A laser line scanning confocal raman imaging device

Abstract

The application relates to a laser line scanning confocal Raman imaging device applied to the field of Raman spectroscopy, which comprises a light source generation module, a scanning module, a focusing and collecting module and a spectrum detection and imaging module; the light source generation module is used for outputting a laser line; the scanning module is used for receiving the laser line generated by the light source generation module and controlling the received laser line to reciprocally move along a direction perpendicular to the laser line; the focusing and collecting module is used for receiving the moving laser line output by the scanning module and focusing the received moving laser line to the surface of a sample to be detected; and the spectrum detection and imaging module is used for receiving scattered light on the surface of the sample to be detected through the scanning module and generating a Raman image corresponding to the sample to be detected according to the received scattered light. During the detection process, the sample to be detected remains static, liquid surface fluctuation and focal plane drift caused by mechanical vibration during traditional sample moving detection are reduced, the imaging quality is improved, and the device is convenient for adapting to samples of different sizes or states.

Description

Technical Field

[0001] This application relates to the field of Raman spectroscopy technology, and in particular to a laser line scanning confocal Raman imaging device. Background Technology

[0002] Raman spectroscopy is an analytical technique based on the Raman scattering effect. By measuring the characteristic spectrum of a substance after it is scattered by a laser, it can provide chemical fingerprint information of the substance and has important application value in fields such as semiconductor detection and new energy battery research.

[0003] Many related technologies employ sample-moving point scanning confocal Raman microscopy, where the optical path remains stationary, a line laser is projected at a fixed position, and a high-precision motorized stage moves the sample in the XY two-dimensional plane to achieve point-by-point scanning of the light spot. The scattered light enters the spectrometer through a slit, and after scanning, the spectra obtained from all scanning points are stitched together to form a two-dimensional image.

[0004] The aforementioned sample-moving point scanning confocal Raman microscopy imaging method generates mechanical vibrations during use, making it unsuitable for liquid samples, live cells, lithium battery electrolytes, and other samples. The moving motion can easily damage the sample state, causing liquid surface fluctuations and focal plane drift, resulting in large imaging errors and low imaging efficiency. Summary of the Invention

[0005] To address the problems of mechanical vibration caused by movement during the use of mobile point-scanning confocal Raman microscopy, which makes it unsuitable for liquid samples, live cells, lithium battery electrolytes, etc., and easily disrupts sample state, causing liquid surface fluctuations, focal plane drift, large imaging errors, and low imaging efficiency, this application provides a laser line-scanning confocal Raman imaging device. The device employs the following technical solution: it includes a light source generation module, a scanning module, a focusing and collecting module, and a spectral detection and imaging module. The light source generation module outputs a laser line. The scanning module receives the laser line generated by the light source generation module and controls the received laser line to reciprocate in a direction perpendicular to the laser line. The focusing and collecting module receives the moving laser line output by the scanning module and focuses it onto the surface of the sample to be tested. The spectral detection and imaging module receives the scattered light from the surface of the sample after passing through the scanning module and generates a Raman image corresponding to the sample based on the received scattered light.

[0006] In one specific implementation, the light source generation module includes a light source unit for outputting excitation light, a galvanometer is provided in the optical path of the excitation light, the excitation light is converted into a laser line output after passing through the galvanometer, and the deflection angle of the galvanometer corresponds to the position of the input end of the spectral detection imaging module.

[0007] In one specific implementation, a first 4F relay assembly for transmitting a laser line beam is provided between the light source generation module and the scanning module. The first 4F relay assembly includes a first lens and a second lens arranged opposite to each other, and the first lens and the second lens constitute a first conjugate imaging unit.

[0008] In one specific implementation, a beam splitting module for separating the laser line and scattered light is provided between the first 4F relay component and the scanning module. The beam splitting module includes a beam splitter, and the beam splitter and the galvanometer are conjugate to each other. The excitation light in the excitation band retained after the laser line passes through the beam splitter enters the focusing and collecting module, and the scattered light retained after the scattered light passes through the beam splitter enters the spectral detection and imaging module.

[0009] In one specific implementation, the scanning module includes a second 4F relay component and a driving unit. The second 4F relay component includes a third lens and a fourth lens, which constitute a second conjugate imaging unit. The driving unit drives the third lens and the fourth lens to translate equidistantly in opposite directions, thereby controlling the laser line to move in a direction perpendicular to the laser line.

[0010] In one specific implementation, a reflector is provided between the scanning module and the focusing and collecting module, and the laser line reflected by the reflector is coaxial with the incident optical axis of the focusing and collecting module.

[0011] In one specific implementation, the focusing and collecting module includes a microscope, which is used to receive a moving laser line output by the scanning module and focus the received moving laser line onto the surface of the sample to be tested. The laser line reflected by the mirror is coaxial with the incident optical axis of the microscope.

[0012] In one specific implementation, a filter is provided between the scanning module and the spectral detection imaging module. The filter is used to filter out stray light from the scattered light that has the same wavelength as the excitation light.

[0013] In one specific implementation, a tube lens is provided between the filter and the spectral detection imaging module, and the rear focal plane of the microscope objective coincides with the front focal plane of the tube lens.

[0014] In one specific implementation, the spectral detection imaging module includes a slit imaging spectrometer and a detector. After exposure, the detector collects scattered light data of laser lines on the surface of the sample to be tested. The slit imaging spectrometer generates a Raman image corresponding to the sample to be tested based on the collected scattered light data.

[0015] In summary, this application offers the following beneficial technical advantages: the light source generation module outputs a laser line, the focusing and collection module focuses the laser line onto the surface of the sample to be tested, the scanning module controls the reciprocating movement of the laser line to achieve two-dimensional scanning, and the spectral detection and imaging module generates a Raman image corresponding to the sample to be tested based on the received scattered light. Throughout the detection process, the sample remains stationary, preserving its physiological state and reducing liquid surface fluctuations and focal plane drift caused by mechanical vibrations during traditional sample movement detection. This improves imaging quality and facilitates adaptation to samples of different sizes or states. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the overall structure of an embodiment of this application.

[0017] Figure 2 This is a schematic diagram illustrating the structure of the scanning module in an embodiment of this application.

[0018] Reference numerals: 1. Light source generation module; 2. Scanning module; 3. Focusing and collection module; 4. Spectral detection and imaging module; 5. Light source unit; 6. Galvanometer; 7. First lens; 8. Second lens; 9. Beam splitter; 10. Third lens; 11. Fourth lens; 12. Reflector; 13. Microscope; 14. Filter; 15. Tube lens; 16. Sample stage. Detailed Implementation

[0019] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0020] This application discloses a laser line scanning confocal Raman imaging device.

[0021] Reference Figure 1 and Figure 2 The laser line scanning confocal Raman imaging device includes a light source generation module 1, a scanning module 2, a focusing and collecting module 3, and a spectral detection and imaging module 4. The light source generation module 1 outputs a laser line. The scanning module 2 receives the laser line generated by the light source generation module 1 and controls the received laser line to reciprocate in a direction perpendicular to the laser line. The focusing and collecting module 3 receives the moving laser line output by the scanning module 2 and focuses the received moving laser line onto the surface of the sample to be tested. The spectral detection and imaging module 4 receives the scattered light from the surface of the sample to be tested after passing through the scanning module 2 and generates a Raman image corresponding to the sample based on the received scattered light. The sample to be tested is placed on the sample stage 16. In this embodiment, semiconductor detection is used as an example, such as a semiconductor chip or wafer.

[0022] In related technologies, the sample-moving point-scanning confocal Raman microscopy imaging method involves point-by-point scanning, where the two-dimensional imaging time accumulates with the number of pixels. Large samples require long scanning times, leading to a long total acquisition time and making the instrument highly sensitive to stability and drift errors during long-term scanning. For example, during in-situ charge-discharge testing of lithium batteries, the mechanical movement of the sample stage 16 can cause electrolyte sloshing, resulting in liquid surface fluctuations and focal plane drift, severely interfering with image quality. When observing living cells or microfluidic chips, vibrations can disrupt the physiological state of the sample. For large wafers or heavy artifacts, the stage travel is limited, and mechanical stitching errors caused by long-distance movement can introduce image artifacts.

[0023] In this embodiment, the light source generation module 1 outputs a laser line, the focusing and collection module 3 focuses the laser line onto the surface of the sample to be tested, the scanning module 2 controls the laser line to reciprocate to achieve two-dimensional scanning, and the spectral detection and imaging module 4 generates a Raman image corresponding to the sample to be tested based on the received scattered light. Throughout the detection process, the sample remains stationary, maintaining its physiological state and reducing liquid surface fluctuations and focal plane drift caused by mechanical vibrations during traditional sample movement detection. This improves imaging quality and facilitates adaptation to samples of different sizes or states. It also eliminates the need for the traditional galvanometer 6 scanning design for two-dimensional push-broom scanning, thus significantly reducing system cost and stability risks.

[0024] Reference Figure 1 and Figure 2 The spectral detection and imaging module 4 includes a slit imaging spectrometer and a detector. After the detector completes the exposure, it collects the scattered light data of the laser lines on the surface of the sample to be tested. The slit imaging spectrometer generates a Raman image corresponding to the sample to be tested based on the collected scattered light data. Specifically, the scattered light of the sample to be tested is imaged onto the slit plane and then enters the imaging spectrometer through the slit. The polychromatic light is dispersed by the grating and collected by the linear array or area array detector to obtain a two-dimensional data frame sequence of "linear direction space × spectrum". Then, the frame sequence is stacked and reconstructed according to the displacement parameters of the scanning module 2 to obtain a two-dimensional Raman mapping image.

[0025] Reference Figure 1 and Figure 2The light source generation module 1 includes a light source unit 5 for outputting excitation light. In this embodiment, the light source unit 5 uses a laser, and a galvanometer 6 is arranged in the optical path of the excitation light. In this embodiment, the deflection angle of the galvanometer 6 corresponds to the position of the slit at the input end of the spectral detection imaging module 4, that is, the scanning angle of the galvanometer 6 matches the height of the slit of the slit imaging spectrometer. The collimated excitation light emitted from the laser is rapidly deflected by the galvanometer 6 to form a spatially elongated virtual laser line output, thereby forming line illumination and matching the slit direction of the slit imaging spectrometer. This ensures that the light signal passing through the slit corresponds to the one-dimensional spatial Raman scattering information of the line illumination area on the sample to be detected, significantly reducing the imaging time. Utilizing the virtual line scanning with rapid deflection of the galvanometer 6, the length and position of the laser line can be defined by software according to the actual situation, greatly improving the system's flexibility and the adjustment of energy density for small areas.

[0026] Reference Figure 1 and Figure 2 A first 4F relay component for transmitting the laser line beam is provided between the light source generation module 1 and the scanning module 2. The first 4F relay component includes a first lens 7 and a second lens 8 arranged opposite to each other, and the first lens 7 and the second lens 8 constitute a first conjugate imaging unit. A beam splitting module for separating the laser line and scattered light is provided between the first 4F relay component and the scanning module 2. The beam splitting module includes a beam splitter 9, and the actual placement angle of the beam splitter 9 is 45 degrees. The galvanometer 6 swings within a certain angle range, and the angle is related to the slit height. In this embodiment, the galvanometer 6, the first 4F relay component, and the beam splitter 9 form a conjugate. The excitation light in the excitation band retained after the laser line passes through the beam splitter 9 enters the focusing and collecting module 3, and the scattered light retained after the scattered light passes through the beam splitter 9 enters the spectral detection and imaging module 4.

[0027] Reference Figure 1 and Figure 2 In this embodiment, the beam splitter 9 specifically employs a dichroic mirror, meaning that the line beam in the excitation band of the laser line is reflected (or transmitted) into the illumination channel of the subsequent microscope 13; the Rayleigh / Raman scattered light in the scattered light of the sample to be detected is guided in the opposite direction through the dichroic mirror into the collection channel of the spectral detection imaging module 4. The first 4F relay unit transmits the dynamic line illumination formed by the scanning angle change of the galvanometer 6 to the dichroic mirror and the subsequent scanning module 2 with a stable pupil plane / image plane relationship, defining the pupil plane and beam diameter of the system, reducing aberrations or cutoff caused by beam drift in the subsequent scanning module 2, and providing optical conditions for stabilizing the incident angle and spot position at the dichroic mirror, so that the laser line can be accurately and stably focused on the beam splitter 9.

[0028] Reference Figure 1 and Figure 2The scanning module 2 includes a second 4F relay component and a driving unit. The second 4F relay component includes a third lens 10 and a fourth lens 11. The distance between the third lens 10 and the fourth lens 11 satisfies the 4F relay imaging condition or the equivalent relay condition. The third lens 10 and the fourth lens 11 constitute a second conjugate imaging unit. The driving unit drives the third lens 10 and the fourth lens 11 to move equidistantly in opposite directions, thereby controlling the laser line to move in a direction perpendicular to the laser line. In this embodiment, the driving unit can use two control motors arranged opposite to each other. The control motors are high-precision linear motors that can be laterally controlled to move. The third lens 10 and the fourth lens 11 are respectively located at the moving ends of the two control motors. The control motors drive the third lens 10 and the fourth lens 11 to move equidistantly and in opposite directions perpendicular to the optical axis, thereby forming a 4F lens equidistant reverse translation scanning.

[0029] Therefore, when the control system drives the control motor to continuously translate the third lens 10 and the fourth lens 11 in the direction perpendicular to the optical axis, according to the Fourier optical imaging principle, the beam path through the optical center of the third lens 10 and the fourth lens 11 changes, thereby changing the angle at which the beam enters the entrance pupil of the microscope objective. After being focused by the objective lens of the microscope 13, this change manifests as the line spot focused on the surface of the sample moving laterally in the direction perpendicular to the line length, thus achieving translational scanning. Since both the return path of the scattered light and the outward path of the laser line pass through the third lens 10 and the fourth lens 11, and the translation of the third lens 10 and the fourth lens 11 is in an equidistant and opposite manner, the image position of the return light at the slit plane is compensated accordingly. The scattered line signal at different push-scan positions remains at a constant position at the slit of the spectral detection imaging module 4, reducing the vibration and return error introduced by the push-scan of the sample stage 16, and achieving spectral image consistency.

[0030] Reference Figure 1 and Figure 2 A reflector 12 is disposed between the scanning module 2 and the focusing and collecting module 3. The laser line reflected by the reflector 12 is coaxial with the incident optical axis of the focusing and collecting module 3. In this embodiment, the positions of the galvanometer 6, the beam splitter 9, and the reflector 12 are conjugate for imaging, achieving conjugate matching between the surface of the sample to be detected and the slit plane of the spectral detection and imaging module 4, ensuring coaxial optical path, stable imaging, and accurate signal. Apertures can also be placed at the positions of the galvanometer 6, the beam splitter 9, and the reflector 12 according to actual conditions to control the numerical aperture and stray light, thereby improving the uniform transmission of the laser line and the integrity of the scattered light.

[0031] Reference Figure 1 and Figure 2The focusing and collecting module 3 includes a microscope 13. The microscope 13 is used to receive the moving laser line output by the scanning module 2 and focus the received moving laser line onto the surface of the sample to be tested. The laser line reflected by the mirror 12 is coaxial with the incident optical axis of the microscope 13. The microscope 13 is used to focus the laser line onto the surface of the sample to be tested to excite the Raman signal and efficiently collect the Raman scattered light generated by the sample to be tested, ensuring that the scattered light is stably transmitted along the original optical path.

[0032] Reference Figure 1 and Figure 2 A filter 14 is provided between the scanning module 2 and the spectral detection and imaging module 4. The filter 14 is used to filter out stray light from the scattered light that has the same wavelength as the excitation light. In this embodiment, the filter 14 is a high-pass cutoff filter 14. The high-pass cutoff filter 14 is used to filter out stray light from the scattered light that has the same wavelength as the excitation light, retain the effective Raman signal, reduce background noise, and improve the sensitivity and accuracy of spectral detection.

[0033] Reference Figure 1 and Figure 2 A tube lens 15 is positioned between the filter 14 and the spectral detection imaging module 4. The rear focal plane of the microscope objective 13 coincides with the front focal plane of the tube lens 15. The tube lens 15 and the microscope objective 13 form an infinity-corrected imaging system, which precisely converges the parallel Raman scattered light collected by the objective lens onto the slit plane of the spectral detection imaging module 4. Simultaneously, it ensures that the sample surface and the slit plane form a conjugate. Combined with a descan compensation mechanism, it ensures that the scattered light falls at a constant point at the slit, maintaining confocal tomography capability and spectral consistency. In this embodiment, the microscope objective 13 and tube lens 15 can be replaced with long-focal-length camera lenses (such as f100, F#2.8) according to the actual situation of the sample to be tested. This enables rapid line-scan Raman measurement for large fields of view (tens of millimeters), which is particularly suitable for rapid Raman scanning of samples such as wafers that require large-area scanning. This can greatly shorten the detection time for a single sample and improve detection efficiency.

[0034] It should be noted that the embodiments of this application can realize rapid surface scanning detection and imaging of large-area samples. The point light source is transformed into a line excitation source through a one-dimensional galvanometer 6. After laser scanning into a line light source, it is projected onto the sample to be detected. The Raman signal generated by the excitation is then collected by the slit imaging spectrometer through the optical path. The line laser in the sample area is conjugate with the slit imaging spectrometer, and the point excitation is transformed into line excitation, which improves the overall scanning time by at least two orders of magnitude. Unlike the traditional method of moving the sample for detection by a moving electric displacement stage, this application achieves two-dimensional scanning imaging by moving the second 4F relay component in the optical path system in the opposite direction at equal distances. The imaging method, which combines the line scanning of the one-dimensional high-frequency galvanometer 6 and the translational push-scanning of the de-scanning lens, two independent physical mechanisms, can greatly shorten the detection time of a single sample and improve the detection efficiency. At the same time, the entire system is modular, and the operator can use a microscope 13 or a scanning mirror with a larger field of view according to the actual needs of the site. The optical path and various components are modularly integrated, which makes it more flexible to use. Combined with the slit confocal design of the spectral detection imaging module 4, it still has excellent axial tomography capability while maintaining ultra-high speed, which is suitable for in-situ monitoring of cell dynamic processes and rapid chemical reactions. The two 4F relay segments of the first and second 4F relay components help maintain the conjugate relationship between the pupil plane and the image plane, and the scanning-compensation mechanism is clear, making it easy to assemble, calibrate, and reproduce in engineering.

[0035] The implementation principle of this application embodiment is as follows: The laser outputs collimated excitation light, which is rapidly deflected by a one-dimensional galvanometer 6 to form a virtual laser line for line illumination. The first lens 7 and the second lens 8 transmit the laser line to a dichroic mirror, which separates the excitation light from the scattered light. The line beam in the excitation band of the laser line is incident on the third lens 10 and the fourth lens 11. The driving part controls the third lens 10 and the fourth lens 11 to perform equidistant reverse translations perpendicular to the optical axis, changing the incident angle of the beam. After being refracted by the reflector 12, the laser line is focused onto the surface of a stationary sample by the objective lens of the microscope 13, realizing a horizontal two-dimensional scanning of the line spot; the sample The Raman scattered light generated by the stimulation is collected by the objective lens of the microscope 13 and returns along the original optical path. When it passes through the fourth lens 11 and the third lens 10 in sequence, it is simultaneously scanned and compensated to keep the position of the scattered light constant at the slit of the spectrometer. After the scattered light is filtered out by the high-pass filter 14 to remove Rayleigh stray light, it is precisely imaged onto the slit plane of the spectral detection imaging module 4 by the tube lens 15. The polychromatic light is dispersed by the grating and collected by the linear array or area array detector to obtain a two-dimensional data frame sequence of "linear direction space × spectrum". Then, the frame sequence is stacked and reconstructed according to the displacement parameters of the scanning module 2 to obtain a two-dimensional Raman mapping image.

[0036] The sample remains stationary throughout the detection process, preserving its physiological state and reducing liquid surface fluctuations and focal plane drift caused by mechanical vibrations during traditional sample movement detection. This improves imaging quality and facilitates adaptation to samples of different sizes or states. It also eliminates the need for the traditional 6-scan galvanometer design to achieve two-dimensional push-broom scanning, thus significantly reducing system cost and stability risks.

[0037] This specific embodiment is merely an explanation of the present invention and is not intended to limit the invention. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A laser line scanning confocal Raman imaging device, characterized in that: It includes a light source generation module (1), a scanning module (2), a focusing and collection module (3), and a spectral detection and imaging module (4); The light source generation module (1) is used to output laser lines; The scanning module (2) is used to receive the laser line generated by the light source generation module (1) and control the received laser line to move back and forth in a direction perpendicular to the laser line. The focusing and collecting module (3) is used to receive the moving laser line output by the scanning module (2) and focus the received moving laser line onto the surface of the sample to be tested. The spectral detection and imaging module (4) is used to receive the scattered light from the surface of the sample to be tested after passing through the scanning module (2), and generate a Raman image corresponding to the sample to be tested based on the received scattered light.

2. The laser line scanning confocal Raman imaging device according to claim 1, characterized in that: The light source generation module (1) includes a light source unit (5) for outputting excitation light. A galvanometer (6) is provided on the optical path of the excitation light. The excitation light is converted into a laser line output after passing through the galvanometer (6). The deflection angle of the galvanometer (6) corresponds to the position of the input end of the spectral detection imaging module (4).

3. The laser line scanning confocal Raman imaging device according to claim 2, characterized in that: A first 4F relay assembly for transmitting laser line beams is provided between the light source generation module (1) and the scanning module (2). The first 4F relay unit includes a first lens (7) and a second lens (8) arranged opposite to each other. The first lens (7) and the second lens (8) constitute a first conjugate imaging unit.

4. The laser line scanning confocal Raman imaging device according to claim 3, characterized in that: A beam splitting module for separating laser lines and scattered light is provided between the first 4F relay component and the scanning module (2). The beam splitting module includes a beam splitter (9). The beam splitter (9) and the galvanometer (6) are conjugate to each other. The excitation light in the excitation band retained after the laser line passes through the beam splitter (9) enters the focusing and collecting module (3). The scattered light retained after the scattered light passes through the beam splitter (9) enters the spectral detection and imaging module (4).

5. The laser line scanning confocal Raman imaging device according to claim 1, characterized in that: The scanning module (2) includes a second 4F relay component and a driving unit. The second 4F relay component includes a third lens (10) and a fourth lens (11). The third lens (10) and the fourth lens (11) constitute a second conjugate imaging unit. The driving unit drives the third lens (10) and the fourth lens (11) to translate in opposite directions at equal intervals, thereby controlling the laser line to move in a direction perpendicular to the laser line.

6. The laser line scanning confocal Raman imaging device according to claim 1, characterized in that: A reflector (12) is provided between the scanning module (2) and the focusing and collecting module (3), and the laser line reflected by the reflector (12) is coaxial with the incident optical axis of the focusing and collecting module (3).

7. The laser line scanning confocal Raman imaging device according to claim 6, characterized in that: The focusing and collecting module (3) includes a microscope (13), which is used to receive the moving laser line output by the scanning module (2) and focus the received moving laser line onto the surface of the sample to be tested. The laser line reflected by the mirror (12) is coaxial with the incident optical axis of the microscope (13).

8. The laser line scanning confocal Raman imaging device according to claim 7, characterized in that: A filter (14) is provided between the scanning module (2) and the spectral detection imaging module (4). The filter (14) is used to filter out stray light that has the same wavelength as the excitation light in the scattered light.

9. The laser line scanning confocal Raman imaging device according to claim 8, characterized in that: A tube lens (15) is provided between the filter (14) and the spectral detection imaging module (4), and the rear focal plane of the objective lens of the microscope (13) coincides with the front focal plane of the tube lens (15).

10. The laser line scanning confocal Raman imaging device according to claim 1, characterized in that: The spectral detection and imaging module (4) includes a slit imaging spectrometer and a detector. After the detector completes the exposure, it collects the scattered light data of the laser lines on the surface of the sample to be tested. The slit imaging spectrometer generates a Raman image corresponding to the sample to be tested based on the collected scattered light data.

Images