic imaging assembly includes a tube lens 7, a first lens 8, and a detector 9, wherein: the tube lens 7 receives a light beam generated from the sample under test 1 and converts the beam into parallel light, while simultaneously focusing the point light source array from the first microlens array 4 onto the sample under test 1; the first lens 8 focuses the parallel light from the tube lens 7 into the detector 9 and the second microlens array 5; the detector 9 receives the light beam from the first lens 8, thus imaging the sample under test 1 in the detector 9. The second microlens array 5 is located at the back focal plane of the tube lens 7.

[0023] In this embodiment of the invention, the spectral range required for the operation of a large-field Raman imager needs to cover 200-2700 cm. -1 The corresponding wavelength range is 400-1000nm. In order to achieve high dynamic range and high response sensitivity, a detector with high quantum efficiency, large pixel size and low noise should be selected. Specifically, in this embodiment of the invention, a CCD detector is used, that is, the imaging light path formed by the first light source 2 is focused on the target surface of the two-dimensional CCD detector to realize the large field of view detection of micro Raman signals.

[0024] In some embodiments, the system further includes a beam shaping optical path, which includes a second lens 11, a bandpass filter 12, and a notch filter 13. The second lens 11 is placed between the first microlens array 4 and the tube mirror 7 to convert the point light source array into parallel light; the bandpass filter 12 is placed between the second lens 11 and the tube mirror 7 to filter out the light of the detector 9 response wavelength from the parallel light from the second lens 11, and transmits the filtered beam to the tube mirror 7 for focusing, so that the sample 1 to be tested is excited by the focused light to form Raman scattered light, and the tube mirror 7 then converts the Raman scattered light into parallel Raman scattered light; the notch filter 13 is placed between the first lens 8 and the second microlens array 5 to filter and denoise the Raman scattered light from the first lens 8, specifically by eliminating the Rayleigh scattering signal and the residual light source signal of the second light source 3 in the Raman scattered light from the first lens 8.

[0025] In some embodiments, a first dichroic mirror 14 is provided between the bandpass filter 12 and the tube lens 7. The first dichroic mirror 14 reflects the parallel light from the bandpass filter 12 onto the tube lens 7, and the light from the tube lens 7 passes through the first dichroic mirror 11 into the second lens 11. In addition, a second dichroic mirror 15 is provided between the first lens 8 and the detector 9. The second dichroic mirror 15 transmits the Raman scattered light from the first lens 8 to the notch filter 13 and reflects the light from the first light source 2 onto the target surface of the detector 9.

[0026] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0027] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A large field of view snapshot Raman imaging system, characterized in that, The application relates to a micro-imaging and Raman spectrum system. The micro-imaging and Raman spectrum system comprises a micro-imaging light path, a Raman excitation light path and an imaging spectrum light path. The micro-imaging light path comprises a first light source and a micro-imaging component, the first light source irradiates a sample to be detected, and the micro-imaging component receives a light beam generated from the sample to be detected and performs micro-imaging on the sample to be detected. The Raman excitation light path comprises a second light source and a first microlens array, the first microlens array corrects the light beam emitted from the second light source into a point light source array for surface excitation, the point light source array irradiates the sample to be detected, and the sample to be detected is excited by the point light source array to form Raman scattering light.

2. The large field of view snapshot Raman imaging system of claim 1, wherein, The imaging spectrum light path comprises a second microlens array and a spectrometer, the Raman scattering light enters the spectrometer through the second microlens array, the second microlens array cuts and divides an image plane of the micro-imaging light path into a plurality of units and rearranges the units in two-dimensional space. The micro-imaging component comprises a cylindrical lens, a first lens and a detector. The cylindrical lens receives the light beam generated from the sample to be detected and converts the light beam into parallel light, and converges the point light source array from the first microlens array onto the sample to be detected. The first lens converges the parallel light from the cylindrical lens into the detector and the second microlens array.

3. The large field of view snapshot Raman imaging system of claim 2, wherein, The detector receives the light beam from the first lens and images the sample to be detected in the detector. The micro-imaging and Raman spectrum system further comprises a beam shaping light path, the beam shaping light path comprises a second lens, a band-pass filter and a notch filter. The second lens is arranged between the first microlens array and the cylindrical lens and converts the point light source array into parallel light. The band-pass filter is arranged between the second lens and the cylindrical lens, filters out light of a wavelength responsive to the detector from the parallel light from the second lens, and transmits the filtered light beam to the cylindrical lens for convergence, so that the sample to be detected is excited by the converged light to form Raman scattering light, and the cylindrical lens converts the Raman scattering light into parallel Raman scattering light.

4. The large field of view snapshot Raman imaging system of claim 2, wherein, The notch filter is arranged between the first lens and the second microlens array and filters and denoises the Raman scattering light from the first lens.

5. The large field of view snapshot Raman imaging system of claim 3, wherein, The second microlens array is located at a back focal plane of the cylindrical lens.

6. The large field of view snapshot Raman imaging system of claim 3, wherein, A first dichroic mirror is arranged between the band-pass filter and the cylindrical lens, the first dichroic mirror reflects the parallel light from the band-pass filter onto the cylindrical lens, and the light from the cylindrical lens transmits through the first dichroic mirror into the second lens. A second dichroic mirror is arranged between the first lens and the detector, the second dichroic mirror transmits the Raman scattering light from the first lens to the notch filter and reflects the light from the first light source to the detector.

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