Line scanning differential confocal Raman microscopic spectrum co-fusion imaging system

Abstract

The invention provides a line scanning differential confocal Raman microscopic spectrum co-fusion imaging system, which belongs to the microscopic imaging technology, and comprises a light spot illumination module, a confocal imaging module, a Raman imaging module, a line scanning module and a control module, the confocal imaging module is used for enabling reflected light of a sample to be detected to equivalently enter the first camera, the second camera and the third camera so as to obtain pre-focus, focal plane and post-focus images of the sample to be detected, and the Raman imaging module is used for obtaining chemical Raman component spectrum information; the control module obtains a confocal image with surface height information of the to-be-detected sample according to the pre-focus image, the focal plane image and the post-focus image of the to-be-detected sample, and synchronously fuses the confocal image and the chemical Raman component spectrum information to obtain a four-dimensional image comprising the three-dimensional surface topography and the chemical Raman component spectrum of the to-be-detected sample. According to the invention, map co-fusion can be realized, and more visual multi-dimensional measurement information can be obtained.

Description

Technical Field

[0001] The present invention belongs to microscopic imaging technology, and in particular relates to a line scanning differential confocal Raman microscopic atlas confocal imaging system. Background Art

[0002] As modern manufacturing industries put forward requirements for high-speed imaging, high resolution and large-scale measurement of three-dimensional information of surface morphology, optical microscope measurement technology with micro-nano precision has been constantly updated. Traditional point scanning confocal measurement technology uses a conjugate imaging pinhole to shield non-focal signals. It only images one point at a time and needs to scan point by point. It is inefficient, and its three-dimensional resolution is limited by the diffraction limit. Line scanning differential confocal measurement technology can solve the defects of point scanning confocal measurement technology. It uses a line shaping mirror to form a line light source and scans it through a high-speed galvanometer, which greatly improves the imaging speed. Despite this, existing detection methods are difficult to achieve efficient, large-scale, high-resolution imaging of the three-dimensional morphology of samples at the same time, and cannot effectively integrate the three-dimensional morphology and chemical composition information in real time, limiting its application in the fields of biomedicine and semiconductor detection. Summary of the Invention

[0003] The purpose of the present invention is to propose a line scanning differential confocal Raman microscopy atlas fusion imaging system, which can achieve atlas fusion and obtain more intuitive multi-dimensional measurement information.

[0004] The present invention is achieved through the following technical solutions:

[0005] A line scanning differential confocal Raman microscopy system includes a spot illumination module, a confocal imaging module, a Raman imaging module, a line scanning module and a control module. The spot illumination module is used to form a line focus spot to focus on the surface of the sample to be tested. The confocal imaging module is used to make the reflected light of the sample to be tested enter the first camera, the second camera and the third camera in equal amounts to obtain the pre-focus, focus plane and post-focus images of the sample to be tested. The Raman imaging module is used to focus the reflected light of the sample to be tested to the spectrometer to obtain chemical Raman component spectrum information. The line scanning module includes an amplifying module, a confocal imaging module, a Raman imaging module, a line scanning module and a control module. A stage is placed on which the sample to be tested is driven to move the sample to be tested in a direction perpendicular to the line. The first camera, the second camera, and the third camera take pictures each time the sample to be tested moves. The control module obtains a confocal image with surface height information of the sample to be tested based on the light intensity difference between the pre-focus, focal plane, and post-focus images of the sample to be tested and a pre-calibrated light intensity difference and axial position response characteristic curve. The confocal image and the chemical Raman component spectrum information are synchronously fused to obtain a four-dimensional image including the three-dimensional surface morphology and chemical Raman component spectrum of the sample to be tested.

[0006] Furthermore, the spot illumination module includes a laser, a beam expander lens group, a line shaping mirror, a first collimating lens group, a spatial light modulator, a polarization beam splitter, a quarter-wave plate, a reflector, a dichroic mirror, a second collimating lens group, an objective lens and a stage connected according to the transmission direction of the light signal.

[0007] Furthermore, the confocal imaging module includes an objective lens, a second collimating lens group, a dichroic mirror, a reflector, a quarter-wave plate, a polarization beam splitter, a third collimating lens group, a first beam splitter and a second beam splitter, and a first camera connected to the second reflector, a second camera connected to the second beam splitter, and a third camera, and the amount of light entering the first camera, the second camera, and the third camera is the same.

[0008] Furthermore, the Raman imaging module includes an objective lens, a second collimating lens group, a dichroic mirror, a fourth collimating lens group, a slit and a spectrometer connected in the direction of light signal transmission.

[0009] Furthermore, the polarization beam splitter reflects S-polarized light and transmits P-polarized light, and the splitting ratios of the first beam splitter and the second beam splitter are both 50R / 50T.

[0010] Furthermore, the control module is respectively connected to the first camera, the second camera, the third camera and the spectrometer

[0011] The images corresponding to the first camera, the second camera, and the third camera are connected, and the difference between each two is obtained to obtain three differential signals. The three-dimensional surface morphology of the sample to be tested is restored according to each differential signal and the pre-calibrated response characteristic curve. The specific Raman peak intensity is mapped to the three-dimensional surface morphology using pseudo-color mapping technology, thereby realizing the fusion of the three-dimensional surface morphology and the chemical Raman component spectrum.

[0012] Furthermore, the wavelength of the laser is 523 nm or 785 nm.

[0013] Furthermore, the line shaping lens includes a cylindrical lens or a Powel prism.

[0014] Furthermore, the second camera is conjugate with the sample, the first camera is located at a distance Δ before the sample is imaged, and the third camera is located at a distance Δ after the sample is imaged, where the value of Δ ranges from 0.5um to 10um.

[0015] Furthermore, the control module includes a computer.

[0016] The present invention has the following beneficial effects:

[0017] 1. The spot illumination module of the present invention forms a line-focused spot focused on the surface of the sample to be tested, and controls the confocal imaging module and the Raman imaging module to simultaneously obtain the light intensity information and chemical Raman component spectrum information of the sample to be tested. The light intensity information includes the scanning information of the test sample before focus, at the focal plane, and after focus. The control module then synchronously fuses the light intensity information and the chemical Raman component spectrum information to obtain a three-dimensional image including the three-dimensional surface morphology and chemical Raman component spectrum of the sample to be tested. In this way, the morphological features and spectral features of the test sample are integrated into the three-dimensional image, that is, the spectrum is integrated, and more intuitive multi-dimensional measurement information is obtained with richer information. Compared with traditional point scanning microscopy imaging devices, there is no need to scan the sample point by point, which greatly improves the imaging speed. The first camera, the second camera, and the third camera respectively obtain the scanning information before focus, at the focal plane, and after focus, eliminating the defocus signal, which can improve the system's axial resolution, signal-to-noise ratio, and anti-interference ability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The present invention will be further described in detail below with reference to the accompanying drawings.

[0019] Figure 1 It is a structural schematic diagram of the present invention.

[0020] Figure 2 Schematic diagram of the optical path structure of the confocal imaging module of the present invention.

[0021] Figure 3 Schematic diagram of the optical path structure of the Raman imaging module of the present invention.

[0022] Among them, 1. Laser; 2. Beam expander lens group; 3. Line shaping mirror; 4. First collimating lens group; 5. Spatial light modulator; 6. Polarization beam splitter; 7. Second collimating lens group; 8. First beam splitter; 9. First camera; 10. Second camera; 11. Second beam splitter; 12. Third camera; 13. Stage; 14. Objective lens; 15. Third collimating lens group; 16. Dichroic mirror; 17. Spectrometer; 18. Slit; 19. Fourth collimating lens group; 20. Reflector; 21. Quarter wave plate. DETAILED DESCRIPTION

[0023] like Figures 1 to 3As shown, the line scanning differential confocal Raman microscopy imaging system includes a spot illumination module, a confocal imaging module, a Raman imaging module, a line scanning module and a control module. The spot illumination module is used to form a line focus spot focused on the surface of the sample to be tested. The confocal imaging module is used to make the reflected light of the sample to be tested enter the first camera 9, the second camera 10 and the third camera 12 in equal amounts to obtain the pre-focus, focus plane and post-focus images of the sample to be tested. The Raman imaging module is used to focus the reflected light excited by the sample to be tested after being irradiated to the spectrometer 17 to obtain the chemical Raman component spectrum information. The line scanning module includes The stage 13 on which the sample to be tested is placed moves the sample to be tested along the vertical direction of the line expansion. The first, second, and third cameras take photos after each movement of the sample to be tested. The control module obtains a confocal image containing surface height information of the sample to be tested based on the intensity difference between the pre-focus, focus plane, and post-focus images of the sample to be tested, as well as a pre-calibrated characteristic curve of intensity difference versus axial position. The confocal image is then synchronously fused with the chemical Raman component spectrum information to obtain a four-dimensional image including the three-dimensional surface topography and chemical Raman component spectrum of the sample to be tested. The "line expansion" refers to the direction in which the length of the line focus spot extends.

[0024] In this embodiment, the control module includes a computer, a stage 13 controller, a motion control card, a laser controller, and a data network cable. The computer transmits signals controlling the actions of the corresponding components via the data network cable. The X, Y, and Z motions of stage 13 are driven by a motor connected to the stage 13 controller, which is in turn connected to the motion control card, which is connected to the computer. The laser 1 is connected to the laser controller, which is in turn connected to the computer. The first, second, and third cameras 9, 10, 12 are all CCD cameras, connected to the computer via high-speed data interfaces. The spectrometer 17 is connected to the computer via a fiber optic interface.

[0025] The spot illumination module includes a laser 1, a beam expander lens group 2, a line shaper 3, a first collimator lens group 4, a spatial light modulator 5, a polarization beam splitter 6, a reflector 20, a dichroic mirror 16, a second collimator lens group 7, an objective lens 14, and a stage 13, all connected in the direction of optical signal transmission. The wavelength of the laser 1 is 523 nm or 785 nm. The beam expander lens group 2 is a 2-3 magnification lens. The line shaper 3 comprises a cylindrical lens or a Powell prism with a divergence angle of 3° to 15°. The first collimator lens group 4 has a focal length range of 75 nm to 100 nm and a refractive index of 1.46. The polarization beam splitter 6 is made of UV fused silica, reflecting S-polarized light and transmitting P-polarized light. The second collimator lens group 7 has a focal length range of 100 nm to 150 nm and a refractive index of 1.46. The dichroic mirror 16 is made of a lens material coated with a filter and an anti-reflection coating.

[0026] The confocal imaging module includes a stage 13, an objective lens 14, a second collimating lens group 7, a dichroic mirror 16, a reflector 20, a polarizing beam splitter 6, a third collimating lens group 15, a first beam splitter 8, a second beam splitter 11, a first camera 9 connected to the second reflector, and a second camera 10 and a third camera 12 connected to the second beam splitter 11. The amount of light entering the first, second, and third cameras 9, 10, 12 is the same, and the first, second, and third cameras 9, 10, 12 respectively acquire pre-focus, focal plane, and post-focus scan information of the sample. More specifically, the second camera 10 is conjugate with the sample, with the first camera 9 positioned a distance Δ before the sample image, and the third camera 12 positioned a distance Δ after the sample image. Δ ranges from 0.5 μm to 10 μm, and the specific value is related to the NA (numerical aperture) value of the objective lens 14. The third collimating lens group 15 has a focal length range of 100 nm to 200 nm and a refractive index of 1.46. The first beam splitter 8 and the second beam splitter 11 are both made of lens material, and the splitting ratio is 50R / 50T. The amount of light entering the first camera 9, the second camera 10 and the third camera 12 is made equal by the existing normalization algorithm, which is a prior art process.

[0027] The Raman imaging module includes a stage 13, an objective lens 14, a second collimating lens group 7, a dichroic mirror 16, a fourth collimating lens group 19, a slit 18, and a spectrometer 17, all connected in the direction of optical signal transmission. The fourth collimating lens group 19 has a focal length range of 100 nm to 200 nm and a refractive index of 1.46.

[0028] Laser 1 emits laser light, which is expanded by beam expander lens group 2 and then forms a line-focused spot by line shaping lens 3. The line-focused spot passes through first collimating lens group 4 and is spatially modulated by spatial light modulator 5. The line-focused spot then passes through polarization beam splitter 6, dichroic mirror 16, second collimating lens group 7 and objective lens 14 in sequence before being focused on the surface of the sample to be measured on stage 13. The movement of objective lens 14 is driven by a motor connected to a computer.

[0029] The reflected light from the sample is split by polarization beam splitter 6, passes through second collimating lens group 7, and then split by first beam splitter 8 and second beam splitter 11. Equal amounts of light enter first camera 9, second camera 10, and third camera 12. Each camera takes a picture each time the sample moves perpendicular to the line spread and feeds the picture back to the computer. The Raman light from the sample is reflected by dichroic mirror 16, then focused by fourth collimating lens group 19 and slit 18 onto spectrometer 17, which acquires chemical composition spectral information and feeds it back to the computer. The computer takes the difference between the pixel points corresponding to the pre-focus image and the focal plane image, and the focal plane image and the post-focus image of the test sample, respectively, to obtain the corresponding light intensity difference. Based on the light intensity difference, the corresponding axial position is obtained from the pre-calibrated response characteristic curve, thereby obtaining a confocal image with the surface height information of the sample to be tested. The response characteristic curve acquisition process is as follows: obtaining the pre-focus, focal plane, and post-focus images of the template sample, the axial position information of the template image is known, thereby obtaining the pre-calibrated light intensity difference and axial position response characteristic curve, which is a prior art process; using pseudo-color mapping technology to map the specific Raman peak intensity to the three-dimensional surface topography (i.e., using the color of the patch on the curved or stepped surface to achieve a visual expression of the spatial distribution of the chemical component), realizing the fusion of the three-dimensional surface topography and the chemical Raman component spectrum. Because the optical path for obtaining the scanning information and the spectral information is illuminated at the same time through the same objective lens 14, the field of view of the two is consistent. Although the acquisition signals are different, the spatial positions of the two are the same, so they can naturally merge, thereby achieving spectrum fusion.

[0030] The above description is merely a preferred embodiment of the present invention and therefore cannot be used to limit the scope of the present invention. In other words, equivalent changes and modifications made according to the scope of the patent application and the contents of the specification should still fall within the scope of the patent of the present invention.

Claims

1. A line scanning differential confocal Raman microscopy imaging system, characterized by: The system includes a spot illumination module, a confocal imaging module, a Raman imaging module, a line scanning module and a control module. The spot illumination module is used to form a line focus spot focused on the surface of the sample to be tested. The confocal imaging module is used to make the reflected light of the sample to be tested enter the first camera, the second camera and the third camera in equal amounts to obtain the pre-focus, focal plane and post-focus images of the sample to be tested. The Raman imaging module is used to focus the reflected light of the sample to be tested onto the spectrometer to obtain chemical Raman component spectrum information. The line scanning module includes a stage for placing the sample to be tested, and the stage drives the sample to be tested to move along the vertical direction of the line expansion. The first camera, the second camera and the third camera take pictures after each movement of the sample to be tested. The control module obtains a confocal image with the surface height information of the sample to be tested based on the light intensity difference of the pre-focus, focal plane and post-focus images of the sample to be tested and the pre-calibrated light intensity difference and axial position response characteristic curve, and synchronously fuses the confocal image and the chemical Raman component spectrum information to obtain a four-dimensional image including the three-dimensional surface morphology and chemical Raman component spectrum of the sample to be tested.

2. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 1, characterized in that: The light spot illumination module includes a laser, a beam expander lens group, a line shaping mirror, a first collimating lens group, a spatial light modulator, a polarization beam splitter, a quarter-wave plate, a reflector, a dichroic mirror, a second collimating lens group, an objective lens and a stage, which are connected according to the transmission direction of the light signal.

3. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 2, characterized in that: The confocal imaging module includes an objective lens, a second collimating lens group, a dichroic mirror, a reflector, a quarter-wave plate, a polarization beam splitter, a third collimating lens group, a first beam splitter and a second beam splitter, as well as a first camera connected to the second reflector, a second camera connected to the second beam splitter, and a third camera. The amount of light entering the first camera, the second camera, and the third camera is the same.

4. A line scanning differential confocal Raman microscopy co-integration imaging system according to claim 1, 2 or 3, characterized in that: The Raman imaging module includes an objective stage, an objective lens, a second collimating lens group, a dichroic mirror, a fourth collimating lens group, a slit and a spectrometer connected in the direction of light signal transmission.

5. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 3, characterized in that: The polarization beam splitter reflects S-polarized light and transmits P-polarized light. The splitting ratios of the first beam splitter and the second beam splitter are both 50R / 50T.

6. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 3, characterized in that: The control module is connected to the first camera, the second camera, the third camera, and the spectrometer, respectively. The images corresponding to the first camera, the second camera, and the third camera are subtracted from each other to obtain three differential signals. The three-dimensional surface morphology of the sample to be tested is restored based on each differential signal and the pre-calibrated response characteristic curve. The specific Raman peak intensity is mapped to the three-dimensional surface morphology using pseudo-color mapping technology, thereby realizing the fusion of the three-dimensional surface morphology and the chemical Raman component spectrum.

7. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 2 or 3, characterized in that: The wavelength of the laser is 523 nm or 785 nm.

8. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 2 or 3, characterized in that: The line shaping lens includes a cylindrical lens or a Powel prism.

9. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 3, characterized in that: The second camera is conjugate with the sample, the first camera is located at a distance Δ before the sample is imaged, and the third camera is located at a distance Δ after the sample is imaged, where the value of Δ ranges from 0.5 um to 10 um.

10. The line scanning differential confocal Raman microscopy co-integration imaging system according to claim 1, 2 or 3, characterized in that: The control module includes a computer.

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